Variant analysis in coarse grain heat affected zone of low carbon steel

Abstract

Coarse Grain Heat Affected Zone (CGHAZ) is a part of Heat Affected Zone (HAZ) that affected by heat during welding process. Application of different heat input dramatically varies CGHAZ microstructures without a noticeable changing in prior austenite grain size. The unique coarse microstructure and crack initiated at CGHAZ show there were possibility changes in crystallographic structure which may relate to the variant selection phenomenon. The aims of this study are to find the effects of heat input to the variant selection especially to the biggest grain at CGHAZ, hence correlate to the toughness and properties of the welded steel. The results show that heat input affected the variant selection at the biggest CGHAZ grain of low carbon steel. As heat input increase, grain area was increased and becomes coarser. Variant selection phenomenon present at low carbon steel due to the increase in grain diameter and high angle value. It was found that variant selections had occurred during the transformation.