Specialty & Stainless Steels

ATI 9™ plate is a nonmagnetic, high tensile strength steel, which displays high toughness and outstanding wear resistance for an austenitic steel. It is similar to the Hadfield steel family except it contains nominal 4.40% Cr and 3.25% Ni whose presence increase corrosion resistance relative to Hadfield steels. As with the Hadfield steels, ATI 9TM alloy exhibits a high work hardening rate. Applications include winding drums for steel cables, coal chutes, mine cars, coal stripping equipment, earth moving equipment, rail car parts, housings for magnets and transformer wedges.

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 50™ / ATI XM-19™ alloy is a nitrogen-strengthened austenitic stainless steel with corrosion resistance superior to Types 316 and 317 austenitic stainless in combination with significantly higher strength. ATI 50 alloy also has very good mechanical properties at both sub-zero and moderately elevated temperatures. The alloy can be fabricated and welded by the conventional equipment and procedures employed for austenitic stainless steel. It is non-magnetic as annealed and after severe cold work. ATI 50 alloy has an excellent combination of corrosion resistance and strength for application in heat exchanger parts, pumps, spent nuclear fuel containers, flood control barriers, pulp and paper, food processing, petrochemical, fertilizer, structural components, and other similar equipment.

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 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 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 321™ (UNS S32100), ATI 347™ (UNS S34700), and ATI 348™ (UNS S34800) alloys are stabilized stainless steels which offer as their main advantage an excellent resistance to intergranular corrosion following exposure to temperatures in the chromium carbide precipitation range from 800 to 1500°F (427 to 816°C). ATI 321 alloy is stabilized against chromium carbide formation by the addition of titanium. ATI 347 and ATI 348 alloys are stabilized by the addition of columbium and tantalum. ATI 348 alloy has restricted cobalt and tantalum content for nuclear applications. While ATI 321, ATI 347 and ATI 348 alloy continue to be employed for prolonged service in the 800 to 1500°F (427 to 816°C) temperature range, ATI 304L™ alloy has supplanted these stabilized grades for applications involving only welding or short time heating. (For information on ATI 304L alloy, consult the Technical Data Sheet for ATI 304L™ alloy.) ATI 321, ATI 347 and ATI 348 stainless steels are also advantageous for high temperature service because of their good mechanical properties. ATI 321, ATI 347 and ATI 348 stainless steels offer higher creep and stress rupture properties than ATI 304 alloy and, particularly, ATI 304L stainless which might also be considered for exposures where sensitization and intergranular corrosion are concerns. This results in higher elevated temperature allowable stresses for these stabilized alloys for ASME Boiler and Pressure Vessel Code applications. The ATI 321, ATI 347 and ATI 348 alloys have maximum use temperatures of 1500°F (816°C) for code applications as does ATI 304™ stainless, whereas ATI T304L™ stainless is limited to 800°F (426°C). The properties of ATI 348 stainless are similar to the properties of ATI 347 alloy, and according to ASTM A240 their chemical compositions are the same except for tantalum and cobalt contents.

ATI’s ATI 332Mo™ alloy is an austenitic stainless steel intended primarily as an economical material for automotive flexible connectors. It was designed to provide resistance to both aqueous corrosion and elevated temperature degradation while maintaining both weldability and formability. This alloy is currently available primarily as Precision Rolled Strip® product. Customers interested in other product forms (i.e., sheet, plate) should inquire. ATI 332Mo™ alloy is an austenitic stainless steel with relatively high chromium and nickel levels for strength, corrosion and
oxidation resistance. The alloy contains a moderate addition of molybdenum for resistance to aqueous corrosion and manganese
for resistance to oxidation in air containing water vapor. A small amount of niobium (columbium) is added for resistance to
sensitization and resultant susceptibility to intergranular corrosion.

ATI 332 alloy is a nickel and chromium austenitic stainless steel designed to resist oxidation and carburization at elevated temperatures. It is the low-carbon equivalent of the well-known ATI 800™ heat-resisting alloy. The nickel content, 32%, makes the alloy highly resistant both to chloride stress corrosion cracking and to embrittlement from precipitation of “sigma” phase. The general corrosion resistance is excellent. In the solution annealed condition, ATI 332™ has superior creep and stress rupture properties. ATI 332 alloy has been approved as a material of construction under ASME Boiler and Pressure Vessel Code, Section I – Power Boilers, Section III – Nuclear Vessels, Section VIII – Unfired Pressure Vessels.

ATI 334Mo® alloy is a proprietary austenitic Fe-Ni-Cr-Mo stainless steel intended primarily as a high performance and economical material for use in automotive flexible couplings. It is a relatively lean alloy that achieves performance similar to ATI 332Mo™ alloy (UNS S35125) by providing resistance to both aqueous corrosion and elevated temperature degradation while possessing excellent weldability and formability. This alloy is currently available as a Precision Rolled Strip® product. Customers interested in other product forms (sheet, plate, etc.) should inquire. ATI 334Mo® alloy has relatively high chromium content for corrosion and oxidation resistance. The alloy contains molybdenum for resistance to aqueous corrosion and manganese for resistance to oxidation in air containing water vapor. A small amount of titanium is added for resistance to sensitization and resultant susceptibility to intergranular corrosion. ATI 334Mo™ alloy contains significantly less nickel than ATI 332Mo™ alloy, making the alloy less expensive and moderating the volatility in its raw materials surcharge.

ATI 321™ (UNS S32100), ATI 347™ (UNS S34700), and ATI 348™ (UNS S34800) alloys are stabilized stainless steels which offer as their main advantage an excellent resistance to intergranular corrosion following exposure to temperatures in the chromium carbide precipitation range from 800 to 1500°F (427 to 816°C). ATI 321 alloy is stabilized against chromium carbide formation by the addition of titanium. ATI 347 and ATI 348 alloys are stabilized by the addition of columbium and tantalum. ATI 348 alloy has restricted cobalt and tantalum content for nuclear applications. While ATI 321, ATI 347 and ATI 348 alloy continue to be employed for prolonged service in the 800 to 1500°F (427 to 816°C) temperature range, ATI 304L™ alloy has supplanted these stabilized grades for applications involving only welding or short time heating. (For information on ATI 304L alloy, consult the Technical Data Sheet for ATI 304L™ alloy.) ATI 321, ATI 347 and ATI 348 stainless steels are also advantageous for high temperature service because of their good mechanical properties. ATI 321, ATI 347 and ATI 348 stainless steels offer higher creep and stress rupture properties than ATI 304 alloy and, particularly, ATI 304L stainless which might also be considered for exposures where sensitization and intergranular corrosion are concerns. This results in higher elevated temperature allowable stresses for these stabilized alloys for ASME Boiler and Pressure Vessel Code applications. The ATI 321, ATI 347 and ATI 348 alloys have maximum use temperatures of 1500°F (816°C) for code applications as does ATI 304™ stainless, whereas ATI T304L™ stainless is limited to 800°F (426°C). The properties of ATI 348 stainless are similar to the properties of ATI 347 alloy, and according to ASTM A240 their chemical compositions are the same except for tantalum and cobalt contents.

ATI 321™ (UNS S32100), ATI 347™ (UNS S34700), and ATI 348™ (UNS S34800) alloys are stabilized stainless steels which offer as their main advantage an excellent resistance to intergranular corrosion following exposure to temperatures in the chromium carbide precipitation range from 800 to 1500°F (427 to 816°C). ATI 321 alloy is stabilized against chromium carbide formation by the addition of titanium. ATI 347 and ATI 348 alloys are stabilized by the addition of columbium and tantalum. ATI 348 alloy has restricted cobalt and tantalum content for nuclear applications. While ATI 321, ATI 347 and ATI 348 alloy continue to be employed for prolonged service in the 800 to 1500°F (427 to 816°C) temperature range, ATI 304L™ alloy has supplanted these stabilized grades for applications involving only welding or short time heating. (For information on ATI 304L alloy, consult the Technical Data Sheet for ATI 304L™ alloy.) ATI 321, ATI 347 and ATI 348 stainless steels are also advantageous for high temperature service because of their good mechanical properties. ATI 321, ATI 347 and ATI 348 stainless steels offer higher creep and stress rupture properties than ATI 304 alloy and, particularly, ATI 304L stainless which might also be considered for exposures where sensitization and intergranular corrosion are concerns. This results in higher elevated temperature allowable stresses for these stabilized alloys for ASME Boiler and Pressure Vessel Code applications. The ATI 321, ATI 347 and ATI 348 alloys have maximum use temperatures of 1500°F (816°C) for code applications as does ATI 304™ stainless, whereas ATI T304L™ stainless is limited to 800°F (426°C). The properties of ATI 348 stainless are similar to the properties of ATI 347 alloy, and according to ASTM A240 their chemical compositions are the same except for tantalum and cobalt contents.

ATI 610™ and ATI 611™ alloys are low-carbon, silicon-containing, austenitic stainless steels. These alloys are typically used for applications in the chemical industry. The high silicon content provides them with very good resistance to oxidizing environments, such as concentrated nitric acid, over a wide range of temperatures. Because of its higher alloy content, ATI 611™ material will be more resistant to highly concentrated (98.5%) nitric acid than ATI 610™ alloy.