The following table is the results from torque testing three different size hexagon keys made from five different Stainless Steel alloys we commonly use.

HEX SIZE 316L 17-4PH INCONEL 718 465 420
1/16" 5 IN. LBS 10 IN. LBS 12 IN. LBS 14 IN. LBS 15 IN. LBS
1/8" 44 IN. LBS 75 IN. LBS 87 IN. LBS 90 IN. LBS 92 IN. LBS
1/4" 373 IN. LBS 570 IN. LBS 618 IN. LBS 735 IN. LBS 776 IN. LBS

This test was conducted where the hexagon was machined onto a round bar and heat treated (excluding 316L). The hexagon was them clamped in a hydraulic chuck and radial torque applied and measured via Mark-10 brand torque tester.

This test is not a simulation of a real life situation and should only be used as a reference to better understand the characteristics of each alloy.

In reality, there will be a tolerance difference between our tools and your fasteners. This tolerance will reduce the torque ability as the loading of the torque will be distributed over the hexagon differently than our test environment. A looser fit will have less torque ability than a tighter fit.

Torque reading are at peak torque: torque was applied until no increase in torque was registered.

This resulted in the hexagon either twisting, sheering, or deforming completely.

316L

No heat treating. Non-Magnetic. 

17-4PH

H900 Condition. Magnetic.

420

Vacuum heat treated to 54 HRC. Magnetic. 

465

H950 Condition. Magnetic.

Inconel 718

H1350 Condition. Non-Magnetic.