Stainless Steel SUS630 (17-4PH)
Introduction to Stainless Steel SUS630 (17-4PH): A Precipitation-Hardening Stainless Steel
Stainless Steel SUS630, commonly known as 17-4PH, is a precipitation-hardening stainless steel alloy that combines high strength, hardness, and corrosion resistance. With a composition primarily consisting of 15–17.5% chromium and 3–5% nickel, this alloy is widely used in high-performance applications, including aerospace, chemical processing, and marine industries. The alloy’s unique combination of properties makes it suitable for components requiring high strength and moderate corrosion resistance.
The precipitation-hardening process allows SUS630 to achieve tensile strengths of up to 1,200 MPa after aging, making it one of the strongest stainless steels available. CNC machining of SUS630 requires specific techniques due to its hardness after heat treatment. At Neway, CNC-machined SUS630 parts undergo precise machining processes to ensure tight tolerances and smooth surface finishes for demanding applications.
SUS630 Stainless Steel: Key Properties and Composition
SUS630 Stainless Steel Chemical Composition
Element | Composition (wt%) | Role/Impact |
|---|---|---|
Carbon (C) | ≤0.07% | Low carbon content minimizes the risk of carbide precipitation, enhancing weldability. |
Manganese (Mn) | 1.00% | Improves strength and toughness at lower temperatures. |
Chromium (Cr) | 15.0–17.5% | Provides resistance to corrosion and oxidation, enhancing durability. |
Nickel (Ni) | 3.0–5.0% | Contributes to formability and increases toughness. |
Copper (Cu) | 3.0–5.0% | Adds precipitation hardening capabilities, improving strength after aging. |
Molybdenum (Mo) | ≤0.60% | Increases resistance to pitting and crevice corrosion, especially in chloride environments. |
SUS630 Stainless Steel Physical Properties
Property | Value | Notes |
|---|---|---|
Density | 7.75 g/cm³ | Similar to other martensitic stainless steels, ensuring durability. |
Melting Point | 1,400–1,530°C | Suitable for both cold and hot working, ideal for high-temperature applications. |
Thermal Conductivity | 25.4 W/m·K | Moderate heat dissipation, suitable for high-heat applications. |
Electrical Resistivity | 7.4×10⁻⁷ Ω·m | Low electrical conductivity, ideal for non-electrical applications. |
SUS630 Stainless Steel Mechanical Properties
Property | Value | Testing Standard/Condition |
|---|---|---|
Tensile Strength | 1,000–1,200 MPa | ASTM A564/A564M standard |
Yield Strength | 900 MPa | Suitable for high-strength applications |
Elongation (50mm gauge) | 10–12% | Moderate ductility for shaping and forming. |
Brinell Hardness | 330–370 HB | Achieved after precipitation hardening, offering excellent wear resistance. |
Machinability Rating | 50% (vs. 1212 steel at 100%) | Suitable for machining, though it requires sharp tooling and lower cutting speeds. |
Key Characteristics of SUS630 Stainless Steel: Benefits and Comparisons
SUS630 (17-4PH) stainless steel is known for its exceptional hardness, strength, and corrosion resistance. Below is a technical comparison highlighting its unique advantages over similar materials like SUS304 Stainless Steel, SUS410 Stainless Steel, and SUS440C Stainless Steel.
1. High Strength and Hardness
Unique Trait: SUS630 offers exceptional strength and hardness after precipitation hardening, reaching up to 1,200 MPa tensile strength.
Comparison:
vs. SUS304 Stainless Steel: SUS304 has much lower strength and hardness compared to SUS630, making it less suitable for high-stress applications.
vs. SUS410 Stainless Steel: SUS410 offers lower hardness and tensile strength compared to SUS630, making it more suitable for general-purpose use.
vs. SUS440C Stainless Steel: SUS440C provides high hardness, but SUS630 offers superior strength and resistance to fatigue.
2. Corrosion Resistance
Unique Trait: SUS630 provides moderate corrosion resistance, making it suitable for industrial and marine environments, though it is not as resistant as austenitic steels.
Comparison:
vs. SUS304 Stainless Steel: SUS304 offers superior corrosion resistance in most environments, especially in acidic and chloride-rich conditions.
vs. SUS410 Stainless Steel: SUS410 has lower corrosion resistance than SUS630, especially in chloride environments.
vs. SUS440C Stainless Steel: SUS440C has better resistance to pitting and corrosion in specific environments, but SUS630 offers higher strength.
3. Machinability
Unique Trait: SUS630 can be easily machined after heat treatment, but due to its hardness, it requires carbide tools and slower machining speeds to achieve precision.
Comparison:
vs. SUS304 Stainless Steel: SUS304 is easier to machine and more ductile, but it does not offer the same hardness or wear resistance as SUS630.
vs. SUS410 Stainless Steel: SUS410 is easier to machine than SUS630, but it offers lower hardness and strength.
vs. SUS440C Stainless Steel: SUS440C is harder to machine than SUS630, but it provides comparable hardness and wear resistance.
4. Cost-Effectiveness
Unique Trait: SUS630 provides excellent strength and corrosion resistance at a reasonable price, making it a cost-effective solution for high-strength applications.
Comparison:
vs. SUS304 Stainless Steel: SUS304 is more expensive due to its higher nickel content and superior corrosion resistance.
vs. SUS410 Stainless Steel: SUS410 is less expensive than SUS630 but does not offer the same level of strength and wear resistance.
vs. SUS440C Stainless Steel: SUS440C is more expensive than SUS630 but offers similar hardness and wear resistance for specific applications.
CNC Machining Challenges and Solutions for SUS630 Stainless Steel
Machining Challenges and Solutions
Challenge | Root Cause | Solution |
|---|---|---|
Work Hardening | High carbon content and hardness | Use carbide tools with TiN coatings to improve tool life. |
Surface Roughness | Brittle material causing "tearing" | Optimize feed rates and use sharp, high-speed tools for smoother finishes. |
Tool Wear | High hardness and abrasiveness | Use high-performance coatings like TiAlN to reduce friction and tool wear. |
Dimensional Inaccuracy | Stresses from machining | Perform stress-relief annealing to reduce dimensional variations and improve precision. |
Chip Control Issues | Hard, continuous chips | Use high-pressure coolant and optimize tool geometry to break chips. |
Optimized Machining Strategies
Strategy | Implementation | Benefit |
|---|---|---|
High-Speed Machining | Spindle speed: 1,200–1,800 RPM | Increases productivity and reduces heat buildup. |
Climb Milling | Cutting in the direction of tool rotation | Improves surface finish (Ra 1.6–3.2 µm). |
Toolpath Optimization | Use trochoidal milling for deep pockets | Reduces cutting forces, minimizing part deflection. |
Stress-Relief Annealing | Preheat to 650°C for 1 hour per inch | Minimizes residual stress and improves machining accuracy. |
Cutting Parameters for SUS630 Stainless Steel
Operation | Tool Type | Spindle Speed (RPM) | Feed Rate (mm/rev) | Depth of Cut (mm) | Notes |
|---|---|---|---|---|---|
Rough Milling | 4-flute carbide end mill | 1,000–1,500 | 0.15–0.25 | 2.0–4.0 | Use coolant to prevent work hardening. |
Finish Milling | 2-flute carbide end mill | 1,500–2,000 | 0.05–0.10 | 0.5–1.0 | Climb milling for smoother finishes (Ra 1.6–3.2 µm). |
Drilling | 135° split-point HSS drill | 600–800 | 0.10–0.15 | Full hole depth | Peck drilling for precise hole formation. |
Turning | CBN or coated carbide insert | 500–700 | 0.20–0.30 | 1.5–3.0 | Dry machining is acceptable with air blast cooling. |
Surface Treatments for CNC Machined SUS630 Stainless Steel Parts
Electroplating: Adds a corrosion-resistant metallic layer, extending part life in humid environments and improving strength.
Polishing: Enhances the surface finish, providing a smooth, shiny appearance ideal for visible components.
Brushing: Creates a satin or matte finish, masking minor surface defects and improving aesthetic quality for architectural components.
PVD Coating: Boosts wear resistance, increasing tool life and part longevity in high-contact environments.
Passivation: Creates a protective oxide layer, enhancing corrosion resistance in mild environments without altering dimensions.
Powder Coating: Offers high durability, UV resistance, and a smooth finish, ideal for outdoor and automotive parts.
Teflon Coating: Provides non-stick and chemical-resistant properties, ideal for food processing and chemical handling components.
Chrome Plating: Adds a shiny, durable finish that enhances corrosion resistance, commonly used in automotive and tooling applications.
Black Oxide: Provides a corrosion-resistant black finish, ideal for parts in low-corrosion environments like gears and fasteners.
Industry Applications of CNC Machined SUS630 Stainless Steel Parts
Aerospace Industry
Turbine Components: SUS630’s high strength and hardness make it ideal for turbine components in aircraft engines.
Automotive Industry
Drive Shafts and Bearings: The material’s wear resistance is suitable for automotive components that undergo continuous friction.
Chemical Processing Industry
Valves and Pumps: SUS630’s corrosion resistance and strength benefit components exposed to harsh chemicals.
Technical FAQs: CNC Machined SUS630 Stainless Steel Parts & Services
How does SUS630 compare to other precipitation-hardened stainless steels like SUS17-4PH regarding mechanical properties?
What are the ideal machining conditions for achieving the best surface finish when machining SUS630?
Can SUS630 be used in marine applications, and how does it compare to SUS316 in terms of corrosion resistance?
What heat treatment process is required to achieve optimal hardness in SUS630 stainless steel?
How does the machinability of SUS630 compare to other martensitic stainless steels like SUS440C?
Explore Related Blogs
