Hot deformation mechanism and microstructure evolution of an ultra-high nitrogen austenitic steel containing Nb and V

Abstract

The flow curves of an ultra-high nitrogen austenitic steel containing niobium (Nb) and vanadium (V) were obtained by hot compression deformation at temperatures ranging from 1000°C to 1200°C and strain rates ranging from 0.001 s⁻¹ to 10 s⁻¹. The mechanical behavior during hot deformation was discussed on the basis of flow curves and hot processing maps. The microstructures were analyzed via scanning electron microscopy and electron backscatter diffraction. The relationship between deformation conditions and grain size after dynamic recrystallization was obtained. The results show that the flow stress and peak strain both increase with decreasing temperature and increasing strain rate. The hot deformation activation energy is approximately 631 kJ/mol, and a hot deformation equation is proposed. (Nb,V)N precipitates with either round, square, or irregular shapes are observed at the grain boundaries and in the matrix after deformation. According to the discussion, the hot working should be processed in the temperature range of 1050°C to 1150°C and in the strain rate range of 0.01 to 1 s⁻¹.

Keywords

austenitic steels / hot deformation / microstructural evolution / nitrides

References

[1] Simmons J.M. Overview: high-nitrogen alloying of stainless steels. Mater. Sci. Eng. A, 1996, 207(2): 159.

[2] Speidel M.O. Nitrogen containing austenitic stainless steels. Mater. Sci. Eng. Technol., 2006, 37(10): 875.

[3] Fu W.T., Zheng Y.Z., He X.K. Resistance of a high nitrogen austenitic steel to cavitation erosion. Wear, 2001, 249(9): 788.

[4] Di Schino A., Kenny J.M., Mecozzi M.G., Barteri M. Development of high nitrogen, low nickel, 18%Cr austenitic stainless steels. J. Mater. Sci., 2000, 35(19): 4803.

[5] Jiang Z.H., Zhang Z.R., Li H.B., Li Z., Ma Q.F. Microstructural evolution and mechanical properties of aging high nitrogen austenitic stainless steels. Int. J. Miner. Metall. Mater., 2010, 17(6): 729.

[6] Li H.B., Jiang Z.H., Yang Y., Cao Y., Zhang Z.R. Pitting corrosion and crevice corrosion behaviors of high nitrogen austenitic stainless steels. Int. J. Miner. Metall. Mater., 2009, 16(5): 517.

[7] Padilha A.F., Machado I.F., Plaut R.L. Microstructures and mechanical properties of Fe–15%Cr–15%Ni austenitic stainless steels containing different levels of niobium additions submitted to various processing stages. J. Mater. Process. Technol., 2005, 170(1-2): 89.

[8] Knutsen R.D., Lang C.I., Basson J.A. Discontinuous cellular precipitation in a Cr–Mn–N steel with niobium and vanadium additions. Acta Mater., 2004, 52(8): 2407.

[9] Tarboton J.N., Matthews L.M., Sutcliffe A., Frost C.M.P., Wessels J.P. The hot workability of CromaniteTM, a high nitrogen austenitic stainless steel. Mater. Sci. Forum, 1999, 318-320, 777.

[10] Wang L.J., Sheng L.Y., Hong C.M. Influence of grain boundary carbides on mechanical properties of high nitrogen austenitic stainless steel. Mater. Des., 2012, 37, 349.

[11] Kim Y.S., Nam S.M., Kim S.J. Strain rate dependence of deformation behavior of high-nitrogen austenitic steels. J. Mater. Process. Technol., 2007, 187-188, 575.

[12] Shin J.H., Lee J.W. Effects of twin intersection on the tensile behavior in high nitrogen austenitic stainless steel. Mater. Charact., 2014, 91, 19.

[13] Hong C.M., Shi J., Sheng L.Y., Cao W.C., Hui W.J., Dong H. Effects of hot-working parameters on microstructural evolution of high nitrogen austenitic stainless steel. Mater. Des., 2011, 32(7): 3711.

[14] Lang Y.P., Zhou Y., Rong F., Chen H.T., Weng Y.Q., Su J. Hot working of high nitrogen austenitic stainless steel. J. Iron Steel Res. Int., 2010, 17(10): 45.

[15] Haj M., Mansouri H., Vafaei R., Ebrahimi G.R., Kanani A. Hot compression deformation behavior of AISI 321 austenitic stainless steel. Int. J. Miner. Metall. Mater., 2013, 20(6): 529.

[16] Zhang W.H., Sun S.H., Zhao D.L., Wang B.Z., Wang Z.H., Fu W.T. Hot deformation behavior of a Nb-containing 316LN stainless steel. Mater. Des., 2011, 32(8-9): 4173.

[17] Prasad Y.V.R.K., Sasidhara S. Hot Working Guide: A Compendium of Processing Maps. ASM International, 1997 3.

[18] Silva E.S., Sousa R.C., Jorge A.M., Balancin O. Hot deformation behavior of an Nb- and N-bearing austenitic stainless steel biomaterial. Mater. Sci. Eng. A, 2012, 543, 69.