Microstructure and Mechanical Properties of Weld in High Strength Low Alloy Steel by Ultra-Narrow Gap Welding

HITEN610U2, high strength low alloy steel, was welded by ultra-narrow gap welding Observed by optical metalloscope, there were large majority of columnar crystal in weld an equiaxial crystal was the weld cross-section of 12.6%. Each weld could be compartmentalized into( original microstructure zone, over heated zone and normalizing zone under next weld thermal cycle in which the microstructures were almost the same. Through quantificational metallographic analysis, it was found there was more than 92.2% of acicular ferrite in weld metal, and other microstructures were fine. Mechanical test indicated that the strength of weld metal was higher than body material, and had outstanding plasticity.