MaterialsSteels

42CrMo4 — 1.7225

The chromium-molybdenum quenched and tempered steel 42CrMo4: designations and equivalents (AISI 4140, SCM440), chemical composition, strength by section size in the quenched and tempered condition, hardness, heat treatment, weldability and machining.

LiveUpdated 11 October 20264 min read

42CrMo4: composition limits and +QT strength by bar size

Minimum yield strength, quenched and tempered, d ≤ 16 mm: 900MPa
Through-hardens in oil up to about this diameter (Ovako): ≈ Ø60mm
Maximum hardness, soft annealed (+A): 241HB
Approximate AISI and JIS equivalents: 4140 / SCM440

42CrMo4 is a chromium-molybdenum alloy steel for quenching and tempering. Its alloying lets it harden through larger sections than a plain carbon steel: compare its quenched and tempered strengths, given up to 250 mm, with those of C45, which stop at 100 mm. It is supplied soft-annealed, treated for shearability or quenched and tempered.

Designations

Name	Number	Note
42CrMo4	1.7225	Base grade
42CrMoS4	1.7227	Specified sulphur range 0.020–0.040 % for better machinability

Approximate equivalents: AISI/SAE 4140 (some makers list 4140H or 4137), JIS SCM440. The governing standard is EN ISO 683-2:2018, which replaced EN 10083-1 and EN 10083-3 (2006).

Chemical composition

Heat analysis, % by mass, EN ISO 683-2:

C	Si	Mn	P max	S max	Cr	Mo	Cu max
0.38–0.45	0.10–0.40	0.60–0.90	0.025	0.035	0.90–1.20	0.15–0.30	0.40

42CrMoS4 has S 0.020–0.040 %. As with C45, the silicon minimum comes with EN ISO 683; the old EN 10083-3 gave only a maximum of 0.40 %.

Mechanical properties, quenched and tempered (+QT)

Diameter d (mm)	Re min (MPa)	Rm (MPa)	A min (%)	Z min (%)	KV min (J)
≤ 16	900	1100–1300	10	40	—
16 < d ≤ 40	750	1000–1200	11	45	35
40 < d ≤ 100	650	900–1100	12	50	35
100 < d ≤ 160	550	800–950	13	50	35
160 < d ≤ 250	500	750–900	14	55	35

For d ≤ 16 mm thyssenkrupp, Lucefin and Deutsche Edelstahlwerke give no impact value; Saarstahl prints 30 J. Ovako states that the steel through-hardens up to about Ø60 mm after oil quenching.

Quenched and tempered (+QT): minimum yield strength Re (line) and tensile strength range Rm (band) against the diameter of the heat-treated section, from the EN ISO 683-1 and EN ISO 683-2 values in the tables. C45 is listed only up to 100 mm. Hover a step to read it.

Hardness: soft-annealed (+A) max 241 HB; treated for shearability (+S) max 255 HB.

Heat treatment

Treatment	Range (°C)	Notes
Normalizing	840–880	Saarstahl 850–880
Soft annealing	680–720
Hardening	820–860	Oil or water; thyssenkrupp gives 820–880, Ovako 840–880
Tempering	540–680	For the +QT strengths above

Heat treatment temperatures from the table above. The thick bar is the range this page uses; thin bars are the values individual makers print. Hover a bar to read it.

Weldability

42CrMo4 is difficult to weld. thyssenkrupp warns of hardening in the heat-affected zone and the weld metal and calls for preheating, an interpass temperature chosen from the CCT diagram, slow cooling and a low-carbon Mo or CrMo filler. Deutsche Edelstahlwerke advises against welded structures and calls for post-weld heat treatment if welding cannot be avoided. Lucefin gives a preheat of 300 °C and stress relieving at 550 °C.

Machining

thyssenkrupp notes that the machinability depends strongly on the microstructure, that is, on the delivery condition. For cutting-force calculations, ISCAR places annealed 42CrMo4 (200 HB) in its group 6 (kc1.1 = 1775 N/mm², mc = 0.24) and Seco uses 42CrMo4 as the reference of its group P5 (kc1.1 = 2020 N/mm², mc = 0.18). At a chip thickness of 0.2 mm the two give nearly the same kc; see cutting forces. For better machinability, makers offer 42CrMoS4 with its controlled sulphur content (Lucefin) or calcium-treated grades (Ovako’s M-Steel).

Sources (11)

Every value and quotation on this page comes from the documents below.