Stainless steel fasteners We often encounter the problem of stainless steel standard parts locking. So why do stainless steel fasteners always lock up? What is the reason! Why haven't you heard that the standard parts of iron do not lock up? This may be seen from the two materials of stainless steel and iron. Stainless steel standard parts are relatively soft and have good ductility. The hardness of stainless steel standard parts is SUS316. Compared with the hardness of iron standard parts, they are softer than iron standard parts of 8.8. Fastener users often reflect: Why do stainless steel fasteners sometimes lock up, and similar phenomena do not often occur when using carbon steel fasteners, are stainless steel fasteners softer and carbon steel? Why are fasteners relatively hard? That's right! There is a fundamental difference between stainless steel and carbon steel. Stainless steel has good ductility, but its hardness is somewhat different from carbon steel.