G42CrMo4 (1.7231) — Cr-Mo quench-and-temper steel

Designation

Grade: G42CrMo4 (1.7231)
UNS: —
EN designation: 1.7231 (G42CrMo4)
Standard: EN 10293
Family: Carbon and low-alloy steels
Density: ≈ 7.85 g/cm³
Usual delivery condition: Quenched (or normalised) and tempered

Chemical composition

Element	Mass fraction, %
C	0.38–0.45
Mn	0.60–1.00
Si	≤ 0.60
Cr	0.80–1.20
Mo	0.15–0.30
Fe	bal.

Main elements only. Phosphorus, sulphur and residual-element limits are specified in the standard and are not reproduced here.

Mechanical properties

Condition	Tensile strength Rm, min. (MPa)	Yield strength Rp0.2, min. (MPa)	Elongation, min. (%)
Quenched (or normalised) and tempered	800–950	600	12

Minimum values (or ranges) for separately cast test bars as specified in EN 10293.

Characteristics

Corrosion and oxidation behaviour: Not corrosion resistant; coating or other protection required in corrosive environments
Weldability: Limited; crack-sensitive, welding only by agreement
Machinability: Good in the appropriate heat-treatment condition
Typical applications: Gears and drives Automotive Structural parts General engineering

International cross-reference

System	Designation	Relationship
ASTM	4140 (SAE J404 / AISI 4140 (cast: ASTM A732 Gr. 8Q))	Comparable properties

Casting and processing considerations

Good castability and moderate pouring temperatures. Surface decarburisation from the reaction between metal, shell and atmosphere has to be considered on heat-treated and wear surfaces; machining allowance or a controlled furnace atmosphere are common countermeasures. Section-size sensitivity of quenched and tempered grades should be reflected in the drawing requirements.

Reference data compiled from the cited standards for orientation. Always work from the current edition of the governing specification; values are not a guaranteed LOSTWAX TR delivery specification.

WCB GP240GH (1.0619) LCC G20Mn5 (1.6220) WC6 G17CrMo5-5 (1.7357) WC9 G17CrMo9-10 (1.7379) 4140 8620