PH Stainless claims superior combination

Citation

(1998), "PH Stainless claims superior combination", Aircraft Engineering and Aerospace Technology, Vol. 70 No. 1. https://doi.org/10.1108/aeat.1998.12770aad.014

PH Stainless claims superior combination

PH Stainless claims superior combination

An unparalleled combination of high strength, fracture toughness and resistance to stress corrosion cracking are claimed in a new speciality stainless steel developed by Carpenter Technology Corp., Reading, PA.

Carpenter Custom 465™ stainless is a premium melted martensitic, age-hardenable alloy which, in addition, is said to be less sensitive to process parameters than other high-strength, precipitation hardening stainless steels.

According to Carpenter its new alloy is capable of about 260 ksi ultimate tensile strength when peak aged (H900 condition). In this condition, it retains higher notch tensile strength and fracture toughness than other PH grades.

A relatively low annealed yield strength, along with a low cold work hardening rate, make the alloy conducive to forming fasteners and drawing small diameter wire. The steel can be cold drawn in excess of 90 per cent reduction, with no intermediate anneal. The company reports that drawn and aged wire of Custom 465 stainless can achieve a strength of more than 300 ksi.

When aged to the Hi000 condition, the new grade claims a fracture toughness in excess of 100 ksi (check)in., compared with about 70 ksi (check)in. for Custom 455® stainless steel.

Custom 465 stainless reportedly has corrosion resistance comparable to that of Custom 455 stainless and PH 13-8 Mo stainless (registered trademark of Armco Inc.) and approaching that of Type 304 stainless, but at significantly higher strength levels. The new alloy can be overaged to 220-240 ksi ultimate tensile strength, and have stress corrosion cracking resistance similar to the other two PH stainless grades at a UTS of 190 ksi.

This new material is designed to be fully solution annealed at 1,800°F (982°C). Annealing at this temperature makes the aged properties of the alloy less sensitive to hot-work finishing temperatures.

A wide range of potential applications for the alloy are suggested, including: aircraft engine mounts, flap tracks, actuators, tail hooks, gears and other structural components; bolts and fasteners requiring a superior combination of high strength, toughness and corrosion resistance.

The alloy could be considered as an upgrade for alloy steel parts that are currently cadmium or chromium plated. It might also be considered for parts, currently made of 15Cr-5Ni or Custom 630 (17Cr-4Ni) PH stainless steels, that could benefit from higher strength, smaller size and/or lower weight.

Nominal chemical composition of Custom 465 stainless steel is: carbon 0.02 per cent max., manganese 0.25 per cent max., phosphorous 0.015 per cent max., sulfur 0.010 per cent max., silicon 0.25 per cent max., chromium 11.0/12.5 per cent, nickel 10.75/11.25 per cent, titanium 1.50/1.80 per cent, molybdenum 0.75/1.25 per cent.

Details from Carpenter Technology Corporation, PO Box 14662, Reading, Pennsylvania 19612-4662, USA. Tel: 610 208 2524; Fax: 610 208 2858.