Stainless Steel - Grade 13-8 (UNS S13800)

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.

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