Study On The Welding Process Optimization Of Pearlitic Steel And Austenitic Steel And The Joint Performances

Welded pressure vessels is made up base metal and welded joint, the use of the welding joint performance, fundamentally determines the quality of the pressure vessel. Especially when there is a dissimilar steel welding equipment container, because of its special properties of welding, determines the between dissimilar steel welding procedure is particularly important.This paper studies the pearlitic steel Q245 R and austenitic steel 06Cr19Ni10 welding technology, tested the welding joint organization and mechanical properties, welding mechanism were analyzed. Further study on the welding method and heat treatment of pearlitic steel and austenitic steel welded joint mechanical properties, the influence of dissimilar steel welding process was optimized.Under the condition of three electrode arc welding technique, the microstructure of Q245 R and 06Cr19Ni10 weld joint is observed, i.e. using multi-layer welding with stringer bead technique or weave technique, interpass temperature below 100 ℃:weld precipitation in the delta ferrite is small, Q245 R side weld joint with coarse grain / fine grain area organization are ferrite and pearlite; otherwise,using multi-layer welding with weave bead technique, interpass temperature is not controlled:weld precipitation in the delta ferrite is big,Q245 R side weld joint for the coarse grain/fine grain ferrite area organization are westergren. Also,using multi-layer welding with stringer bead technique,Mechanical properties of the weld joint is optimal. Second, in the submerged arc welding condition, weld joint microstructure observed: weld microstructure is austenite and delta ferrite,the Microstructure of HZA coarse grain by Q245 R side is bainite and westergren body; using ER308 welding wire, precipitate the delta ferrite content in the weld wire is more; but,using ER309 welding wire, less precipitation the delta ferrite content in the weld. Mechanical properties showed that the former process conditions, the tensile strength of the weld joint is bigger. Through metallographic also observed that under two kinds of welding methods, near the fusion zone of Q245 R base side there is an obvious transition layer.Scanning electron microscopy(sem) on the tensile fracture Q245 R and 06Cr19Ni10 sample observation and structural analysis. The results show that the three electrode arc welding process, the sample fracture is toughening fossa fracture characteristic; in the two kinds of submerged arc welding process of sample 15-04 in grain boundary cracking characteristics, the area should be welding hot crack, sample 15-05 toughening fossa fracture characteristics. And can be observed in the microstructure near the fusion zone near the Q245 R base side there is an obvious layer.This article has used the company welding pearlitic and austenitic steel welding procedure qualification test, expanded the process factors such as heat treatment, the line energy of pearlitic steel and austenitic steel welded joint effect of mechanical properties, the results show that heat-treatment specimens in the weld HAZ impact significantly greater than the impact energy of nonthermal specimen HAZ area, sample’s HAZ impact energy with big line energy is bigger than the sample’s HAZ impact energy with little line energy.Conclusion: welded pressure vessels is pearlitic steel and austenitic steel dissimilar welded joint, using SMAW, as far as possible use multilayer multipass welding, interpass temperature control under 100 ℃, in order to obtain the comprehensive mechanics performance good welding joint; Using submerged arc welding, welded pressure vessels in the use of low temperature and the weld material ER308- HJ260, can meet the using performance of the product.