Effects of rare earth elements on inclusions and impact toughness of high-carbon chromium bearing steel

doi:10.1016/j.jmst.2019.01.015

Abstract

Abstract:

High-carbon chromium bearing steels with different rare earth (RE) contents were prepared to investigate the effects of RE on inclusions and impact toughness by different techniques. The results showed that RE addition could modify irregular Al₂O₃ and MnS into regular RE inclusions. With the increase of RE content, the reaction sequence of RE and potential inclusion forming elements should be O, S, As, P and C successively. RE inclusions containing C might precipitate in molten steel and solid state, but the precipitation temperature was significantly higher than that of carbides in high-carbon chromium bearing steel. For experimental bearing steels, the volume fraction of inclusions increased steadily with the increase of RE content, but smaller and more dispersed inclusions could be obtained by 0.018% RE content compared with bearing steel without RE, whereas the continuous increase of RE content led to an increasing trend for inclusion size and a gradual deterioration for inclusion distribution. RE addition could improve the transverse impact toughness and isotropy of bearing steel, and for modified high-carbon chromium bearing steel by RE alloying, the increase of RE content continuously increased both transverse and longitudinal impact toughness until excessive RE addition.

Key words: High-carbon chromium bearing steel, Rare earth, Inclusions, Impact toughness

Chaoyun Yang, Yikun Luan, Dianzhong Li, Yiyi Li. Effects of rare earth elements on inclusions and impact toughness of high-carbon chromium bearing steel[J]. J. Mater. Sci. Technol., 2019, 35(7): 1298-1308.

Figures/Tables 16

Table 1 Chemical compositions of the experimental steels (wt%).

Number	C	Si	Mn	Cr	S	As	P	La	Ce	O
1	0.99	0.26	0.30	1.45	0.004	<0.001	0.01	---	---	0.0008
2	0.99	0.25	0.36	1.43	0.0052	<0.001	0.009	0.0059	0.012	0.0008
3	0.99	0.24	0.35	1.42	0.0037	<0.001	0.009	0.01	0.025	0.0007
4	0.99	0.25	0.36	1.45	0.006	<0.001	0.01	0.024	0.052	0.0008
5	0.99	0.24	0.35	1.45	0.007	<0.001	0.01	0.046	0.094	0.0014
6	0.95	0.23	0.35	1.41	0.0013	<0.001	0.011	0.18	0.4	0.0019

Fig. 1. Diagram of isothermal spheroidizing heat treatment.

Fig. 2. SEM images and EDS analysis results of inclusions in test steels with different RE contents: (a, b) No.1 steel; (c, d) No.2 steel; (e, f) No.3 steel; (g) No.4 steel; (h) No.5 steel; (k) No.6 steel.

Fig. 3. SEM images and EDS maps of element distribution of inclusions in No.3 steel: (a) RE-S-As inclusion; (b) RE-S-As-P inclusion.

Fig. 4. EPMA images and element distribution maps of inclusions and carbides in No.6 steel.

Fig. 5. Average size and maximum size of inclusions in No.6 steel before and after solid solution treatment.

Fig. 6. Statistic results of (a) size distribution and (b) volume fraction of inclusions in test steels with different RE contents.

Fig. 7. Overview of inclusions in (a) No.1 steel, (b) No.2 steel, (c) No.3 steel, (d) No.4 steel, (e) No.5 steel and (f) No.6 steel.

Fig. 8. Effects of RE content on (a) impact absorbed energy and (b) the ratio of transverse impact energy to longitudinal impact energy.

Fig. 9. SEM fractograph of No.1 longitudinal impact specimen (a) and EDS of fractured complex inclusion (b).

Fig. 10. SEM fractographs of crack initiation regions of (a) No.2, (b) No.3, (c) No.4, (d) No.5 and (e) No.6 longitudinal impact specimens.

Fig. 11. SIMS images and the distribution of P in (a) No.2 and (b) No.4 impact specimens.

Fig. 12. SEM fractographs of crack initiation and slow propagation regions from (a) No.3, (b) No.4 and (c) No.6 longitudinal impact specimens.

Fig. 13. SEM fractographs of crack fast propagation region from (a) No.3, (b) No.4 and (c) No.6 longitudinal impact specimens.

Fig. 14. Fracture morphologies close to crack source of (a) No.2, (b) No.3, (c) No.4, (d) No.5 and (e) No.6 longitudinal impact specimens.

Fig. 15. Models of crack growth influenced by inclusions: (a) No.1 longitudinal impact specimen; (b) No.1 transverse impact specimen; (c) No.2-5 impact specimens; (d) No.6 impact specimen.

References

[1]	K. Hashimoto, T. Fujimatsu, N. Tsunekage, K. Hiraoka, K. Kida, E.C. Santos, Mater. Des. 32(2011) 1605-1611
[2]	J.M. Zhang, S.X. Li, Z.G. Yang, G.Y. Li, W.J. Hui, Y.Q. Weng, Int. J. Fatigue 29 (2007) 765-771
[3]	J. Courbon, G. Lormand, G. Dudragne, P. Daguier, A. Vincent Tribol. Int. 36(2003) 921-928
[4]	P. Trady, L. Tolnay, Gy. Károly, J. Mezei, ISIJ, Nagoya, JapanProc. 6th Int. Iron and Steel Cong.1990 Proc. 6th Int. Iron and Steel Cong. (1990) 629
[5]	Y.Q. Liu, L.J. Wang, G.Z. Zhou, J. Rare Earths 32 (2014) 759-766
[6]	J.H. Ahn, H.D. Jung, J.H. Im, K.H. Jung, B.M. Moon, Mater. Sci. Eng. A 658 (2016) 255-262
[7]	J. Zhao, T. Zhao, C.S. Hou, F.C. Zhang, T.S. Wang, Mater. Des. 86(2015) 215-220
[8]	C. Huang, C.L. Zhang, L. Jiang, Y. Yang, Y.Z. Liu, J. Alloys Compd. 660(2016) 131-135
[9]	Z.X. Li, C.S. Li, J.Y. Ren, B.Z. Li, J. Zhang, Y.Q. Ma, Mater. Sci. Eng. A 674 (2016) 262-269
[10]	J. Chakraborty, D. Bhattacharjee, I. Manna, Scr. Mater. 61(2009) 604-607
[11]	I. Velkavrh, F. Ausserer, S. Klien, J. Voyer, A. Ristow, J. Brenner, P. Forêt, A. Diem, Tribol. Int. 98(2016) 155-171
[12]	M. Drábik, V. Ballo, M. Truchly, J. Frkáň, T. Roch, L. Kvetková, L. Satrapinskyy, P. Kú?, Surf. Coat. Technol. 293(2016) 2-9
[13]	W. Yue, Z.Q. Fu, S. Wang, X.C. Gao, H.P. Huang, J.J. Liu, Tribol. Int. 74(2014) 72-78
[14]	N. Raje, T. Slack, F. Sadeghi, Int. J. Fatigue 31 (2009) 346-360
[15]	E.S. Alley, R.W. Neu, Int. J. Fatigue 32 (2010) 841-850
[16]	T. Slack, F. Sadeghi, Tribol. Int. 44(2011) 797-804
[17]	K. Hashimoto, T. Fujimatsu, N. Tsunekage, K. Hiraoka, K. Kida, E.C. Santos, Mater. Des. 32(2011) 4980-4985
[18]	T. Sakai, B. Lian, M. Takeda, K. Shiozawa, N. Oguma, Y. Ochi, M. Nakajima, T. Nakamura, Int. J. Fatigue 32 (2010) 497-504
[19]	G. Chai, Int. J. Fatigue 28 (2006) 1533-1539
[20]	K. Shiozawa, Y. Morii, S. Nishino, L. Lu, Int. J. Fatigue 28 (2006) 1521-1532
[21]	J. Zhao, T.S. Wang, B. Lv, F.C. Zhang, Mater. Sci. Eng. A 628 (2015) 327-331
[22]	H.K.D.H. Bhadeshia, Sci. Technol. Adv. Mater. 14(2013) 014202
[23]	H.J. Liu, J.J. Sun, T. Jiang, S.W. Guo, Y.N. Liu, Scr. Mater. 90-91(2014) 17-20
[24]	A. Leiro, E. Vuorien, K.G. Sundin, B. Prakash, T. Sourmail, V. Smaio, F.G. Caballero, C. Garcia-Mateo, E. Roberto, Wear 298 (2013) 42-47
[25]	F. Pan, J. Zhang, H.L. Chen, Y.H. Su, Y.H. Su, W.S. Hwang, Sci. Rep. 6(2016) 35843
[26]	Y. Li, C. Liu, C. Li, M. Jiang, J. Iron Steel Res. Int. 22(2015) 457-463
[27]	C.C. Xu, L.S. Zhang, J. Xi’an, Inst. Metall. Constr. Eng. 50(1987) 71-78 (in Chinese)
[28]	A. Melander, Int. J. Fatigue 19 (1997) 13-24
[29]	J. Hufenbach, A. Helth, M.H. Lee, H. Wendrock, L. Giebeler, C.Y. Choe, K.H. Kim, U. Kühn, T.S. Kim, J. Eckert, Mater. Sci. Eng. A 674 (2016) 366-374
[30]	C.Y. Yang, Y.K. Luan, D.Z. Li, Y.Y. Li, Steelmaking 32 (2016) 54-59 (in Chinese)
[31]	S.H. Song, Y.W. Xu, X.M. Chen, X. Jiang, J. Rare Earths 34 (2016) 1062-1068
[32]	Y.W. Xu, S.H. Song, Metals 6 (2016) 187