| 摘要 |
Provided is a heat treatment method of a nodular graphite cast iron work roll. The heat treatment method according to the present invention improves the mechanical property of a material by stabilizing a structure after quenching, and comprises: a first step of forming an austenite structure inside a structure inside the work roll, which is manufactured by casting, by heating the structure inside the work roll to a first predetermined temperature, and then maintaining the first predetermined temperature for a predetermined time in order to stabilize the formed austenite structure inside the structure; a second step of cooling to a second determined temperature lower than the first predetermined temperature after maintaining the first predetermined temperature for the predetermined time, and then maintaining the second predetermined temperature for a predetermined time; a third step of forming perlite inside the structure inside the work roll by quenching to a third predetermined temperature after maintaining the second predetermined temperature, and then maintaining the third predetermined temperature for a predetermined time; a fourth step of cooling to a fourth predetermined temperature at which remaining austenite inside the structure is transformed into bainite, and then maintaining the fourth predetermined temperature for a predetermined time; and a fifth step of tempering at a predetermined temperature in order to stabilize a structure, which is formed by cooling, after maintaining the fourth predetermined temperature, wherein the remaining austenite inside the structure is generated by quenching to the third predetermined temperature. [Reference numerals] (AA) Start; (BB) End; (S10) Maintain a first predetermined temperature for a predetermined time after heating a work roll to the first predetermined temperature at which austenite can be formed; (S20) Maintain a second predetermined temperature after cooling to the second temperature lower than the first predetermined temperature; (S30) Maintain a third predetermined temperature after quenching from the second predetermined temperature to the third predetermined temperature at which perlite can be generated; (S40) Maintain a fourth predetermined temperature after cooling to the fourth predetermined temperature at which remaining austenite can be transformed into bainite; (S50) Perform tempering by heating from the fourth predetermined temperature |
