Cold Heading Steel Round Bar
Introduction:
ML20Cr is a high-quality cold heading alloy structural steel complying with GB/T 6478 standard, specially developed for cold forging, cold extrusion and cold upsetting forming processes. With ultra-low impurity control, uniform chemical composition and fine grain structure, the steel features excellent cold forming performance, low deformation resistance and no cracking during high-rate cold heading.
Product Overview
ML20Cr is a high-quality cold heading alloy structural steel complying with GB/T 6478 standard, specially developed for cold forging, cold extrusion and cold upsetting forming processes. With ultra-low impurity control, uniform chemical composition and fine grain structure, the steel features excellent cold forming performance, low deformation resistance and no cracking during high-rate cold heading. It has stable carburizing and quenching performance, high surface hardness and wear resistance after heat treatment, as well as good core toughness and fatigue resistance. Strict surface and internal quality inspection ensures no decarburization, cracks or inclusions. It is the preferred material for manufacturing high-strength standard fasteners and precision cold-formed parts in automotive, mechanical and electrical industries.
Representative Grades
Representative Grade: ML20Cr
Core Characteristics & Application: ML20Cr is low-carbon chromium alloy cold heading steel. It features superior cold formability, uniform hardness, low internal stress and excellent carburizing hardenability. It can withstand one-time complex cold upsetting forming without cracking. After carburizing and quenching, it obtains high surface hardness and wear resistance while retaining sufficient core toughness. It is mainly used for manufacturing medium and high-strength fasteners, precision bolts, screws, pins and cold-extruded mechanical parts that require wear resistance and fatigue resistance.
Grade Description
ML20Cr is coded according to Chinese cold heading steel naming rules. The prefix "ML" indicates special steel for cold heading; "20" stands for average carbon content of 0.20%, ensuring excellent cold plastic toughness and avoiding cracking during cold forming. The Cr (chromium) element significantly improves hardenability, surface hardness and wear resistance after carburizing treatment, and enhances structural stability and fatigue life. Standard chemical composition: C: 0.18–0.23%, Si: 0.10–0.30%, Mn: 0.60–0.90%, Cr: 0.90–1.20%, S≤0.025%, P≤0.025%, Alt≥0.020%. Standard mechanical properties: Tensile Strength ≥785MPa, Yield Strength ≥588MPa, Elongation ≥10%, Section Shrinkage ≥40%, Delivery Annealed Hardness ≤179HB. It is widely applicable for precision cold forming and heat-treated fastener products.
Product Specifications
Basic technical parameters of ML20Cr cold heading steel round bar (table in pure English):
|
Item |
Technical Parameter |
|
Product Name |
ML20Cr Cold Heading Steel Round Bar |
|
Executive Standard |
GB/T 6478 |
|
Common Diameter Range |
Φ16mm–Φ200mm (Custom sizes available) |
|
Delivery Condition |
Hot Rolled / Annealed |
|
Delivery Hardness |
≤ 179 HB (Annealed state) |
|
Surface Quality |
Smooth surface, no crack, no fold, no decarburization layer |
|
Cold Heading Performance |
Qualified for 1/2, 1/3, 1/4 cold upsetting test |
|
Dimension Tolerance |
National standard precision tolerance, high precision customizable |
|
Custom Service |
Fixed-length cutting, straightening, polishing, stress relief annealing |
Core Advantages
1. Excellent Cold Forming Performance: Low hardness and uniform texture in delivery state, strong plastic toughness, no cracking during high-speed cold heading and cold extrusion.
2. Ultra-low Impurity & Clean Steel Quality: Strict control of S and P elements, low gas content, no internal inclusions and porosity, high finished product yield.
3. No Surface Decarburization: Stable rolling and annealing process, uniform surface layer, ensuring consistent thread strength and surface hardness of fasteners.
4. Stable Heat Treatment Performance: Good carburizing hardenability, small quenching deformation, high dimensional accuracy and stable fatigue resistance.
5. High Batch Consistency: Uniform composition and mechanical properties of different batches, suitable for fully automated mass production of fasteners.
6. Wide Specification Coverage: Complete round bar size range, flexible customization to meet diversified precision cold forming needs.
Main Application Fields
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Automotive Industry
Automotive engine fasteners, chassis bolts, studs, pins and precision cold-formed structural parts.
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Mechanical Equipment Industry
High-strength bolts, screws, rivets and connecting fasteners for general machinery and engineering equipment.
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Electrical & Hardware Industry
Precision standard parts, instrument fasteners and small wear-resistant cold-forged components.
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New Energy Equipment
Structural fasteners and precision cold-extruded parts for new energy vehicles and energy storage equipment.
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Mold & Processing Industry
Medium-hardness wear-resistant mechanical parts requiring carburizing and quenching strengthening.
Packaging & Services
Packaging: Adopt standard export seaworthy packaging. Round bars are bundled with high-strength steel strips, wrapped with waterproof and moisture-proof kraft paper and plastic film. Each bundle is marked with grade, specification, heat number, batch number and standard information to prevent rust, oxidation and deformation during long-distance transportation.
Services: Provide complete original Mill Test Certificate (MTC) including chemical composition and mechanical property data. Support SGS, BV third-party inspection and factory witness test. Provide customized processing such as fixed-length cutting, straightening, polishing and stress-relief annealing. Flexible trade terms: FOB, CFR, CIF, DAP. Offer professional technical support for cold heading process, heat treatment scheme and grade selection.
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- WhatsApp: +86-185 9567 2991
- Email: martinliu@rongtianmetal.com
- Tel: +86-185 9567 2991
- Address: 8F, Bldg 2, Jinke Zhihui Valley No. 65 Hongyuan Rd., Jinshui Dist. Zhengzhou, China.
