Ultrafine powder, high-strength steel sintered and methods for their preparation

摘要

PROBLEM TO BE SOLVED: To provide superfine powder for a high strength steel sintered compact having high room temperature strength and high temperature creep strength, a high strength sintered compact, and methods for producing them.SOLUTION: Provided is a method for producing a high strength steel sintered compact comprising: a first step in which, by an arc plasma forced evaporation method of performing arc discharge to a steel in a hydrogen gas-containing atmosphere, the superfine powder of the steel of 20 to 300 nm is produced; and a second step in which the superfine powder is introduced into an oxygen gas atmosphere, and heating is performed to produce copper oxide fine powder whose surface is oxidized. Also provided is a method for producing a high strength steel sintered compact further comprising a third step in which the steel oxide fine powder is heated at above 700°C to less than 1,000°C by discharge plasma while pressurizing the steel oxide fine powder to produce a sintered compact in which the fine oxide grains of 10 to 100 nm are dispersed at an intergranular distance of less than 100 nm into the crystal grains in which the crystal grain size after sintering is above 500 nm to less than 1,000 nm.