Quasi-Situ Characterization of Deformation in Low-Carbon Steel with Equiaxed and Lamellar Microstructure Treated by the Quenching and Partitioning Process

doi:10.1007/s40195-020-01135-8

Abstract

Abstract:

The relationship between microstructure morphology and mechanical properties of the low-carbon steel (Fe-0.20C-2.59Mn-2.13Si) treated by different intercritical annealed quenching and partitioning (Q&P) processes was investigated through interrupted tensile tests plus quasi-situ electron backscatter diffraction measurements. Results show that size and distribution of retained austenite (RA) directly affect the sequence of deformation induced martensitic transformation. As strain increases, the equiaxed RA grains wrapped by ferrite transform first, followed by the equiaxed and film-like RA grains adjacent to martensite. Compared with traditional intercritical annealed Q&P steel with equiaxed structure, the steel with quenching pretreatment contains uniform lamellar structure and the relatively film-like type of RA, leading to the higher yield strength, tensile strength, and elongation, as well as the steady increase in dislocation density upon straining.

Key words: Steel, Quenching and partitioning, Austenite, Martensitic transformation, Electron backscatter diffraction (EBSD), Tensile test

Pengfei Gao, Weijian Chen, Feng Li, Beijia Ning, Zhengzhi Zhao. Quasi-Situ Characterization of Deformation in Low-Carbon Steel with Equiaxed and Lamellar Microstructure Treated by the Quenching and Partitioning Process[J]. Acta Metallurgica Sinica (English Letters), 2020, 33(12): 1657-1665.

Figures/Tables 16

Fig. 1 Schematic diagrams of heat treatments

Fig. 2 Schematic diagrams of interrupted tensile plus quasi-situ EBSD samples: a specific dimensions (in mm) of the specimen with the location of the micro-Vickers indents and the EBSD region; b schematic diagram of the specimen during electropolishing, red parts were wrapped with electrical tapes; c schematic diagram of the specimen during interrupted tensile tests, blue part was wrapped with electrostatic tape (ND: normal direction, TD: transverse direction, RD: rolling direction, the same below)

Fig. 3 SEM microstructures of the a D-QP b P-QP before (-1) and after (-2) Q&P processes. The F, P, TM, and M/A represent ferrite, pearlite, tempered martensite, and martensite/austenite islands, respectively. The dotted boxes of ellipse (in green) and rectangle (in yellow) mark the typical areas of equiaxed ferrite and layered ferrite, respectively

Table 1 Phase volume fraction of the D-QP and P-QP (vol.%)

	Retained austenite	Ferrite	Martensite
D-QP	15.5	35.5	49.0
P-QP	10.0	32.0	58.0

Fig. 4 TEM microstructures and diffraction pattern of the a D-QP b P-QP before (-1, -2) and after (-3) tensile tests. The F, M, and RA represent ferrite, martensite, and retained austenite, respectively. The dotted boxes of rounded rectangle (in red) mark the typical areas of twin

Table 2 Proportion and average size of RA with different morphologies

	Equiaxed RA		Film-like RA
	Proportion of RA	Average size	Proportion of RA	Average size
D-QP	32%	1.10 μm	68%	0.12 μm
P-QP	0%	-	100%	0.10 μm

Fig. 5 Engineering stress-strain curves a, true stress-strain curves and work hardening rates b of the D-QP and P-QP

Table 3 Mechanical properties of the D-QP and P-QP

	Yield strength (YS, MPa)	Tensile strength (TS, MPa)	Total elongation (TE,%)	YS/TS	TS×TE (GPa%)
D-QP	858.29±21.25	1333.29±9.35	19.78±1.03	0.6437±0.0114	26.37±1.56
P-QP	1024.82±28.41	1401.09±12.13	21.02±0.84	0.7314±0.0139	29.45±1.43

Fig. 6 Engineering stress-displacement curves obtained from regular and quasi-situ tensile tests of a D-QP b P-QP

Fig. 7 Combined quasi-situ phase maps of RA and image quality (IQ) maps of a D-QP b P-QP at different displacements of (-0) 0 mm; (-1) 0.4 mm; (-2) 1.1 mm and (-3) 1.7 mm. The green areas correspond to the fcc lattice. The arrows and arrowhead in Fig. 7a0 indicate equiaxed RA grains. The deformations of the grains at the five-pointed star positions are shown in Fig. 9

Fig. 8 Schematic diagram of the formation of RA in sample D-QP. The arrows corresponding the carbon diffusion direction

Fig. 9 Deformation of different phases after 1.7 mm displacement. The examined areas correspond to the positions shown by the five-pointed star in Fig. 7

Fig. 10 RA volume fraction of D-QP and P-QP under different displacements

Fig. 11 Quasi-situ KAM maps of a D-QP b P-QP at different displacements of (-0) 0 mm; (-1) 0.4 mm; (-2) 1.1 mm and (-3) 1.7 mm. The silver and black lines delineate the phase interface and the large angle grain boundary, respectively. The white dotted lines indicate the increase of KAM value of the local area

Fig. 12 Fraction of KAM of a D-QP b P-QP; c average KAM value of D-QP and P-QP under different displacements

Fig. 13 Fraction of KAM a around (~120 nm) b of (-1) equiaxed RA in D-QP; (-2) film-like RA in D-QP and (-3) P-QP under different displacements

References 35

[1]	J.G. Speer, E. De Moor, A.J. Clarke, Mater. Sci. Technol. 31, 3(2015)
[2]	S.H. Sun, A.M. Zhao, R. Ding, X.G. Li, Acta Metall Sin. -Engl. Lett. 31, 216(2018)
[3]	Z. Wang, M.X. Huang, Metall. Mater. Trans. A 50, 5650 (2019)
[4]	B.B. He, M. Wang, L. Liu, M.X. Huang, Mater. Sci. Technol, 35, 2109 (2019)
[5]	J.G. Speer, D.K. Matlock, B.C. De Cooman, J.G. Schroth, Acta Mater. 51, 2611(2003) DOI URL
[6]	X. Wang, L. Liu, R.D. Liu, M.X. Huang, Metall. Mater. Trans. A 49, 1460 (2018)
[7]	D.H. Kim, J.H. Kang, J.H. Ryu, S.J. Kim, Mater. Sci. Technol, 35, 2115 (2019)
[8]	M.X. Huang, B.B. He, Mater. Sci. Technol. 34, 417(2018)
[9]	A.S. Nishikawa, G. Miyarnoto, T. Furuhara, A.P. Tschiptschin, H. Goldenstein, Acta Mater. 179, 1(2019)
[10]	D.D. Knijf, R. Petrov, C. Föjer, L.A. Kestens, Mater. Sci. Eng. A 615, 107 (2014)
[11]	S.H. Sun, A.M. Zhao, Mater. Sci. Technol. 34, 347(2018)
[12]	A. Mark, M. Westphal, D. Boyd, J. McDermid, D. Embury, Can. Metall. Q. 48, 237(2009)
[13]	A. Zinsaz-Borujerdi, A. Zarei-Hanzaki, H.R. Abedi, M. Karam- Abian, H. Ding, D. Han, N. Kheradmand, Mater. Sci. Eng. A 725, 341 (2018)
[14]	L. Li, Z.L. Mi, Z. Wang, Y.G. Yang, Z.C. Yu, Mater. Res. Express 5, 066553 (2018)
[15]	Y. Chong, G.Y. Deng, A.O. Yi, A. Shibata, N. Tsuji, J. Alloys Compd 811, 152040(2019)
[16]	R. Ding, D. Tang, A. Zhao, Scr. Mater. 88, 21(2014) DOI URL
[17]	R. Ding, Z. Dai, M. Huang, Z. Yang, C. Zhang, H. Chen, Acta Mater. 147, 59(2018) DOI URL
[18]	X. Long, R. Zhang, F. Zhang, G. Du, X. Zhao, Mater. Sci. Eng. A 760, 158 (2019)
[19]	J. Zhao, F. Zhang, Mater. Sci. Eng. A 711, 138637 (2020)
[20]	O. Matsumura, Y.S. Sakuma, H.S. TakeChi, Trans. Iron Steel Inst. Jpn. 27, 570(1987)
[21]	J.G. Speer, D.K. Matlock, B.C. DeCooman, J.G. Schroth, Scr. Mater. 52, 83(2005)
[22]	A.J. Clarke, J.G. Speer, M.K. Miller, R.E. Hackenberg, D.V. Edmonds, D.K. Matlock, F.C. Rizzoe, K.D. Clarkea, E. De Moorf, Acta Mater. 56, 16(2008)
[23]	J. Jung, S.J. Lee, S. Kim, B.C.D. Cooman, Steel Res Int. 82, 857(2011)
[24]	D.V. Shtansky, K. Nakai, Y. Ohmori, Acta Mater. 47, 2619(1999)
[25]	D. De Knijf, C. Föjer, L.A.I. Kestens, R. Petrov, Mater. Sci. Eng. A 638, 219 (2015)
[26]	S.H. Sun, A.M. Zhao, R. Ding, X.G. Li, Acta Metall Sin. -Engl. Lett. 31, 216(2017)
[27]	P. Huyghe, L. Malet, M. Caruso, C. Georges, S. Godet, Mater. Sci. Eng. A 701, 254 (2017)
[28]	D.C. Ludwigson, J.A. Berger, J. Iron Steel Inst 207, 63(1969)
[29]	I. Tamura, Met. Sci. 16, 245(1982) DOI URL
[30]	A. Devaraj, Z. Xu, F. Abu-Farha, X. Sun, L.G. Hector, JOM 70, 1752 (2018)
[31]	S. Zhang, E. Fan, J. Wan, J. Liu, Y. Huang, X. Li, Corros. Sci. 139, 83(2018)
[32]	J. Samei, Y. Salib, M. Amirmaleki, D.S. Wilkinson, Scr. Mater. 173, 86(2019)
[33]	Z. Xiong, P.J. Jacques, A. Perlade, T. Pardoen, Metall. Mater. Trans. A 50, 3502 (2019)
[34]	J. Hidalgo, C. Celada-Casero, M.J. Santofimia, Mater. Sci. Eng. A 754, 766 (2019)
[35]	P. Jacques, Q. Furnemont, T. Pardoen, F. Delannay, Acta Mater. 49, 139(2001)