42CrMo4 Steel: Technical Properties and Application Areas

What is 42CrMo4?

42CrMo4 (Material No: 1.7225, SAE/AISI 4140) is one of the most widely used quenched and tempered steels worldwide. This chromium-molybdenum alloy steel is an indispensable material for engineering applications with its combination of high strength and toughness.

Chemical Composition

Chemical composition of 42CrMo4 steel according to EN 10083-3 standard:

Element	Min (%)	Max (%)
Carbon (C)	0.38	0.45
Silicon (Si)	-	0.40
Manganese (Mn)	0.60	0.90
Chromium (Cr)	0.90	1.20
Molybdenum (Mo)	0.15	0.30
Phosphorus (P)	-	0.025
Sulfur (S)	-	0.035

Chromium increases hardenability while molybdenum provides protection against temper brittleness and improves high-temperature strength.

Mechanical Properties

Quenched and Tempered Condition (Q+T)

• Tensile Strength (Rm): 900-1100 MPa
• Yield Strength (Re): min. 650 MPa
• Elongation (A5): min. 12%
• Impact Strength: min. 35 J (longitudinal, 20°C)
• Hardness: 260-320 HB

Normalized Condition

• Tensile Strength: 750-900 MPa
• Hardness: 210-250 HB

Heat Treatment Parameters

Quenching & Tempering

1. Austenitizing: 840-880°C, quenching in oil or water
2. Tempering: 540-680°C range, air cooling
3. Hardness range: Tempering temperature is adjusted according to desired mechanical properties

Stress Relieving

• Temperature: 600-650°C
• Duration: Depending on cross-section thickness (approximately 1 hour/25 mm)

Normalizing

• Temperature: 850-880°C
• Cooling: Still air

For hardness conversion calculations, you can use our Hardness Converter tool.

Application Areas

Automotive Sector

• Crankshafts and connecting rods
• Gearbox components
• Suspension parts
• Axle shafts and joints

General Mechanical Engineering

• Hydraulic cylinder piston rods
• Heavy-duty shafts and spindles
• Press and machine tool components
• Fasteners (high strength class)

Oil and Gas Industry

• Drilling equipment
• Valve bodies and stems
• High-pressure pipe fittings
• Pump shafts

Energy Sector

• Wind turbine main shafts
• Generator shafts
• Turbine components

Equivalent Grades

Standard	Equivalent
DIN/EN	42CrMo4 (1.7225)
AISI/SAE	4140
JIS	SCM440
GOST	38ХМ / 40ХМ
BS	708M40

For grade equivalents, check our Grade Equivalence Table tool.

Machinability and Welding

The machinability of 42CrMo4 steel depends on its heat treatment condition. The best machining performance is achieved in the soft annealed condition (max. 220 HB). When welding is required, preheating (200-300°C) must be applied and post-weld stress relieving must be performed.

42CrMo4 Supply from Aktif Celik

As Aktif Celik, we stock 42CrMo4 grade in hot-rolled round bar, square bar and bright drawn forms in a wide diameter range. We offer the most suitable solution for your projects with 3.1 certified, heat-treated or normalized options. Contact our team for technical consultancy and custom cutting services.