PURPOSE: To greatly improve compressibility without subjecting tool steel powder produced by an atomization method to a decarburization treatment by heating said tool steel powder under specific conditions to deposit primary carbide, then slowly cooling the powder under specific conditions.

CONSTITUTION: The tool steel powder produced by the atomization method, more particularly an oil atomization method and gas atomization method is heated for ≥10min and within 60min to the temp. between (Tm-80°C)W(Tm-30°C) (Tm: liquidus line temp.) in a vacuum or inert gas. The carbon solutionized supersaturatedly in the powder is thereby previously deposited as the carbide. This powder is thereafter slowly cooled down to ≤700°C at ≤50°C cooling rate per hour. The softening is insufficient or the deposition of the secondary carbide is insufficient and the necessary characteristics are not obtainable if the conditions deviate from the above- mentioned slow cooling conditions.