Study On Welding Process Of Friction Hydro Pillar Processing For Pipeline Steel

For the good characteristics of the high efficiency, welding quality and high adaptapbilityto circumstance, Friction Hydro Pillar Processing has widely used in repairing marine steelstructure crack underwater and steel structure in shipping industry. Because of the furtheradvantages in repairing thick structure, the process has already become the hot topic. TheFHPP welding process of the pipeline steel will be studied in this paper, to lay a theoreticalfoundation for solving burn-through and hydrogen-induced crack problems during thein-service welding repair process for pipeline steel.Using X65pipeline steel as the experimental material, the effects of welding quality withdifferent process parameters were investigated, the results show that rotational speed is themost important process parameters for the welding process. The higher rotational speed, thebetter welding quality. The influence of feeding speed on welding quality is restricted byrotational speed. Under the condition of high rotational speed, the increase of feeding speed isgood for welding quality. Under the condition of lower rotational speed, the increase offeeding speed is bad for welding quality. Choose the higer rotational speed and feed speed canget a defect-free welded joint with good apparance when adopt the ball bottom metal barwhich diameter is ten millimeter matches with the ball bottom hole which diameter is twelvemillimeter. After welding, analyze the microstructure and test the microhadness. It is observedthat the microstructure of X65pipeline steel FHPP joint is influenced by friction heating andcooling conditions. The main microstructure can get is ferrite and medium temperatureproducts, a small quantity of martensite can also be got under the condition of fast cooling,but ferrite is still the main microstructure. Microhardness test results are consistent withmicrostructure, the microhareness of the plastic metal filling area which is formed by metalbar and HAZ is higher than base metal. Based on the unit weld process, choose the procee parameters from the defect-freewelded zone to test the stitch weldment. The jump continued method is adopted in stitchwelding. The results show that the welding strength of stitch weldment is considerably largerthan base metal. The impact abortion energy of weld-seam position is higher than fusion line.Microhadness test results show that the subsequent forming units have the effect of heattreatment on the previous units and lower the microhadness. Fracture analysis shows that thefracture surface is nests, is a typical ductile fracture.