Stainless steel
It features high hardness and strength, corrosion resistance, and good thermal stability, as well as excellent rigidity and durability, making it suitable for demanding structural components.
Process options:
- CNC machining
- Laser cutting
- Sheet metal
- Surface finish
Surface finish : Mechanical Polishing,Brushed / Satin Finish,Sand Blasting / Bead Blasting,Passivation,Electropolishing,PVD,Nickel / Chrome Plating.
What is stainless steel material?
Stainless steel is an alloy steel with an iron base that acquires excellent corrosion resistance through the addition of alloying elements—such as chromium—which form a passivating protective film. Depending on its composition, it can be classified into categories such as austenitic, ferritic, and martensitic, while simultaneously possessing a favorable balance of strength and formability.
Main Types for stainless steel cnc machining
304 stainless steel
Feature:As the most commonly used austenitic stainless steel, it possesses excellent corrosion resistance, heat resistance, and formability, and is easy to weld and process.
Application:Widely used in food processing, chemical, and medical fields, such as kitchen equipment, chemical containers, and medical device components.
Tensile Strength, Yield (MPa)：215
Shear Modulus (GPa) ：77
Elongation at Break (%) ：70
Hardness (Brinell) ：123
Density (g/cm^3) ：8
316 Stainless steel
Feature:The addition of molybdenum to 304 stainless steel significantly improves corrosion resistance, particularly against chloride ion corrosion, while maintaining good high-temperature performance.
Application:Suitable for equipment and components in harsh environments such as marine environments, chemical processing, and pharmaceuticals, including seawater treatment equipment, chemical reactors, and medical devices.
Tensile Strength, Yield (MPa)：205
Shear Modulus (GPa) ：74
Elongation at Break (%) ：40
Hardness (Brinell) ：187
Density (g/cm^3) ：8.03
416 Stainless steel
Feature : Martensitic stainless steel, with added sulfur to improve machinability, also possesses high strength and hardness, as well as good corrosion resistance.
Applications : Suitable for manufacturing mechanical parts requiring high strength and good machinability, such as pump bodies, valves, and automotive transmission components.
Tensile Strength, Yield (MPa)：275
Shear Modulus (GPa) ：83
Elongation at Break (%) ：30
Hardness (Brinell) ：156
Density (g/cm^3) ：7.8
420 stainless steel
Feature ：Martensitic stainless steel, possessing high hardness and wear resistance. Its mechanical properties can be adjusted through heat treatment to meet various requirements.
Application : Suitable for manufacturing cutting tools, molds, surgical instruments, and other components requiring high hardness and wear resistance.
Tensile Strength, Yield (MPa)：345
Shear Modulus (GPa) ：80.7
Elongation at Break (%) ：25
Hardness (Brinell) ：198
Density (g/cm^3) ：7.8
303 stainless steel
Feature:Sulfur is added to improve machinability and ease of machining, while maintaining basic corrosion resistance.
Applications: Suitable for manufacturing parts that require frequent machining and do not have extremely high corrosion resistance requirements, such as nuts, bolts, shafts, and parts for automated equipment.
Tensile Strength, Yield (MPa)：240
Shear Modulus (GPa) ：77.2
Elongation at Break (%) ：50
Hardness (Brinell) ：160
Density (g/cm^3) ：8
2205 Duplex Stainless Steel
Feature : Combining the advantages of austenitic and ferritic stainless steels, it possesses excellent corrosion resistance, high strength, and good weldability, while also being cost-effective.
Applications : Suitable for equipment and components in high-stress, high-corrosion environments in industries such as oil, gas, and chemicals, such as pipes, valves, and pump bodies.
Tensile Strength, Yield (MPa)：620～900
Shear Modulus (GPa) ：220
Elongation at Break (%) ：27
Hardness (Brinell) ：300
Density (g/cm^3) ：7.8
410 stainless steel
Feature :Chromium-containing martensitic stainless steel possesses high hardness and strength, good wear resistance, and some corrosion resistance. It is heat-treatable, magnetic, and has a low nickel content.
Application : It is widely used in the manufacture of knives and tableware, machine parts processing, some medical device production, and the production of atmospheric corrosion-resistant components in the petrochemical industry. (Bearings, gears, pump shafts, valve components, scalpels, pipes, fasteners)
Tensile Strength, Yield (MPa)：310
Shear Modulus (GPa) ：73
Elongation at Break (%) ：25
Hardness (Brinell) ：148
Density (g/cm^3) ：7.8
17-4PH stainless steel
Feature: Precipitation-hardening martensitic stainless steel with high strength, high hardness and excellent corrosion resistance, outstanding overall mechanical properties. Performance adjustable via heat treatment, strong magnetism, excellent dimensional stability, suitable for high-precision working conditions.
Application: Widely used in aerospace components, oil and gas equipment, high-strength mechanical parts, valve assemblies, pump shafts, fasteners, chemical equipment and structural parts requiring both strength and corrosion resistance.
Tensile Strength (MPa): 1150
Yield Strength (MPa): 810
Elongation at Break (%): 13
Hardness (Brinell): 340
Density (g/cm³): 7.8
Surface finish for stainless steel parts
Surface finish is crucial for improving the performance and appearance of the parts. It not only improves surface quality and enhances corrosion and wear resistance but also adds to their aesthetic appeal. The following introduces several practical surface finish methods for stainless steel parts.
Machined finish
The prototype processed by the machine tool retains traces of tool machining.
Anodizing
Polish
Sand blasting
Uses high-pressure abrasives to create a clean, rough, matte surface finish.
Brushed finish
Powder coating
Uses electrostatic application and heat curing to form a dense layer, improving corrosion resistance on parts.
Electroplating finish
Deposits a metal layer to improve corrosion and wear resistance.
Black oxidize
Forms a low-cost, anti-reflective coating on metal surfaces via simple chemical oxidation.
Alodine
Forms a corrosion-resistant coating via chemical conversion, improving adhesion and conductivity.
Heat treatment
Guideline of cnc machining stainless steel :
Material Inspection : Stainless steel composition is analyzed using a spectrometer. For 304 series stainless steel, ensure Cr ≥ 16% and Ni ≥ 8%, and generate a material report.
Process Planning : Process is broken down according to the 3D model (STEP/IGS), prioritizing high-speed machining (HSC), with a cutting speed of 100-300 m/min.
Tool Selection : Carbide TiAlN coated tools, feed rate 0.1-0.3 mm/r, depth of cut 0.5-2 mm. PCD tools are used for difficult-to-machine materials such as 316L.
Key Control Points : After rough machining, low-temperature aging at 200℃ for 2 hours to relieve internal stress and prevent deformation.
Cutting Parameters : Milling of 304 stainless steel, VC = 150 m/min, f = 0.15 mm/z, ap = 1.5 mm, oil mist lubrication and cooling.
First Article Inspection : The first article of each batch is inspected dimensionally using a CMM, and a PPAP document is generated.
Inspection frequency : 3 pieces are randomly selected from every 50 pieces produced in batches, and critical dimensions are monitored online using a laser diameter gauge.
Record requirements : Complete machining parameter records (cutting speed, feed rate, tool life) must be maintained for at least 3 years.
Capability of machining stainless steel :
Maximum dimensions : 1500mm×800mm×600mm
Minimum machining dimensions : 5mm×5mm×0.5mm
Maximum machining length : 3000mm
Diameter range : φ3mm-φ500mm
Positioning accuracy : X/Y/Z axis positioning accuracy up to ±0.005mm, repeatability ±0.003mm
Linear dimensional tolerance : Up to IT5 grade (±0.013mm/300mm)
Angle tolerance : ±5″
Surface quality : Mirror finish Ra≤0.2μm, precision grinding Ra≤0.4μm, conventional milling Ra≤1.6μm
Geometric tolerances : Flatness ≤0.01mm/1000mm, Cylindricity ≤0.005mm, Perpendicularity ≤0.008mm/300mm
Advantage of stainless steel material
1. Excellent corrosion resistance, preventing rust even in humid, acidic or alkaline environments.
2. Good strength and toughness with stable structure and high resistance to deformation.
3. Attractive surface that is easy to clean, ideal for hygienic applications such as food and medical industries.
4. Outstanding high and low temperature resistance, performing reliably over a wide temperature range.
5. Eco-friendly and recyclable, with long service life and no release of harmful substances.
Application of stainless steel part
Aerospace：Machines turbine blades and hydraulic parts, using heat and corrosion resistance (e.g., 310S up to 1900°F) for harsh conditions.
Medical Devices：Produces implants, biopsy tubes, and holders, meeting strict sterility and biocompatibility requirements.
Automotive Industry：Manufactures shafts, gears, and fuel parts, combining wear resistance with aesthetic quality.
Food Processing Equipment：Machines valves and fittings with 304/304L stainless steel, ensuring corrosion resistance and easy cleaning.
Marine Engineering：Produces ship and offshore parts using 316L stainless steel for excellent seawater corrosion resistance.
Chemical & Petroleum：Makes pumps, valves, and reactors, designed to withstand acids, alkalis, and high temperature/pressure environments.
FAQ of stainless steel material
Is stainless steel self-healing?
Stainless steel does not possess true self-healing capabilities; however, the chromium oxide passivation film formed on its surface can regenerate upon exposure to oxygen after sustaining minor damage, thereby providing a protective effect akin to self-healing.
Is 304 or 316 stainless steel better?
There is no absolute “better” between 304 and 316 stainless steel; it depends on the application.304 is more cost-effective for indoor, dry environments and general food equipment.316 offers significantly higher corrosion resistance due to molybdenum content, making it more durable in humid, coastal, seawater or acidic conditions.
What is the best grade of stainless steel?
There is no single “best” grade of stainless steel, as the most suitable one depends entirely on the application. For general‑purpose use with balanced performance and cost, 304 is the most common choice; for superior corrosion resistance in marine, chemical or harsh environments, 316L is preferred; and for applications requiring high strength and heat treatability, precipitation‑hardening grades such as 17‑4PH are more appropriate.
