Introduce the locking phenomenon of stainless steel fasteners in detail

Fastener users often report: why stainless steel fasteners sometimes have locking problems, while similar phenomena do not often occur when using carbon steel fasteners. Is the material of stainless steel fasteners softer? What is the reason why fasteners are relatively hard? That's right! Stainless steel and carbon steel are fundamentally different. Stainless steel has good ductility, but its hardness has a certain gap with carbon steel. The hardness of the austenitic stainless steel grade 316 head A4-80 can actually only reach 8.8 which is equivalent to the hardness of carbon steel. However, this statement can only be said to be half true.

ThreadGalling (ThreadGalling, or seizure) often occurs on fasteners made of stainless steel, aluminum alloy and titanium alloy. These types of metal alloys have anti-corrosion properties and will be damaged on the surface. A thin oxide layer (chromium oxide in the case of austenitic stainless steel) is produced on the metal surface to prevent further and deeper corrosion. When the stainless steel fastener is locked, the pressure between the teeth is Heat will destroy and erase the chromium oxide layer in between, causing the metal tooth pattern to block/shear directly, and then the phenomenon of adhesion will occur. When the sticking phenomenon continues (usually no more than a complete tooth diameter), the stainless steel fasteners will be completely locked and can no longer be removed or locked. Usually this series of actions of blocking→cutting→adhesive→locking occurs in just a few seconds. Therefore, understanding the characteristics of stainless steel products and following the correct operating procedures are the first steps to prevent stainless steel fasteners from locking. step.