Heat Treatment to Slow Strain Aging in Threaded Steel Bolts

Abstract

As a rule, cold-deformed bolts do not contain alloying elements, which slow strain aging. Therefore, natural and artificial strain aging may decrease their resistance to ductile and brittle fracture. The mechanical properties of M12 × 1.75 × 70 mm 1.1152 steel bolts (strength class 5.8) are investigated after strain aging. A method is proposed for slowing the strain aging of cold-deformed steel fasteners: specifically, favorable dislocational structure is produced from the initial structure by heat treatment.