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Abstract
A method for the powder-metallurgy fabrication of tool-steel bar stock has been developed that requires neither isostatic compaction nor low-oxygen powders. The powder is heated in sealed steel tubes and directly step-forged to 99·5% density. Further reduction by rolling raises the density to 100%. A reducing agent and an oxygen getter are enclosed in the container, together with the powder for in situ reduction of particle surface oxides. This makes initial evacuation of the containers unnecessary and allows powders with high oxygen contents to be used. Mechanical properties compare well with those of material rolled from ingot.
Notes
* Manuscript received 29 April 1974. Contribution to a Symposium on ‘Factors Affecting the Uses of PM Products’, to be held in Eastbourne on 28–30 October 1974.