Effect of atomization method on the hot deformation behavior of PM superalloy FGH98

The hot deformation behavior of as-HIPed PM superalloy FGH98 in the temperature range of 1 050-1 150 ℃ and strain rate range of 0.005~1.000 s-1was investigated by using isothermal constant strain rate compressing tests.The powder was prepared with different atomization methods.On the basis of dynamic material modeling,processing maps for the two atomized billet were established.The results show that the rheological curves of the two kinds of billets are similar.Under the same deformation condition,the peak stress of argon gas atomization(AA) powder billet is lower than that of plasma rotating electrode process(PREP) powder billet.The optimum deformation window for AA powder billet is 1 088-1 108 ℃/0.005-0.016 s-1,the efficiency of power dissipation η is higher than 42%.But the optimum deformation window for PREP powder billet is 1 098-1 120 ℃/0.010-0.016 s-1,η is higher than 40%.