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China Stainless Steel CNC Machining Services - Leading Suppliers and Factory for High Precision Parts
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
Aerospace Grade
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
PH Grade
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 (can be hardened to 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
Q
What is the difference between 304 and 316 stainless steel?
The primary difference is that 316 stainless steel contains molybdenum (typically 2–3%), which significantly enhances its resistance to chloride-induced corrosion and pitting. This makes 316 the preferred choice for marine environments, pharmaceutical, and chemical processing applications, while 304 is more commonly used in general-purpose and food-grade applications.
Q
What is precipitation-hardening stainless steel, and when should I use it?
Precipitation-hardening (PH) stainless steels, such as 17-4 PH and 15-5 PH, achieve high strength through an aging heat treatment process. They are ideal when you need a combination of high mechanical strength, good corrosion resistance, and dimensional stability — commonly required in aerospace, defense, marine, and high-stress structural components.
Q
Which stainless steel grade offers the best machinability?
303 and 416 stainless steels are specifically designed for free-machining. They contain added sulfur which improves chip breakage and reduces tool wear, making them excellent choices for high-volume CNC machining of complex parts such as threaded components, shafts, and fittings.
Q
Which stainless steel grade is best for high-wear applications like bearings and valve seats?
440C stainless steel offers the highest hardness (up to HRC 58+) among standard stainless grades, making it excellent for bearings and cutting tools. For applications where galling and seizing resistance is critical — such as valve seats, bushings, and food processing equipment — Nitronic 60 (218 SS) provides an exceptional combination of wear resistance, strength, and corrosion resistance.
Q
Can martensitic stainless steels like 410 and 420 be heat treated?
Yes. Martensitic stainless steels including 410, 420, 416, and 440C can be hardened through heat treatment. 410 offers moderate hardness and corrosion resistance after hardening, while 420 and 440C, with higher carbon content, can achieve significantly greater hardness — making them suitable for molds, cutlery, surgical instruments, and wear-resistant components.
Q
What is the difference between 17-4 PH and 15-5 PH stainless steel?
Both are precipitation-hardening stainless steels with similar strength and corrosion resistance profiles. The key distinction is that 15-5 PH offers improved transverse toughness and better dimensional stability during heat treatment compared to 17-4 PH. This makes 15-5 PH preferable for applications where consistent mechanical properties in all directions and tight dimensional tolerances are 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.
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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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