42CrMo4 / ASTM 4140
QT alloy steel round bar for high-load hydraulic and rotating parts.
This grade combines strength, toughness, and fatigue resistance, which is why it is commonly used for critical components in hydraulic systems, wind power equipment, and marine applications.
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42CrMo4
Key point
Stable QT performance with flexible machining support.
Suitable for rods, shafts, flanges, gears, and other heavy-duty parts.
Product Summary
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Introduction
42CrMo4 (EN 1.7225) / ASTM 4140 is a core quenched and tempered alloy steel round bar grade with high strength, good toughness, and excellent fatigue resistance.
Equivalent grades
EN
42CrMo4 / 1.7225
ASTM
A29 / A322 - 4140
DIN
42CrMo4
JIS
SCM440
Detailed source notes 53 more points
GB
42CrMo
Chemical composition
C
0.38 - 0.45
Si
0.15 - 0.40
Mn
0.60 - 0.90
Cr
0.90 - 1.20
Mo
0.15 - 0.30
Mechanical properties
Tensile strength
850 - 1000 MPa
Yield strength
≥ 650 MPa
Elongation
≥ 13%
Impact toughness
Good at room temperature
Specifications
Form
Round bar
Diameter
20 - 400 mm
Length
3 - 12 m
Condition
Quenched and tempered (QT)
Surface
Black / Peeled / Machined
Typical applications
Hydraulic cylinder rods and piston rods
Wind power shafts and flanges
Marine drive shafts and coupling components
Heavy-duty gears, spindles, and mechanical shafts
Manufacturing options
Hot rolled and forged bars
Customized QT heat treatment
Rough machining and precision machining
Surface treatments upon request
Inspection points
Chemical composition analysis
Mechanical testing
Ultrasonic testing (UT)
Dimensional inspection and third-party inspection available
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