Stainless Steel Grade 651 - AISI Type 651 (19-9 DL)
About Grade 651 Stainless Steel
Grade AISI 651 Stainless Steel is also known as AISI 651, ASTM A453 Grade 651 and UNS S63198. It is a martensitic stainless steel with high propositions of carbon and chromium. It is largely used in high-temperature bolting applications for its hardness, strength, and resistance to wear and abrasion.
Let us delve into the detailed study of AISI 651.
AISI 651 Chemical Composition
AISI 651 is known for its hardness and strength owing to its meticulous chemical composition. Here is the detailed chemical composition of AISI 651, with the names of the chemical elements it constitutes along with their proposition.
|
|
|||
|
Carbon, C |
0.28 - 0.35 % |
|
|
|
Chromium, Cr |
18 - 21 % |
|
|
|
Copper, Cu |
<= 0.50 % |
|
|
|
Iron, Fe |
64 % |
|
|
|
Manganese, Mn |
0.75 - 1.5 % |
|
|
|
Molybdenum, Mo |
1.0 - 1.75 % |
|
|
|
Nickel, Ni |
8.0 - 11 % |
|
|
|
Niobium,Nb (Columbium, Cb) |
0.25 - 0.60 % |
|
|
|
Phosphorus, P |
<= 0.040 % |
|
|
|
Silicon, Si |
0.30 - 0.80 % |
|
|
|
Sulfur, S |
<= 0.030 % |
|
|
|
Titanium, Ti |
0.10 - 0.35 % |
|
|
|
Tungsten, W |
1.0 - 1.75 % |
|
|
Physical Properties
Grade AISI 651 stainless steel is a high-carbon, high-chromium stainless steel. Its unique physical properties make it suitable for applications requiring hardness and wear resistance. Here are the physical properties of AISI 651 stainless steel:
● Density: 7.75 g/cm³
● Melting Range: 1425-1510°C
● Thermal Conductivity: 24 W/m·K
● Specific Heat Capacity: 460 J/kg·K
● Electrical Resistivity: 0.6 μΩ·m
Mechanical Properties
A specific and wide change in the heat treatment of the AISI Grade 651 stainless steel will greatly alter its mechanical properties. Here are its mechanical properties in a heat-treated state:
● Ultimate Tensile Strength: 1300-1500 MPa (heat-treated)
● Yield Strength: 950-1100 MPa (heat-treated)
● Elongation at Break: 10-15%
● Hardness: 50-58 HRC (heat-treated)
● Young's Modulus: 210 GPa
It is possible to attain different combinations of hardness and toughness by using different tempering temperatures. The trend shows that lower tempering temperatures will have higher hardness and strength, while higher tempering temperatures will have higher toughness, compromising on hardness and strength.
Thermal Properties
Thermal properties of AISI Grade 651 stainless steel explain the behaviour of AISI Grade 651 in high-temperature applications and during their thermal processing. Here are the thermal properties of AISI 651.
● Thermal Conductivity: 24 W/m·K at 20°C
● Specific Heat Capacity: 460 J/kg·K
● Coefficient of Thermal Expansion: 10.5 x 10⁻⁶ /°C (20-100°C)
● Melting Point: 1425-1510°C
● Thermal Diffusivity: 0.05 cm²/s
Applications
AISI Grade 651 stainless steel being hard and strong is used for various applications. Some of its common applications are:
● Its hardness and wear resistance make it suitable for making knives and cutting tools.
● It is also used to make bearing applications and valve parts because of its high wear resistance properties.
● It is used in making machinery parts, dies and moulds that require high strength and wear resistance.
● It is hard and retains sharp edges making it suitable for surgical cutting tools. It is also used for making orthopaedic tools because of its high durability and wear resistance.
● It possesses high strength and wear resistance and hence is good for making automotive and aerospace components.
● It is also used for applications requiring springs with high strength and resistance to deformation.
● It is also suitable for making components of drilling equipment and pumps.
● It is widely used for military and defence purposes in the production of weapon parts, armour and other defensive tools where strength and durability are crucial.