Effect of Nb and aging time on phosphorus segregation in hot-rolled medium-manganese TRIP steel

doi:10.13251/j.issn.0254-6051.2020.03.012

Abstract

Abstract:

The phosphorus segregation and precipitation behavior in a hot-rolled medium-manganese TRIP steel treated with 650 ℃ annealing for 2 h+550 ℃ isothermal aging were investigated by field emission scanning electron microscopy (FE-SEM). The results show that the grain boundary segregation of P is a non-equilibrium phenomenon. The critical time is about 50 h, which is consistent with the theoretical calculation result of 48 h. C and P co-segregation exists in certain local regions, where the segregations of C and P are both higher. The alloying element Nb has an inhibitory effect on phosphorus segregation in the steel, the maximum P segregation content can be reduced relatively by 6.57%-19.5% within the aging time of 20-70 h. According to the Kikuchi line analysis in the electron backscatter diffraction, P is in solid solution when the content of segregation is less than 2.28at%, while P will be in the precipitated phase when the content of segregation is more than 2.28at%.

Key words: medium-manganese steel, isothermal aging, phosphorus segregation, non-equilibrium segregation, critical time

CLC Number:

TG142.3

Li Yan, Fu Jixue, Zhao Zengwu, Ding Wei. Effect of Nb and aging time on phosphorus segregation in hot-rolled medium-manganese TRIP steel[J]. HTM, 2020, 45(3): 59-63.

References

[1]Lea C. Stress corrosion cracking and temper brittleness: Effect of phosphorus grain boundary segregation in a low-alloy steel[J]. Metal Science Journal, 2013, 14(3): 107-112.
[2]黄传根, 宋波, 辛文彬, 等. 稀土La对含As、Sn低碳钢高温热塑性的影响[J]. 金属热处理, 2015, 40(10): 1-6.
Huang Chuangen, Song Bo, Xin Wenbin, et al. Influence of rare earth La on hot ductility of low carbon steel containing As and Sn[J]. Heat Treatment of Metals, 2015, 40(10): 1-6.
[3]Xing W T, Kalidindi A R, Amram D, et al. Solute interaction effects on grain boundary segregation in ternary alloys[J]. Acta Materialia, 2018, 161: 285-294.
[4]Min J H, Heo Y U, Kwon S H, et al. Embrittlement mechanism in a low-carbon steel at intermediate temperature[J]. Materials Characterization, 2019, 149: 34-40.
[5]Mclean D, Maradudin A. Grain boundaries in metals[J]. Physics Today, 1958, 11(7): 35-36.
[6]Zhang X L, Liu T. Segregation mechanism of phosphorus in Ti-stabilized interstitial-free steel[J]. Applied Surface Science, 2015, 344: 171-175.
[7]Aust K T, Hanneman R E, Niessen P, et al. Solute induced hardening near grain boundaries in zone refined metals[J]. Acta Metallurgica, 1968, 16(3): 291-302.
[8]Anthony T R. Solute segregation in vacancy gradients generated by sintering and temperature changes[J]. Acta Metallurgica, 1969, 17(5): 603-609.
[9]Song S H, Zhao Y, Si H. Non-equilibrium phosphorus grain boundary segregation and its effect on embrittlement in a niobium-stabilized interstitial-free[J]. Materials Letters, 2015, 140: 20-22.
[10]李晓源, 孙颖. 硫、磷晶界偏聚对40CrNi2Mo钢冲击性能的影响[J]. 金属热处理, 2013, 38(4): 16-19.
Li Xiaoyuan, Sun Ying. Influence of sulphur and phosphorus grain-boundary segregation on impact property for 40CrNi2Mo steel[J]. Heat Treatment of Metals, 2013, 38(4): 16-19.
[11]Yang Y, Chen S L. Thermodynamic and kinetic modeling of grain boundary equilibrium segregation of P in α-Fe[J]. Calphad, 2017, 57: 134-141.
[12]Zhang S, Huang L J, Zhang A W, et al. Segregation of phosphorus and precipitation of MNP-Type phosphide at the grain boundary of IN706 superalloy[J]. Journal of Materials Science and Technology, 2017, 33(2): 187-191.
[13]李岩, 蔡旭东, 赵增武, 等. 临界区退火对热轧中锰TRIP钢P偏聚的影响[J]. 钢铁研究学报, 2018(11): 894-899.
Li Yan, Cai Xudong, Zhao Zengwu, et al. Effects of intercritical annealing on phosphorus segregation in hot-rolled medium-manganese TRIP steel[J]. Journal of Iron and Steel Research, 2018(11): 894-899.
[14]Erhart H, Grabke H J. Equilibrium segregation of phosphorus at grain boundaries of Fe-P, Fe-C-P, Fe-Cr-P, and Fe-Cr-C-P alloys[J]. Metal Science Journal, 1981, 15(9): 401-408.
[15]Bhadeshia H K D H, Suh D W. Is low phosphorus content in steel a product requirement[J]. Ironmaking and Steelmaking, 2015, 42(4): 259-267.
[16]Ando T, Krauss G. The effect of phosphorus content on grain boundary cementite formation in AISI 52100 steel[J]. Metallurgical Transactions A, 1981, 12(7): 1283-1290.
[17]Suzuki S, Obata M, Abiko K, et al. Effect of carbon on the grain boundary segregation of phosphorus in α-iron[J]. Scripta Metallurgica, 1983, 17(11): 1325-1328.
[18]Xu T D, Cheng B Y. Kinetics of non-equilibrium grain-boundary segregation[J]. Journal of Materials Science, 2004, 49(2): 109-208.
[19]Xu T D, Song S H. A kinetic model of non-equilibrium grain-boundary segregation[J]. Acta Metallurgica, 1989, 37(9): 2499-2506.
[20]Faulkner R G. Non-equilibrium grain-boundary segregation in austenitic alloys[J]. Journal of Materials Science, 1981, 16(2): 373-383.
[21]Xu T D. The critical time and critical cooling rate of non-equilibrium grain-boundary segregations[J]. Journal of Materials Science Letters, 1988, 7(3): 241-242.
[22]Seibel G. Diffusion of S and P in solid Fe[J]. Mem Sci Rev Met, 1964, 61: 413-436.
[23]Song S H, Xu T D. Combined equilibrium and non-equilibrium segregation mechanism of temper embrittlement[J]. Journal of Materials Science, 1994, 29(1): 61-66.
[24]Faulkner R G. Segregation to boundaries and interfaces in solids[J]. International Materials Reviews, 1996, 41(5): 198-208.
[25]余永宁. 金属学原理[M]. 北京: 冶金工业出版社, 2013.
[26]Takeuchi A, Inoue A. Classification of bulk metallic glasses by atomic size difference, heat of mixing and period of constituent elements and its application to characterization of the main alloying element[J]. Materials Transactions, 2005, 46(12): 2817-2829.