Grades of engineering alloy steel for quenching and tempering


34Cr4 - 1.7033 - AISI 5132 - 30H - Chromium steel
32HA - Chromium steel
37Cr4 - 1.7034 - AISI 5135 - Chromium steel with reduced carbon, sulfur and phosphorus content
40NiCr6 - 1.5711 - 40ChN - Chromium-nickel steel
35NiCr6 - 36NiCr6 - 35NC6 - 1.5710 - 1.5815 - Chromium-nickel steel
28Mn6 - 1.1170 - AISI 1330 - 30Mn5 - 30G2 - Manganese steel
38ChS - 37HS - Chromium-silicon steel
30ХГСА - 30ChGSA - 30HGSA - Chromium-manganese-silicon steel
15CDV6, 1.7734 - Chromium-molybdenum-vanadium steel
35ХГСА - 35ChGSA - 35ChGS - Chromium-manganese-silicon steel
30ХГСН2А - 30ChGSN2A - 30HGSNA -Chromium-nickel-silicon-manganese steel
25CrMo4 - 1.7218 - AISI 4130 - Chromium-molybdenum steel
34CrMo4 - 1.7220 - AISI 4135 - Chromium-molybdenum steel
42CrMo4 - 1.7225 - AISI 4140 - Chromium-molybdenum steel
50CrMo4 - 1.7228 - AISI 4150 - Chromium-molybdenum steel
34CrNiMo6 - 1.6582 - 817M40 - Chromium-nickel-molybdenum steel
30HN2MFA - Chromium-nickel-molybdenum-vanadium steel for bolts
36CrNiMo4 - 1.6511 - Chromium-nickel-molybdenum steel
39NiCrMo3 - 1.6510 - Chromium-nickel-molybdenum steel
40NiCrMo7 - AISI 4340 - 40HNMA - 40NiCrMo6 - 1.6565 - 40NiCrMo8-4 - Chromium-nickel-molybdenum steel
41NiCrMo7-3-2 - 1.6563 - A320 gr. L43 - Chromium-nickel-molybdenum steel
36NiCrMo16 - 1.6773 - Chromium-nickel-molybdenum steel for most loaded machine parts
30NiCrMo12 - 32NiCrMo12-5 - 1.6655 - Chromium-nickel-molybdenum steel
45ХН2МФА - 45ХНМФА - 45HNMF - 45HNMFA - Chromium-nickel-molybdenum-vanadium steel
40XMФA - 40ChMFA - 40H2MF - 40HMFA - Chromium-molybdenum-vanadium steel
23MnNiCrMo5-3 - 1.6540 - 23MnNiCrMo5-4 - 1.6758 - Steel for chain links
15NiCr13 - 1.5752 - 12XН3А - 12HN3A - Chromium-nickel steel
12Х2Н4А - 12H2N4A - 12Ch2N4A - 14NiCrMo13-4 - 1.6657 - Chromium-nickel steel
20ХН3А - 20HN3A - 20ChN3A - Chromium-nickel steel
20Х2Н4А - 20H2N4A - 20Ch2N4A - Chromium-nickel steel
30CrNiMo8 - 1.6580 - Chromium-nickel steel with molybdenum additive
AISI 4330V - 4330 Mod. - Special heat-treated engineering steel
AISI 4145 - AISI 4145H - Chromium-molybdenum engineering steel



Steels for thermal improvement, i.e. hardening and tempering - characteristics of the material group

The grades of this carbon structural steel feature greater tensile strength, plasticity, crack resistance at dynamic loads, better hardening capacity, and uniform properties across the entire cross section. The group of structural steel alloys with a carbon range of about 0.25-0.50%, which require good mechanical properties with good ductility, and the ability to perform machining after heat treatment.

The heat treatment (+ QT, -T) of the materials consists of a combination of tempering operations at about 800-1000 ℃ and high tempering at about 500-700 ℃, resulting in the formation of a sorbite (ferrite and cementite), thanks to which the material acquires the appropriate qualities. The described structural steels only in improved state achieve their properties in relation to, for example, softened state.

By hardening and tempering, you can obtain parameters which are determined by the chemical composition of the material and the specification. The rule confirms that quality alloy constructional steels should only be used in an improved condition. Products in the described grades are delivered in a softened state (steels for improvement), heat-treated (steels improved thermally), normalized, or raw.

Chemical composition - alloy additives and subgroups

Structural alloys for improvement include in most cases additional or higher concentrations of elements such as Manganese - Mn, Chromium - Cr, Silicon - Si, Nickel - Ni, Molybdenum - Mo, and additionally Tungsten - W, Vanadium - V, and Bor - B, normally not exceeding 4.8%.

On the list of products for improvement, there are also steels for improvements without nickel and molybdenum, such as:

  • Chromium-silicon steels (eg. 37HS)
  • chromium steels (eg. 30H, 40H, 45H, 38HA)
  • manganese steels with improved hardening capacity (eg. 20G2, 30G2, 35G2A,40G2, 45G2),
  • Steel with boron addition 27MnCrB5-2, 1.7182, 33MnCrB5-2, 1.7185, 32CrB4, 1.7076, 36CrB4, 1.7077
  • abrasion-resistant silico-manganese steels (eg. , 40GS, 45SG)
  • and chromium-manganese-silicon steels (eg. 20HGS, 25HGS, 30HGSA, 35HGSA, 35HGSNA)

which also has high hardness, tensile strength, yield strength and abrasion resistance without any additional elements. A manganese content of more than 1.8% may reduce the material's ductility, so some of the grades are supplemented with a suitable silicon concentration (35SG, 30HGSA).

Other interesting facts about steel for hardening and tempering

Forging of alloy steels at too high temperatures leads to coarseness and brittleness of the product, while at low temperatures it causes harmful stresses and cracks.

Steels for improvement do not show practically no resistance to atmospheric corrosion. Quite high carbon content, low chromium concentration, and nickel will automatically appear after contact with the outside atmosphere. Products with this composition of elements and structure acts as part of heavily loaded machines and vehicles, such as shafts, gears, axles, bolts, valves, pins requiring high ductility and plasticity.

Among steels for thermal improvement there is also steel for the mining chains 23GHNMA.

Other grades for quenching and tempering: 25H2N4WA, 37HN3A, , 30HN3A, , 65S2WA, 30HGSNA, 35NiCrMoV12-5, 1.6959, 37HGNM


The above-described steels for thermal improvement of structural alloy steels are defined by the standards PN-72/H-84035, PN-89/H-84030-04, according to which are delivered:

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