42CrMoA is a chromium–molybdenum alloy structural steel with excellent strength, toughness, and hardenability. It is widely used for mechanical parts and forged components that operate under high load and impact conditions. Compared with standard 42CrMo, the “A” grade indicates controlled composition and improved purity, ensuring better performance consistency and fatigue resistance.
Chemical Composition (%):
C: 0.38–0.45
Si: 0.17–0.37
Mn: 0.50–0.80
Cr: 0.90–1.20
Mo: 0.15–0.25
P: ≤ 0.025
S: ≤ 0.025
Key Properties
High tensile strength and yield strength after quenching and tempering
Good impact resistance and low-temperature toughness
Uniform hardenability and strong fatigue strength
Suitable for surface hardening, nitriding, and induction treatment
Reliable machinability and dimensional stability
Typical Applications
42CrMoA steel is commonly used in:
Forged shafts, gears, and crankshafts
High-pressure bolts and connecting rods
Oil drilling tools and collars
Hydraulic parts and heavy-duty machine components
Automotive and engineering equipment parts
Equivalent Grades
ASTM/SAE: 4140 (approx.)
DIN: 42CrMo4 / 1.7225
JIS: SCM440
Professional 42CrMoA Steel Supplier – ChinaSpecSteel
ChinaSpecSteel provides high-quality 42CrMoA alloy steel produced by Jiyuan Iron & Steel Group, one of China’s leading manufacturers of special steels. With a complete long-process production system and advanced testing facilities, each batch of steel meets strict chemical and mechanical property standards required for global engineering applications.
What We Offer:
Hot rolled, forged, and heat-treated 42CrMoA bars and billets
Customized sizes and technical support for B2B clients
Mill test certificates with SGS or BV inspection available
Consistent quality and competitive factory pricing
Global export logistics with secure packaging
Supply Range:
Round and square bars
Forged billets and precision shafts
Heat-treated blanks for OEM manufacturing
About Jiyuan Iron & Steel
Jiyuan Iron & Steel Group operates a long-process steelmaking system that integrates ironmaking, steelmaking, and rolling. The company’s facilities are equipped with advanced inspection and automation technologies, achieving an internationally advanced level of production and quality control. It serves as a major production base in China for special steel bars and wire rods.
Main steel grades include bearing steel, spring steel, cord steel, cold heading steel, gear steel, free-cutting steel, non-quenched and tempered steel, alloy structural steel, carbon structural steel, high-strength wear-resistant steel, tube billet steel, anchor chain steel, and continuous cast iron profiles.
Deep-processed products include precision wire, heat-treated bars, bright bars, and fasteners, widely used in automotive, machinery, energy, and heavy industrial sectors.
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