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A 262 Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless SteelsA 941 Terminology Relating to Steel, Stainless Steel, Related Alloys and FerroalloysA 1016/A 1016M Specification for General Requirements for Ferritic Alloy Steel, Austenitic Alloy Steel, and Stainless Steel TubesE 112 Test Methods for Determining Average Grain SizeE 527 Practice for Numbering Metals and Alloys (UNS)2.2Other Standard:SAE J1086 Practice for Numbering Metals and Alloys(UNS)4
904L is an austenitic stainless steel. Though notably softer than 316L, its molybdenum addition gives it superior resistance to localized attack (pitting and crevice corrosion) by chlorides and greater resistance reducing acids and in particular its copper addition gives it useful corrosion resistance to all concentrations of sulphuric acid. Its high alloying content also gives it greater resistance to chloride stress corrosion cracking, but it is still susceptible. Its low carbon content makes it resistant to sensitization by welding and which prevents intergranular corrosion
254SMO is a 18% Ni, 20% Cr, 6% Mo super austenitic stainless-steel grade with 0.2% nitrogen additions, particularly designed to be cost effective. The 18% nickel and 0.7% copper additions combined with the chromium and molybdenum additions enhance the performance of the steel in many corrosive solutions encountered for example in chemical and petrochemical processes or chloride containing solutions.The alloy is also seawater resistant and has extensively been used in offshore applications (It is not recommended for use in stagnant seawater applications with temperatures higher than 30°C (86°F).Alloy 254 SMO is a high end, molybdenum and nitrogen alloyed super austenitic stainless steel with low carbon content. It demonstrates outstanding resistance to pitting, crevice corrosion stress cracking, and corrosion fatigue uniform corrosion. Alloy 254 SMO is substantially stronger than the common austenitic grades, with strength nearly twice that of 300 series stainless steel. It is also characterized by high ductility and impact strength. With high levels of chromium, molybdenum, and nitrogen, Alloy 254 SMO is frequently used in high chloride environments, such as brackish water, seawater, pulp mill bleach plants, and other chloride process streams. In some applications it has even been found to be a more cost effective substitute for high nickel and titanium alloys.
253 MA is a lean austenitic heat resistant alloy with high strength and outstanding oxidation resistance.253 MA maintains its heat resistant properties by advanced control of micro alloy additions. The use of rare earth metals in combination with silicon gives superior oxidation resistance up to 2000°F. Nitrogen, carbon and a dispersion of rare earth and alkali metal oxides combine to provide creep rupture strength comparable to the nickel base alloys. A wide variety of components requiring high strength at elevated temperatures such as heat exchangers, kilns, stack dampers and oven components are common applications for 253 MA.253 MA Stainless steel is readily fabricated by standard commercial procedures.In comparison to carbon steel, stainless steels are tougher and tend to work harden rapidly. However, with positive feeds and slow speeds combined with abundant cutting fluid this alloys tendency to work harden may be minimized.Solution Treatment (Annealing) - Heat to 1050-1150°C and cool rapidly. It is recommended that the material be solution treated after 10-20% cold work to achieve maximum creep strength in service.This grade cannot be hardened by thermal treatment.
SAE 310S stainless steel is the low carbon version of 310 and is suggested for applications where sensitization, and subsequent corrosion by high temperature gases or condensates during shutdown may pose a problem.SAE 310 stainless steel is a highly alloyed austenitic stainless steel used for high temperature application. The high chromium and nickel content give the steel excellent oxidation resistance as well as high strength at high temperature. This grade is also very ductile and has good weldability enabling its widespread usage in many applications.310/310S find wide application in all high-temperature environments where scaling and corrosion resistance, as well as high temperature strength and good creep resistance are required.
310moln stainless steel grade is a fully austenitic stainless steel that does not have intermetallic phases such as intergranular carbide precipitations. For applications in urea plants 310MoLN steel grade has a specififically designed optimized chemical composition. To stabilize and strengthen the austenitic phase the nitrogen in the chemical composition helps. 310 MoLN, material gives excellent corrosion-resistance in urea carbamate environments such as high-pressure strippers. Among wrought austenitic stainless steels it has a fairly high base cost. And it has a fairly high embodied energy and a fairly low ductility.
Alloy 317L (UNS S31703) is a low carbon corrosion resistant austenitic chromium-nickel-molybdenum stainless steel. The high levels of these elements assure the alloy has superior chloride pitting and general corrosion resistance to the conventional 304/304L and 316/316L grades. The alloy provides improved resistance relative to 316L in strongly corrosive environments containing sulfurous media, chlorides, and other halides.The low carbon content of Alloy 317L enables it to be welded without intergranular corrosion resulting from chromium carbide precipitation enabling it to be used in the as-welded condition. With the addition of nitrogen as a strengthening agent, the alloy can be dual certified as Alloy 317 (UNS S31700).Alloy 317L is non-magnetic in the annealed condition. It cannot be hardened by heat treatment; however the material will harden due to cold working. Alloy 317L can be easily welded and processed by standard shop fabrication practices.
Alloys 309 and Alloys 309S are austenitic chromium-nickel stainless steels that are often used for higher temperature applications. Due to their high chromium and nickel content, Alloys 309 and 309S are highly corrosion resistant, have outstanding resistance to oxidation, and excellent heat resistance while providing good strength at room and elevated temperatures. The only significant difference between 309 and 309S is the carbon content. Alloy 309S has a much less carbon composition which minimizes carbide precipitation and improves weldability.Alloy 309 (UNS S30900) is an austenitic stainless steel developed for use in high temperature corrosion resistance applications. The alloy resists oxidation up to 1900°F (1038°C) under non-cyclic conditions. Frequent thermal cycling reduces oxidation resistance to approximately 1850°F (1010°C).Because of its high chromium and low nickel content, Alloy 309 can be utilized in sulfur containing atmospheres up to 1832°F (1000°C). The alloy is not recommended for use in highly carburizing atmospheres since it exhibits only moderate resistance to carbon absorption. Alloy 309 can be utilized in slightly oxidizing, nitriding, cementing and thermal cycling applications, albeit, the maximum service temperature must be reduced.
347 Stainless Steel347 stainless steel is an austenitic grade that contains chromium, nickel, and columbium stabilized by titanium. This type of stainless steel offers excellent intergranular corrosion resistance after welding or stress relieving. It can operate at high temperatures (up to 1500F) without suffering from carbide precipitation. This type of steel has good strength retention in both high and low-temperature environments, as well as good oxidation resistance.347H Stainless SteelThe “H” in 347H stands for “high carbon” content. This variety of stainless steel has higher amounts of carbon than standard 347 stainless steel, with increased tensile strength and creep resistance at elevated temperatures. Due to its higher carbon content, this type of stainless steel provides better stress rupture properties than the standard version. It also offers excellent resistance to oxidation in intermittent service up to 1600F and continuous service up to 1700 degrees F.
Excellent in a range of atmospheric environments and many corrosive media - generally more resistant than 304. Subject to pitting and crevice corrosion in warm chloride environments, and to stress corrosion cracking above about 60°C. Considered resistant to potable water with up to about 1000mg/L chlorides at ambient temperatures, reducing to about 500mg/L at 60°C.316 is usually regarded as the standard “marine grade stainless steel”, but it is not resistant to warm sea water. In many marine environments 316 does exhibit surface corrosion, usually visible as brown staining. This is particularly associated with crevices and rough surface finish.
Stainless steel grade 314 can be heat treated by annealing the material at 1038-1149°C (1900-2100°F), and then quenching in water or rapidly air cooling. Grade 314 steel can be hardened only through cold working. To perform machinability of grade 314, coolant and high-speed turning tools are recommended.After slowly heating the material to 871°C (1600°F), it should be thoroughly soaked, and then followed by quickly heating to 1093 -1232°C (2000-2250°F) , to perform forging, flanging, or working.
Grades 321 and 347 are the basic austenitic 18/8 steel (Grade 304) stabilized by Titanium (321) or Niobium (347) additions. These grades are used because they are not sensitive to intergranular corrosion after heating within the carbide precipitation range of 425-850°C. Grade 321 is the grade of choice for applications in the temperature range of up to about 900°C, combining high strength, resistance to scaling and phase stability with resistance to subsequent aqueous corrosion.Grade 321H is a modification of 321 with a higher carbon content, to provide improved high temperature strength.A limitation with 321 is that titanium does not transfer well across a high temperature arc, so is not recommended as a welding consumable. In this case grade 347 is preferred - the niobium performs the same carbide stabilization task but can be transferred across a welding arc. Grade 347 is therefore the standard consumable for welding 321. Grade 347 is only occasionally used as parent plate material.Like other austenitic grades, 321 and 347 have excellent forming and welding characteristics, are readily brake or roll formed and have outstanding welding characteristics. Post-weld annealing is not required. They also have excellent toughness, even down to cryogenic temperatures. Grade 321 does not polish well, so is not recommended for decorative applications.
304, 304H and 304L all possess the same nominal chromium and nickel content and thus possess the same corrosion resistance, ease of fabrication and weldability. The difference between 304, 304H and 304L is the carbon content which is >0.03, >0.05 and <0.03 respectively.The carbon content of 304H (UNS S30409) is restricted to 0.04–0.10%, which provides optimal high temperature strength.The carbon content of 304L (UNS 30403) is restricted to a maximum of 0.03%, which prevents sensitization during welding. Sensitization is the formation of chromium carbides along grain boundaries when a stainless steel is exposed to temperatures in the approximate range of 900–1,500 °F (480–820 °C). The subsequent formation of chromium carbide results in reduced corrosion resistance along the grain boundary leaving the stainless steel susceptible to unanticipated corrosion in an environment where 304 would be expected to be corrosion resistant. This grain boundary corrosive attack is known as intergranular corrosion.
304L has good resistance in:· Organic acids at moderate temperatures· Salt solutions, e.g. sulphates, sulphides and sulphites· Caustic solutions at moderate temperatures· Oxidizing acids like nitric acid· Stress corrosion cracking· Austenitic steels are susceptible to stress corrosion cracking. This may occur at temperatures above about 60°C (140°F), if the steel is subjected to tensile stresses and at the same time comes into contact with certain solutions, particularly those containing chlorides. In applications demanding high resistance to stress corrosion cracking, we recommend the duplex steel S32205
TP 316Ti (1.4571, UNS S31635) is generally considered but is not resistant to hot sea water. Hot chloride environments may cause pitting and crevice corrosion. TP 316Ti (1.4571, UNS S31635) HEAT RESISTANCE 316 exhibits good resistance to oxidation in continuous service to a temperature of 870 ° C and a temperature of 925 ° C. However, if corrosion resistance to water is required, continuous use at 425-860 ° C is not recommended. In this case, 316L is recommended due to resistance to carbide precipitation. When high temperatures are required at temperatures above 500 ° C, class 316H is recommended.TP316Ti /1.4571/UNSS31635, is a titanium-stabilized, molybdenum-alloyed austenitic chromium-nickel steel with improved machinability. has similar characteristics to AISI 316L, but the TP 316Ti has better mechanical properties and strength at high temperatures. TP 316Ti (1.4571, UNS S31635) due to the addition of titanium shows higher corrosion resistance.
316LN is a nitrogen alloyed austenitic stainless steel with Mo addition. Its low carbon content avoids intergranular corrosion, even after welding. 316LN exhibits an austenitic microstructure, free of deleterious carbide precipitations. The grade contains residual ferrite after solution annealing (1050 - 1150°C /1922 - 2102°F) and water quenching. Higher Molybdenum content improves uniform and localized corrosion resistance. Nitrogen addition improves the structure stability and increases the yield strength compared to 316L. Main properties of 316LN are: high ductility, good weldability. Typical applications are food and beverage processing industry, chemical industry and chemical tankers. A ferrite free, non magnetic version of the grade has been developed for nuclear physics applications at 4°K