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China Stainless Steel CNC Machining Factory: Leading Suppliers of Precision Parts and Custom Solutions
We maintain a full inventory of austenitic, martensitic, precipitation-hardening, and specialty stainless steels to meet the most demanding mechanical performance and corrosion resistance requirements:
303 Stainless Steel
Free-Machining
A free-machining austenitic stainless steel with excellent machinability, ideal for high-volume automated parts, threaded components, and fittings requiring good corrosion resistance.
304 / 304L (18-8) Stainless Steel
Most Versatile
The most versatile austenitic stainless steel, offering superior corrosion resistance, formability, and weldability. Widely used in food processing, chemical, medical device, and general machinery applications.
316 / 316L Stainless Steel
Marine Grade
Molybdenum-enhanced austenitic stainless steel with significantly better resistance to chloride corrosion and pitting than 304 series. The preferred choice for marine environments, chemical equipment, high-end medical devices, and pharmaceutical industries.
416 Stainless Steel
Martensitic
A free-machining martensitic stainless steel that achieves higher strength through heat treatment. Suitable for shafts, gears, and valve components requiring good machinability along with moderate strength and corrosion resistance.
17-4 PH (630) Stainless Steel
Precipitation-Hardening
The most widely used precipitation-hardening stainless steel. It achieves high strength (up to H1100 condition) through aging treatment while maintaining good corrosion resistance. Ideal for aerospace, marine, and high-stress structural applications.
15-5 PH Stainless Steel
Enhanced Toughness
An improved precipitation-hardening stainless steel with performance similar to 17-4 PH, but offering better transverse toughness and dimensional stability during heat treatment.
410 & 420 Stainless Steel
General Purpose
General-purpose martensitic stainless steels. 410 offers moderate strength and corrosion resistance; 420, with higher carbon content, achieves greater hardness through heat treatment. Commonly used in cutlery, shafts, molds, and wear-resistant parts.
440C Stainless Steel
Highest Hardness
A high-carbon, high-chromium martensitic stainless steel with the highest hardness among stainless steels (HRC 58+). Exceptional wear resistance makes it ideal for high-end bearings, valve components, surgical instruments, and cutlery.
Nitronic 60 (218 SS)
High Performance
A high-performance nitrogen-strengthened austenitic stainless steel offering an exceptional combination of high wear resistance, strength, and corrosion resistance. Particularly suitable for critical applications involving galling and seizing resistance, such as bearings, valve seats, bushings, and food processing equipment.
Frequently Asked Questions
QWhat is the difference between 304 and 316 stainless steel?
The primary difference is that 316 stainless steel contains molybdenum (approximately 2–3%), which significantly improves its resistance to chloride corrosion and pitting. This makes 316 the preferred choice for marine, chemical, and pharmaceutical environments, while 304 is more economical and suitable for general-purpose applications.
QWhen should I choose a precipitation-hardening stainless steel like 17-4 PH or 15-5 PH?
Precipitation-hardening grades such as 17-4 PH and 15-5 PH are ideal when you need a combination of high strength, good corrosion resistance, and the ability to be machined before final aging treatment. They are commonly specified for aerospace components, marine hardware, and high-stress structural parts where standard austenitic grades lack sufficient strength.
QWhich stainless steel grade offers the best machinability for high-volume CNC production?
303 and 416 stainless steels are specifically engineered as free-machining grades. 303 is austenitic and offers good corrosion resistance alongside excellent machinability, making it ideal for automated CNC production of threaded parts and fittings. 416 is martensitic and can be heat-treated for higher strength after machining.
QWhat stainless steel is best suited for bearing and wear-resistant applications?
440C stainless steel is the top choice for applications requiring maximum hardness (HRC 58+) and wear resistance, such as high-end bearings and surgical instruments. Nitronic 60 is preferred when both wear resistance and galling/seizing resistance are critical, such as in valve seats, bushings, and food processing equipment.
QIs 304L or 316L better than standard 304 or 316 for welded assemblies?
Yes. The "L" (low carbon) variants — 304L and 316L — are specifically recommended for welded assemblies. Their reduced carbon content minimizes the risk of carbide precipitation (sensitization) at weld heat-affected zones, which can lead to intergranular corrosion in standard grades. For most welded applications, L-grades are the safer and more reliable choice.
QHow do martensitic stainless steels like 410, 420, and 440C compare to austenitic grades?
Martensitic stainless steels (410, 420, 440C) can be hardened through heat treatment to achieve significantly higher hardness and strength than austenitic grades (304, 316). However, they generally offer lower corrosion resistance and are magnetic. They are best suited for applications requiring hardness and wear resistance — such as cutlery, molds, and valve components — rather than maximum corrosion protection.
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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