A Metallurgical Study on the Weld Heat Affected Zone in Steels with a Reproduing Apparatus for weld Thermal Cycles (Report 1)

Abstract

The effect of heating duration on the properties of oil quenched high steels was investigated comparing the long heating in usual heat treatment with the short heating in welding. The short heating and quenching which was impractical in a furnace, was realized on a bar specimen with a reproducing apparatus for rapid thermal cycles. V-Charpy impact test hardness measurment and examination of microstructure were made for two high strength steels, manganese-silicon and manganese-vanadiumtitanium, and the following conclusions were obtained;
(1) The specimen with the weld thermal cycle reproduced in it was found to be satisfactory for the test purpose. The short heated and quenched microsructures were very similer to those in welding.
(2) The transition temperature, hardness and microstructures of short heated specimen were considerably different from those of long heated one, thus resulting in a conclusion that the usual heat treatment such as Jominy test may not be adequate to evaluate the properties of welded steels.
(3) The effect of vanadium and titanium addition to the composition of steel was not so effective in reducing the maximum hardness in the heat affected zone.