On the Brittleness of Heat-affected Zone (Report 2)

Brittlfying by Single Bead Weld

Abstract

In this experiment the authors investigated the true reasons causing the brittleness in the range of heat-affected zone by observing Izod impact test, hardness measurement and Xray diffraction method in the single bead weld, and compared the states of the brittleness about both Killed and Rimmed steel. As the result it was recognized that the main factor to cause brittleness is the precipitation of super-saturated carbon in ferrite grain, and that state is used to caused by the rapid cooling from the neighbour-of A₁ transformation point, and the most brittle part of Killed steel seems to somewhat above A₁, Rimmed steel somewhat below A₁, i. e. the mechanisms causing brittleness are somewhat different. The brittleness of Rimmed steel is more predominent than Killed steel.