+86-13928348837
Alloy Steel CNC Machining Services by China Factory - Expert 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
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.
High-Speed 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)
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.
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.
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.
Heavy-Duty / 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)
Air-Hardening · Precision Dies
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.
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
Q
What is the difference between 4130 and 4140 alloy steel?
Both 4130 and 4140 are chromium-molybdenum alloy steels, but 4140 has a higher carbon content (0.38–0.43% vs. 0.28–0.33%), which gives it greater strength and hardness after heat treatment. 4130 offers better weldability and is preferred for aerospace tubing and thin-walled structures, while 4140 is more commonly used for heavy-duty mechanical components such as gears, shafts, and die sets.
Q
When should I choose 4140 PH (Pre-Hardened) steel over standard 4140?
4140 PH steel is ideal when you need to avoid the risk of dimensional distortion that can occur during post-machining heat treatment. Since it is supplied pre-quenched and tempered to HRC 28–32, it can be machined directly to final dimensions, saving time and reducing scrap rates. Standard 4140 is preferred when higher hardness levels are required through custom heat treatment.
Q
What makes 4340 steel suitable for critical aerospace and automotive applications?
4340 is a nickel-chromium-molybdenum alloy steel that offers an exceptional combination of high tensile strength, toughness, and fatigue resistance. Its deep hardenability makes it effective even in large cross-sections, which is critical for components like aircraft landing gear and heavy-duty crankshafts that must withstand extreme cyclic loads without failure.
Q
What is the advantage of using 1215 free-machining steel in mass production?
1215 steel contains elevated sulfur and phosphorus levels that promote the formation of short, brittle chips during machining. This reduces tool wear, allows for faster cutting speeds, and produces a superior surface finish compared to standard low-carbon steels. These properties make it highly cost-effective for high-volume production of fasteners, bushings, and precision turned parts.
Q
How do A2 and O1 tool steels differ in terms of heat treatment and application?
A2 tool steel is air-hardened, meaning it cools in still air after austenitizing, which minimizes distortion and cracking — making it ideal for precision dies and gauges. O1 tool steel is oil-hardened, which requires quenching in oil and is better suited for general-purpose tooling where ease of heat treatment and excellent machinability are priorities. O1 also offers superior edge retention for cutting tools and hand tools.
Q
Can 1018 steel be used for structural components requiring high surface hardness?
Yes. Although 1018 is a low-carbon steel with relatively low base hardness, it responds well to surface carburizing and case hardening processes. This creates a hard, wear-resistant outer layer while retaining a tough, ductile core — making it suitable for shafts, pins, and gears where surface wear resistance and core toughness are both required.
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.
-
Passivation or Chromate Conversion Coating:
-
Powder Coating:
-
Painting:
-
Physical Vapor Deposition (PVD):
Design and Machining Considerations
-
Process Selection:
-
Design Considerations:
-
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.
Ready to Start Your CNC Project?
Send us your drawings to receive professional manufacturing solutions.