Abstract
Tensile tests at high temperatures and creep rupture tests of the ausformed 9%W-2.5%Cr tool steel (SKD 5) were carried out, and the data were compared with those of the same steel heat treated conventionally.
The results obtained are as follows:
(1) The ultimate tensile strength of the 60, 40 and 20% ausformed steel and the conventionally heat treated steel are smaller in that order up to the testing temperature of 700°C. The ultimate tensile strength of the ausformed steels do not decrease remarkably until 500°C, while that of the conventionally heat treated steel decreases remarkably from 400°C, and the ultimate tensile strength of both steels become nearly equal at 700°C. The elongation of the ausformed steels are a little smaller than that of the conventionally heat treated steel, and those of both steels decrease gradually up to 300°C, but begin to increase with increase in testing temperature.
(2) At the testing temperature of 500°C, the creep rupture strength of both 60 and 30% ausformed steels are larger than that of the conventionally heat treated steel till a creep rupture time of 1000 hours, and the 30% ausformed steel is stronger than the 60% ausformed steel after 200 hours, though it is weaker till the hour. At 600°C, the creep rupture strength of the ausformed steels are larger than that of the conventionally heat treated steel until about 50 hours. Beyond about 50 hours, however, the creep rupture strength of the ausformed steels become smaller than that of the conventionally heat treated steel. At 650°C, the creep rupture strength of the ausformed steels are rather small than that of the conventionally heat treated steel.
