Sandvik 11R51® is an austenitic stainless steel alloyed with molybdenum. The grade is characterized by high tensile strength and high resistance to corrosion, fatigue and relaxation.
Compared to most other steels of ASTM 302 type (for example Sandvik 12R10/gusab T302), Sandvik 11R51® offers:
- Higher tensile strength and tempering effect
- Higher relaxation resistance, especially at elevated temperatures
- Higher fatigue strength
- Better corrosion resistance, through the addition of molybdenum
Service temperature: -200 to 300°C (-330 to 570°F).
Standards
- UNS: S30151
- ISO: X9 CrNi 18-8
- EN Number: 1.4310
- EN Name: X10 CrNi 18-8
Product standards
| EN | 10270-3 |
| ISO | 6931-1 |
| ASTM | A 313/A 313M |
Chemical composition (nominal) %
| C | Si | Mn | P | S | Cr | Ni | Mo |
|---|---|---|---|---|---|---|---|
| 0.08 | 1.5 | 1.8 | ≤0.025 | ≤0.010 | 17 | 7.5 | 0.7 |
Forms of supply
| Surface finish | Size range, mm |
|---|---|
| Coated | 0.20 - 8.50 |
| Nicoat A (nickel coating) | 0.22 - 2.50 |
| Bright | 0.15 - 0.80 |
| Nicoat B (nickel coating + bright) | 0.18 - 0.80 |
|
Mechanically polished
|
0.40 - 6.00 |
|
Flat wire
|
|
| Width | 0.50 - 7.00 |
| Thickness | 0.05 - 4.00 |
|
W/t
|
< 25 |
Delivery forms
Standard delivery forms are:
- Coils with weight up to 150 kg
- Spools of various types with wire weight up to 1000 kg
- Compact coils with weight up to 1200 kg
- Straightened lengths up to 4 m
Physical properties
Density: 7.9 g/cm3, 0.29 lb/in3
| 500 J/kg °C | in the temperature range 50 - 100°C |
|---|---|
| 0.12 Btu/lb °F | in the temperature range 120 - 210°F |
| Temperature, °C | W/m °C | Temperature, °F | Btu/ft h °F |
|---|---|---|---|
| 20 | 15 | 68 | 9 |
| 100 | 16 | 210 | 9 |
| 200 | 18 | 390 | 10.5 |
| 300 | 19 | 570 | 11.5 |
| Temperature, °C | μΩm | Temperature, °F | μΩin. |
|---|---|---|---|
| 20 | 0.90 | 70 | 35.0 |
| 100 | 0.95 | 210 | 37.0 |
| 200 | 1.00 | 390 | 39.0 |
| 300 | 1.05 | 570 | 41.5 |
| Temperature, °C | per °C | Temperature, °F | per °F |
|---|---|---|---|
| 20 - 100 | 17 | 68 - 210 | 9.5 |
| 20 - 200 | 17.5 | 68 - 390 | 9.5 |
| 20 - 300 | 18.5 | 68 - 570 | 10.0 |
1) Mean values in temperatur ranges ( x10- 6 )
Permeability, μmax: about 35
Shear modulus, MPa (ksi)
As delivered: approx. 71 000 (10 295)
Tempered: approx. 73 000 (10 585)
Modulus of elasticity, MPa (ksi)
As delivered: approx.185 000 ( 26 825)
Tempered: approx. 190 000 (27 550)
The strength will decrease by 3–4% per 100°C increase in service temperature.
Mechanical properties
Mechanical properties in the `as delivered´ condition
Tensile strength and proof strength, MPa (ksi)
| Wire diameter | Nominal, Rm1 | Nominal Rp0,2 | |||
|---|---|---|---|---|---|
| mm | in. | MPa | ksi | MPa | ksi |
| 0.15 – 0.20 | 0.0059 - 0.0079 | 2530 | 367 | 2150 | 312 |
| >0.20 – 0.30 | >0.0079 - 0.012 | 2470 | 358 | 2100 | 305 |
| >0.30 – 0.40 | >0.012 - 0.016 | 2420 | 351 | 2060 | 299 |
| >0.40 – 0.50 | >0.016 - 0.020 | 2365 | 343 | 2010 | 292 |
| >0.50 – 0.65 | >0.020 - 0.026 | 2310 | 335 | 1960 | 284 |
| >0.65 – 0.80 | >0.026 - 0.031 | 2260 | 328 | 1920 | 278 |
| >0.80 – 1.00 | >0.031 - 0.039 | 2200 | 319 | 1870 | 271 |
| >1.00 – 1.25 | >0.039 - 0.049 | 2150 | 312 | 1830 | 265 |
| >1.25 – 1.50 | >0.049 - 0.059 | 2100 | 305 | 1785 | 259 |
| >1.50 – 1.75 | >0.059 - 0.069 | 2040 | 296 | 1730 | 251 |
| >1.75 – 2.00 | >0.069 - 0.079 | 1990 | 289 | 1690 | 245 |
| >2.00 – 2.50 | >0.079 - 0.098 | 1880 | 273 | 1600 | 232 |
| >2.50 – 3.00 | >0.098 - 0.118 | 1830 | 265 | 1555 | 225 |
| >3.00 – 3.50 | >0.118 - 0.138 | 1775 | 257 | 1510 | 219 |
| >3.50 – 4.25 | >0.138 - 0.167 | 1720 | 249 | 1460 | 212 |
| >4.25 – 5.00 | >0.167 - 0.197 | 1670 | 242 | 1420 | 206 |
| >5.00 – 6.00 | >0.197 - 0.236 | 1610 | 233 | 1370 | 199 |
| >6.00 – 7.00 | >0.236 - 0.276 | 1560 | 226 | 1330 | 193 |
| >7.00 – 8.50 | >0.276 - 0.335 | 1505 | 218 | 1280 | 186 |
| Flat wire | 850-2400 | 123 - 348 | 0.85 * Rm | 0,85 * ksi | |
| Other strength levels | On request | ||||
1) tolerance on tensile strength + / - 7.0 % in accordance with En 10 270-3 grade 1.4310HS.
The tensile strength can be increased by 150–300 MPa ( 22 - 44 ksi) by tempering. The tensile strength variation between spools/coils within the same production lot is ±50 MPa (7 ksi) maximum. The proof strength in the tempered condition is approx. 90 % of the tempered tensile strength. The tensile strength values are guaranteed and are measured directly after production. During storage, the strength will increase marginally due to ageing. Depending on the storage conditions, ageing can increase the strength by 0 - 80 MPa (0 - 12 ksi).
Straightened lengths
After straightening the strength is approx. 7% lower.
Strength data
The strength data below are based on laboratory tests performed at Sandvik's R&D center. The data apply at 20°C (68°F) in normal, dry atmosphere, unless otherwise stated. They are not guaranteed values but shall be taken as recommendations in the choice of wire gauge, stress level, etc. A description of the testing procedure will be found, together with explanations under following items:
The diagrams are valid for springs with the spring index 10 (mean diameter of spring/wire diameter).
Figure 1. Setting limit, curve A, and maximum permissible shear stress, curve B, as a function of the wire diameter. The setting limit is defined as the shear stress at which the relaxation is 2% after a load time of 24 hours. Curve B lies 25% below curve A.
Figure 2. Relaxation (load loss) at various shear stresses as a function of service temperature. This diagram refers to a wire diameter of 1.0 mm.
Heat treatment
By tempering springs at 425°C (780°F)/0.5 - 4 h, the tensile strength will increase by about 150-300 MPa (20 - 45 ksi). If a shorter tempering time is used the tempering effect will be lower. In continuous conveyor furnaces, where the holding time at temperature is very short (min. 3 minutes), the temperature can be increased to about 475° (780°F).
In the `as delivered´ condition the ratio of proof strength/tensile strength is about 0.85. After tempering the ratio will be about 0.90.
Note that tension springs coiled with initial tension must not be tempered at the same high temperature as other types of spring. We recommend batch tempering at 250°C (480°F)/0.5–3 h, or continuous tempering in a conveyor furnace with a holding time of 3–5 minutes at about 300°C (570°F).
Bending
The minimum bending radius should not be less than half the wire diameter. The wire surface should be free from any tooling damage, since slight imperfections in the surface can lead to fracture even at large bending radii.