Study on the thermal deformation behavior and microstructure of FGH96 heat extrusion alloy during two-pass hot deformation

Abstract

The change rules associated with hot deformation of FGH96 alloy were investigated by isothermal two-pass hot deformation tests in the temperature range 1050–1125°C and at strain rates ranging from 0.001 to 0.1 s⁻¹ on a Gleeble 3500 thermo-simulation machine. The results showed that the softening degree of the alloy between passes decreases with increasing temperature and decreasing strain rates. The critical strain of the first-pass is greater than that of the second-pass. The true stress-true strain curves showed that single-peak dynamic recrystallization, multi- peak dynamic recrystallization, and dynamic response occur when the strain rate is 0.1, 0.01, and 0.001 s⁻¹, respectively. The alloy contains three different grain structures after hot deformation: partially recrystallized tissue, completely fine recrystallized tissue, coarse-grained grains. The small-angle grain boundaries increase with increasing temperature. Increasing strain rates cause the small-angle grain boundaries to first increase and then decrease.

Keywords

FGH96 super-alloy / two-pass hot deformation / microstructure / grain orientation

References

[1] Semiatin SL, Shank JM, Shiveley AR, Saurber WM, Gaussa EF, Pilchak AL. The effect of forging variables on the supersolvus heat-treatment response of powder-metallurgy nickel-base superalloys. Metall. Mater. Trans. A., 2014, 45(13): 6231.

[2] Li J, Wang HM. Microstructure and mechanical properties of rapid directionally solidified Ni-base superalloy Rene41 by laser melting deposition manufacturing. Mater. Sci. Eng. A, 2010, 527(18–19): 4823.

[3] Zhang MJ, Li FG, Wang SY, Liu CY. Effect of powder preparation technology on the hot deformation behavior of HIPed P/M Nickel-base superalloy FGH96. Mater. Sci. Eng. A, 2011, 528(12): 4030.

[4] Zhang MJ, Li FG, Yuan ZW, Li J, Wang SY. Effect of heat treatment on the micro-indentation behavior of powder metallurgy nickel based superalloy FGH96. Mater. Des., 2013, 49, 705.

[5] Liu CZ, Liu F, Lan H, Jiang L. Effect of hot extrusion and heat treatment on microstructure of nickel-base superalloy. Trans. Nonferrous Met. Soc. China, 2014, 24(8): 2544.

[6] Xie XH, Yao ZK, Ning YQ, Guo HZ, Tao Y, Zhang YW. Dynamic recrystallization and grain refining of superalloy FGH4096. J. Aeronaut. Mater., 2011, 31(1): 20.

[7] Yao ZH, Dong JX, Zhang MC. Microstructure control and prediction of GH738 superalloy during hot deformation I. Construction of microstructure evolution model. Acta Metall. Sin., 2011, 47, 1581.

[8] Liu PF, Liu D, Luo ZJ, Sun WR, Guo SR, Hu ZQ. Flow behavior and dynamic recrystallization model for GH761 superalloy during hot deformation. Rare Met. Mater. Eng., 2009, 38(2): 275.

[9] Wu ZG, Li DF, Guo SL, Guo QM, Peng HJ. Dynamic recrystallization models of GH625 Ni-based superalloy. Rare. Met. Mater. Eng., 2012, 41, 235.

[10] Fang B, Ji Z, Liu M, Tian GF, Jia CC, Zeng TT, Hu BF, Chang YH. Critical strain and models of dynamic recrystallization for FGH96 superalloy during two-pass hot deformation. Mater. Sci. Eng. A, 2014, 593, 8.

[11] Fang B, Ji Z, Liu M, Tian GF, Jia CC, Zeng TT, Hu BF, Wang CC. Study on constitutive relationships and processing maps for FGH96 alloy during two-pass hot deformation. Mater. Sci. Eng. A, 2014, 590, 255.

[12] Fang B, Ji Z, Tian GF, Jia CC, Hu BF, Cui ZW. Flow behavior and processing map of FGH96 superalloy during two-pass hot deformation. Chin. J. Eng., 2015, 37(3): 336.

[13] He DG, Lin YC, Chen MS, Ling L. Kinetics equations and microstructural evolution during metadynamic recrystallization in a nickel-based superalloy with δ phase. J. Alloys Compd., 2017, 690, 971.

[14] Lin YC, Liu YX, Chen MS, Huang MH, Ma X, Long ZL. Study of static recrystallization behavior in hot deformed Ni-based superalloy using cellular automaton model. Mater. Des., 2016, 99, 107.

[15] He DG, Lin YC, Chen J, Chen DD, Huang J, Tang Y, Chen MS. Microstructural evolution and support vector regression model for an aged Ni-based superalloy during two-stage hot forming with stepped strain rates. Mater. Des., 2018, 154, 51.

[16] Lin YC, Wu F, Wang QW, Chen DD, Singh SK. Microstructural evolution of a Ni-Fe-Cr-base superalloy during non-isothermal two-stage hot deformation. Vacuum., 2018, 151, 283.