20MnV6 hard chrome plated bar is a vanadium micro-alloyed low-carbon steel with a refined grain structure, offering strong fatigue performance, weldability, and machinability. It outperforms standard C45E under cyclic loading while its low carbon content simplifies welding preparation, making it a preferred choice for piston rods in industrial environments and welded assemblies.
Highlights
- Vanadium grain refinement — Higher fatigue strength than standard C45E, suited for cyclic or shock-loaded piston rods
- Low carbon (0.16–0.22%) with controlled CEV — Reduces pre-heating requirements and cold cracking risk in the HAZ, supporting easier weldability
- Enhanced machinability — Refined steelmaking plus vanadium micro-alloying gives strong chip-breaking behavior, faster cycle times, and lower tool wear
- Induction hardened — Improves surface impact resistance while preserving core toughness, suited for cold or marine environments
- Ra ≤ 0.2 µm chrome surface, 800–1000 HV — Direct compatibility with standard O-ring and lip seals
- High dimensional stability — Consistent microstructure and controlled CEV support tight ISO f7/f8 tolerances across production batches
- R9/120h corrosion resistance (ISO 9227 / ISO 10289) — Suitable for outdoor, agricultural, and humid industrial use; double chrome layering available for offshore environments
Specifications
| OD Tolerance | f7、f8 |
|---|---|
| Surface Roughness | Ra 0.2μm max |
| Hard Chrome Thickness | Below Φ22.225mm: min 15μm Φ24mm and above: min 20μm |
| Chrome Layer Hardness | 800~1000 HV |
| Straightness | Below Φ20mm: max 0.3mm/1000mm Φ20mm and above: max 0.2mm/1000mm |
| Roundness | 1/2 of tolerance |
| Standard Length | 3M–6M and up |
| Standard Size | Φ6~255mm（Φ1/4"~Φ10"） |
| Corrosion Resistance (ISO 9227 / ISO 10289 NSS) | Below Φ20mm: R9/72hr Φ20mm and above: R9/120hr |
| Steel Grade | 20MnV6 |
Technical Features
- Superior fatigue strength — Vanadium grain refinement improves fatigue performance over standard normalized C45E under equivalent cyclic loading
- Lower hidden production costs — Low carbon content and controlled CEV reduce pre-heating needs and HAZ cold cracking risk; strong chip-breaking behavior also shortens machining cycles and reduces tool wear
- Induction hardening balances surface toughness and core ductility — Hardening resists chrome "eggshell effect" under local impact, while the unhardened core preserves sub-zero impact toughness and weldability (the hardened case should be ground off in the weld zone prior to jointing, with preheat requirements based on wall thickness and ambient temperature per applicable welding standards)
- Strong seal compatibility — Precise surface finish and the chrome layer's micro-crack network retain oil film, reducing friction and extending seal life
- Consistent dimensional behavior across batches — Uniform microstructure supports stable grinding and straightening, minimizing cross-batch variance for automated assembly lines
- Corrosion resistance meets international standards — Standard chrome plating (≥20 µm for Ø≥24mm) achieves R9/120h per ISO 10289; double chrome layering available for high-salinity or offshore exposure
- Q1: What advantage does 20MnV6 hard chrome plated bar have over C45E? A1: Vanadium micro-alloying refines the grain structure of 20MnV6, improving fatigue strength over standard normalized C45E under equivalent cyclic loading conditions — making it well suited for piston rods subject to continuous cyclic stress or shock loading.
- Q2: How do I choose between 20MnV6 and 38MnVS6 hard chrome plated bar? A2: Both are micro-alloyed steels, but they serve different priorities. 20MnV6 has lower carbon content (0.16–0.22%), offering better weldability and toughness, suited for welded assemblies or cold/marine environments. 38MnVS6 has higher carbon content and is a non-Q&T steel reaching up to 950 MPa tensile strength and HRC 55±2 induction-hardened surface hardness, better suited for higher-strength, high-volume production where welding isn't required. Choose 20MnV6 when welding or low-temperature toughness matters most; choose 38MnVS6 when strength and production throughput are the priority.
- Q3: How weldable is 20MnV6 hard chrome plated bar? A3: 20MnV6's low carbon content and controlled Carbon Equivalent Value (CEV) reduce pre-heating requirements under standard conditions and lower the risk of cold cracking in the heat-affected zone (HAZ). If the bar has been induction hardened, the hardened case must be ground off in the weld zone before jointing, with preheat requirements determined by wall thickness and ambient temperature per applicable welding standards.
- Q4: What applications suit induction-hardened 20MnV6? A4: Induction Hardened creates a resilient layer that resists chrome "eggshell effect" under local impact, while the unhardened core retains its sub-zero impact toughness and weldability — making it suitable for cold-environment or marine applications requiring both surface impact resistance and core toughness.
- Q5: What corrosion resistance standard does it meet? A5: It meets ISO 9227 Neutral Salt Spray (NSS) and ISO 10289 standards. Standard chrome plating (≥20 µm for Ø≥24mm) achieves R9/120 hours, suitable for outdoor machinery, agricultural equipment, and humid industrial settings. Double chrome layering is available for high-salinity or offshore environments requiring extended protection.
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