Seiichi Ando

Narrow gap automatic gas shielded arc welding of high carbon steel

Summary Rail steel is a typical high carbon material and has previously been extensively researched to improve its weldability. This paper describes an investigation of narrow gap automatic gas shielded arc welding of rails to determine the effects of the process parameters, weld metal carbon content, and post weld heat treatment through observations of defects and microstructures, hardness measurements, and tensile tests of welded joints. Through adjustment of the temperature of the water-cooled copper block surrounding the rail welds, the heat input to the base material can be controlled and the weld quality thus improved. Suitable post weld heat treatment and welding conditions improve the weld properties. Control of the weld metal carbon content is an important factor in prevention of hot cracking. Hot cracking in the HAZ is influenced by MnS inclusions and can be prevented through application of suitable process parameters.

Effects of zirconium on mechanical properties of 7050 aluminum alloy welds by electron beam welding.

7050 aluminum alloy extruded plates 12mm in thickness were electron beam welded. Effects of Zr up to 0.16% in the base metal on the microstructures and mechanical properties of welds were investigated. Tensile strength, ductility and fatigue strength of the welded joints naturally aged after welding are affected by Zr contents. The welds of Zr added base metal show higher tensile strength and elongation than those of Zr free one owing to refined grain size in the fusion zone. The properties of welded joints T7-tempered after welding are, however, above 90% irrespective of Zr contents. Nevertheless, T7-tempered welds show considerably lower ductility and impact absorbed energy than the base metal. The optimum Zr content 0.12% in the base metal is recommended.