Patent ID: 8645080

Claim:
A bolt inspection method for inspecting a bolt which is manufactured through heat treatment and made of chromium molybdenum steel, thereby the bolt is manufactured through heat treatment process and it is judged judging whether or not the bolt, has Charpy impact strength of more than or equal to 27[J] with respect to a condition of minus 20° C., without performing Charpy impact test, the method comprising the steps of: manufacturing, through heat treatment, a bolt made of chromium molybdenum steel calculating J parameter that is expressed in a formula, J =(Si %÷Mn %)×(P %÷Sn %)×10 4 by use of Si %, Mn %, P %, and Sn % denoting silicon percentage content, manganese percentage content, phosphorus percentage content and tin percentage content in mass %, respectively, each percentage content in the chromium molybdenum steel being described in a steel material inspection certificate, and judging whether or not the bolt has Charpy impact strength of more than or equal to 27[J] with respect to a condition of minus 20° C., by use of the calculated J parameter and a diameter at a typical length of a shaft part of the bolt.