초록 ▼

A method for the heat treatment of steel, comprising carburization hardening said steel, to form carburized steel, followed by a second hardening, reduces the grain size of steel while precipitating carbonitrides inside the grains of steel, thereby increasing the strength of the heat-treated steel.

A method for the heat treatment of steel, comprising carburization hardening said steel, to form carburized steel, followed by a second hardening, reduces the grain size of steel while precipitating carbonitrides inside the grains of steel, thereby increasing the strength of the heat-treated steel. The carburization hardening comprises heating the steel to a first austenitic temperature range in an atmosphere comprising a carburizing gas and optionally ammonia, cooling the steel to a martensitic temperature range, and quenching the steel, and the second hardening comprises heating the carburized steel to a second austenitic temperature range in an atmosphere comprising a carburizing gas and ammonia, and quenching the steel.

대표청구항 ▼

[ What is claimed is:] [1.] A method for the heat treatment of steel, comprising:carburization hardening said steel, to form carburized steel, followed bya second hardening,wherein carburization hardening comprisesheating said steel to a first austenitic temperature range in an atmosphere comprising

[ What is claimed is:] [1.] A method for the heat treatment of steel, comprising:carburization hardening said steel, to form carburized steel, followed bya second hardening,wherein carburization hardening comprisesheating said steel to a first austenitic temperature range in an atmosphere comprising a carburizing gas,cooling said steel to a martensitic temperature range, andquenching said steel, andsaid second hardening comprises heating said carburized steel to a second austenitic temperature range in an atmosphere comprising a carburizing gas and ammonia, andquenching said steel.