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Stainless Steel CNC Machining Services in China - Reliable Suppliers and Factory for 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:
Austenitic Stainless Steels
303 Stainless Steel
A free-machining austenitic stainless steel with excellent machinability, ideal for high-volume automated parts, threaded components, and fittings requiring good corrosion resistance.
Free-Machining
Threaded Parts
Fittings
304 / 304L (18-8) Stainless Steel
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.
Food Processing
Medical
Chemical
316 / 316L Stainless Steel
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.
Marine Grade
Pharmaceutical
Anti-Pitting
Nitronic 60 (218 SS)
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.
Galling Resistant
Bearings
Valve Seats
Martensitic Stainless Steels
416 Stainless Steel
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.
Shafts & Gears
Heat Treatable
410 & 420 Stainless Steel
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.
Cutlery
Molds
Wear Resistant
440C Stainless Steel
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.
HRC 58+
Surgical Instruments
High-End Bearings
Max Hardness
Precipitation-Hardening Stainless Steels
17-4 PH (630) Stainless Steel
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.
Aerospace
High Strength
H1100
15-5 PH Stainless Steel
An improved precipitation-hardening stainless steel with performance similar to 17-4 PH, but offering better transverse toughness and dimensional stability during heat treatment.
Improved Toughness
Dimensional Stability
Q
What is the difference between 304 and 316 stainless steel, and how do I choose?
The primary difference is that 316 contains molybdenum (Mo), which significantly enhances resistance to chloride corrosion and pitting. If your application involves exposure to saltwater, marine environments, chemical processing, or pharmaceutical production, 316/316L is the recommended choice. For general food processing, household products, or indoor structural components, 304/304L offers excellent performance at a lower cost.
Q
What makes precipitation-hardening stainless steels like 17-4 PH and 15-5 PH unique?
Precipitation-hardening (PH) stainless steels achieve very high strength through an aging heat treatment process, while retaining good corrosion resistance. Unlike martensitic grades, PH steels can be machined in the annealed condition and then hardened with minimal dimensional distortion. 17-4 PH is the most widely used PH grade; 15-5 PH offers improved transverse toughness and is preferred when directional properties are critical.
Q
When should I choose a free-machining grade like 303 or 416 stainless steel?
Free-machining grades (303 for austenitic, 416 for martensitic) are formulated with added sulfur or selenium to improve chip breaking and tool life during machining. They are ideal for high-volume CNC production of complex parts such as threaded fasteners, fittings, shafts, and connectors. However, their weldability and corrosion resistance are slightly reduced compared to standard grades, so they are best suited for machined components rather than welded assemblies.
Q
Which stainless steel grade offers the highest hardness and wear resistance?
440C stainless steel achieves the highest hardness among all stainless steels, reaching HRC 58+ after heat treatment. Its high carbon and chromium content provide outstanding wear resistance, making it the top choice for precision bearings, valve components, surgical cutting instruments, and high-end cutlery. For applications where both wear resistance and anti-galling properties are critical, Nitronic 60 (218 SS) is also an excellent option.
Q
What is Nitronic 60, and what advantages does it offer over standard stainless steels?
Nitronic 60 (218 SS) is a nitrogen-strengthened austenitic stainless steel engineered specifically to resist galling and seizing — a common failure mode in metal-to-metal contact applications. Compared to standard grades like 304 or 316, it offers approximately twice the yield strength and significantly superior resistance to wear and surface damage without requiring heat treatment. It is widely used for valve seats, bushings, bearings, and food processing equipment where galling is a concern.
Q
Can martensitic stainless steels like 410, 420, and 440C be welded?
Martensitic stainless steels have limited weldability compared to austenitic grades. Their higher carbon content increases the risk of cracking during welding. When welding is required, pre-heating and post-weld heat treatment are typically necessary to minimize residual stresses and prevent cracking. For applications requiring both good weldability and moderate strength, austenitic grades (304, 316) or precipitation-hardening grades (17-4 PH) are generally preferred.
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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