A “Galling Development” – What Every Distributor Should Know about Thread Galling

Reprint from LINK, Spring 2021

A number of year’s back I was engaged by a Midwestern distributor to review an application problem that had intermittently plagued one of their more important customers. Upon meeting with their customer, I learned the problem occurred during the assembly of a stainless steel Nylon insert lock nut to a like stainless steel screw. Although this was a sporadic problem, when it occurred the customer would experience assembly difficulties like nuts that were very hard to turn, nuts that reached installation torque levels before seating, and in the worst cases, nuts that became totally frozen (seized) in mid-run down position, often breaking the screw in torsion.

The Basics of Stainless Steel

Reprint from Fastener World Magazine, Vol. 160

In 1913 English metallurgist Harry Brearley was working on a project to develop an improved steel for gun barrels that was more erosion resistant than the current steel of the day. He was experimenting with Chromium alloy steels and happened to try one that had 12.8% Chromium and 0.24% Carbon. As often happens, what begins with one goal in mind results in an entirely different outcome. In this case, Mr. Brearley’s erosion resistant experiments would result in a steel far more corrosion resistant than normal steel. Stainless steel was born.

Today stainless steels are a part of everyday life and are used in a wide variety of applications from appliance coverings, pots and pans, marine components, automotive components, and even fasteners. Stainless steels are a logical choice when the primary goal of the designer is corrosion resistance, although other properties such as appearance and strength may be determining factors in a choice to use them. There are over 300 different iron based alloys containing a minimum of 11.5% chromium that comprise those materials considered stainless steels.