631 Stainless Steel Coil: High-Strength, Corrosion-Resistant Precipitation-Hardening Stainless Steel
Meta Description: Discover 631 stainless steel coil, offering up to 1650 MPa strength and superior corrosion resistance. Ideal for aerospace, medical components, and high-performance fasteners.
Introduction
631 Stainless Steel Coil (UNS S17700) is a semi-austenitic precipitation-hardening stainless steel that delivers the highest strength among precipitation-hardening stainless steels—up to 1650 MPa. This exceptional strength is complemented by excellent corrosion resistance, making it a preferred choice for critical applications in aerospace, medical, and high-performance sectors. Whether you're manufacturing aircraft fasteners, medical instruments, or turbine components, 631 stainless steel coil offers a robust material that ensures long-lasting performance under extreme conditions.
With excellent fatigue resistance, machinability in annealed conditions, and high tensile strength, 631 stainless steel coil stands out as one of the top materials in its class. As a semi-austenitic grade, it exhibits superior performance compared to standard stainless steels like 304 and 316. This grade shares its composition with 17-7PH stainless steel, making it ideal for pre-stressed springs, surgical instruments, and pressure vessels that require high resistance to stress, fatigue, and corrosion.
From solution annealed to precipitation hardened conditions, 631 stainless steel coil can be tailored to meet specific application needs, offering a versatile solution for a range of industries. In addition, our direct relationships with mills allow us to provide the best 631 stainless steel coil price with fastest global delivery, backed by comprehensive quality assurance processes, including ultrasonic testing and PMI testing.
Product Overview & Key Advantages
- Exceptional Strength: 631 stainless steel coil offers up to 1650 MPa yield strength, making it ideal for high-stress applications such as aerospace springs and medical devices.
- Corrosion Resistance: Excellent resistance to pitting, stress corrosion cracking, and general corrosion, particularly in chloride-rich environments.
- High Fatigue Resistance: The semi-austenitic structure provides superior fatigue performance, making it perfect for components subjected to cyclic loading.
- Machinability in Annealed Condition: Can be easily processed and machined in its solution annealed condition, reducing manufacturing costs and improving production efficiency.
- Precipitation Hardening: Ability to achieve different mechanical properties by controlling aging conditions (RH950, CH900, TH1050, TH1100), offering flexibility for various applications.
- Widely Used in Aerospace and Medical: Ideal for aerospace springs, aircraft fasteners, medical surgical tools, and pressure vessel components.
- High-Performance Fasteners: Offers reliable performance in extreme conditions, including high pressure and temperatures, making it a go-to material for high-strength fasteners.
Chemical Composition
| Element | Percentage (%) |
|---|---|
| Chromium (Cr) | 16–18 |
| Nickel (Ni) | 6.5–7.75 |
| Aluminum (Al) | 0.75–1.5 |
| Iron (Fe) | Balance |
| Carbon (C) | ≤ 0.07 |
| Manganese (Mn) | ≤ 1.0 |
| Silicon (Si) | ≤ 1.0 |
| Phosphorus (P) | ≤ 0.04 |
| Sulfur (S) | ≤ 0.03 |
| Niobium (Nb) | 0.15–0.45 |
631 stainless steel coil is composed of high chromium (16–18%) and nickel (6.5–7.75%), ensuring its high strength and resistance to corrosion in aggressive environments. Aluminum is added to improve the precipitation-hardening properties, enhancing its strength further. The low carbon content minimizes the risk of carbide precipitation, preserving the material's integrity and enhancing its corrosion resistance.
Mechanical Properties
| Condition | Yield Strength (MPa) | Ultimate Tensile Strength (MPa) | Elongation (%) | Hardness (HRC) |
|---|---|---|---|---|
| Solution Annealed | 550 | 850 | 20 | 25–30 |
| RH950 | 950 | 1150 | 10 | 38–42 |
| CH900 | 900 | 1100 | 10 | 35–40 |
| TH1050 | 1050 | 1200 | 6 | 40–44 |
| TH1100 | 1100 | 1250 | 5 | 42–46 |
631 stainless steel coil exhibits superior strength in all heat-treated conditions, from solution annealed to high-strength conditions like RH950 and TH1100. The RH950 condition provides an optimal balance of strength and ductility, achieving a yield strength of 950 MPa. The TH1050 and TH1100 conditions offer the highest tensile strength, up to 1250 MPa, making 631 stainless steel coil ideal for critical applications where high fatigue resistance and strength are required.
Physical Properties
| Property | Value |
|---|---|
| Density (g/cm³) | 7.75 |
| Thermal Conductivity (W/m·K) | 16.3 |
| Specific Heat (J/kg·K) | 460 |
| Electrical Resistivity (Ω·cm) | 0.00074 |
| Magnetic (after hardening) | Yes |
631 stainless steel coil has a density of 7.75 g/cm³ and exhibits moderate thermal conductivity and electrical resistivity, offering reliable performance in applications requiring temperature stability and resistance to electrical currents. After hardening, it becomes magnetic, which is a key consideration for certain applications where non-magnetic properties are required.
631 vs 630 vs 17-7PH vs 304 vs 316 Coil Comparison
| Property | 631 Stainless Steel | 630 Stainless Steel | 17-7PH Stainless Steel | 304 Stainless Steel | 316 Stainless Steel |
|---|---|---|---|---|---|
| Yield Strength (MPa) | 1650 | 1300 | 1100 | 250 | 290 |
| Corrosion Resistance | Excellent | Good | Excellent | Good | Excellent |
| Hardness (HRC) | 38–48 | 35–45 | 38–44 | 20–30 | 25–35 |
| Heat Treatment | RH950, CH900, TH1050 | H900, H925 | RH950, CH900 | Annealed | Annealed |
| Cost | High | Moderate | Moderate | Low | High |
631 stainless steel coil provides higher strength than 630 and 17-7PH, making it the best option for applications that demand maximum tensile strength and fatigue resistance. Compared to 304 and 316, 631 offers better mechanical properties while still maintaining excellent corrosion resistance.
Available Specifications
| Thickness (mm) | Width (mm) | ID (mm) | Finish Types |
|---|---|---|---|
| 0.3–6.0 | 20–1500 | 300/400/508/610 | 2B, 2D, Bright Annealed, No.4, Polished |
Our 631 stainless steel coil is available in various thicknesses from 0.3 mm to 6.0 mm and widths up to 1500 mm. We also offer various inner diameters for coils, including 300 mm, 400 mm, 508 mm, and 610 mm. Available finishes include 2B, bright annealed, No.4, and polished, allowing you to select the finish that best suits your needs.
Heat Treatment & Precipitation Hardening Guide
631 stainless steel undergoes solution annealing at 1040 °C and can be aged to achieve desired mechanical properties. Aging conditions such as RH950, CH900, TH1050, and TH1100 can be applied to achieve the appropriate strength and hardness, ranging from 38 HRC to 48 HRC.
Major Applications
- Aerospace structural springs
- Aircraft fasteners
- Medical instrument components
- High-strength bellows
- Pressure vessel diaphragms
- Turbine parts
- Nuclear reactor components
- Surgical tools
- High-performance springs
- Chemical processing coil tubing
631 stainless steel coil is widely used in aerospace, medical, and industrial applications where both high strength and corrosion resistance are essential. From aircraft springs to medical tools, this material excels in demanding environments.
Product Images
Hot-rolled 631 stainless steel coils ready for shipment
Professional infographic 631 stainless steel coil data sheet + mechanical properties chart
Real-application collage – 631 coils used in aerospace springs, medical instruments, and high-performance components
Why We Are the Best 631 Stainless Steel Coil Distributor
As a top-tier 631 stainless steel coil supplier, we offer extensive stocks across all conditions, including solution annealed and precipitation-hardened grades. Our direct relationships with mills ensure the best 631 stainless steel coil price, along with ultrasonic testing, PMI testing, and precision slitting capabilities. We provide fast global delivery, oscillated winding, and full EN 10204 3.1/3.2 certificates for every order.
Packaging & Delivery Standards
We use export-standard wooden saddles, VCI paper for corrosion protection, and steel edge protection to ensure the safe delivery of your 631 stainless steel coil. Weight limits are strictly adhered to, ensuring efficient transport and delivery.
FAQ Section
- What is the maximum hardness of 631 stainless steel coil?
- 48 HRC in TH1100 condition.
- Is 631 stainless steel coil magnetic after hardening?
- Yes, it becomes magnetic.
- 631 vs 17-7PH differences?
- 631 is the same as 17-7PH but with higher strength.
- Can 631 coil be welded and what filler?
- Yes, use 17-7PH filler wire.
- Recommended condition for maximum strength?
- CH900 or TH1100 for maximum strength.
- Corrosion resistance in chloride environments?
- Excellent, especially in chloride-rich and seawater environments.
- Minimum order quantity?
- Contact us for MOQ details.
- Lead time for RH950 condition 631 coil?
- Typically 4–6 weeks.
- Is 631 coil suitable for cryogenic applications?
- Yes, 631 retains excellent low-temperature performance.
Conclusion + Urgent Call-to-Action
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