Study On Friction Welding Processing Of Hollow Sucker Rods

Friction welding is a modern solid phase pressure welding technique, which has the characters of high efficiency and energy-saving. The welded joint has the forging microstructure, so it hardly appears crystal defects such as porosity, segregation, sludge and cracking which are always emerged in the casting microstructure. The strength of the friction welding joint can reach that of the base material, and are far great than that of the melting or brazing welded joint. So the friction welding is quite suit for connecting the different high strength low alloy steels.An oil mechanical factory products the D grade sucker rods, which connected the 35CrMo rod head and 42CrMo rod body by friction welding, and then tempered the joint at 560℃using local induction heating and wiping off the flash width.Firstly, the fracture and metallographic of the failed welded joint is analyzed. There are bainite and troosite in the joint, which induced maybe by unsuitable welding parameters. The high energy input made the area near the surface high temperature and low cooling rate, most of overcooled austenite in the flowing area become bainite and troosite, which greatly affect the toughness and the strength of the heat affected zone. Therefore, optimizing the parameters and amending the microstructure are helpful to improve the mechanical properties of the joint. To decrease the energy input and the cooling rate, a serious of experiments are carried out at various welding parameters. The results show that a proper joint are obtained, which has a eliminated bainite and troosite microstructures and a reduced heat affected zone width, in the parameter of less friction time, high friction and forge pressure.The sucker rod can not attain the property of D grade, only by adjusting the welding parameters, because of the rolled microstructure body. The heat treatment must be carried out. A optimum heat treatment regime is obtained by choosing various quenching and temper temperatures. Temper at 550℃for 30minites then air cooled ,then keeping the sucker rods at 880℃for 15minites, quenched by water, and then temper at 600℃for 30minites then air cooled.