Technological Tests on Dual Phase Seamless Steel Pipe Made from Q345 Steel and Evaluation of its Forming Performance

By applying intermediate frequency induction heating and spray ring cooling on a Q345 seamless steel pipe, a dual phase seamless steel pipe containing ferrite and martensite is made.Analyzed the influence of different intercritical annealing temperatures on the structure and properties of the dual phase seamless steel pipe. Also evaluated is the forming performance of the testing pipe by the pipe end expanding test.The results of the tests indicate that when a Q345 seamless steel pipe is heated to intercritical temperature by intermediate frequency induction heating and then treated by annealing, a dual phase seamless steel pipe with high strength and high forming performance will be made.For example, after being annealed at 750℃, the testing pipe will have a relatively homogeneous phase distribution, a stress-strain curve showing continuous yielding and a product of strength and elongation reaching 16 510 MPa·%.