Thermal hardening of round bar steel for fastener fabrication

Possible application of thermally hardened steels for fastener fabrication is studied. Hardening and tempering have been used. Investigation have been carried out on 16, 18, 19 and 20 mm diameter made of 20 and 20sub(kp) steels. It is shown that application of thermally hardened semi-finished rolled products, made of low-carbon steels, for fastener fabrication permits to increase its strength by 1-2 classes depending on the hardening degree of semifinished rolled products and on technology of its further processing. It simplifies the technological scheme of fastener fabrication due to exclusion of operations of hardening and tempering of finished products. As a result expenditures on the fastener fabrication should be noticably reduced