15-7 - UNS S15700:

Type 15-7 PH is a semi-austenitic precipitation-hardening stainless steel that provides high strength and hardness, good corrosion resistance and minimum distortion on heat treatment. It is easily formed in the annealed condition and develops an effective balance of properties by simple aging heat treatments. In the heat-treated condition, Type 15-7 PH provides excellent mechanical properties at temperatures up to 900°F (482°C). Its corrosion resistance is superior to that of the hardenable straight chromium types. In some environments, corrosion resistance approximates that of the austenitic chromium-nickel stainless steels. 15-7 is weldable by common fusion and resistance methods; however, this particular alloy is generally considered to have poorer weldability compared to more common PH grades (17-4 PH) due to the high Al content of this alloy, which degrades penetration and enhances weld slag formation during arc welding.

Physical Properties:

• Melting Point: 2550 - 2640°F (1400 – 1450°C)
• Density: 0.282 lbs/in3 / 7.8 g/cm3
• Modulus of Elasticity in Tension: 29.0 X 106 psi / 200 GPa

Mechanical Properties:

Condition: Annealed (A)
• Tensile Strength Minimum (psi): 130,000
• Yield Strength Minimum 0.2% offset (psi): 55,000
• % Elongation in 2” Typical: 35%
• Hardness: Rockwell B88

Condition: Hardened + Aged (TH1050)
• Tensile Strength Typical (psi): 210,000
• Yield Strength Typical 2% offset (psi): 200,000
• % Elongation in 2": 7%
• Hardness: Rockwell C44

Condition: Hardened, Cryogenic Quench + Aged (RH950)
• Tensile Strength Typical (psi): 240,000
• Yield Strength Typical 2% offset (psi): 225,000
• % Elongation in 2": 6%
• Hardness: Rockwell C48

Condition: Cold Rolled/Worked + Aged (CH900)
• Tensile Strength Typical (psi): 265,000
• Yield Strength Typical 2% offset (psi): 260,000
• % Elongation in 2": 2%
• Hardness: Rockwell C50

Composition:

• Carbon: 0.09 max
• Manganese: 1.00 max
• Phosphorus: 0.040 max
• Sulfur: 0.040 max
• Silicon: 1.00 max
• Chromium: 14.00 - 16.00
• Nickel: 6.50 - 7.75
• Molybdenum: 2.00 - 3.00
• Aluminum: 0.75 - 1.50
• Iron: Balance

Heat Treatments:

17-5 requires three essential steps in heat treating:

1. Austenite conditioning.
2. Cooling to transform the austenite to martensite
3. Precipitation hardening to Condition TH 1050 or RH 950
4. Alternatively, to obtain the highest mechanical properties from the alloy, Condition A material is transformed to martensite at the mill by cold reduction to Condition C. Hardening to Condition CH 900 is accomplished with a single, low-temperature aging heat treatment.

Corrosion Resistance:

The general level of corrosion resistance of type 15-7 PH in Conditions TH 1050 and RH 950 is superior to standard hardenable types of stainless such as Types 410, 420 and 431, and nearly approaches that of Type 304. In all conditions of heat treatment, the alloy, like other types of stainless steel, will develop superficial rust in some environments.

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