Failure Analysis Of Domestically Made Conduct Roller And Research On Laser Welding Of Hastelloy

Hastelloy C-22 performs excellently in corrosion-proof field, widely used in various manufacturing industries, including spaceflight, paper manufacture, electric plating and etc., Baosteel Cold Rolling Company used imported conduct roller to produce galvanized steel sheets. In the process of localization of conduct roller, one domestic factory relied on GTAW technique to make Hastelloy conduct roller. However, its service life was short.This paper examined fracture surface, observed microstructure, made EDAX and XRD analysis to reveal advanced failure reason of domestically made conduct roller, which could be used for reference to make one by laser welding technique.This paper systematically studied on the influence from groove dimension, gap, laser power, welding speed, composition and flow rate of side blowing gas, flow rate of back blowing gas and surface condition of weldment on weld seam formation, mechanical property, hot crack and pore sensibility, probed into the influence and form mechanism of hot cracks and pores on Hastelloy C-22 by laser welding. As a result, proper laser welding method was determined and corresponding specification was optimized.This paper designed and manufactured one special jig for butt joints welding of Hastelloy plates and the other for longitudinal seam welding of Hastelloy cylinder. According to following procedure, we made two conduct rollers with 1m in diameter, 2.46m in width, and 10.5mm in thickness: plasma cutting, groove machining, laser butt welding, inspection, reeling, laser longitudinal welding, inspection, solution treatment, circle-checking, precise calibration, hot jacket, TIG filler welding, precisely machining of outer circle of cylinder, grinding and etc., Two conduct rollers are proved to reach world-class level in quality and service life.