42CrMo Steel Round Bar | GB/T 3077 Alloy Structural Steel Bar Supplier

概述

42CrMo (GB/T 3077) is a medium-carbon, chromium-molybdenum alloy structural steel widely used for high-strength machine components requiring good toughness, hardenability, and wear resistance. With 0.38–0.45% carbon, 0.90–1.20% chromium, and 0.15–0.25% molybdenum, it responds well to quenching and tempering (Q&T), achieving tensile strengths of 980–1,200 MPa with good ductility. 42CrMo round bar is one of the most commonly specified alloy steel bars in Chinese mechanical engineering, serving as the domestic equivalent of AISI 4140 / 42CrMo4 (EN). It is supplied in spheroidize-annealed, normalized, or quenched-and-tempered condition for machining into shafts, gears, bolts, and pressure-bearing components.

尺寸范围

• Diameter — Hot-Rolled (mm):10 – 350
• Diameter — Forged (mm):80 – 800
• Diameter — Peeled / Turned (mm):20 – 400
• Diameter — Cold-Drawn (mm):4 – 80
• Length:3,000 – 9,000 mm (standard 6,000 mm)
• Standard Lengths (m):3 / 4 / 5 / 6 / 7 / 8 / 9
• Surface Finish:Hot-rolled (black), peeled (bright), ground, polished
• Tolerance — Hot-Rolled (d ≤ 50 mm):h11 (±0.15 mm)
• Tolerance — Hot-Rolled (50 < d ≤ 120 mm):h11 (±0.22 mm)
• Tolerance — Peeled (h9):±0.05 mm (d ≤ 50); ±0.07 mm (50–100)
• Tolerance — Cold-Drawn (h8/h9):±0.02 – ±0.04 mm
• Tolerance — Ground (h7/h8):±0.015 – ±0.025 mm
• Straightness:≤ 2 mm/m (hot-rolled); ≤ 1 mm/m (peeled); ≤ 0.5 mm/m (ground)
• Out-of-Roundness:≤ 50% of diameter tolerance
• Decarburization Depth:≤ 0.8 mm (hot-rolled); ≤ 0.3 mm (peeled)
• Surface Roughness (Ra):0.4 µm (ground), 1.6 µm (peeled), 6.3 µm (hot-rolled)
• Weight Tolerance:±5% individual, ±3% batch

牌号标准

化学成分

机械性能

物理性能

应用场景

• Automotive & Transportation
• Heavy Machinery & Mining
• Oil & Gas
• Power Generation
• Aerospace & Defense
• Industrial Fasteners
• Tooling & Dies
• General Engineering