GB/T 3098.6-2014 specifies the mechanical properties of bolts, screws, and studs made from corrosion-resistant stainless steels when tested at an ambient temperature range of 10°C to 35°C. This standard applies to fasteners with nominal thread diameters from 5 mm to 100 mm, ensuring reliable performance in various industrial applications. It categorizes stainless steels into austenitic, martensitic, and ferritic groups, defining property classes based on tensile strength, yield strength, elongation, and hardness.
機械的特性
The mechanical properties outlined in GB/T 3098.6-2014 ensure that stainless steel fasteners meet specific strength and ductility requirements. These properties are critical for applications requiring corrosion resistance combined with mechanical integrity. The table below details the minimum values for tensile strength (Rm), proof stress (Rp0.2), elongation after fracture (A), and hardness ranges for different steel groups and property classes.
| スチールグループ | Steel Grade | プロパティクラス | Tensile Strength Rm (MPa) min | Proof Stress Rp0.2 (MPa) min | Elongation A min (in multiples of d) | Hardness HB | Hardness HRC | Hardness HV | |||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 分 | 最大 | 分 | 最大 | 分 | 最大 | ||||||
| Austenitic | A1, A2, A3, A4, A5 | 50 | 500 | 210 | 0.6d | – | – | – | – | – | – |
| 70 | 700 | 450 | 0.4d | – | – | – | – | – | – | ||
| 80 | 800 | 600 | 0.3d | – | – | – | – | – | – | ||
| Martensitic | C1 | 50 | 500 | 250 | 0.2d | 147 | 209 | – | – | 155 | 220 |
| 70 | 700 | 410 | 0.2d | 209 | 314 | 20 | 34 | 220 | 330 | ||
| 1101 | 1100 | 820 | 0.2d | – | – | 36 | 45 | 350 | 440 | ||
| Martensitic | C3 | 80 | 800 | 640 | 0.2d | 228 | 323 | 21 | 35 | 240 | 340 |
| Martensitic | C4 | 50 | 500 | 250 | 0.2d | 147 | 209 | – | – | 155 | 220 |
| 70 | 700 | 410 | 0.2d | 209 | 314 | 20 | 34 | 220 | 330 | ||
| Ferritic | F12 | 45 | 450 | 250 | 0.2d | 128 | 209 | – | – | 135 | 220 |
| 60 | 600 | 410 | 0.2d | 171 | 271 | – | – | 180 | 285 | ||
1 Quenched and tempered at a minimum tempering temperature of 275°C.
2 For nominal thread diameter d ≤ 24 mm.
Chemical Composition
The chemical composition requirements in GB/T 3098.6-2014 define the elemental limits for stainless steel grades used in fasteners. These compositions ensure corrosion resistance, mechanical properties, and manufacturability. The table below provides the percentage limits for key elements in each steel grade.
| Steel Grade | スチールグループ | C (%) | Si (%) max | Mn (%) max | P (%) max | S (%) | N (%) max | Cr (%) | Mo (%) | Ni (%) | Cu (%) | Others (%) | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 分 | 最大 | 分 | 最大 | 分 | 最大 | 分 | 最大 | 分 | 最大 | 分 | 最大 | |||||||
| A1 | Austenitic | – | 0.12 | 1 | 6.5 | 0.20 | 0.153 | 0.353 | – | 16 | 19 | – | 0.70 | 5.04 | 10.05 | 1.75 | 2.25 | – |
| A2 | – | 0.106 | 1 | 2.0 | 0.05 | – | 0.03 | – | 157 | 20 | – | –8 | 8.0 | 19.0 | – | 4.0 | – | |
| A39 | – | 0.08 | 1 | 2.0 | 0.05 | – | 0.03 | – | 17 | 19 | – | – | 9.0 | 12.0 | – | 1.0 | – | |
| A410 | – | 0.086 | 1 | 2.0 | 0.05 | – | 0.03 | – | 16 | 18 | 2 | 3 | 10.0 | 15.0 | – | 4.0 | – | |
| A59,10 | – | 0.08 | 1 | 2.0 | 0.05 | – | 0.03 | – | 16 | 19 | 2 | 3 | 10.5 | 14.0 | – | 1.0 | – | |
| C110 | Martensitic | 0.09 | 0.15 | 1 | 1.0 | 0.05 | – | 0.03 | – | 12 | 14 | – | – | – | 1.0 | – | – | – |
| C3 | 0.17 | 0.25 | 1 | 1.0 | 0.04 | – | 0.03 | – | 16 | 18 | – | – | 1.5 | 2.5 | – | – | – | |
| C410 | 0.08 | 0.15 | 1 | 1.5 | 0.06 | 0.153 | 0.353 | – | 12 | 14 | – | 0.60 | – | 1.0 | – | – | – | |
| F111 | Ferritic | – | 0.12 | 1 | 1.0 | 0.04 | – | 0.03 | – | 15 | 18 | – | –12 | – | 1.0 | – | – | – |
3 Sulfur may be replaced by selenium.
4 If the nickel content is below 8%, the minimum manganese content must be 5%.
5 If the nickel content is above 8%, there is no limit for the minimum copper content.
6 For austenitic steels with a maximum carbon content of 0.03%, nitrogen may be present up to 0.22%.
7 If the chromium content is below 17%, the minimum nickel content must be 12%.
8 Molybdenum may be present at the discretion of the manufacturer. For some applications, limits on the molybdenum content may be specified in the order.
9 Stabilized grades: Titanium content ≥ 5×C% up to 0.8%, or niobium and/or tantalum ≥ 10×C% up to 1.0%.
10 For products with larger diameters, to achieve the specified mechanical properties, a higher carbon content may be used, up to 0.12% for austenitic steels.
11 May contain titanium ≥ 5×C% up to 0.8%, or niobium and/or tantalum ≥ 10×C% up to 1.0%.
12 Molybdenum may be present at the discretion of the manufacturer.
よくある質問（FAQ）
- 1. What is the scope of GB/T 3098.6-2014?
- This standard applies to stainless steel bolts, screws, and studs with nominal thread diameters from 5 mm to 100 mm, tested at ambient temperatures between 10°C and 35°C.
- 2. How are property classes designated in this standard?
- Property classes such as 50, 70, 80, and 110 indicate the nominal tensile strength in MPa divided by 10, tailored to austenitic, martensitic, or ferritic stainless steels.
- 3. What heat treatment is required for martensitic steel grade C1 in property class 110?
- It must be quenched and tempered with a minimum tempering temperature of 275°C to achieve the specified mechanical properties.
- 4. Are there restrictions on thread diameter for ferritic steel grade F1?
- Yes, the properties for F1 apply to fasteners with nominal thread diameters up to 24 mm.
- 5. How does the standard handle stabilization in austenitic grades like A3 and A5?
- Stabilization is achieved through additions of titanium (≥ 5×C% up to 0.8%) or niobium/tantalum (≥ 10×C% up to 1.0%) to prevent carbide precipitation and enhance corrosion resistance.
- 6. Can molybdenum content be adjusted in grade A2?
- Molybdenum may be added at the manufacturer’s discretion, but specific limits should be noted in the purchase order for applications requiring precise control.
