+86-13928348837
China Stainless Steel CNC Machining: Reliable Suppliers & 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:
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
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
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 improves its resistance to chloride corrosion, pitting, and crevice corrosion compared to 304. This makes 316 the preferred choice for marine, chemical processing, and pharmaceutical applications, while 304 is more cost-effective for general-purpose use.
Q
When should I choose a precipitation-hardening stainless steel like 17-4 PH over standard austenitic grades?
Precipitation-hardening grades such as 17-4 PH or 15-5 PH are ideal when you need a combination of high strength, good corrosion resistance, and dimensional stability after heat treatment — requirements that standard austenitic grades like 304 or 316 cannot fully meet. They are commonly specified for aerospace components, high-stress structural parts, and precision mechanical assemblies.
Q
What makes 303 and 416 stainless steels "free-machining"?
Both 303 and 416 contain added sulfur (and sometimes selenium), which improves chip breaking during machining and reduces tool wear. This makes them significantly easier and more economical to machine at high volumes compared to standard 304 or 410 grades, though the added sulfur slightly reduces corrosion resistance and weldability.
Q
Which stainless steel grade offers the best wear resistance?
440C stainless steel offers the highest hardness (up to HRC 58+) among standard stainless steels, making it excellent for wear-critical applications such as bearings and cutting tools. For applications also requiring galling and seizing resistance, Nitronic 60 (218 SS) is the superior choice due to its unique combination of wear resistance, strength, and corrosion resistance.
Q
Can martensitic stainless steels like 410 and 420 be hardened?
Yes. Martensitic stainless steels such as 410, 420, and 440C can be hardened through conventional heat treatment (austenitizing and quenching). 420 achieves greater hardness than 410 due to its higher carbon content, and 440C achieves the highest hardness of the group. This makes them well-suited for cutlery, molds, shafts, and wear-resistant components.
Q
What is Nitronic 60 and why is it used in galling-prone applications?
Nitronic 60 (also known as 218 SS) is a nitrogen-strengthened austenitic stainless steel developed specifically to resist galling and seizing — a form of severe adhesive wear that occurs between metal surfaces under sliding contact. Its high silicon and manganese content, combined with nitrogen strengthening, provides outstanding anti-galling properties, making it the material of choice for valve seats, bushings, bearings, and food processing equipment where standard stainless steels would fail prematurely.
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.