Heat-treatable steels are in the mechanical construction steel range. They are characterized by carbon content usually in excess of 0.25%, and may or may not be alloys.
Heat-treatable steels are used to fabricate parts that require a combination of strength and tenacity, with relatively uniform values throughout the cross section or down to a certain depth. These properties are attained by means of quenching and tempering, which comprise the heat-treatment process.
High hardenability, with good hardened-layer depth, appropriate for conditions of severe fatigue, abrasion, impact, and stress at high temperature. May undergo thermal treatment after machining.
Crankshafts, connecting rods, car axles, stabilizers, gears, high-resistance bolts and leaf-spring clamps.
COPANT 4140; SAE 4140; AISI 4140; UNS G41400; DIN 42CrMo4 (1.7225); AFNOR 40CD 4, 42 CD 4; JIS SCM 4 H, SCM 4;
Chemical Composition (% BY WEIGHT)
0,38 – 0,43
0,75 – 1,00
0,15 – 0,35
0,80 – 1,10
0,15 – 0,25
THERMAL TREATMENT AND PROCESSING TEMPERATURES (°C)