Evaluation of Hot Cracking Susceptibility of High Strength Steel Using the Varestraint Test

Abstract

A newly developed high strength steel HY130(NSC), to which copper has been richly added, is investigated for practical usage. The influence of addition of a large amount of copper on weldability had been so little known that this investigation was carried out to make claer this influence. A hot cracking susceptibility was mainly investigated using the Varestraint Test. HY130(T) and NS63 were also tested to compare with the result of HY130(NSC). Scanning electron micrographs of hot cracks were taken. Distributions of some components were studied with an electron probe microanalyser.
The results are as follows:
(1) Hot cracks occur only in bead nearly perpendicular to a ripple line.
(2) A difference between hot cracking susceptibility of HY130(NSC) and that of HY130(T) is hardly found.
(3) Scanning electron micrographs of hot cracks show that growth of dendreits relates to hot cracks.