Study on Charpy Impact Properties of Welds (Report 1)

Relationship Between Charpy Impact Properties and Micro Structures of Si-Mn Weld Metals

Abstract

Relations among Charpy impact properties microstructures and Si, Mn or O content about Si-Mn weld metal with submerged arc welding were investigated for the purpose of finding out the way to improve Charpy impact properties of weld metal.
Results can be summarized as follows.
(1) In Si-Mn weld metals, effects of Si and Mn content on Charpy impact properties are related with the change of microstructure and the decrease of oxigen content. And when the chemical composition of weld metal is the range of 0.10-0.25% Si and 0.8-1.0% Mn Charpy impact properties of weld metal is the best.
(2) The growth of coarsened-grain ferrite and needle like ferrite on the microstructure deteriorate the Charpy impact properties, the growth of the mixed structure of them and fine-grain ferrite improve the Charpy impact properties.
From these results it is thought the control of micro-structure is the most important factor for the improvement of Charpy impact properties on the weld metals.