Patent ID: 8137482

Claim:
A carburization heat treatment method of a vehicle workpiece sensitive to heat deformation, comprising: heating the workpiece to a carburizing temperature within a temperature range of A 1 ˜A 3 ; carburizing a surface of the workpiece in presence of a carburizing gas; and quenching the workpiece using a high-pressure gas so that the surface of the workpiece is formed with martensite and a core thereof is formed with a mixture of martensite and initial ferrite which is not subjected to phase transformation; wherein the workpiece is made of carburizing alloy steel, including chromium alloy steel, chromium-molybdenum alloy steel, or chromium-nickel-molybdenum alloy steel, each of which has a carbon content of 0.10˜0.35 wt %, and the method is conducted in a vacuum atmosphere using a vacuum carburizing furnace.