FLOW STRESS BEHAVIOR OF VALVE ALLOY Ni30 UNDER HOT COMPRESSION
In this paper,the Ni30 alloy forging bar made by vacuum induction smelting and forging was selected.The sample Φ 10 mm × 17 mm was cut from the alloy forging bar along the axis direction,and then machined into small cylindrical sample Φ 8 mm × 15 mm.The hot compression experiment was carried out by Gleeble-1500 thermal simulation experimental machine.The experimental strain rates are 5 s1,20 s-1 and 50 s-1,and the deformation temperatures are 1 000 ℃,1 050 ℃ and 1 100 ℃,respectively,with the dependent variable of 0.5.The heating rate of the hot compression test was 10 ℃/s,and the holding time was 5 mins.The samples were water-cooled immediately after the hot compression test.Origin2019b software was used to process the data obtained from the Ni30 alloy hot compression experiment,and the true stress-strain curve was fitted.The relationship between thermal deformation temperature,strain rate and flow stress of the alloy is described by the constitutive equation,which was ε=2.14 × 1010[sinh(0.002 9σ)]3 57 exp[-240 190/(RT)].It also reflects the dynamic equilibrium relationship between work hardening and recrystallization softening of the material.According to the constitutive equation established,the hot deformation activation energy of the alloy is 240.19 kJ/mol.Through the observation of the microstructure changes of the alloy after thermal deformation,it is found that the recrystallization degree of the alloy can be improved by decreasing the strain rate or increasing the deformation temperature.
万方数据
维普
