Method for producing steel member

Abstract

This method for producing a steel member includes: a carburizing step of causing carbon to infiltrate into a steel member in an austenitized state by heating the steel member to a temperature equal to or higher than an austenitic transformation completion temperature, at a carbon concentration at which the steel member and the carbon have a hypoeutectoid composition, and removing cold from the steel member in which the carbon has been caused to infiltrate; and a quenching step of, after the carburizing step, heating the steel member again to a temperature equal to or higher than the austenitic transformation completion temperature, and rapidly cooling the steel member that has been heated.

1 . A method for producing a steel member comprising:
 a carburizing step of causing carbon to infiltrate into a steel member in an austenitized state by heating the steel member to a temperature equal to or higher than an austenitic transformation completion temperature, at a carbon concentration at which the steel member and the carbon have a hypoeutectoid composition, and slowly cooling the steel member in which the carbon has been caused to infiltrate; and   a quenching step of, after the carburizing step, heating the steel member again to a temperature equal to or higher than the austenitic transformation completion temperature, and rapidly cooling the steel member that has been heated.   
     
     
         2 . The method for producing a steel member according to  claim 1 , further comprising a nitriding step of, after the carburizing step and before the quenching step, causing nitrogen to infiltrate into the steel member in a state where the steel member is heated to a temperature lower than the austenitic transformation completion temperature. 
     
     
         3 . The method for producing a steel member according to  claim 2 , wherein the quenching step is a step of, immediately after the nitriding step, heating the steel member from the temperature lower than the austenitic transformation completion temperature to the temperature equal to or higher than the austenitic transformation completion temperature, and rapidly cooling the steel member that has been heated. 
     
     
         4 . The method for producing a steel member according to  claim 2 , wherein the nitriding step is a step of causing the nitrogen to infiltrate into the steel member at a temperature equal to or higher than an austenitic transformation start temperature and lower than the austenitic transformation completion temperature. 
     
     
         5 . The method for producing a steel member according to  claim 2 , wherein the nitriding step is a step of causing the nitrogen to infiltrate into the steel member such that a nitrogen concentration in a surface of the steel member is 0.5% or lower. 
     
     
         6 . The method for producing a steel member according to  claim 1 , wherein the carburizing step is performed on the steel member that has been cold forged.