Metal resistance to deformation of drill pipes steels

To define the energy and force parameters of metal forming processes, it is needful to know the value of the strain resistance. Evaluation of influence of hot deformation technological parameters of steels on the value of metal resistance to plastic deformation was done. For the study samples of 25ХГФМА and 32Г2У steels were used in the form of cylinders of 8.0 mm diameter and 12.0 mm height. The hot upsetting of the samples was accomplished at the Gleeble-3800 simulator of thermo-mechanical processes. Heating of the samples, placed in a vacuum chamber, was done directly by passing electric current through them. The samples were heated to deformation temperature with rate of 5 °C/sec, followed by an isothermal exposure within 3 min to make the temperature even in the sample volume. The deformation was accomplished at the temperatures 1000, 1050, 1100, 1150, 1200, 1250°C and deformation rate 1.0 and 0.1 sec–1. To prevent welding of the samples to the surface of the working instrument (hardmetal striker), a 0.1 mm thick molybdenum foil was placed between a sample and strikers. In the process of the experiment, the sample temperature, deformation force and current variation of a sample height were recorded. It was determined, that parameters of resistance to deformation, obtained in the process of the experiment by using Gleeble-3800, were higher by 25–30%, than those cited in literature, which were obtained by using a multi-cam plastometer. The specified data on the resistance to deformation were intended for application at PJSC “Tagmet” when designing technological modes of ends upsetting of drill pipes made of steels 32Г2У and 25ХГМФА to define the upsetting force.