GALVANIZING METHOD OF HIGH-TENSION BOLT FORMED BY COLD FORGING

摘要

PURPOSE:To form a plating layer having excellent adhesion in the stage of succeeding galvanizing by blasting a high-tension bolt, which is formed by cold forging and is subjected to a heat treatment such as hardening, tempering or the like, by means of grit or cut wires having sharp angles. CONSTITUTION:A steel wire rod used as a raw material is cold forged to produce a bolt which is then subjected to a hardening and tempering treatment to form a high-tension bolt. The lubricating film formed in the stage of cold forging is stuck to the surface of the high-tension bolt and therefore even if the bolt is galvanized, the plating layer has low adhesion strength and exfoliates to make the bolt easily corrosive. The high-tension bolt after the heat treatment is blasted by shot having sharp angles such as grit having 0.5-1.4mm. average size or cut wires having 0.2-1.0mm. average size or the like in order to prevent such corrosion. The lubricating film is thoroughly removed from the bolt surface and the galvanizing layer having excellent adhesion is formed.