Specialty & Stainless Steels
AL 29-4C® alloy is a superferritic stainless steel developed by ATI Allegheny Ludlum for extreme resistance to chloride ion pitting, crevice corrosion and stress corrosion cracking (SCC), as well as general corrosion in oxidizing and moderately reducing environments. The alloy was developed in the early 1980s for welded condenser tubing to be used in seawater and brackish water by the power generation industry. It is this extreme resistance to pitting and crevice corrosion that has led to the installation of over 2000 miles of AL 29-4C tubing in power plant condensers and heat exchangers. The superferritic stainless steel AL 29-4C alloy shows excellent resistance to chloride ion pitting, crevice corrosion and stress corrosion cracking (SCC). This resistance makes it an ideal choice for battling the corrosive condensate of partially and fully condensing natural gas and propane burning appliances (except for high sulfur fuel sources). Its low alloy content, compared to other high-performance alloys, makes it an economical choice as well.
AL-6XN PLUS® alloy is an enhanced version of the standard AL-6XN ® alloy. Both satisfy the composition requirements of UNS N08367, but the AL-6XN PLUS® alloy contains a greater concentration of the alloying elements (Cr, Mo, and N) which promote corrosion resistance. Resistance to Localized Chloride Attack The relative pitting resistance of a stainless steel can be correlated to alloy composition using the Pitting Resistance Equivalent (PREN). (PREN) = %Cr + 3.3 %Mo + 30 %N Typically the AL-6XN alloy composition would have a PREN of about 47. By increasing the Cr, Mo, and N content of the alloy to near the maximum levels per-mitted by specification, the PREN can be increased.
ATI Allegheny Ludlum AL-6XN® alloy (UNS N08367) is the most corrosion resistant iron-base austenitic stainless alloy produced by Allegheny Technologies at this time. It is a low carbon, high purity, nitrogen-bearing “super-austenitic” stainless alloy. The AL-6XN alloy was designed to be a seawater resistant material and has since been demonstrated to be resistant to a broad range of very corrosive environments. It is readily available from stock in a wide range of product forms, including thick plate that is suitable for multi-pass welding during field fabrication. The high strength and corrosion resistance of the AL-6XN alloy make it a better choice than the conventional duplex stainless steels and a cost effective alter native to more expensive nickel-base alloys in applications where excellent formability, weldability, strength and corrosion resistance are essential. It is also a cost-effective alternative to less expensive alloys, such as Type 316, that do not have the strength or corrosion resistance required to minimize life cycle costs in certain applications. The high nickel and molybdenum contents provide improved resistance to chloride stress-corrosion cracking. Copper (Cu) has been intentionally kept to a residual level for improved performance in seawater40. The high alloy composition of the AL-6XN alloy resists crevice corrosion and pitting in oxidizing chloride solutions to a degree previously achieved only by nickel-base alloys and titanium. AL-6XN alloy is well suited for such applications as: • Chemical process tanks and pipelines • Process systems for offshore oil and gas platforms • Condensers, heat exchangers and piping containing seawater or crude oil • Filter washers, vats and press rolls in pulp bleaching plants • Power plant flue gas scrubber environments • Tall oil distillation columns and packing • Desalination equipment and pumps • Service water piping systems for nuclear power plants • Transformer cases exposed to marine environments • Pharmaceutical equipment (for product purity) • Food processing equipment AL-6XN alloy offers the following distinct advantages: Corrosion Resistance The intrinsic corrosion resistance of the AL-6XN alloy in both acidic and alkaline environments provides protection against metallic contamination of process streams and prevents rapid degradation of components made of the alloy. Cost Effectiveness The AL-6XN alloy is often a viable alternative to nonmetallic materials that can provide high levels of corrosion resistance but are costly to install and maintain. AL-6XN alloy is significantly less costly than most nickel-base alloys. Workability The toughness and ductility of the AL-6XN alloy provide for relative ease of fabrication in the shop or in the field. The formability and weldability of the AL-6XN alloy are much better than that of high alloy ferritic or duplex stainless steels that demonstrate comparable resistance to corrosion. As-Welded Properties The low carbon and high nitrogen contents in AL-6XN alloy minimize the precipitation of carbides and secondary phases that can occur during welding. Therefore as-welded assemblies can be placed in service, provided that a suitable over-matched filler metal is used and the assembly has been properly cleaned. AL-6XN alloy can be welded in the field using procedures similar to those used with other austenitic stainless steels. Wide Range of Product Forms AL-6XN alloy is readily available in a wide range of product forms,such as tube, pipe, sheet, plate, bar, billet and forgings. Components such as pumps, valves, fittings, fasteners and castings are also available.
AM 350® Precipitation Hardening Alloy (S35000) is a chromium-nickel-molybdenum precipitation hardening stainless steel used for applications requiring high strength and excellent weldability along with corrosion resistance. The S35000 alloy has been available for many years and has found application in a variety of aerospace applications and especially in edge welded bellows applications that require high strength. Non-aerospace applications include use in precision seals, in couplings for semiconductor processing equipment, and in high vacuum systems. AM 350® precipitation hardening alloy may be formed in a soft austenitic condition and hardened to a high strength level by low temperature heat treatments. The low temperature allows minimum distortion compared to conventional quench and temper hardening processes.
ATI 13-8 Supertough® Alloy (UNS S13800) is a modification of the standard ATI 13-8 alloy, and has superior fracture toughness and Charpy impact energies, even at cryogenic temperatures. These improvements have been achieved with tighter chemistry controls and thermo-mechanical processing practices. This improved alloy is a martensitic precipitation-hardening stainless steel that has excellent strength, high hardness, and good corrosion resistance. Transverse fracture toughness properties of 120 ksi/in. minimum in the H1000 condition is achieved by tight chemical composition control, low carbon content, and double vacuum melting. The alloy is produced by vacuum induction melting (VIM), followed by vacuum arc remelting (VAR).This melt practice ensures excellent macro and micro-cleanliness, and tight compositional control. The strengthening mechanism (precipitation hardening in a martensitic matrix) makes it possible to achieve uniform strengthening in heavy sections. Strength and ductility levels can be tailored to the application by varying the aging temperature. ATI 13-8 Supertough® Alloy is available as ingot, billet, block, round bar, rolled shapes and rectangles, rolled and drawn rod, and wire. Typical applications are large airframe structural components.
ATI 13-8™ alloy (UNS S13800) is a martensitic precipitation-hardening stainless steel that has excellent strength, high hardness, superior toughness, and good corrosion resistance. Good transverse toughness properties are achieved by tight chemical composition control, low carbon content, and vacuum melting. The alloy is produced by vacuum induction melting (VIM) followed by electro-slag remelting (ESR). This melt practice promotes excellent macro- and microcleanliness, and tight compositional control. The strengthening mechanism (precipitation hardening in a martensitic matrix) makes it possible to achieve uniform strengthening in heavy sections. Strength and ductility levels can be tailored to the application by varying the aging temperature. Typical applications are large airframe structural components, injection molding equipment and slide gates to control water flow. The S13800 alloy is martensitic in structure in the solution annealed condition and is further strengthened by a relatively low temperature heat treatment, which precipitates a strengthening phase in the alloy. Like the S17400 alloy, the S13800 alloy requires only a simple heat treatment, a one step process conducted at a temperature in the range 950°F (510°C) to 1150°F (620°C) depending on the combination of strength and toughness desired. A wide range of properties can be produced by this one step heat treatment. Heat treatment at about 950°F (510°C) produces the highest strength.
ATI 15-5™ precipitation hardening stainless steel (S15500) is a variant of the older ATI 17-4™ (S17400) chromium-nickel-copper precipitation hardening stainless steel. Both alloys exhibit high strength and moderate corrosion resistance. High strength is maintained to approximately 600°F (316°C). This alloy is designated Grade or Type XM-12 in several specifications. The ATI 15-5™ alloy was designed to have greater toughness than S17400, especially in the through-thickness (short transverse) direction. This improved toughness is achieved by reduced delta ferrite content and control of inclusion size and shape. The composition and processing of ATI 15-5™ alloy is carefully controlled to minimize its content of delta ferrite, which is present in the S17400 material. Inclusion control is done by consumable electrode remelting using the electro-slag remelting (ESR) process. A wide range of properties can be produced by this one-step heat treatment. Heat treatment in the 900°F (482°C) range produces the highest strength, although it is slightly less than those of semi-austenitic alloys like S17700 or S15700. The latter precipitation hardening stainless steels generally require more steps to complete heat treatment. The ATI 15-5™ alloy is generally better suited for plate applications than are the semiaustenitic alloys.
ATI 15-7™ Precipitation Hardening Alloy (S15700, AISI Type 632) is a chromium-nickel-molybdenum-aluminum semi-austenitic precipitation hardening stainless steel used for applications requiring high strength and a moderate level of corrosion resistance. The ATI 15-7 precipitation hardening alloy may be formed in a soft austenitic condition and hardened to a high strength level by low temperature heat treatments. The low temperature heat treatment required for developing high strength allows minimum distortion compared to conventional quench and temper hardening processes. In addition to material produced by the standard refining procedures, material which has been vacuum arc or electroslag re-melted is available for further increase in resistance to fatigue, for those applications subject to cyclic stresses.
ATI 17-4™ precipitation hardening stainless steel (S17400), Type 630, is a chromium-nickel-copper precipitation hardening stainless steel used for applications requiring high strength and a moderate level of corrosion resistance. High strength is maintained to approximately 600°F (316°C). This alloy is designated Grade or Type 630 in several specifications. The S17400 alloy is martensitic in structure in the annealed condition and is further strengthened by a low temperature treatment which precipitates a copper containing phase in the alloy. In comparison to many alloys in the precipitation hardening family, the S17400 alloy requires a simple heat treatment; a one step process conducted at a temperature in the range 900°F (482°C) to 1150°F (621°C) depending on the combination of strength and toughness desired. A wide range of properties can be produced by this one step heat treatment. Heat treatment in the 900°F (482°C) range produces highest strength, although slightly less than that of alloys like S17700 or S15700. The latter precipitation hardening stainless steels generally require more steps to complete heat treatment.
ATI 17-7™ Precipitation Hardening Alloy (S17700) is a chromium-nickel-aluminum precipitation hardening stainless steel used for applications requiring high strength and a moderate level of corrosion resistance. The S17700 alloy has been available for many years and has found application in aerospace and many spring type applications requiring high strength. ATI 17-7 precipitation hardening alloy may be formed in a soft austenitic condition and hardened to a high strength level by low temperature heat treatments. The low temperature allows minimum distortion compared to conventional quench and temper hardening processes. In addition to material produced by the standard refining procedures, material which has been vacuum arc or electroslag remelted is available for further increase in resistance to fatigue, for those applications subject to cyclic stresses.
ATI's AL 18CrCb™ stainless steel is a heat-resisting ferritic grade providing good oxidation and corrosion resistance for applications like automotive exhaust system components. Ferritic alloys are not inherently strong at elevated temperatures, but columbium additions coupled with appropriate solution annealing markedly improve long-time creep-rupture strength properties. ATI 18CrCb™ alloy is dual stabilized with columbium and titanium to provide good weld ductility and resistance to intergranular corrosion in the weld heat affected zone. ATI 18CrCb™ alloy has been developed for the severe tube bending and forming operations typical in automotive exhaust manifold fabrication. Tight control on carbon and nitrogen levels plus improved mill processing result in enhanced formability in terms of higher tube bending speeds and lower breakage or scrap rate.
ATI 2003® (UNS S32003) lean duplex stainless steel (LDSS) is a molybdenum-enhance, proprietary* duplex stainless steel alloy. Cr, Ni, Mo, and N are controlled to give a phase balance similar to that of ATI 2205™ duplex stainless steel, while reducing costs. The alloy fills a gap between Type 316 and the ATI 2205™ alloy in terms of corrosion resistance, while processing the higher mechanical properties characteristic of a duplex stainless steel. ATI 2003® LDSS can be an economic alternative to Type 316L stainless steel, providing enhanced strength and corrosion resistance.
Types ATI 201 HP™ and ATI 201L HP™ are comparable to chromium-nickel types 301, 304, 304L in many respects, but they can provide some advantages over the 18-8 grades in certain applications. Lower cost manganese and nitrogen additions are partial substitutes for nickel in types ATI 201 HP™ and ATI 201L HP™, making them more economical alloys. Because they possess a very desirable combination of economy plus good mechanical properties and corrosion resistance, they have been used in a wide variety of consumer and transportation applications, as illustrated in the following table.
Type 201 austenitic stainless steel has been available for over 50 years and has gained acceptance in a number of applications. Compared to the 300 series alloys, the lower-nickel 200 series alloys offer an economical way to obtain superior mechanical properties. ATI has created a special composition of type 201 specifically for sub-zero temperature service as welded tanks and vessels. This alloy, designated ATI 201LN, also identified by the Unified Numbering System Designation S20153, has replaced familiar 300 series stainlesses such as type 301 or type 304 in many applications based upon technical equivalency and economic considerations. Consequently, ATI 201LN alloy is often a good choice for use at temperatures down to -320°F (-196°F). ATI 201LN alloy is also suited for many ambient temperature structural applications, such as railroad freight cars, truck trailers, coal handling and other bulk transport equipment where there is a need for a good combination of corrosion resistance, strength, toughness and ease of fabrication
ATI 20-25+Nb™ alloy is an austenitic stainless steel intended primarily for elevated temperature service. This alloy fills a performance gap between conventional heat-resistant stainless steels and nickel-base superalloys, providing high performance with an economical composition. The chromium, nickel, and manganese levels result in superior resistance to high temperature oxidation in air and steam-bearing atmospheres. Additions of nitrogen and molybdenum provide solidsolution-strengthening, resulting in superior room and elevated temperature strength. Control of niobium (columbium) and carbon additions, along with advanced thermo-mechanical processing (TMP) results in the formation of a very fine dispersion of carbides and carbonitride particles with particle size ranging down to the nanoscale. This results in excellent resistance to elevated temperature creep and stress-rupture, while exhibiting austenite phase stability superior to many heat and corrosionresistant alloys, which allows for retention of mechanical properties after elevated temperature exposures.
ATI 20™ alloy (UNS N08020) has been available for many years and has found applications in many environments, such as in chlorides and in sulfuric and sulfurous acids. Although ATI 20 alloy was developed for improved resistance to corrosion by sulfuric acid, it finds wide use throughout the chemical industry. It is used extensively in the manufacture of solvents, explosives, plastics, synthetic fibers, organic chemicals, pharmaceuticals, and food-processing equipment. Containment of acid mixtures and chloride stress corrosion resistance are examples of successful applications for ATI 20 alloy. Where purity must be maintained in the processing of products such as foodstuffs or dyes, ATI 20 alloy is used to protect end products from the danger of contamination by metallic ions through corrosion. ATI 20 alloy has been applied economically in many areas where other materials may provide the necessary corrosion resistance, but are either higher in initial cost or more expensive to install and maintain. Important advantages of ATI 20 alloy are its excellent mechanical properties and comparative ease of fabrication. The presence of columbium in the alloy minimizes the precipitation of carbides in heat-affected zones during welding so that assemblies can usually be placed in service in the as-welded condition. Welds with matching filler metal will be slightly less corrosion resistant than the base alloy.
ATI 2102® (UNS S82011) alloy is a proprietary* lean duplex stainless steel (LDSS) in which the composition is controlled to create a material with the structure and properties of more highly alloyed duplex grades at a lower and more stable cost. ATI 2102® LDSS has better corrosion resistance than Type 304L in most applications and performs as well as Type 316L in many environments, while at the same time having the higher strength characteristic of duplex stainless steels.
ATI 219™ alloy, also known by the more familiar 21-6-9 or XM-11 designations* is a nitrogen-bearing austenitic stainless steel that has substantially higher strength than standard austenitic stainless steels. The alloy remains non-magnetic even after substantial cold forming and exposure to subzero temperatures. Many of the applications for the ATI 219™ alloy make use of the combination of high strength and nonmagnetic properties of the alloy, even at very low temperatures. The ATI 219™ alloy has good general corrosion resistance comparable to that of the familiar Type 304 stainless steel. The ATI 219™ alloy is produced to a lower carbon level and is more resistant to intergranular corrosion in the welded condition than higher carbon content alloys. Weldability of the ATI 219™ alloy is very good. The alloy may be welded by all the standard methods used for stainless steels. Welding procedures should be designed to retain the nitrogen level of the alloy within the weld-fusion zone.
ATI 2205™alloy (UNS S31803 and/or S32205) is a nitrogen-enhanced duplex stainless steel alloy. The nitrogen serves to significantly improve the corrosion resistance of the alloy; especially in the welded condition. The ATI 2205™ alloy is the most widely used of the duplex stainless steels and is often used in the form of welded pipe or tubular components. The alloy has also been applied as a formed and welded sheet product in environments where resistance to general corrosion and chloride stress corrosion cracking is important.
ATI 2304 alloy is a lean duplex stainless steel (LDSS) that contains 23% Cr, 4% Ni, and very little Mo. The corrosion resistance of ATI 2304 LDSS is similar to that of Type 316L, but its strength is much higher. The strength advantage that duplex alloys have compared to austenitic grades often allows for significant weight savings to be realized in applications where the design thickness is related to yield or tensile strength. If an alloy with similar corrosion resistance and even higher strength than ATI 2304 LDSS is desired, ATI 2102® and ATI 2003® lean duplex alloys should be considered. ATI 2304 LDSS has a duplex microstructure that consists of a nearly equal mixture of ferrite and austenite. The microstructure and composition of ATI 2304 alloy provide stresscorrosion cracking resistance that is superior to that of Types 304 or 316.
ATI 255™ alloy is a 25% chromium ferritic-austenitic duplex stainless steel designed to provide a superior combination of high strength and excellent corrosion resistance for a wide variety of applications. The alloy possesses a microstructure which is a balanced mixture of austenite and ferrite. The combination of these phases develops the unique combination of strength and chloride stress-corrosion cracking resistance of this alloy. The alloy finds application in marine corrosion areas, equipment for phosphoric acid and fertilizer industry, pollution control equipment, the pulp and paper industry and the petrochemical industry.
ATI 301™ (S30100) is an austenitic stainless steel with a nominal composition of 17 percent chromium and 7 percent nickel. The high strengths of this grade of steel in the six available conditions or tempers, its resistance to atmosphere corrosion and its bright, attractive surface make it an excellent choice for decorative structural applications. Automobile molding and trim, wheel covers, conveyor belts, kitchen equipment, roof drainage systems, hose clamps, springs, truck and trailer bodies, railway and subway cars are some of the major applications for this versatile grade. By varying the chemical composition within the limits set by the ASTM specifications and by temper rolling, a broad range of magnetic and mechanical properties can be obtained for a variety of applications.
ATI 302™ (S30200), ATI 304™ (S30400), ATI 304L™ (S30403), and ATI 305™ (S30500) stainless steels are variations of the 18 percent chromium – 8 percent nickel austenitic alloy, the most familiar and most frequently used alloy in the stainless steel family. These alloys may be considered for a wide variety of applications where one or more of the following properties are important: 1. Resistance to corrosion 2. Prevention of product contamination 3. Resistance to oxidation 4. Ease of fabrication 5. Excellent formability 6. Beauty of appearance 7. Ease of cleaning 8. High strength with low weight 9. Good strength and toughness at cryogenic temperatures 10. Ready availability of a wide range of product forms. Each alloy represents an excellent combination of corrosion resistance and fabricability. This combination of properties is the reason for the extensive use of these alloys which represent nearly one half of the total U.S. stainless steel production. ATI 304 alloy represents the largest volume followed by ATI 304L alloy. ATI 302 and ATI 305 alloys are used in smaller quantities.
ATI 303 alloy is a free-machining stainless steel specifically designed to exhibit improved machinability. It is a non-magnetic austenitic stainless steel which is not hardenable by heat treatment. It is the free-machining modification of the basic 18% chromium – 8% nickel stainless steel. Sulfur is added to produce the free-machining characteristics. The good mechanical and corrosion-resistant properties of the lower-sulfur grade are retained to the extent possible
ATI 304DA tri-ply composite consists of a dual stabilized, low carbon steel center “sandwiched” between Type 304 stainless steel. The top and bottom stainless steel surfaces (cladding), each representing approximately 20% of the product thickness, are bonded to the carbon steel core during hot rolling, thereby providing a metallurgical bond which remains sound during subsequent cold forming operations. This composite product provides the excellent corrosion resistance of ATI 304 stainless steel along with the good heat transfer characteristics of carbon steel. ATI developed this proprietary composite which is covered by U.S. Patent Nos. 5,370,946 and 5,529,644. This patented material has excellent cold forming properties. Carbon from the core does not migrate into the stainless steel cladding during hot processing, and thereby enhances formability by eliminating the possibility of “hook cracks” caused by carbide precipitation at the stain-less/carbon steel interface.
ATI 302™ (S30200), ATI 304™ (S30400), ATI 304L™ (S30403), and ATI 305™ (S30500) stainless steels are variations of the 18 percent chromium – 8 percent nickel austenitic alloy, the most familiar and most frequently used alloy in the stainless steel family. These alloys may be considered for a wide variety of applications where one or more of the following properties are important: 1. Resistance to corrosion 2. Prevention of product contamination 3. Resistance to oxidation 4. Ease of fabrication 5. Excellent formability 6. Beauty of appearance 7. Ease of cleaning 8. High strength with low weight 9. Good strength and toughness at cryogenic temperatures 10. Ready availability of a wide range of product forms. Past users of ATI 302 stainless are generally now using ATI 304 alloy since AOD technology has made lower carbon levels more easily attainable and economical. There are instances, such as in temper rolled products, when ATI 302 alloy is preferred over ATI 304 since the higher carbon permits meeting of yield and tensile strength requirements while maintaining a higher level of ductility (elongation) versus that of the lower carbon T304. ATI 304L alloy is used for welded products which might be exposed to conditions which could cause intergranular corrosion in service.
ATI 302™ (S30200), ATI 304™ (S30400), ATI 304L™ (S30403), and ATI 305™ (S30500) stainless steels are variations of the 18 percent chromium – 8 percent nickel austenitic alloy, the most familiar and most frequently used alloy in the stainless steel family. These alloys may be considered for a wide variety of applications where one or more of the following properties are important: 1. Resistance to corrosion 2. Prevention of product contamination 3. Resistance to oxidation 4. Ease of fabrication 5. Excellent formability 6. Beauty of appearance 7. Ease of cleaning 8. High strength with low weight 9. Good strength and toughness at cryogenic temperatures 10. Ready availability of a wide range of product forms. Past users of ATI 302 stainless are generally now using ATI 304 alloy since AOD technology has made lower carbon levels more easily attainable and economical. There are instances, such as in temper rolled products, when ATI 302 alloy is preferred over ATI 304 since the higher carbon permits meeting of yield and tensile strength requirements while maintaining a higher level of ductility (elongation) versus that of the lower carbon T304. ATI 304L alloy is used for welded products which might be exposed to conditions which could cause intergranular corrosion in service.
ATI 302™ (S30200), ATI 304™ (S30400), ATI 304L™ (S30403), and ATI 305™ (S30500) stainless steels are variations of the 18 percent chromium – 8 percent nickel austenitic alloy, the most familiar and most frequently used alloy in the stainless steel family. These alloys may be considered for a wide variety of applications where one or more of the following properties are important: 1. Resistance to corrosion 2. Prevention of product contamination 3. Resistance to oxidation 4. Ease of fabrication 5. Excellent formability 6. Beauty of appearance 7. Ease of cleaning 8. High strength with low weight 9. Good strength and toughness at cryogenic temperatures 10. Ready availability of a wide range of product forms. Past users of ATI 302 stainless are generally now using ATI 304 alloy since AOD technology has made lower carbon levels more easily attainable and economical. There are instances, such as in temper rolled products, when ATI 302 alloy is preferred over ATI 304 since the higher carbon permits meeting of yield and tensile strength requirements while maintaining a higher level of ductility (elongation) versus that of the lower carbon T304. ATI 304L alloy is used for welded products which might be exposed to conditions which could cause intergranular corrosion in service.
ATI 309™ and ATI 310™ austenitic stainless steels are typically used for elevated temperature applications. Their high chromium and nickel contents provide comparable corrosion resistance, superior resistance to oxidation and the retention of a larger fraction of room temperature strength than the common austenitic alloys like Type 304.
ATI 309™ and ATI 310™ austenitic stainless steels are typically used for elevated temperature applications. Their high chromium and nickel contents provide comparable corrosion resistance, superior resistance to oxidation and the retention of a larger fraction of room temperature strength than the common austenitic alloys like Type 304.
ATI 309™ and ATI 310™ austenitic stainless steels are typically used for elevated temperature applications. Their high chromium and nickel contents provide comparable corrosion resistance, superior resistance to oxidation and the retention of a larger fraction of room temperature strength than the common austenitic alloys like Type 304.
ATI 309™ and ATI 310™ austenitic stainless steels are typically used for elevated temperature applications. Their high chromium and nickel contents provide comparable corrosion resistance, superior resistance to oxidation and the retention of a larger fraction of room temperature strength than the common austenitic alloys like Type 304.
ATI 316LN (UNS S31653) stainless is a low-carbon, nitrogen-enhanced version of Type 316 molybdenum-bearing austenitic stainless steel. It is also known as DIN/EN designation No. 1.4406. The Type 316 alloys are more resistant to general corrosion and pitting/crevice corrosion than the conventional chromium-nickel austenitic stainless steels such as Type 304. They also offer higher creep, stress-rupture and tensile strength at elevated temperature. ATI 316 stainless steel can be susceptible to sensitization – the formation of grain boundary chromium carbides at temperatures between approximately 900 and 1500 °F (425 to 815 °C) – which can result in rapid corrosion. Reduced carbon ATI 316L alloy is resistant to sensitization; however, extended exposures in this temperature range will eventually result in sensitization of even the low carbon grade. The nitrogen in ATI 316LN alloy adds additional resistance to sensitization in some circumstances. The nitrogen content of ATI 316LN stainless steel also provides some solid solution hardening, raising its minimum specified yield strength compared to ATI 316L stainless steel. Like ATI 316 and ATI 316L alloys, the ATI 316LN alloy also offers excellent resistance to general corrosion and pitting/crevice corrosion.
ATI 316™ (UNS S31600), ATI 316L™ (S31603), ATI 317™ (S31700) and ATI 317L™ (S31703) alloys are molybdenum-bearing austenitic stainless steels which are more resistant to general corrosion and pitting/crevice corrosion than the conventional chromium-nickel austenitic stainless steels such as ATI 304. These alloys also offer higher creep, stress-to-rupture and tensile strength at elevated temperature. ATI 317™ and ATI 317L™ alloys containing 3 to 4% molybdenum are preferred to ATI 316™ or ATI 316L™ alloys which contain 2 to 3% molybdenum in applications requiring enhanced pitting and general corrosion resistance. ATI 316LM™ alloy (W.Nr. 1.4404), a 2.5% minimum Mo version of ATI 316L™ stainless steel, is available only by special order. Austenitic stainless steels with higher molybdenum or molybdenum plus nitrogen content which provide even greater resistance to pitting, crevice corrosion and general corrosion are also available in flat-rolled products. These include ATI 316LN™ (UNS S31653), ATI 317LX™ (UNS S31725, 4-5% Mo), ATI 317LXN™ (S31726, 4-5% Mo and 0.1-0.2% N), and AL-6XN® (N08367, 6-7% Mo and 0.18-0.25% N) alloys. Properties of these alloys are described in separate ATI technical data publications available.
ATI 316Ti stainless is a titanium-stabilized version of Type 316 molybdenum-bearing austenitic stainless steel. It is also known as DIN/EN designation No. 1.4571. The Type 316 alloys offer excellent resistance to general corrosion and pitting/crevice corrosion, which is better than the conventional chromium-nickel austenitic stainless steels such as Type 304. They also offer higher creep, stress-rupture and tensile strength at elevated temperature. Type 316 stainless steel can be susceptible to sensitization – the formation of grain boundary chromium carbides at temperatures between approximately 900 and 1500 °F (425 to 815 °C) – which can result in rapid corrosion. Reduced carbon Type 316L is resistant to sensitization; however, extended exposures in this temperature range will eventually result in sensitization of even the low carbon grade. Resistance to sensitization is achieved in Type 316Ti with titanium additions to stabilize the structure against chromium carbide precipitation, which is the source of sensitization. This stabilization is achieved by an intermediate-temperature heat treatment, during which the titanium reacts with carbon to form titanium carbides. This significantly reduces susceptibility to sensitization in service by limiting the formation of chromium carbides. Thus, the alloy can be used for extended periods at elevated temperatures without compromising its corrosion resistance.
ATI 316™ (UNS S31600), ATI 316L™ (S31603), ATI 317™ (S31700) and ATI 317L™ (S31703) alloys are molybdenum-bearing austenitic stainless steels which are more resistant to general corrosion and pitting/crevice corrosion than the conventional chromium-nickel austenitic stainless steels such as ATI 304. These alloys also offer higher creep, stress-to-rupture and tensile strength at elevated temperature. ATI 317™ and ATI 317L™ alloys containing 3 to 4% molybdenum are preferred to ATI 316™ or ATI 316L™ alloys which contain 2 to 3% molybdenum in applications requiring enhanced pitting and general corrosion resistance. ATI 316LM™ alloy (W.Nr. 1.4404), a 2.5% minimum Mo version of ATI 316L™ stainless steel, is available only by special order. Austenitic stainless steels with higher molybdenum or molybdenum plus nitrogen content which provide even greater resistance to pitting, crevice corrosion and general corrosion are also available in flat-rolled products. These include ATI 316LN™ (UNS S31653), ATI 317LX™ (UNS S31725, 4-5% Mo), ATI 317LXN™ (S31726, 4-5% Mo and 0.1-0.2% N), and AL-6XN® (N08367, 6-7% Mo and 0.18-0.25% N) alloys. Properties of these alloys are described in separate ATI technical data publications available.
ATI 317LMN™ alloy, ATI 317LM™ alloy and ATI 317L alloy are molybdenum-bearing austenitic stainless steels with greatly increased resistance to chemical attack as compared to the conventional chromium-nickel austenitic stainless steels such as ATI 304. In addition, ATI 317LMN, ATI 317LM and ATI 317L alloys also offer higher creep, stress-to-rupture, and tensile strengths at elevated temperatures than conventional stainless steels. These alloys represent significant improvements over conventional ATI 317 stainless. All are low carbon or “L” grades to provide resistance to sensitization during welding and other thermal processes. The “M” and “N” designations indicate that the compositions contain increased levels of molybdenum and nitrogen respectively. The combination of molybdenum and nitrogen is particularly effective in enhancing resistance to pitting and crevice corrosion, especially in process streams containing acids, chlorides and sulfur compounds at elevated temperatures. Nitrogen also serves to increase the strength of these alloys. All three alloys are intended for severe service conditions such as flue gas desulfurization (FGD) systems. ATI 317LMN, ATI 317LM and ATI 317L stainless steels are available in the form of plate, sheet and strip.
ATI 316™ (UNS S31600), ATI 316L™ (S31603), ATI 317™ (S31700) and ATI 317L™ (S31703) alloys are molybdenum-bearing austenitic stainless steels which are more resistant to general corrosion and pitting/crevice corrosion than the conventional chromium-nickel austenitic stainless steels such as ATI 304. These alloys also offer higher creep, stress-to-rupture and tensile strength at elevated temperature. ATI 317™ and ATI 317L™ alloys containing 3 to 4% molybdenum are preferred to ATI 316™ or ATI 316L™ alloys which contain 2 to 3% molybdenum in applications requiring enhanced pitting and general corrosion resistance. ATI 316LM™ alloy (W.Nr. 1.4404), a 2.5% minimum Mo version of ATI 316L™ stainless steel, is available only by special order. Austenitic stainless steels with higher molybdenum or molybdenum plus nitrogen content which provide even greater resistance to pitting, crevice corrosion and general corrosion are also available in flat-rolled products. These include ATI 316LN™ (UNS S31653), ATI 317LX™ (UNS S31725, 4-5% Mo), ATI 317LXN™ (S31726, 4-5% Mo and 0.1-0.2% N), and AL-6XN® (N08367, 6-7% Mo and 0.18-0.25% N) alloys. Properties of these alloys are described in separate ATI technical data publications available
ATI 316™ (UNS S31600), ATI 316L™ (S31603), ATI 317™ (S31700) and ATI 317L™ (S31703) alloys are molybdenum-bearing austenitic stainless steels which are more resistant to general corrosion and pitting/crevice corrosion than the conventional chromium-nickel austenitic stainless steels such as ATI 304. These alloys also offer higher creep, stress-to-rupture and tensile strength at elevated temperature. ATI 317™ and ATI 317L™ alloys containing 3 to 4% molybdenum are preferred to ATI 316™ or ATI 316L™ alloys which contain 2 to 3% molybdenum in applications requiring enhanced pitting and general corrosion resistance. ATI 316LM™ alloy (W.Nr. 1.4404), a 2.5% minimum Mo version of ATI 316L™ stainless steel, is available only by special order. Austenitic stainless steels with higher molybdenum or molybdenum plus nitrogen content which provide even greater resistance to pitting, crevice corrosion and general corrosion are also available in flat-rolled products. These include ATI 316LN™ (UNS S31653), ATI 317LX™ (UNS S31725, 4-5% Mo), ATI 317LXN™ (S31726, 4-5% Mo and 0.1-0.2% N), and AL-6XN® (N08367, 6-7% Mo and 0.18-0.25% N) alloys. Properties of these alloys are described in separate ATI technical data publications available
ATI 31™ alloy is a superaustenitic stainless steel designed to have a high level of corrosion resistance, equalling that of some Ni-based alloys. The alloy contains high levels of chromium and nickel with additions of molybdenum and copper, which provide excellent corrosion resistance in many environments. The carbon content is kept low to promote good properties in the welded condition. ATI 31™ alloy is suitable for use in a variety of service environments, such as in chemical and petrochemical plants, oil & gas production, and in flue gas desulfurization units in power plants and aboard marine vessels.
Nickel Superalloys
ATI 10242™ alloy is an age-hardenable nickel-molybdenum-chromium alloy designed for use in moderately high temperature applications up to ~1400°F that require good elevated temperature strength, low thermal expansion, and good oxidation resistance. The strength stems from a long range ordering reaction during aging. This ordering reaction not only provides the alloy’s strength, but also imparts excellent thermal stability
The ATI 188™ alloy is a cobalt-based, solid-solution strengthened alloy that has excellent high temperature strength, excellent oxidation resistance up to 2000°F (1093°C), and good sulfidation resistance. This alloy also has good forming and welding characteristics, which make it useful in fabricating gas turbine components such as combustion cans and transition ducts. The alloy has a face-centered cubic structure. High tungsten content provides solid solution strengthening, while the precipitation of M6C and M23C6 carbides further increases the strength. High chromium content and the addition of lanthanum promote oxidation resistance through formation of a tenacious oxide.
ATI 200 alloy (UNS Designation N02200) and ATI 201 alloy (UNS Designation N02201) are wrought commercially pure nickel. The alloys differ only in the maximum carbon level allowed by specification, 0.15 percent maximum for ATI 200 alloy and 0.02 percent maximum for ATI 201 alloy. Either alloy provides highly ductile mechanical properties across a wide temperature range. Either alloy provides corrosion resistance in neutral to moderately reducing environments. In the annealed condition, either alloy possesses the approximate strength of mild steel. As-rolled material is sometimes furnished to provide higher strength levels.
ATI 200 alloy (UNS Designation N02200) and ATI 201 alloy (UNS Designation N02201) are wrought commercially pure nickel. The alloys differ only in the maximum carbon level allowed by specification, 0.15 percent maximum for ATI 200 alloy and 0.02 percent maximum for ATI 201 alloy. Either alloy provides highly ductile mechanical properties across a wide temperature range. Either alloy provides corrosion resistance in neutral to moderately reducing environments. In the annealed condition, either alloy possesses the approximate strength of mild steel. As-rolled material is sometimes furnished to provide higher strength levels.
ATI 22™ alloy is a Ni-Cr-Mo alloy that provides outstanding resistance to pitting, crevice corrosion, intergranular attack, and stress corrosion cracking. The combination of Cr, Ni, Mo, and W provides excellent resistance to a broad range of both oxidizing and reducing environments. ATI’s plate mill has been producing this alloy since 1987. The alloy is used in a wide range of applications including fluegas desulfurization systems, bleaching processes in pulp-and-paper plants, waste incinerators, sour gas service, chemical processing plants, pharmaceutical plants, and radioactive waste storage. The ATI 22™ alloy possesses high strength, good ductility, excellent welding and forming characteristics. The UNS N06022 alloy has been incorporated in ASTM and ASME specifications and is available in a wide range of product forms such as plate, sheet, strip, tube, pipe, bar, billet, and forgings.
ATI 276™ alloy (UNS Designation N10276) is a nickel-molybdenum-chromium-iron-tungsten alloy which is among the most corrosion resistant of alloys currently available. The ATI 276 alloy is widely used in the severest environments encountered in the chemical and petrochemical processing, flue gas desulfurization, pulp and paper and other specialized fields. Design of the alloy allows a high level of corrosion resistance to be retained even in the welded condition. ATI 276™ alloy also has good high temperature strength and moderate oxidation resistance although the alloy will eventually form embrittling high temperature precipitates. ATI 276™ alloy has been available for several years and has been used in ASME Boiler and Pressure Vessel related construction. The alloy is covered in ASME Section VIII Divisions 1 and 2, in numerous product forms.
Titanium
ATI 15Mo™ Alloys (UNS R58150) is a beta titanium alloy capable of a wide variety of properties depending on the metallurgical condition. The achievable properties include low modulus of elasticity, high strength, excellent fatigue strength, good ductility/formability, exceptional corrosion resistance, and well-documented biocompatibility1 . ATI 15Mo™ Alloys are manufactured as bar, rod, and wire product forms primarily for orthopedic, trauma, spinal, dental, orthodontic, and cardiovascular applications. Other product forms can be made available by request.
ATI Ti-5Al-2Sn-2Zr-4Cr-4Mo Alloy (UNS R58650), also known as Ti-17, was developed by General Electric as a high strength, deep hardening alloy for fan and compressor discs and for other large components. It has been classified as a “beta-rich” alpha-beta alloy. The alloy may be processed in the beta region, or in the alpha plus beta region. This Ti-17 alloy has higher tensile and creep strengths than Ti-6Al-4V. While its hardenability is similar to other beta alloys, ATI 17™ Alloy has a lower density and a higher modulus than most other beta titanium alloys. ATI 17™ Alloy is normally produced by plasma cold hearth melting (PAM), and is followed by vacuum arc remelting (VAR). The alloy is normally supplied as forging billet, but it may also be supplied as forged or rolled bar.
ATI offers corrosion-resistant titanium produced as plate, sheet, and strip products. Titanium’s low density and high strength-to-weight ratio make it the material of choice for many corrosive chemical environments, including oxidizing chloride solutions (including seawater) and chlorine-based bleaches.