Study On High Temperature Deformation Behavior And Die Forging Process Of 300M Steel

300M steel has high strength,fracture toughness and good fatigue resistance,so it is widely used in aircraft landing gear and other large load-bearing structural parts.High-bar die forgings made of 300 M steel have complex shape,difficult cavity filling and large forming load.Therefore,it is necessary to systematically study the hot deformation behavior of 300 M steel and the forming process and limit of high bar forgings.In this paper,the thermal compression test is carried out on a thermal simulation testing machine.The flow stress curve of 300 M steel is analyzed and the friction correction of the curve is carried out.The constitutive model of 300 M steel is constructed and the change rule of the flow stress curve is revealed.The critical condition model and dynamic recrystallization grain size model of 300 M steel were established based on the flow stress curve obtained from the hot compression test results.The single-ribbed forging model was abstracted from complex reinforcement plate forgings.The forging process of 300 M steel was studied by numerical simulation,and the metal filling behavior and metal flow law of such forgings were analyzed.The results show that the filling speed of the metal at the center of the bottom plate of the single-rib forgings is the fastest,and the metal at the edge of the rib plate tends to fill inwardly due to the influence of the friction in the die cavity.The results show that the forming limit and filling quality of 300 M steel single-rib forgings are directly proportional to the thickness of the bottom plate,the radius of fillet and the inclination of drawing die,but inversely proportional to the rib width.