17-7PH, Stainless Steel, Precipitation Hardening Stainless Steel

Overview

17-7PH is achromium-nickel-aluminumsemi-austenitic stainless steel which is austenitic in the annealed condition, but martensitic in the hardened condition. 17-7PH provides high strength and hardness, excellent fatigue properties, good corrosion resistance and minimum distortion upon heat treatment. It is easily formed in the annealed condition, then hardened to high strength levels by simple heat treatments.

Characteristics

17-7PH may be formed in a soft austenitic condition and hardened to a high strength level by low temperature heat treatments. The low temperature allows minimum distortion compared to conventional quench and temper hardening processes. In addition to material produced by the standard refining procedures, material which has been vacuum arc or electroslag remelted is available for further increase in resistance to fatigue, for those applications subject to cyclic stresses.

Chemical Composition (wt% as per AMS 5568)

C	Si	Mn	P	S
≤0.09	≤1.0	≤1.0	≤0.040	≤0.030
Cr	Ni	Al
16.0~18.0	6.50~7.75	0.75~1.50

Corrosion Resistance

Tests have shown that the corrosion resistance of 17-7PHis comparable to that of Type 304 stainless steel in most media. In general, the corrosion resistance of 17-7PHis superior to that of the hardenable 400 series stainless steels.Its intergranular corrosion may be a problem if the material is heated between 800°F (427°C) and 1650°F (899°C) or cooled slowly through that range.

Mechanical Property (AMS 5568)

Solution heat treated condition

Tensile Strength: 150 KSI min (1034 MPa min)

Yield Strength(0.2% Offset): 55 KSI min(379 MPa min)

Elongation: 20% min

Hardness: HRB92 max.

Afterausteniteconditioning andprecipitationheattreated

Ultimate Tensile Strength: 180 KSI min (1241 MPa min)

Yield Strength: 150 KSl min (1034 MPa min)

Elongation: 6%min

Hardness: HRC38 max.

Heat Treatment

17-7PH, in all forms, the material is furnished in the annealed condition.

Solution Heat Treatment

Tubing shall be solution heat treated by heating to1950±25°F (1066℃±14℃), holding at heat for a time commensurate with wall thickness and heating equipment and procedure used, and cooling in air or quenching in water.

Afterausteniteconditioning andprecipitationheattreating, tubing shall have the properties shown inaboveafter being austenite conditioned by heating to 1400±25°F (760±14°C), holding at heat for 90±5 minutes, cooling to 55±5°F (13±3℃) within one hour, holding at that temperature for not less than 30 minutes, and precipitation heat treated by heating to 1050±10°F (566±6℃), holding at heat for 90±5minutes, and cooling to room temperature.

Product Forms

Form	Size range
Capillary tube	OD 0.08 ~ 6.0 mm WT 0.015 ~ 1.5 mm
Thin wall & Ultra thin wall seamless tube	OD6.0~80.0 mm WT 0.05~4.5 mm
Micro ID and heavythick wall seamless tube	OD3.0~50.0 mm ID0.30~5.0mm
Precision conic seamless tube	Bigger end: OD3.0 - 426.0mm Smaller end: OD2.5 - 346.0mm WT: 0.15 - 40.0mm
HP/UHP BA+ tube EP tube	OD 1.0 ~ 76 mm WT 0.10 ~ 10.0 mm
Small caliber precision seamless tube	OD6.0 ~89mm WT 0.50 ~9.0 mm
Profiled seamless tube	Build to drawing Build to specification
Bourdon tube	Y40, Y50, Y60, Y70, Y100, Y150