Stainless Steel for Instruments Combines High Strength and Toughness

Technical Guide

Custom 465® stainless, a stainless alloy, has provided high strength and fracture toughness for instruments used in the medical industry. The material already has been used for screwdrivers and nut drivers. It can be considered also, Carpenter reports, for clamping and spreading instruments, as well as impacting instruments.

The characteristics of Custom 465 stainless exceed the properties of Custom 630 stainless (17Cr-4Ni), Custom 450® stainless, Custom 455® stainless and PH 13-8 Mo1 stainless. All have been used for medical instrument applications. Like Custom 450 stainless and Custom 630 stainless, the new grade offers corrosion resistance similar to that provided by Type 304 stainless steel.

In the peak aged condition, the strength of Custom 465 stainless exceeds that of Custom 455 stainless - 260 ksi ultimate tensile strength (UTS) for Custom 465 stainless, compared with 250 ksi for Custom 455 stainless.

Custom 465 stainless and PH 13-8 Mo stainless have comparable, high fatigue strength and better fracture toughness than the other alloy choices. The fracture toughness of Custom 465 stainless in the peak aged condition is 70 ksi in., which is exceptional at the alloy's higher strength level.

When peak aged (H900 condition), Custom 465 stainless retains higher notch tensile strength than other precipitation-hardenable grades. Its excellent notch toughness offers potential design advantages, including the ability to reduce instrument size and utilize tighter radii.

Custom 465 stainless is a premium melted, martensitic, age-hardenable alloy which is less sensitive to process parameters than other high-strength, PH stainless steels.

Overaging to the H1000 condition provides a superior combination of strength, toughness and stress corrosion cracking resistance compared with other high-strength PH stainless alloys that have been used for medical instruments. In this condition, for example, the alloy's fracture toughness can exceed 100 ksi in.

1 registered trademark of AK Steel Corp.

Robert Brown