A POWDER-METALLURGICALLY PRODUCED HOT-WOEK STEEL AND METHOD OF PRODUCING THE SAME

摘要

A powder metallurgically produced hot work steel has the composition (by wt.) 0.25-0.45% C, 2.40-4.25% Cr, 2.50-4.40% Mo, 0.20-0.95% V, 2.10-3.90% Co, 0.10-0.80% Si, 0.15-0.65% Mn, balance Fe and impurities. Preferably, the steel has a purity K1 of less than 10 mu m. Also claimed is powder metallurgical production of the above hot work steel by (a) atomising a steel melt of the above composition in a high purity nitrogen atmosphere; (b) filling the resulting powder into capsules designed such that the final product achieves its intended shape with maximum material yield; (c) shaking the filled capsules to achieve maximum filling density; (d) evacuating and then gas-tightly sealing the capsules; and (e) hot isostatically pressing the capsules at 1000-1230 degrees C and 0.8-3.5 (preferably 1) kbar pressure for ≥ 3 hrs.