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China Alloy Steel CNC Machining Services - Reliable Suppliers & Factory Solutions for High-Quality Parts
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
1018
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.
Shafts · Pins · Gears
1215
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.
Bolts · Nuts · Bushings
Chromium-Molybdenum Alloy Structural Steel (High-Strength)
4130
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.
Aerospace · Racing Chassis
4140
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.
Gears · Shafts · Couplings
4140 PH
4140 PH Steel
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.
HRC 28–32 · Pre-Hardened · Dies
4340
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.
Landing Gear · Drive Shafts · Crankshafts
Tool Steel (High Wear Resistance / High Hardness)
A2
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.
Stamping Dies · Shear Blades · Gauges
O1
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.
Hand Tools · Cutting Tools · Molds
Frequently Asked Questions
Q
What is the difference between 4140 Steel and 4140 PH Steel?
4140 Steel is supplied in an annealed or normalized condition and requires heat treatment after machining to achieve the desired hardness. 4140 PH (Pre-Hardened) Steel is already quenched and tempered to approximately HRC 28–32 before delivery, allowing it to be machined directly and used without further heat treatment. This reduces the risk of dimensional distortion and simplifies the production process.
Q
When should I choose 4340 Steel over 4140 Steel?
4340 Steel contains additional nickel, which significantly improves its hardenability, fatigue resistance, and toughness in large cross-sections. It is the preferred choice when parts are subject to heavy dynamic loads, large section sizes, or critical safety requirements — such as aircraft landing gear or heavy-duty crankshafts. For general-purpose high-strength applications, 4140 is typically sufficient and more cost-effective.
Q
What makes 1215 Steel a good choice for high-volume machining?
1215 Steel is a free-machining steel with elevated sulfur content, which promotes the formation of short, brittle chips during cutting. This reduces tool wear, allows higher cutting speeds, and produces excellent surface finishes. These properties make it highly efficient for CNC turning and screw machine operations when producing large quantities of fasteners, bushings, and fittings.
Q
What is the key advantage of A2 Tool Steel over O1 Tool Steel?
A2 Tool Steel is air-hardened, meaning it undergoes significantly less distortion during heat treatment compared to O1, which is oil-hardened. This makes A2 the preferred choice for precision dies and tooling where dimensional stability after hardening is critical. O1, on the other hand, offers better machinability and edge sharpness, making it ideal for cutting tools, gauges, and hand tools where extreme precision in heat treatment is less critical.
Q
Can 4130 Steel be welded, and what precautions are needed?
Yes, 4130 Steel has good weldability compared to many other alloy steels. However, for thicker sections or highly stressed applications, preheating (typically 300–500°F / 150–260°C) is recommended to minimize the risk of hydrogen-induced cracking. Post-weld stress relief or annealing may also be required to restore toughness in the heat-affected zone.
Q
How do I select the right alloy steel for my application?
Selecting the right alloy steel depends on several key factors: the required strength and hardness level, the type of loading (static, dynamic, or fatigue), the part's cross-section size, machinability requirements, heat treatment capability, and cost constraints. For example, 1018 suits low-stress carburized parts; 4140 covers most general high-strength needs; 4340 is reserved for critical, large, or heavily loaded components; and tool steels like A2 or O1 are chosen when extreme wear resistance and hardness are the primary requirements.
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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