Compared to carbon steel, Stainless Steel is soft… It tends to twist, deform, and sheer at a much lower level of torque than the same tool you would buy at a typical hardware store.

Here are a few comparisons to give you an idea of its limitations (tests conducted using a MARK-10 torque meter):

PART# DESCRIPTION MATERIAL SHEER POINT
NA1/8" HEX x 3/8 DR CV (STEEL)135 in-lbs
109131/8" HEX x 3/8 DR465 Stainless85 in-lbs
109901/8" BALL HEX x 1/4 DR465 Stainless45 in-lbs*
409181/4" BALL HEX x 3/8 DRInconel 718**300 in-lbs
109951/4" BALL HEX x 1/4 DR465 Stainless490 in-lbs
109181/4" HEX x 3/8 DR465 Stainless560 in-lbs - part began to deform
NA1/4" HEX x 3/8 DRCV (STEEL)>600 in-lbs***

*Ball end hex will sheer at a lower level of torque due to the neck of the ball being less than the across flats dimension.

**Inconel 718 = Non-Magnetic Stainless Steel. 300 series is not recommended for this application.

***Near fixture limit. Testing capped at 600 IN-LBS.

A fasteners fitment to the tool will also determine how much torque can be applied before either the fastener or the tool will deform. This is especially important when dealing with HEX tools and SOCKET SCREWS & BOLTS. A loose fitting combination will deform with a lower torque value than a tight tolerance fit.