不銹鋼の自動熔接

Abstract

Cr-Ni austenitic stainless steel electrode wire were welded by submerged arc welder. In this case as the welding composition, grade 90 and 20 flux made by Linde Air Product Co. were used, and 18-8-Cb, 20-10-Mo, 17-13-Mo and 26-23 Cr-Ni welding rods made in our laboratory and comercial mild steel and two kinds of stainless steel mother plate were used on trial. Research on penetration, hardness and microstructure at welded part by single bead, recovery of hardness at heat affected zone by annealing, strength of austenitic stainless steel junction and mechanical properties and corrosion resistance of austenitic stainless steel weld metals was carried out.The results obtained are as follows:(1) Each single bead by submerged welding has very fine appearances and hardness of austenitic stainless steel is nearly equal to that of the austenitic steel mother plate, but is increased by being poor of Cr and Ni on welding to mild steel and 13 Cr stainless steel. In order to reduce the maximum hardness on heat affected zone and weld metal, it is necessary to be annealed and to be welded by the use of high Cr-Ni austenitic stainless steel electrode wire such as 26 Cr-23 Ni. Both penetration and amount of deposited metal on welding to stainless steel plate are larger than the mild steel.(2) From the mechanical test of junction it was recognized both I and V butt welding are good, and grade 90 flux is superior to grade 20 one, and 22 Cr-10Ni-Mo is most desirable in all electrode wires. This result is nearly equal to that of manual weld.(3) Mechanical properties of weld matal are not inferior to that by manual welding and it was known that grade 90 flux is somewhat excellent after mechanical test of weld metals, While acid resistivity of weld metals prepared by using grade 20 is excellent especially in H2SO4, except in HCl, but some stress corrosion cracks were seen on the specimens occasionally.