Sandvik 11R51 and Sandvik 11R51 HV (vacuum remelted) are austenitic stainless steels alloyed with molybdenum that are characterized by high tensile strength and high resistance to corrosion, fatigue and relaxation.
Vacuum-remelted Sandvik 11R51 HV offers higher cleanliness compared to Sandvik 11R51, which is usually required for medical applications.
Compared with the standard grade Sandvik 12R10 medical wire, Sandvik 11R51 and Sandvik 11R51 HV offer:
- 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)
These grades are used for applications such as root canal files, reamers, broaches, surgical suture needles, braces, and acupuncture needles.
Iso: X9 CrNi 18-8
|ASTM||F 899, A 313/A 313M|
Sandvik 11R51 medical wire is used in applications such as root canal files, reamers, broaches, surgical suture needles, braces, and acupuncture needles.
Chemical composition (nominal) %
Forms of supply
Wire is delivered in a number of different forms to suit customers' requirements:
- In coils with weights up to 150 kg
- On various types of spools with wire weights up to 500 kg
- In straightened lengths up to 4 m
Click on the following items for detailed information about surfaces finishes, delivery forms spools and coils, diameter tolerances and ovality.
|Surface finish||Size range, mm|
|Nicoat A (nickel coating)||0.22- 2.50|
|Nicoat P (nickel coating + bright)||0.40- 6.00|
|Mechanically polished||0.40 - 6.00|
Mechanical properties in the `as delivered´ condition
Tensile strength and proof strength, 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|
|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. Please click on heat treatment for further information. 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). S-2140
After straightening the strength is approx. 7% lower.
Static strength, tempered and pre-stressed cylindrical helical springs
Sandvik Product Research
The strength data below is based on laboratory tests performed by Sandvik R&D. The data applies at 20°C in normal, dry atmosphere, unless otherwise stated. They are not guaranteed values but should be taken as recommendations in the choice of wire gauge, stress level, etc. A description of the testing procedure can be found, together with explanations under the following items:
E- and G-moduli
Strength and mechanical testing
The physical properties of a steel are related to a number of factors, including alloying elements, heat treatment and manufacturing route , but the following data can be used for rough calculations.
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|
|Temperature, °C||μΩm||Temperature, °F||μΩin.|
|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 temperature ranges (x10- 6)
Magnetic 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 (180oF) increase in service temperature.
It is very important to avoid corrosion in spring applications so as not to impair spring properties. Sandvik 11R51/11R51HV are austenitic stainless steels and have sufficient corrosion resistance in most spring applications.
The corrosion resistance of the material is slightly higher compared to Sandvik 12R10 and standard ASTM 301, due to the addition of molybdenum.
Compared to other stainless spring steels, Sandvik 11R51/11R51HV have superior performance. However, all austenitic steels of this type are susceptible to stress corrosion cracking (SCC) when in contact with chloride solutions at elevated temperatures.
By tempering 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°C (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.
Please 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). S-2131. Click here for information on heat treatment in batch, continuous furnaces and on Why temper springs? S-2140
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.