抄録
The purpose of this report is to examine some mechanical properties—ultimate tensile strength, elongation, Vickers hardness, Charpy impact value and endurance limit—of the ausformed 9%W-3%Cr tool steels and to compare their properties with the same steels heat-treated conventionally. The results obtained are as follows:
(1) The ultimate tensile strength and Vickers hardness increase almost lineally manner with increase in the amount of deformation (reduction in thickness) at ausforming, and the rate of increase per 1% reduction is 0.7 kg/mm2 for the ultimate tensile strength and 2.2 for the Vickers hardness.
(2) The effect of deformation temperature on the ultimate tensile strength, hardness and elongation can hardly be observed over the temperature range (500°∼600°C) in this investigation.
(3) The elongation decreases slightly with increase in deformation at ausforming, but when the amount of deformation exceeds a certain degree (for instance, 70% reduction for the deformation temperature 600°C, 65% for 550°C and 50% for 500°C) the elongation decreases rapidly.
(4) The ausformed steel is superior to the conventionally hardened steel in the ultimate tensile strength and hardness, but slightly inferior in the elongation and impact strength. And the difference of these properties between the two steels does not change up to the tempering temperatures of 550°∼600°C.
(5) The impact strength of the ausformed steel decreases slightly with increase in the amount of deformation.
(6) The fatigue life and endurance limit of the ausformed steel tempered at 500°C are about 5 and 1.5 times as large as those of the steel conventionally heat-treated, respectively.
(7) The energy transition temperature is −150°C for the ausformed steel (tempered) and −130°C for the conventional steel.
