13-8 - UNS S13800:

Type 13-8 is a martensitic precipitation age-hardenable stainless steel. The principal features of Type 13-8 are good resistance to general and stress corrosion cracking, and high strength that is developed by a single low temperature heat treatment. In addition, the alloy exhibits good ductility and toughness in large sections in both the longitudinal and transverse directions. 13-8 should be considered where high strength, toughness, corrosion resistance, and resistance to stress-corrosion cracking are required in a steel showing minimal directionality in properties. Type 13-8 has been used in aircraft components such as landing gear and structural sections, valves, shafts, and components in the petrochemical and nuclear industries.

Physical Properties:

• Melting Point: 2560 - 2680°F (1404 - 1471°C)
• Density (Condition H1000): 0.280 lbs/in3 / 7.75 g/cm3
• Modulus of Elasticity in Tension: 28.3 X 106 psi / 195 GPa

Mechanical Properties:

Condition: Aged (H950)
• Tensile Strength Minimum (psi): 220,000
• Yield Strength Minimum 0.2% offset (psi): 205,000
• % Elongation in 2” Typical: 10%
• Hardness: Rockwell C45

Condition: Aged (H1025)
• Tensile Strength Typical (psi): 185,000
• Yield Strength Typical 2% offset (psi): 175,000
• % Elongation in 2": 12%
• Hardness: Rockwell C38

Condition: Aged (H1150)
• Tensile Strength Typical (psi): 135,000
• Yield Strength Typical 2% offset (psi): 90,000
• % Elongation in 2": 7%
• Hardness: Rockwell C30

Composition:

• Carbon: 0.05 max
• Manganese: 0.10 max
• Phosphorus: 0.010 max
• Sulfur: 0.008 max
• Silicon: 0.10 max
• Chromium: 12.25 - 13.25
• Nickel: 7.50 - 8.50
• Molybdenum: 2.00 - 2.50
• Aluminum: 0.90 - 1.35
• Nitrogen: 0.01 max
• Iron: Balance

Heat Treatments:

13-8 stainless is hardened by heating solution-treated material, Condition A, to a temperature of 950°F (510°C) to 1150°F (621°C) for four hours, then air cooling. The various heat treatments are as follows:

Condition	Heat To (+/- 15°F / 8.4°C)	Time at Temperature (h)
H950	950°F / 510°C	4
H1025	1025°F / 551°C	4
H1150	1150°F / 621°C	4

Corrosion Resistance:

The general-corrosion resistance of 13-8 stainless approaches that of Type 304 in strongly oxidizing and reducing acids and in atmospheric exposures. As with other precipitation hardening stainless steels, the alloy's level of general-corrosion resistance is greatest in the fully hardened condition and decreases slightly as the aging temperature is increased. In Condition H 950, 13-8 stainless has rusting resistance similar to that of Type 304 Stainless in 5 wt% NaCl fog.

OD (in.)	KVA STAINLESS MSS As-Welded Tube Capabilities In Inches
0.500
0.625
0.750
0.875
1.00
1.125
1.250
1.375
1.500
1.750
2.000
2.500
	0.016	0.020	0.024	0.028	0.031	0.035	0.039	0.043	0.047	0.051	0.055	0.059	0.063	0.067	0.071	0.075	0.079	0.098	0.110
Wall Thickness (in.)
				New Tooling Required								In House Tooling

OD (mm)	KVA STAINLESS MSS As-Welded Tube Capabilities In Millimeters
12.7
16.0
19.1
22.2
25.4
28.6
31.8
34.9
38.1
44.4
50.8
63.5
	0.40	0.50	0.60	0.70	0.80	0.90	1.00	1.10	1.20	1.30	1.40	1.50	1.60	1.70	1.80	1.90	2.00	2.50	2.75
Wall Thickness (mm)
				New Tooling Required								In House Tooling