Steel Grades Selection and Equivalents

When selecting the material for a project, I find myself spending considerable time to research materials. The local steel supplier makes this easier since he only stocks commonly used materials. But I still like to understand which material is best for which application.

Carbon Steel

    EN3A – 070M20 /C22/ 1018 -  Mild Steel - Red
    EN8 – 080M40/  C45/ 1038 - Medium Carbon - Yellow
    EN9 – 070M55 / C55 /1060 - High Carbon - Green

Alloy Steel

    EN19 – 709M40/ 42CrMo4/4240 - Black
    EN24 – 817M40/ 40CrMo8/ 4340 -
    EN26 – 826M40/ 40NiMoCr10-5/ 1.6745 -
    EN30B – 835M30/ 36NiCrMo16/ 1.6773 -
    EN36B – 655M13/ 15NiCr13/ 3316/ 1.5752 -

Specification: EN8 – 080M40

Colour Code: Yellow

Availability: Bright Cold Drawn Round Bar: 6mm diameter to 75mm diameter Bright Peeled Round Bar: 16mm diameter to 160mm diameter Bright Cold Drawn Hexagon Bar: 8mm A/F to 55mm A/F Black Round Bar: 16mm diameter  to 400mm diameter (as rolled and as forged) Black Square Bar: 25mm A/F to 105mm A/F

Characteristics: Commonly known in South Africa as “Axle Steel” or “40 Ton Steel” Known as “40 Carbon” in steelmakers parlance Good enough welding properties as the carbon content is relatively low. When welding, pre heating the steel to approximately 100⁰Celcius is recommended as well as the use of low hydrogen electrodes. Tig or Mig welding is recommended Machinability is good but allow 6% on outside diameter for removal of surface defects EN8 is preferred to EN3A to machine as the material “chips” and makes machining easier and a better machined finish can be achieved Not recommended for high tensile applications for example. 50-60 ton tensile Heat treatment only to limited ruling sections (see schedule below)

Applications: All uses where a higher tensile in Carbon Steel is required including the more popular uses for spindles, shafts, axles, cylinders, bolts and nuts Armature, dynamo and motor shafts Heat treated bolts Connecting  rods Driving rings Flanges Railway Couplings Brackets, bushes and studs Pulleys (both light and heavy duty) Housing and parts not subject to high stresses or severe wear Uses where the tensile rating of 510MPa minimum is a requirement Bolt Specification: 8.8 (in condition “Q”) Bolt Specification: 9.8 (in condition “Q”) Bolt Specification: 10.9 (in condition “R”)

Comparable Specifications: Din C45 SAE 1038/44 Deutsche W/No 1.1186/1.0511 Euro Norm EN10083-1 (1991) 970 Part1; C40E BS970 Part 1 1983, 080M40 BS970 of 1955 EN8 American AISI 1042

Chemical Composition (%): Carbon (C) 0.36 (Min) – 0.44 (Max) Silicon (Si) 0.10 (Min) – 0.40 (Max) Manganese (Mn) 0.60 (Min) – 1.00 Max) Sulphur (S) Nil (Min) – 0.050 (Max) Phosphorus (P) Nil (Min) – 0.050 Max)

Mechanical Properties: Normalised Condition “Q” Condition “R” Ruling Section 254mm 65mm 20mm Tensile Strength 510/540 MPa 620/770 MPa 690/850 MPa Yield Stress (Min) 245 MPa 385 MPa 465 MPa Elongation 17% 16% 16% ISO V Impact 20 Joule 33 Joule 33 Joule Hardness 152/207 Brinell 179/229 Brinell 201/255 Brinell

Heat Treatment: Normalise at a temperature of 830⁰/860⁰Celsius Harden in oil from a temperature between 830⁰/860⁰ Celsius Temper at a suitable temperature, 550⁰Celsius for condition “R” and 660 – Celsius for condition “Q”

Specification: EN9 – 070M55

Colour Code: Green
Availability: Black Round Bar: 20mm diameter to 400mm diameter
Characteristics: This material is the highest carbon steel available from special steel merchants in South Africa for general use Heat treatment only to limited ruling sections It lends itself to induction hardening and shorterising (flame hardening) Care should be taken that hardened  components are properly tempered after quenching in water as the material can become “glass hard” and brittle Should small components require a “glass hard” surface, temper by boiling in brine for 30 minutes minimum. Brine of 9% salt in water is required Machinability is good  but allow 6% on outside diameter  for removal of surface defects Material can be welded on but is not recommended Ideal for 45 ton tensile applications Not recommended for carburising
Typical Applications: This steel is also used to make machine collets. After quenching, ensure that the components are tempered three times (spring tempering) All applications where wear resistance is required Can be used in the “as forged” condition for bending brake tools Commonly used for press eccentric shafts and bending brake tools Also used for shafts, spindles and general machine components including sprockets, cylinders, cams, crankshafts, small gears, machine tools, keys, grinding balls for ball mills, pulleys, ball race rings, bolts and nuts No bolt specifications are applied to this specification
Comparable Specifications: Din C55 SAE 1060 Deutsche W/No  1.0535 Euro Norm EN 10083-1 (1991) 970 Part 1; C55E. BS970 Part 1 1983, 070M55 BS970 of 1955 EN9
Chemical Composition (%): Carbon (C) 0.50 (Min)- 0.60 (Max) Silicon (Si)                         0.10 (Min) – 0.40 (Max) Manganese (Mn) 0.50 (Min) – 0.90 (Max) Sulphur (S)                      Nil (Min) – 0.05 (Max) Phosphorus (P)              Nil (Min) – 0.05 (Max)
Mechanical Properties: Normalised Condition “R” Condition “S” Condition “T” Ruling Section 254mm 100mm 65mm 20mm Tensile Strength 600/700 MPa 690/850 MPa 770/930 MPa 850/1000 MPa Yield Stress (Min) 310 MPa 415 MPa 480 MPa 570 MPa Elongation 13% 14% 14% 12% ISO V Impact Void Void Void Void Hardness 201/255 Brinell 201/255 Brinell 223/277 Brinell 248/302 Brinell
Heat Treatment: Normalise at a temperature of  810C/840CCelsius Harden in oil from a temperature between  810C/840CCelsius Temper at a suitable temperature, 550CCelsius for condition “T”, 610CCelsius for condition “S” and 660C Celsius for condition “R”  Specification: EN19 – 709M40 Colour Code: Black Availability: Black Round Bar in “as rolled “ and hardened and tempered to condition “T” Black rolled and forged surface: 16mm diameter to 350mm diameter Bright Peeled Round Bar, “as rolled” and condition “T”: 16mm diameter to 160mm diameter Characteristics: This material distorts when machining shafts or long spindles, especially once hardened and tempered In practice, the work pieces should be rough machined to plus tolerance and left in the open on the floor for 36 hours after which the material would have “aged” and stress relieved itself and thereby minimising distortion on the finishing of the product Machinability is good but allow 6% on outside diameter for removal of surface defects This material can be welded but welding should only be attempted by using the appropriate methods and materials as advised by welding expertise Ideal for 60 ton tensile applications up to 100mm max Sizes above limited ruling section will be heat treated to hardness only, with no guarantee on mechanical properties Applications: Utilised when higher than carbon steel mechanical properties are required Commonly used for axles, drive shafts, crankshaft connecting rods, high tensile bolts, studs, propeller shaft joints, rifle barrels, and induction hardened pins Bolt specification: 9.8 (in condition “T”) Bolt specification: 10.9 (in condition “U”) Comparable Specifications: Din 42CrMo4 SAE 4240 Deutsche W/No  1.7225 Euro Norm EN 10083-1 (1991) 970 Part 1; 42CrMo4 BS970 Part 1 1983, 709M40 BS970 of 1955 EN19 Chemical Composition (%): Carbon (C) 0.36 (Min) – 0.44 (Max) Silicon (Si) 0.10 (Min)- 0.40 (Max) Manganese (Mn) 0.70 (Min) -  1.00 (Max) Chromium (Cr) 0.90 (Min) – 1.20 (Max) Sulphur (S) nil (Min) – 0.04 (Max) Phosphorus (P) nil (Min)- 0.035 (Max) Molybdenum (Mo) 0.25 (Min) – 0.35 (Max) Working and Heat Treatment: Forging: Forge within the temperature range of 1250C/900C Celsius Anneal: Anneal at a temperature of 850C Celsius and cool steadily Normalising: not applicable Hardening: oil quench from a temperature of  850C/880C Celsius Mechanical Properties: Annealed R S T U V W Y Ruling Section (mm) 150 150 100 65 65 30 30 25 Tensile Strength (MPa) 680/720 690/850 770/930 850/1000 930/1080 1000/1160 1080/1240 1280 Yield Stress (MPa) 440/480 480 570 665 740 835 895 1050 Elongation (% Min) 22 15 15 13 12 12 10 10 ISO V Impact (Joule) 30 30 30 30 25 25 22 7 Hardness (Brinell) 190/210 201/255 223/277 248/302 269/321 293/341 311/375 363/415 Proof Stress (0.2%) if required (MPa, Min) 495 550 630 710 770 850 985 Specification: EN24 – 817M40 Colour Code: Blue and Black Availability: Black Round Bar in “as rolled” or hardened and tempered to condition “T” Black Round Bar: 20mm diameter to 350mm diameter (as rolled / as forged) Characteristics: This is more versatile specification than 709M40 as the limiting ruling sections for heat treatment are amplified because of the addition of Nickel Welding should only be attempted by using the appropriate methods and materials as advised by welding expertise Machinability is good and has little distortion in machining  Allow 6% on the outside diameter for removal of surface defects during machining Ideal for 60 ton tensile applications up to 250mm diameter max This material is often used in the annealed, as rolled or as forged condition for machining.  Subsequent heat treatment is used to achieve a higher tensile i.e. condition “T”, “U”,” V”,     ”W”, “X”, “Y” and “Z” This material can be certified as a safety specification in lifting equipment when such equipment is subject to impacts and requires a high tensile property, such as shaft sinking equipment in the mining industry Applications: This material is used where high tensile strengths and good impact values are required Some of the more popular uses include differential shafts, pinion sleeves, eccentric crusher shafts, eccentric high pressure shafts, high duty connection rods, power transmission slide gears and slide cams, mandrels for tube mills, heavy axles and high tensile gears, bolts and nuts Bolt Specification: 10.9 (in condition “U”) Bolt Specification: 12.9 (in condition “V”) Comparable Specifications: Din 40CrM0 8 – 4 SAE 4340 Deutsche W/No 1.6562 Euro Norm EN10083-1 (1991) 970 Part 1; 34CrN1Mo6 BS970 Part 1 1983, 817M40 BS970 of 1955 EN24 American AISI 4340 Chemical Composition (%): Carbon (C) 0.36 (Min) – 0.44 (Max)                                  Silicon (Si) 0.10 (Min) – 0.35 (Max) Manganese (Mn) 0.45 (Min) – 0.70 (Max) Sulphur (S) Nil (Min) – 0.04 (Max) Phosphorus (P) Nil (Min) – 0.040(Max) Nickel (Ni) 1.30 (Min) – 1.70 (Max) Chromium (Cr) 1.00 (Min) – 1.40 (Max) Molybdenum (Mo) 0.20 (Min) – 0.35 (Max) Working and Heat Treatment: Forging within the temperature range 1100⁰/850⁰ Celsius Anneal at a temperature of 760⁰ Celsius, soaking for four hours after reaching temperature Normalising is not applicable Hardening by oil quench at a temperature of 820⁰/850 Celsius after soaking through Mechanical Properties: Annealed S T U V W X Y Z Ruling Section (mm) 250 250 250 100 65 30 30 30 30 Tensile Strength (MPa) 620 680/770 850/1000 930/1080 1000/1160 1080/1240 1235 (Min) 1540 (Min) 1540 (Min) Yield Stress (MPa) 410 480 635 740 835 925 1005 1130 1130 Elongation (% Min) 16 16 12 12 12 11 10 5 5 ISO V Impact (Joule) 30 32 40.7 47.5 47.5 40.7 34 30 10 Hardness (Brinell) 180/220 223/277 248/302 269/321 293/341 311/375 341/388 363/415 444 (Min) Proof Stress (0.2%) if required (MPa, Min) 550 630 710 770 850 910 990 1235 Note: Interestingly, the impact values do not alter between condition “U” and condition “V”. Specification: EN26 – 826M40 Colour Code:  Black/Orange Availability: Availability is extremely limited in the South African market Prospective users of this specification are advised to check availability before any commitments Characteristics: A 6% allowance should always be made for removal of surface defects during machining Welding is not recommended on this specification Machinability good Ideal for heat treated condition (U/60/70 ton tensile) or V (65/75 ton tensile) As with EN24, this material is ordered in the annealed, as rolled or as forged condition for machining.  Subsequent heat treatment is used to achieve higher tensile strength                                        i.e. Condition T, U, V, W, X, Y and Z Some applications require this material to be heat treated to BS2772 Part 2 Grade 826M31 to qualify as a safety standard Applications: Similar applications and uses as EN24 817M40 but for higher tensile requirements This specification is prescribed by the mining industry in South Africa for lifting equipment e.g. stress parts in winches and cranes and general lifting tackle such as eyebolts, shackles and hooks. However, the material has to be manufactured to 826M31 procedures to qualify as a safety standard When this material is specified for safety reasons it is used in spline shafts, gear shafts, winder equipment parts, heavy duty mining head gears and in other safety critical mining applications It is further used as high impact eccentric shafts, crusher shafts, turnbuckles, brake pins, tie rods and main line railway armature shafts Comparable Specifications: Din 40NiMoCr 10-5 Deutsche W/No 1.6745 BS970 Part 1 1983, 826M40 BS970 of 1955 EN26 Chemical Composition (%): Carbon (C) 0.36 (Min)- 0.44 (Max)                                   Silicon (Si)                               0.10 (Min) – 0.35 (Max) Manganese (Mn) 0.45 (Min) – 0.70 (Max) Sulphur (S) Nil (Min) – 0.040 (Max) Phosphorus (P)                     Nil (Min) – 0.040 (Max) Nickel (Ni)                              2.30 (Min) – 2.80 (Max) Chromium (Cr)                      0.50 (Min) – 0.80 (Max) Molybdenum (Mo) 0.45 (Min) – 0.65 (Max) Working and Heat Treatment: Forging is done within the temperature range 1100⁰ / 850⁰ Celsius Annealing at a temperature of 670⁰ Celsius, soaking for 4 hours after reaching temperature Normalising, not applicable Hardening, oil quench at a temperature of 820⁰/850⁰ Celsius, after soaking through Mechanical Properties: U V W X Y Z Ruling Section (mm) 150 150 150 100 100 100 Tensile Strength (MPa) 930/1080 1000/1160 1080/1240 1235 (Min) 1540 (Min) 1540 (Min) Yield Stress (MPa) 740 835 925 1005 1130 1130 Elongation (% Min) 17 14 13 14 14 10 ISO V Impact (Joule) 47.5 47.5 40.7 34 34 14 Hardness (Brinell) 269/321 293/341 311/375 341/388 363/415 444 (Min) Proof Stress (0.2%) if required (Mpa, Min) 710 770 850 910 990 1235 Specification: EN30B – 835M30 (Annealed) Colour Code: Orange Availability: Black Round Bars supplied only in the annealed condition Availability is extremely restricted and prospective users of this specification are advised to check availability before committing to using it Characteristics: This is a very expensive steel specification not just because of the high alloying elements but also the refining methods utilised to keep the hydrogen (H) content of the steel to less than two parts per million, (H = ≤ 2PPM). It is more costly than other B.S. 970 specifications This is 1500 MPa minimum tensile steel , air hardening in sections up to 65mm diameter Specially recommended for intricately shaped parts where an air hardening steel is preferred This material can be case hardened , can be carburised and induction hardened or shorterised (flame hardened) Applications: 835M30 is a versatile specification. The applications of this material are numerous and includes the following In Engineering: ultra high tensile applications, shafts, gears, bolts, spline shafts, crusher shafts, eccentric shafts, hard wearing bushes and high impact pistons In mining: rock drill, knock off bits, mill hammers, cyclone plates, high tensile mechanical and thermal shock applications In Tooling: plastic extrusion dies, die bolster rings and punches Comparable Specifications: Din 36NiCrMo16 Deutsche W/No 1.6773 Euro Norm EN 10220-3 (1999) 36NiCrMo16 Chemical Composition (%): Carbon (C) 0.26% (Min) 0.34% (Max) Silicon (Si) 0.10% (Min) 0.35% (Max) Manganese (Mn) 0.40% (Min) 0.60% (Max) Sulphur (S) Nil 0.25% (Max) Phosphorus (P) Nil 0.25% (Max) Nickel (Ni) 3.90% (Min) 4.30% (Max) Chronium (Cr) 1.10% (Min) 1.40% (Max) Molybdenum (Mo) 0.20% (Min) 0.40% (Max) Mechanical Properties: Tensile Strength 1500 MPa (Min) Yield Stress 1300 MPa (Min) Elongation 10% (Min) ISO V Impact 20 Joule (Min) Hardness 444 Brinell (Min) Working and Heat Treatment: Forging: Do not charge into a hot or preheated furnace. Heat from cold to forging temperature 950⁰/1000⁰Celsius. Do not exceed 1100⁰ Celsius. Forge carefully and do not work on the steel  below 850⁰/900⁰ Celsius as the material is then hardening and this condition excessive stresses will build up in the workpiece. Cool the forging slowly and out of draughts or bury in lime or ashes. Annealing: Heat carefully to 810⁰ Celsius and allow to cool in the furnace or still air. Re-heat the steel slowly in the furnace to 630⁰/640⁰ Celsius and soak for about four hours after wich it may be cooled in still air (sub critically annealed). All parts for machining should be annealed. Normalising: Not applicable Hardening:  To harden in air or oil, heat the parts gradually and uniformly to a temperature of 810⁰/830⁰ Celsius. When air hardening, place the parts out of draughts to avoid unequal hardening and consequent stresses. For up to 65mm diameter the properties are obtainable through air hardening. For larger sections, oil hardening should be performed. Tempering: Where extreme toughness is desired, the pieces, whether air or oil hardened should be subsequently tempered at a maximum temperature of 250⁰ Celsius allowing time for tempering through. Test results obtained on a 30mm diameter test piece after hardening at 820⁰ Celsius and tempering at 250⁰ Celsius   Specification: EN36B – 655M13 Colour Code:  White Availability: Black Round Bars: 20mm diameter to 350mm diameter (as rolled and as forged) Characteristics: This material is also known as 3% Nickel-Chromium Case-Hardening Steel This specification is good for welding, prior to Carburising and Case Hardening Machinability is good but allow 6% on the outside diameter  for removal of surface defects Required hardness can be achieved by case hardening the outer surface by means of one of the following, Carburising, Carbonitriding, Nitriding, Nitrocarbursing, Tufftriding Applications: This material is often used in the manufacturing of gears, worm shafts, pinion shafts and spline shafts This specification is largely utilised when wear resistant hard surface is required along with high core strength Other common uses include Auto and heavy vehicle transmission components, engineering machinery gear box parts, aircraft gears mining steering worms, chuck jaws, track pins, gudgeon pins,mining gearbox gears, pinions and cogs Comparable Specifications: Din 15NiCr13 SAE 3316 Deutsche W NO 1.5752 Euro Norm EN 10084 (1998) 15NiCr13 BS970 Part 1 1983, 655M13 BS970 of 1955 EN36B Chemical Composition  (%): % Min % Max Carbon (C) 0.10 0.16 Silicon (Si) 0.10 0.035 Manganese (Mn) 0.35 0.60 Phosphorus (P) Nil 0.04 Sulphur (S) Nil 0.04 Chromium (Cr) 0.70 1.00 Nickel (Ni) 3.0 3.75 Mechanical Properties: Mechanical Properties of the core of a case hardened test bar of 28mm diameter Hardness of the test bar surface, Rc65 Tensile Strength (Min) 1000 MPa Elongation (Min) 9% ISO V Impact 40 Joule Working and Heat Treatment: Carburise at a temperature of 900⁰/930⁰ Celsius Refine at a temperature of 860⁰/880⁰ Celsius (see Note) Harden at a temperature of 760⁰/780⁰ Celsius in oil Note:  A “Single Quench” treatment may suffice to obtain the specified results. Intricate parts, or  parts of large sectional differences may distort in the refining treatment, thus the tendency to avoid refining after carburising. However, should the hardness not be uniform, cryogenic (sub zero) treatment is recommended. Through the analysis (chemical composition), the refining treatment after carburising may be omitted  an a “Single Quench” treatment may be employed