SS 13-8 MO

UNS S13800 | DIN 1.4534 | ASME SA693 | ASTM A 564 | AMS 5629 | DMS 2100 | HMS 6 1105

Introduction

13-8 stainless is a martensitic precipitation hardening stainless steel that has excellent strength, high hardness, superior toughness and good corrosion resistance. Good transverse toughness properties are achieved by tight chemical composition control, low carbon content, and vacuum melting. Typical applications are large airframe structural components and injection molding equipment.

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.

Chemistry

  Ni Cr Mo C P S Si Mn N Al Fe
MIN 7.5 12.25 2.0 – – – – – – 0.90 –
MAX 8.5 13.25 2.5 0.05 0.01 0.008 0.1 0.2 0.1 1.35 Balance

Chemical Composition

The chemical composition of stainless steel-grade 13-8 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

Inventory

  • 13-8 PH Round Bar

Common Trade Names

  • 13-8 Stainless

Features

  • Martensitic, precipitation hardening (maraging) stainless steel.

Applications

  • Aerospace components
  • Injection molding equipment
  • Components in the petrochemical and nuclear industries

Physical Properties

Density: 0.279 lb/inch3
Melting Range: 2560 – 2680°F
Electrical Resistivity: 613 Ohm-circ mil/ft

Temperature, °F 70 212 392 572
Coefficient of Thermal Expansion, in/in°F x 10-6 – 7.2 7.5 7.8
Thermal Conductivity
Btu • ft/ft2 • hr • °F		 8.6 9.2 9.8 10.4
Modulus of Elasticity,
psi X 106		 29.0 28.1 27.0 26.1

70°F to indicated temperature

Mechanical Properties

Strength varies with heat treatment condition. The following table shows minimum mechanical properties for the various aged conditions, per AMS 5864.

H950 H1000 H1025 H1050 H1100 H1150
0.2 Offset Yield Strength, ksi 205 190 175 165 135 90
Ultimate Tensile Strength, ksi 220 205 185 175 150 135
Elongation in 2″, % 10 10 11 12 14 14
Reduction of Area, % (Longitudinal) 45 50 50 50 50 50
Reduction of Area, % (Transverse) 45 50 50 50 50 50
Reduction of Area, % (Short-Transverse) 35 40 45 45 50 50
Min Hardness, Rockwell 45 43 – 40 34 30

Heat Treament

13-8 Stainless is available in the annealed condition, which is also called the solution heat treat condition or Condition A. Solution treat from 1675 – 1725°F for 15 to 30 minutes at temperature. Air cool or oil quench to below 60°F to effect complete transformation to martensite. Aging is normally carried out from 950 – 1150°F, depending on the desired final properties. Heat treatment is usually performed in air. Heat treatment of brazed components may be done in inert atmospheres. Reducing atmospheres should not be used because of the potential for nitrogen contamination.

Condition H950 H1000 H1025 H1050 H1100 H1150
Temperature, °F 950±10 1000±10 1025±10 1050±10 1100±10 1150±10
Time, hours 4±0.25 4±0.25 4±0.25 4±0.25 4±0.25 4±0.25

Specifications

AMS 5629
DIN 1.4534
ASTM A 564
EN 1.4548
AISI 632
UNS S13800
W. Nr./EN 1.4548
Werkstoff 1.4548

 

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