Determination of the dynamic recrystallization kinetics model for SCM435 steel

Abstract

The flow stress behavior of SCM435 steel was studied by using a MMS-200 thermal simulation machine, under the conditions with deformation temperatures of 1023–1323 K and strain rate of 0.01–10 s⁻¹. The experimental results indicated that the critical strain would get smaller with the increment in temperature and the decrement in strain rate, leaving the dynamic recrystallization easier to occur. The peak stress constitutive equation of SCM435 steel under high temperatures was established by the form of hyperbolic sine, and the activation energy of deformation under high temperature was obtained by regression equation. The critical strain ɛ _c for dynamic recrystallization was accurately derived from the θ-σ curve containing strain hardening rate θ and flow stress σ. Then the correlation between peak stress, peak strain, critical stress, critical strain and the parameter Z was further obtained. The Avrami kinetic equation of dynamic recrystallization for SCM435 steel was developed from stress-strain curve, and the Avrami exponent m was abstracted. Observations also indicated that the Avrami constants would decrease with increments in temperature, but increase with increments in strain rate. The Avrami constant took small influence from the deforming temperature, but significant influence from strain rate, and the correlation between Avrami constant and the strain rate was obtained by regression equation.

Keywords

SCM435 steel / dynamic recrystallization / activation energy / critical strain

References

[1] He X, Yu Z, Lai Xinmin A Method to Predict flow Stress Considering Dynamic Recrystallization during Hot Deformation [J]. Comput. Mater. Sci., 2008, 44: 760-764.

[2] Shaban M, Eghbali B Characterization of Austenite Dynamic Recrystallization under Different Z Parameters in a Microalloyed Steel [J]. J. Mater. Sci. Technol., 2011, 27: 359-363.

[3] Mejía I, Bedolla-Jacuinde A, Maldonado C, . Determination of the Critical Conditions for the Initiation of Dynamic Recrystallization in Boron Microalloyed Steels[J]. Mater. Sci. Eng. A, 2011, 528: 4 133-4 140.

[4] Liu P, Liu R, Wei Y, . Austenite Dynamic Recrystallization of the Microalloyed Forging Steels 38MnVS during Forging Process[J]. Procedia Engineering, 2012, 27: 63-71.

[5] Lan L, Qiu C, Zhao D, . Dynamic and Static Recrystallization Behavior of Low Carbon High Niobium Microalloyed Steel[J]. J. Iron Steel Res. Int., 2011, 18: 55-60.

[6] Sellars CM, Tegart WJM Relationship between Strength and Structure in Deformation at Elevated Temperatures[J]. Mem. Sci. Rev. Met., 1966, 63: 731-738.

[7] Zener C, Hollomon H Effect of Strain Rate Upon Plastic Flow of Steel [J]. J Appl Phys., 1944, 15: 22-32.

[8] Li H, Luo H, Yang C, . Dynamic Recrystallization Kinetics in Austenitic Stainless Steel [J]. J. Iron Steel Res., 2008, 20: 32-39.

[9] Zhang H, Zhang B, Liu Jiantao Dynamics Measurement and Mathematical Models of Dynamic Recrystallization of Steel [J]. J. Shanghai Jiaotong Univ., 2003, 7: 1 053-1 060.

[10] Chen F, Cui Z, Chen Shijia Recrystallization of 30Cr2Ni4MoV Ultra-super-critical Rotor Steel during Hot Deformation Part I Dynamic recrystallization [J]. Mater. Sci. Eng. A, 2011, 528: 5 073-5 080.

[11] Najafizadeh A, Jonas J J Predicting the Critical Stress for Initiation of Dynamic Recrystallization [J]. ISIJ Int., 2006, 46: 1 679-1 684.

[12] Wu H, Du L, Liu Xianghua Dynamic Recrystallization and Precipitation Behavior of Mn-Cu-V Weathering Steel [J]. J. Mater. Sci. Technol., 2011, 27: 1 131-1 138.

[13] Xu Y, Tang D, Song Y, . Dynamic Recrystallization Kinetics Model of X70 Pipeline Steel [J]. Mater. Design, 2012, 39: 168-174.

[14] Kim SI, Choi SH, Lee Y Influence of Phosphorous and Boron on Dynamic Recrystallization and Microstructures of Hot-rolled Interstitial Free Steel [J]. Mater. Sci. Eng. A, 2005, 406: 125-133.

[15] Cho JR, Jeong HS, Cha DJ, . Prediction of Microstructural Evolution and Recrystallization Behaviors of a Hot Working Die Steel by FEM [J]. J. Mater. Process Tech., 2005, 160: 1-8.

[16] El Wahabi M, Gavard L, Montheille F, . Effect of Initial Grain Size on Dynamic Recrystallization in High Purity Austenitic Stainless Steels [J]. Acta Materialia, 2005, 53: 4 605-4 612.

[17] Sarkar A, Marchattiwar A, Chakravartty JK, . Kinetics of Dynamic Recrystallization in Ti-modified 15Cr-15Ni-2Mo Austenitic Stainless Steel [J]. J. Nucl. Mater., 2012, 22: 20-52.

[18] Chen M, Lin YC, Ma XueSong The Kinetics of Dynamic Recrystallization of 42CrMo Steel [J]. Mater. Sci. Eng. A, 2012, 556: 260-266.