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Alloy Steel CNC Machining by China Factory - Trusted Suppliers for Precision Parts and Prototypes
We maintain a complete inventory of high-quality alloy steels, including structural steel, carburizing steel, quenched & tempered steel, and tool steel, to meet the stringent requirements of diverse applications:
🔩 Low-Carbon Steel / Free-Machining Steel
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General Purpose
1018 Steel
A general-purpose low-carbon steel with excellent weldability and machinability. Suitable for surface carburizing/quenching to achieve a hard, wear-resistant surface with a tough core. Commonly used for shafts, pins, gears, etc.
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Free-Machining
1215 Steel
A high-sulfur free-machining steel with superior chip-breaking performance, enabling high surface finish quality and faster machining speeds. Ideal for mass production of standard parts such as bolts, nuts, and bushings.
🏗️ Chromium-Molybdenum Alloy Structural Steel (High-Strength)
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Aerospace / Racing
4130 Steel
A chromium-molybdenum alloy steel with excellent strength, toughness, and weldability. A classic material for aerospace structural tubing (e.g., aircraft engine mounts) and high-performance racing chassis, typically normalized or quenched & tempered.
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Most Widely Used
4140 Steel
One of the most widely used chromium-molybdenum alloy steels, offering high strength, good wear resistance, and impact toughness. Achieves different strength levels through quenching & tempering. Widely used for gears, shafts, couplings, and die sets.
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Pre-Hardened · HRC 28–32
4140 PH Steel (Pre-Hardened)
Supplied in a pre-quenched & tempered condition (typically HRC 28–32), offering stable mechanical properties and machinability. Can be machined directly without post-heat treatment, avoiding deformation risks. Commonly used for dies and mechanical components.
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High-Strength / Critical Load
4340 Steel
A high-strength nickel-chromium-molybdenum alloy steel with exceptional strength, toughness, and fatigue resistance, especially suitable for large-section critical load-bearing components. The preferred material for aircraft landing gear, heavy-duty drive shafts, and high-performance racing crankshafts.
🔧 Tool Steel (High Wear Resistance / High Hardness)
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Air-Hardening · Cold-Work
A2 Tool Steel
An air-hardening cold-work tool steel with good wear resistance, moderate toughness, and minimal heat treatment deformation. Widely used for precision stamping dies, shear blades, and gauges.
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Oil-Hardening · General Purpose
O1 Tool Steel
An oil-hardening general-purpose tool steel renowned for excellent edge retention, machinability, and simple heat treatment. Commonly used for hand tools, gauges, cutting tools, and low-life molds.
❓ Frequently Asked Questions
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What is the difference between 4140 Steel and 4140 PH (Pre-Hardened) Steel?
Standard 4140 Steel is supplied in an annealed or normalized condition and requires post-machining heat treatment to achieve the desired hardness. 4140 PH Steel is pre-quenched and tempered to a hardness of HRC 28–32, allowing it to be machined directly without further heat treatment, which reduces the risk of dimensional distortion in finished parts.
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When should I choose 4340 Steel over 4140 Steel?
4340 Steel is the better choice when your application involves large cross-section components, extremely high loads, or demanding fatigue conditions — such as aircraft landing gear or heavy-duty crankshafts. 4140 Steel is more cost-effective and suitable for general high-strength applications like gears, shafts, and couplings where the extreme performance of 4340 is not required.
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What is the advantage of using 1215 Free-Machining Steel in mass production?
1215 Steel contains a higher sulfur content, which promotes the formation of short, easily broken chips during machining. This results in significantly faster cutting speeds, improved surface finish quality, and extended tool life — all of which reduce production costs and cycle times when manufacturing high volumes of standard parts such as bolts, nuts, and bushings.
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What is the key difference between A2 and O1 Tool Steel?
The primary difference lies in their hardening method and application focus. A2 Tool Steel is air-hardened, which means it experiences minimal dimensional change during heat treatment — making it ideal for precision dies and gauges. O1 Tool Steel is oil-hardened, offers excellent edge retention and easier machinability, and is a popular choice for cutting tools, hand tools, and general-purpose molds.
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Can 4130 Steel be used in welded structures?
Yes. 4130 Steel is well known for its excellent weldability among chromium-molybdenum alloy steels. It is commonly used in welded aerospace structural tubing and racing chassis frames. For best results, preheating before welding and post-weld stress relief are recommended to maintain the mechanical properties of the heat-affected zone.
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Is 1018 Steel suitable for applications requiring high surface hardness?
Yes, but with surface treatment. 1018 Steel is a low-carbon steel that is not inherently hard, but it responds very well to case hardening processes such as carburizing and quenching. This creates a hard, wear-resistant surface layer while maintaining a tough, ductile core — making it a practical and cost-effective solution for shafts, pins, and gears that require both surface durability and impact resistance.
Finishes and Post-Processing Options
The zinc alloy substrate is highly suitable for various surface treatments to enhance decoration, protection, or functionality:
Electroplating: Such as chrome, nickel, gold, or silver plating, providing a highly decorative appearance, excellent wear and corrosion resistance. This is the most common choice.
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Passivation or Chromate Conversion Coating:
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Powder Coating:
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Painting:
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Physical Vapor Deposition (PVD):
Design and Machining Considerations
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Process Selection:
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Design Considerations:
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Material Selection:
Zamak 3 and 5 are suitable for the vast majority of general-purpose parts requiring good appearance and strength; ZA-8 is better for wear and bearing applications; for making rapid tooling, choose specialized alloys like Kirksite.
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