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- Sep 04, 2018 -

Bolts, mechanical parts and cylindrical threaded fasteners with nuts. A type of fastener consisting of a head and a screw (cylindrical body with external threads) fitted with a nut for fastening two parts with through holes. This connection is called bolt connection. If the nut is screwed down from the bolt, the two parts can be separated, so the bolted connection is a detachable connection.

According to relevant standards, the bolt performance grade is divided into 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9 and more than 10 grades, of which 8.8 and above bolts are made of low-carbon alloy steel or medium-carbon steel and heat treatment (quenching, tempering), commonly known as high-strength bolts, the rest known as ordinary bolts. The bolt performance grade is composed of two parts, which represent the nominal tensile strength and yield ratio of bolt material.