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

Description (English)

Vertex 42CrMo steel round bar is a medium-carbon chromium-molybdenum alloy structural steel conforming to GB/T 3077, equivalent to AISI 4140 / EN 42CrMo4 (1.7225) / JIS SCM440. With 0.38–0.45% carbon, 0.90–1.20% chromium, and 0.15–0.25% molybdenum, it delivers excellent hardenability, high tensile strength (980–1,200 MPa after quenching and tempering), good toughness, and superior wear resistance. The molybdenum addition effectively prevents temper embrittlement, making it suitable for high-stress applications. Available in hot-rolled, forged, peeled, and cold-drawn finishes, 42CrMo round bar is supplied in annealed, normalized, or quenched-and-tempered condition, with diameter ranges from 10 mm to 800 mm. It responds well to induction hardening, nitriding, and standard machining operations. Widely used in automotive, heavy machinery, oil & gas, power generation, and industrial fastener manufacturing for crankshafts, gears, drill collars, high-strength bolts (Grade 10.9/12.9), hydraulic cylinder rods, and pressure-bearing components. FAQ: Q: What are the equivalent grades of 42CrMo? A:42CrMo is equivalent to AISI 4140 (USA, UNS G41400), EN 42CrMo4 / 1.7225 (Europe), JIS SCM440 (Japan), BS 708M40 / En19 (UK), and DIN 1.7225 (Germany).

Size Range

• 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

Grade Specification

Chemical Composition

Mechanical Properties

Physical Properties

Applications

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