| 摘要 |
PROBLEM TO BE SOLVED: To provide a carburization method for a steel which stabilizes the mechanical properties of steel subjected to carburizing treatment. SOLUTION: In the carburization method for steel, in order that an object to be treated which has been carburized to have a surface carbon concentration of 0.7 to 0.9 mass% is subjected to reheating and quenching treatment so that the surface carbon concentration reaches an objective surface carbon concentration, the object is arranged at the inside of a heating chamber, the heating chamber is filled with a carburizing gas mixed with N<SB>2</SB>, H<SB>2</SB>, CO and CO<SB>2</SB>and an enrich gas containing at least one selected from CH<SB>4</SB>, C<SB>3</SB>H<SB>8</SB>and C<SB>4</SB>H<SB>10</SB>, further, the object is heated, and till the temperature of the object reaches a first carburizing temperature T<SB>1</SB>set on the A<SB>1</SB>point of carbon steel, the carbon potential (CP value) at the inside of the heating chamber is set to a first CP value CP<SB>1</SB>lower than the objective surface carbon concentration, and when the temperature of the object reaches the first carburizing temperature T<SB>1</SB>, the CP value is increased to a second CP value CP<SB>2</SB>equal to the objective surface carbon concentration, and the object is subjected to carburizing treatment, and is subjected to quenching treatment. COPYRIGHT: (C)2010,JPO&INPIT |
