Research On Mechanism Of Refinement And Strengthening And Toughness Of Pumping Rod Steel

Pumping rod is the important part in oil field. Now the pumping rod we used is heat-treated steel, which includes expensive alloying ingredient. It will waste energy in the heat processing because of alloys. So the oil field is looking forward to the appearance of the new technology of the pumping rod steel. The purpose of the research is to explore microstructure transformation rule by the process of rolling, and supple transition point of dynamic CCT and static CCT. This paper analyzes the formation principle of the second-phase, and then finds out the mechanism of structure transmutation,strengthening and toughening during the process of hot deforming. The results of research as follows:Dynamic CCT and static CCT can be got from the experience date, and curves are flat, which include two parts: ferrite and pearlite. The first curve has a larger transition zone of ferrite. Ar3, Ar1 and transition temperature of dynamic CCT and static CCT can be found in experiment. Deforming can induce higher Ar3 and Ar1, which has no obvious influence. Ar3 and Ar1 are reducing with the increasing cooling velocity at the different transition temperature of ferrite and pearlite.Compared with dynamic microstructure and static microstructure, the former grain is finer than the static one because of deformation that influent ferrite to produce deformation or deformation band.The best technology was 700℃, under the condition of 5℃/s and 10s-1). The final microstructure is fine ferrite and degeneration pearlite, which calculate metal plastic model of resistance to deformation. The model offers theory gist for calculation of draught pressure and energy of calculation of it and energy of medium carbon steel used in pumping rod.The spheroidization of pearlite needs a long period, but there is not enough time for the diffusion of carbon under the high strain rate. When the strain rate is lower, it offers enough time, and forms high concentration gradient of carbon around austenite because of the ferrite precipitation. Carbon diffuses adequately by reason of long deforming time, and it is beneficial for acceleration of spheroidization of pearlite from lamina. Ferrite and pearlite appear during the process of continuous cooling. Ferrite has very little carbon, and the diffuse velocity of carbon in ferrite is faster than that of in cementite. So it is easy to go spheroidization to cementite in the around of ferrite and cementite.