Improvement of Toughness of High Strength Steel Weld Metal

Abstract

Many investigations on low carbon weld metals have revealed that weld metal composed of fine acicular ferrite has sufficient toughness and the addition of Ti or T1-B into weld metals effectively forms the acicular ferrite microstructures. However, the majority of these investigations were concerned in the approximate strength range of 50-70 kg/mm² and not in the range over 70 kg/mm².
The toughness of baimtic and/or ferntic weld metal of high strength steel was investigated in this report.
The specimens of weld metal were prepared by DC-GMA welding process and the effects of the oxygen content and silicon content on the toughness of weld metal were investigated
The oxygen levels affected the microstructure change of high strength steel weld metal as had been found in 50-70 kg/mm². And decreasing silicon content in weld metal was remarkably effective in producing the fine microstructure and imrpoving charpy impact properties of high strength steel weld metal
The test results could be explained in terms of decreasing martensite-austenite (M-A) constituent with decreasing silicon content.