Influence of Addition of Fe2O3 and CaO on the Performance of Manual SHS Welding Slag

Fe2O3、CaO have been added into the combustion system of manual SHS welding as slagging elements and the effects of their addition have been studied. Results showed that the combustion velocity and the adiabatic combustion temperature both became lower as the amount of the additives increased. The additives have dropped the density and the solidification temperature of the slag, which accelerated the separation of the slag and gas from the weld pool. (0.2~2.0) g of Fe2O3 and (0.2~1.2) g of CaO have been added into the rod. Experiments showed that the appropriate added amounts of Fe2O3 and CaO for each combustion weld rod were 1.2g and 0.6g respectively. The weld slag was honeycomb, brittle and easy to be removed from the weld metal. Analysis of the microstructure and composition showed that the matrix of the weld slag was glass, with some ceramics distrabuting on it. The ceramics had high content of Al2O3, which was created in the combustion reaction. The matrix of the weld alloy was α-Cu solid solution, on which a second phase with high content of Fe precipitated. There were no non-metallic inclusions in the weld metal ultimately. The weld joint had favorable mechanical performance, which tensile strength reached 400MPa, that fulfil the requirement of emergency welding.