SAE steel grades

SAE International, as a standards organization, maintainsseveral alloy numbering systems, one of which, for steelgrades, is the SAE steel grades system.In the 1930s and 1940s the American Iron and Steel In-stitute (AISI) and SAE were both involved in eorts tostandardize such a numbering system for steels. These ef-forts were similar and overlapped signicantly. For sev-eral decades the systems were united into a joint systemdesignated theAISI/SAE steel grades. In 1995 the AISIturned over future maintenance of the system to SAE be-cause the AISI never wrote any of the specications.[1]

Today steel quotes and certications commonlymake ref-erence to both SAE andAISI, not always with precise dif-ferentiation. For example, in the alloy/grade eld, a certmight say 4140, AISI 4140, or SAE 4140, and inmost light-industrial applications any of the above is ac-cepted as adequate, and considered equivalent, for the jobat hand, as long as the specic specication called out bythe designer (for example, 4140 bar per ASTM-A108"or 4140 bar per AMS 6349") is certied to on the cer-ticate. The alloy number is simply a general classier,whereas it is the specication itself that narrows down thesteel to a very specic standard.The SAE steel grade systems correspondence to otheralloy numbering systems, such as the ASTM-SAEunied numbering system (UNS), can be seen in cross-referencing tables (including the ones given below).The AISI system used a letter prex to denote thesteelmaking process. The prex C denoted open-hearthfurnace, electric arc furnace or basic oxygen furnace,while E denotes electric arc furnace steel.[2][3] A let-ter L within the grade name indicates lead as an addedingredient; for example, 12L14 is a common grade thatis 1214 with lead added for machinability.

1 Carbon and alloy steel

Main articles: Carbon steel and Alloy steel

Carbon steels and alloy steels are designated by a fourdigit number, where the rst digit indicates the mainalloying element(s), the second digit indicates the sec-ondary alloying element(s), and the last two digits indi-cate the amount of carbon, in hundredths of a percent(basis points) by weight. For example, a 1060 steel is aplain-carbon steel containing 0.60 wt% C.[4]

An H sux can be added to any designation to denotehardenability is a major requirement. The chemical re-quirements are loosened but hardness values dened forvarious distances on a Jominy test.[3]

2 Stainless steelMain article: Stainless steel

Type 102austenitic general purpose stainless steelworking for furniture

200 Seriesaustenitic chromium-nickel-manganese alloys

Type 201austenitic that is hardenablethrough cold working

Type 202austenitic general purpose stain-less steel

300 Seriesaustenitic chromium-nickel alloys Type 301highly ductile, for formed prod-ucts. Also hardens rapidly during mechanicalworking. Good weldability. Better wear resis-tance and fatigue strength than 304.

Type 302same corrosion resistance as 304,with slightly higher strength due to additionalcarbon.

Type 303free machining version of 304 viaaddition of sulfur and phosphorus. Also re-ferred to as A1 in accordance with ISO3506.[6]

Type 304the most common grade; the clas-sic 18/8 (18% chromium, 8% nickel) stainlesssteel. Outside of the US it is commonly knownas A2 stainless steel, in accordance with ISO3506 (not to be confused with A2 tool steel).[6]

Type 304Lsame as the 304 grade but lowercarbon content to increase weldability. Isslightly weaker than 304.

Type 304LNsame as 304L, but also nitro-gen is added to obtain a much higher yield andtensile strength than 304L.

Type 308used as the ller metal when weld-ing 304.

1

2 5 REFERENCES

Type 309better temperature resistance than304, also sometimes used as ller metal whenwelding dissimilar steels, along with inconel.

Type 316the second most common grade(after 304); for food and surgical stainless steeluses; alloy addition of molybdenum preventsspecic forms of corrosion. It is also knownas marine grade stainless steel due to its in-creased resistance to chloride corrosion com-pared to type 304. 316 is often used for build-ing nuclear reprocessing plants.

Type 316Lis an extra low carbon grade of316, generally used in stainless steel watchesand marine applications, as well exclusively inthe fabrication of reactor pressure vessels forboiling water reactors, due to its high resis-tance to corrosion. Also referred to as A4in accordance with ISO 3506.[6]

Type 316Tivariant of type 316 that includestitanium for heat resistance. It is used in ex-ible chimney liners.

Type 321similar to 304 but lower risk ofweld decay due to addition of titanium. Seealso 347 with addition of niobium for desensi-tization during welding.

400 Seriesferritic and martensitic chromium al-loys

Type 405ferritic for welding applications Type 408heat-resistant; poor corrosion re-sistance; 11% chromium, 8% nickel.

Type 409cheapest type; used forautomobile exhausts; ferritic (iron/chromiumonly).

Type 410martensitic (high-strengthiron/chromium). Wear-resistant, but lesscorrosion-resistant.

Type 416easy to machine due to additionalsulfur

Type 420Cutlery Grademartensitic; similarto the Brearleys original rustless steel. Excel-lent polishability.

Type 430decorative, e.g., for automotivetrim; ferritic. Good formability, but with re-duced temperature and corrosion resistance.

Type 439ferritic grade, a higher grade ver-sion of 409 used for catalytic converter ex-haust sections. Increased chromium for im-proved high temperature corrosion/oxidationresistance.

Type 440a higher grade of cutlery steel,with more carbon, allowing for much betteredge retention when properly heat-treated. Itcan be hardened to approximately Rockwell

58 hardness, making it one of the hardeststainless steels. Due to its toughness and rel-atively low cost, most display-only and replicaswords or knives are made of 440 stainless.Available in four grades: 440A, 440B, 440C,and the uncommon 440F (free machinable).440A, having the least amount of carbon init, is the most stain-resistant; 440C, having themost, is the strongest and is usually consideredmore desirable in knifemaking than 440A, ex-cept for diving or other salt-water applications.

Type 446For elevated temperature service 500 Seriesheat-resisting chromium alloys 600 Seriesoriginally created for proprietary al-loys, which are no longer given SAE gradenumbers[7]

601 through 604: Martensitic low-alloy steels. 610 through 613: Martensitic secondary hard-ening steels.

614 through 619: Martensitic chromiumsteels.

630 through 635: Semiaustenitic and marten-sitic precipitation hardening stainless steels. Type 630 is most common PH stainless,better known as 17-4; 17% chromium,4% nickel.

650 through 653: Austenitic steels strength-ened by hot/cold work.

660 through 665: Austenitic superalloys; allgrades except alloy 661 are strengthened bysecond-phase precipitation.

3 High-strength low-alloy steelMain article: HSLA steel

4 See also ASTM International Steel grades Unied numbering system

5 References

5.1 Notes[1] Bringas, John E. (2004). Handbook of Comparative

World Steel Standards: Third Edition (3rd ed.). ASTM

5.2 Bibliography 3

International. p. 14. ISBN 0-8031-3362-6. Archivedfrom the original on January 27, 2007.

[2] Jeus, p. 635.

[3] Degarmo, p. 115.

[4] Degarmo, p. 113

[5] Oberg, p. 406.

[6] Stainless Steel Fasteners. Australian Stainless Steel De-velopment Association. Archived from the original on2007-09-29. Retrieved 2007-08-13.

[7] Cobb, Harold (September 2007). The Naming andNumbering of Stainless Steels. Advanced Materials &Processes: 3944.

[8] Oberg, pp. 411-412.

[9] What is Stainless Steel?". Nickel Institute. Retrieved2007-08-13.

[10] section 2, part A:Standard specication for chromiumand chromium-nickel stainless steel plate, sheet, and stripfor pressure vessels and for general applications. ASTMA SA-240/SA-540M. 2007. p. 385.

[11] Precipitation-Hardening Stainless Steel Type 17-4PH(S17400)" (PDF).

5.2 Bibliography Degarmo, E. Paul; Black, J T.; Kohser, Ronald A.(2003). Materials and Processes in Manufacturing(9th ed.). Wiley. ISBN 0-471-65653-4.

Jeus, Larry F. (2002). Welding: Principles and Ap-plications. Cengage Learning. ISBN 1-4018-1046-2.

Oberg, E. et al. (1996). Machinerys Handbook(25th ed.). Industrial Press Inc.

Cobb, Harold (September 2007). The Naming andNumbering of Stainless Steels. AdvancedMaterials& Processes: 3944.

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