| 摘要 |
PURPOSE:To improve carburizing resistance, by heating high Cr austenite-containing heat resistant steel in stmosphere on a specific condition to form a compact oxidized film with a Cr2O3 base on the surface. CONSTITUTION:If a pipe material of austenite-containing stainless steel containing 20-35% Cr is used in an atmosphere containing carbon at a high temperature, it is carburized in its surface part and it is deteriorated in toughness and damaged. To prevent this damage, the pipe material is preoxidization-treated in atmosphere on the condition meeting formula I to form a compact oxidized film with a Cr2O3 base on the surface. Thus, the surface of the heat resistnat steel is prevented from being curburized and damaged. In formula I, T shows a preoxidation temperature ( deg.K), t a preoxidation time (min) and T<=1,300 deg.K. |
