What Is AISI 630 Stainless Steel Ground Tube?
Jan 13, 2026
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What is AISI 630 stainless steel ground tube?
AISI 630 Precision ground tubing refers to tubing with an outer diameter (OD) that has been precisely ground, exhibiting the following characteristics:
1. Extremely tight diameter and roundness tolerances
2. High surface finish, typically Ra 0.2–0.4 μm
3. Higher concentricity, reducing vibration in rotating applications
AISI 630 stainless steel precision ground tubing is suitable for high-speed shafts and spindles, hydraulic cylinders, and aerospace and automotive structural components
Chemical Composition of SS 630
| Element | Chromium (Cr) | Nickel (Ni) | Copper (Cu) | Niobium (Nb) | Carbon (C) | Manganese (Mn) | Silicon (Si) | Phosphorus (P) | Sulfur (S) |
| Percentage (%) | 15-17.5 | 3-5 | 3-5 | 0.15-0.45 | ≤0.07 | ≤1.00 | ≤1.00 | ≤0.04 | ≤0.03 |
Mechanical Properties of SS 630
| Condition | Properties | Tensile Strength (MPa/ksi) | Yield Strength (MPa/ksi) | Vickers Hardness (HV) | Brinell Hardness (HB) | Rockwell Hardness (HRC) | Elongation (%) | Elastic Modulus (GPa/ksi) |
| Condition A | Tensile Strength | 930-1080 / 135-157 | 725-860 / 105-125 | 293-353 | 280-360 | 29-35 | 20-25 | 200 / 29000 |
| Condition H900 | Tensile Strength | 1310 / 190 | 1170 / 170 | 410 | 375 | 44 | 10-12 | 200 / 29000 |
| Condition H1025 | Tensile Strength | 1070 / 155 | 1000 / 145 | 360 | 340 | 38 | 12-15 | 200 / 29000 |
| Condition H1075 | Tensile Strength | 1000 / 145 | 930 / 135 | 340 | 320 | 35 | 13-16 | 200 / 29000 |
| Condition H1150 | Tensile Strength | 930 / 135 | 860 / 125 | 310 | 300 | 30 | 16-18 | 200 / 29000 |
Physical Properties of SS 630
| Property | Metric (SI) | Imperial (US) |
| Density | 7.80 g/cm³ | 0.282 lb/in³ |
| Melting Point | 1400-1440°C | 2550-2625°F |
| Thermal Conductivity | 16.3 W/m·K | 9.4 BTU/(hr·ft·°F) |
| Electrical Resistivity | 0.8 x 10⁻⁶ Ω·m | 31.5 x 10⁻⁶ Ω·in |
| Specific Heat Capacity | 460 J/kg·K | 0.11 BTU/lb·°F |
| Thermal Expansion Coefficient | 10.8 x 10⁻⁶ /K (20-100°C) | 6.0 x 10⁻⁶ /°F (70-212°F) |
Equivalent Grades of 630 Stainless Steel
| Equivalent Grade | Europe (EN) | Japan (JIS) | China (GB) | India (IS) |
| 630 Stainless Steel | 1.4542 | SUS630 | 0Cr17Ni4Cu4Nb | X5CrNiCuNb16-4 |
What is the difference between a standard tube and a ground tube?
A ground tube is precision-ground on the OD, providing tighter tolerances, smoother surface finish, and better roundness compared to a standard tube.
Can AISI 630 ground tubes be welded?
Yes, but welding requires proper heat treatment before and after welding to maintain strength and corrosion resistance.
What is the maximum hardness of AISI 630 stainless steel?
After full precipitation hardening, it can reach 45–50 HRC, offering excellent wear resistance.
Are AISI 630 ground tubes suitable for marine applications?
Yes, they resist corrosion in mild marine environments, but for highly saline or submerged applications, 316 stainless steel may be better.
If you have project requirements for 630 stainless steel pipes, we welcome your order. GNEE has a large inventory of popular products for you to choose from. Available in both seamless and welded forms, please contact our factory immediately for detailed chemical composition information and free samples. We offer competitive prices and excellent service.
The pipes are packaged with waterproof paper and steel straps, meeting standard export sea freight packaging requirements, suitable for various transportation methods, or customized according to customer requirements.
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