42CrMo4 Hard Chrome Plated Bar
Model: JIS SCM440／SAE 4140／EN 42CrMo4／EN19
Supplier: GOLDEN ASIA INDUSTRIAL CO., LTD.
42CrMo4 hard chrome plated bar is a chromium-molybdenum steel (EN 10083-3, W.Nr. 1.7225) reaching 900–1100 MPa core tensile strength after quench and tempering — the highest in the standard chrome bar range. It's available in three supply conditions — chrome, Q&T, and Q&T + induction hardened — to match strength and surface hardness to mining, offshore, and heavy construction application.
Highlights
- 900–1100 MPa core tensile strength — Higher than 20MnV6 (550–790 MPa) and 38MnVS6 (up to 950 MPa) in the Q&T condition
- Three supply conditions available — Standard chrome, Q&T, and Q&T + induction hardened, configurable to your application
- Yield strength ≥ 650 MPa — Strong resistance to high-pressure buckling and thread shear stresses in the Q&T condition
- Induction hardened surface up to HRC 58±3 — Localized 0.5–1.5mm case hardening for superior wear armor
- Ra ≤ 0.2 µm chrome surface, 900–1100 HV — Highest chrome hardness in the standard product line
- ISO f7/ f8 tolerance maintained after Q&T and induction hardening — Multi-stage precision straightening preserves dimensional accuracy
- R9/120h corrosion resistance (ISO 9227/10289)
Specifications
| OD Tolerance | f7、f8 |
|---|---|
| Surface Roughness | Ra 0.2μm max |
| Hard Chrome Thickness | Below Φ22.225mm: min 15μm Φ24mm and above: min 20μm |
| Surface Hardness | HV 850 min |
| Straightness | Below Φ20mm: max 0.3mm/1000mm Φ20mm and above: max 0.2mm/1000mm |
| Roundness | 1/2 of tolerance |
| Standard Length | 2M–6M |
| Standard Size | Φ10~200mm（Φ1/4"~Φ10"） |
| Corrosion Resistance (ISO 9227/10289 NSS) | Below Φ20mm: R9/72hr Φ20mm and above: R9/120hr |
| Induction Hardened Surface Hardness | HRC 58° ± 3° (optional) |
| Steel Grade Equivalent | JIS SCM440、SAE 4140、EN 42CrMo4、BS 708M40/EN19 |
Technical Features
- Highest core strength in the standard chrome bar range — Suited when system pressure, rod diameter, and buckling calculations require tensile strength consistently above 900 MPa
- One steel grade, three configurations — Covers everything from high-pressure structural applications to abrasive surface protection without switching material grades
- Tempered martensitic structure improves fatigue resistance — Under high-cycle reciprocating motion, fatigue life measurably exceeds normalized carbon steel of equivalent diameter, standard for heavy-duty cylinders in mining, construction, and industrial presses
- Minimized end-chipping risk during CNC machining — Precisely calibrated induction parameters and stabilized cooling maintain a uniform hardness transition zone between case and core, reducing micro-cracking risk (deep end-cutting should still follow appropriate feeds, tool geometry, and stress-relief sequences)
- Engineered chrome micro-crack network — Ra ≤ 0.2 µm, 900–1100 HV chrome layer with tightly controlled bath temperature and current density retains oil film and reduces seal friction
- ISO f7/ f8 tolerance maintained after Q&T and induction hardening — Multi-stage precision straightening keeps all three supply conditions within standard dimensional tolerance
- Enhanced corrosion certification available — Beyond standard R9/120h, in-house and Taiwan Metal Industries R&D Centre, with ISO 9227 CASS testing also available
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