Sep 20 2012
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
Cold Working
Welding
Forging
Forming
Machinability
Heat Treatment
Hot Working
Applications
Introduction
Stainless steels are known as high-alloy steels. These steels contain good corrosion resistance in comparison with other steels because they contain larger amounts of chromium.
Stainless steels are available in three different groups based on their crystalline structure. These groups include martensitic, austenitic and ferritic. The combination of martensitic and ferritic steels forms a fourth group of stainless steels known as precipitation-hardened steels.
Stainless steel-grade 13-8 is an age hardenable, precipitation stainless steel. This steel has good resistance to stress and general corrosion cracking, high transverse toughness and high strength obtained by a single low temperature heat treatment.
The following datasheet provides an overview of stainless steel-grade13-8.
Chemical Composition
The chemical composition of stainless steel-grade13-8 is outlined in the following table.
|
Element |
Content (%) |
|
Iron, Fe |
76 |
|
Chromium, Cr |
12.25-13.25 |
|
Nickel, Ni |
7.50-8.50 |
|
Molybdenum, Mo |
2.0-2.50 |
|
Aluminum, Al |
0.90-1.35 |
|
Manganese, Mn |
0.10 |
|
Silicon, Si |
0.10 |
|
Carbon, C |
0.050 |
|
Nitrogen, N |
0.010 |
|
Phosphorous, P |
0.010 |
|
Sulfur, S |
0.0080 |
Physical Properties
The following table shows the physical properties of stainless steel-grade13-8.
|
Properties |
Metric |
Imperial |
|
Density |
7.80 g/cm3 |
0.282 lb/in³ |
Mechanical Properties
The mechanical properties of stainless steel-grade 13-8 are displayed in the following table.
|
Properties |
Metric |
Imperial |
|
Tensile strength |
1620 MPa |
235000 psi |
|
Yield strength (@strain 0.200%) |
1480 MPa |
215000 psi |
|
Elastic modulus |
203 GPa |
29443 ksi |
|
Poisson's ratio |
0.27-0.30 |
0.27-0.30 |
|
Elongation at break (In 50 mm) |
12.00% |
12.00% |
|
Charpy Impact |
27.0 J |
19.9 ft-lb |
|
Machinability (35-40 average, based on 100 machinability for AISI 1212 steel) |
35.0-40.0 |
35.0-40.0 |
Thermal Properties
The thermal properties of stainless steel-grade 13-8 are given in the following table.
|
Properties |
Metric |
Imperial |
|
Thermal expansion co-efficient (@21-95°C/69.8-203°F) |
10.6 µm/m°C |
5.89 µin/in°F |
|
Thermal conductivity (in condition A, @100°C/212°F) |
14.0 W/mK |
97.2 BTU in/hr.ft².°F |
Other Designations
Equivalent materials to stainless steel-grade 13-8 are:
-
AISI 632
-
AMS 5629
-
AMS 5864
-
ASTM A564 (XM-13)
-
ASTM A693 (XM-13)
-
ASTM A705 (XM-13)
-
DIN 1.4534
Fabrication and Heat Treatment
Cold Working
Stainless steel-grade 13-8 can be cold worked in a satisfied manner despite its high initial yield strength.
Welding
Stainless steel-grade 13-8 can be welded in the solution annealed condition with the usage of 13-8 MO filler material. Inert gas shielded and resistance methods can also be used to cold wok this alloy.
Forging
Stainless steel-grade 13-8 alloy can be forged at 1177°C (2150°F) for 1 h. The alloy is then solution treated, hardened and finally cooled at room temperature.
Forming
Conventional methods are used to form stainless steel-grade 13-8 alloy, wherein the degree of formability is limited by high initial yield strength.
Machinability
Stainless steel-grade 13-8 can be machined under all conditions thought this steel is known as a tough machining stainless steel. Good machinability results are obtained when this steel type is machined in condition H1150M.
Heat Treatment
Stainless steel-grade 13-8 can be heat treated in the following conditions:
-
CONDITION A: Soak at 927°C (1700°F) and cool for 1 h below 16°C (60°F).
-
CONDITION RH 950: Treat Condition A material for 2 h at -73°C (-100°F), air warm to room temperature, heat the cold treated material to 510°C (950°F) for 4 h and finally cool the material in air.
-
CONDITION H950, H1000, H1050, H1100, H1150: Soak solution treated material for 4 h at specific temperature and then cool the material in air.
-
CONDITION H1150M: Soak solution treated material for 2 h at 760°C (1400°F), cool in air, re-heat for 4 h to 620°C (1150°F) and finally cool the material in air.
Hot Working
Stainless steel-grade 13-8 can be hot worked in a satisfied manner. After being hot worked, the material is first solution annealed and then hardened to obtain better results.
Applications
Stainless steel-grade 13-8 can be used in components in the nuclear and petrochemical industries, and also aircraft components such as structural sections and landing gears, shafts and valves.