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ENGINEERING TRIPOS, PART IIA

MANUFACTURING ENGINEERING TRIPOS, PART IIA

MODULE 3C1: MATERIALS PROCESSING AND DESIGN

MODULE 3P1: MATERIALS INTO PRODUCTS

DATASHEET FOR HEAT TREATMENT OF STEELS

Classification and Uses of Ferrous Alloys

UK Steel Designations

Equivalent Diameters for standard component shapes

CCT Diagrams for selected steels

H.R. Shercliff October 2012

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Classification and Uses of Ferrous Alloys

Class Applications Main reasons for Typical heat y KIC Cost

alloying treatments (MPa) (MPam) (£/kg) (1999)

Low carbon Structural use (ships, Low C for modest, Normalised 250-400 40-80 0.25-0.45 steels buildings, bridges), strength, high toughness (< 0.3% C) automotive sheet, cans and ductility

Medium Shafts, gears, Medium C for good Normalised 300-1750 30-65 0.25-0.45 carbon steels forgings, tools strength, hardenability Quenched/ (0.3-0.7% C) and toughness tempered

High carbon Springs, dies, tools, High C for high Quenched/ 330-1120 25-50 0.25-0.45 steels railway track hardness, but toughness tempered (0.7-1.7% C) low

Cast irons Castings: lathe beds, High C for low Tm Normalised; 65-800 9-55 0.1-0.55 (2-4% C) engine blocks, steam and good castability some quenched/ turbine housings, vices tempered

Low alloy High strength use Alloyed for good Normalised 250-2250 15-210 0.25-0.65 steels (pipes, automotive strength, toughness, Quenched/ (0.2% C, up sheet, performance and hardenability tempered to 5% Ni, Cr, bicycles) Mo, V, Ti, Nb)

High alloy Cutting tools, dies Very high strength Quenched/ 700-2800 15-40 1-10 tool steels (retained at high T) tempered (0.7% C, and hardenability 18% W, 1% V, 4% Cr) High alloy High temperature and Cr for corrosion Normalised 180-2100 12-250 0.9-6 stainless steels chemical plant (pipes, resistance; Ni to stabilise (< 0.1% C, pressure vessels), fcc austenite. Good 18% Cr, cutlery, surgical strength, with high 8% Ni) instruments, toughness cryogenic vessels

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UK Steel designations

There is no internationally agreed system for classifying steels - the current UK system is detailed in British Standard BS970, using 6 digit codes (e.g. 080M40, 304S12). The first 3 numbers relate to the class of steel: 000-199 C steels, C-Mn steels (the figures give the mean Mn content, from 0-1.99%) 200-240 Free machining steels (2nd and 3rd figures indicate sulphur content, from 0-0.4%) 250 Spring steels (Si-Mn steels) 300-499 Stainless, Heat-resisting and Valve steels 500-999 Alloy steels (subdivided by main alloy types, e.g. Ni-Cr, Ni-Cr-Mo etc) The character refers to the supply conditions, or indicates stainless steel: A chemical composition only H hardenability requirements given M mechanical requirements given S stainless steel The last 2 numbers give the mean carbon content, for A, H and M steels (from 0-0.99%). Example: 080M40 = 0.8%Mn, 0.4% carbon steel with specified composition and properties Many product forms are also covered by British Standards, e.g. steel sheet, forgings, reinforcing bar etc. The national steel trade association, UK Steel, maintains a data handbook for all steels available in the UK (over 1000 specifications). This has recently been made available on CD with a full list of suppliers and a search engine.

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Equivalent Diameters for standard component shapes

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Correlation between bar diameter (oil-quenched) and distance along Jominy bar which have equivalent cooling rates

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CCT Diagrams for selected steels

BS 080M40, AISI 1040 (En8)

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BS 220M07, AISI 1213 (En1A)

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BS 503M40 (En12)

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BS 653M31 (En23)

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BS 817M40, AISI 4340 (En24)