Research on the Elimination of Banded Structure in SAE8620H Gear Steel

Abstract:

In order to eliminating the banded structure in SAE8620H gear steel,an isothermal annealing process and its mechanism has been studied in this paper. Results showed that isothermal annealing process can effectively eliminate banded structure in SAE8620H gear steel.With isothermal temperature 640°C-a certain low temperature indeed high undercooling,and for high nucleation at this temperature resulting in the decrease of nucleation rate difference in all areas,banded structure level decreased to 1 level.When isothermal temperature decreased to 610°C and 590°C,although the undercooling is so high that various regions began to nucleate at the same time,the transition temperature is so low that alloy elements in the regions previously occupied by pearlite bands diffuse faster than other regions,thus proeutectoid ferrite grains in these regions grow faster,regenerating the banded structure .

• Periodical: Advanced Materials Research (Volumes 1120-1121)
• Pages: 1276-1280
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1120-1121.1276
• Online since: July 2015
• Authors: Jing Li*, Zhen Ming Lin, Heng Hua Zhang, Man Jin
• Keywords: Banded Structure, Isothermal Annealing, Nucleation Rate, SAE8620H Gear Steel, Undercooling

References

[1] Kong Xianghua, Sun Ruihong, Tang Jing, et al. Influence of cooling speed in two-phase region on banded structure of 20CrMnTi steel[J]. Transactions of Materials and Heat Treatment, 2012, 33(4) : 1-4.

[2] Shanmugan P, Pathak S D. Some studies on the impact behavior of banded microalloyed steel[J]. Engineering Fracture Mechanics, 1996, 53(4) : 991- 1002.

DOI: 10.1016/0013-7944(95)00159-x

[3] Garcia N V, Gonzalo O, Quintana I, et al．Residual stresses and structural changes generated at different steps of the manufacturing of gears: Effect of banded structures[J]. Materials Science and Engineering A, 2011, 528(15) : 5146 -5157.

DOI: 10.1016/j.msea.2011.03.004

[4] Liu Zongchang, Wang Yufeng, ectal. The banding structure of forging rolling bar of 42CrMo steel[J]. Journal of Baotou University of Iron and Steel Technology, 2003, 22 (4): 323-325.

[5] Offerman S E, Vandijk N H, Rekveldt M T. Ferrite/PearliteBand Formation in Hot Rolled Medium Carbon Steel [J]. Material Science and Technology, 2002(18)297.

DOI: 10.1179/026708301225000752

[6] Grossterlinden R, Kawalla R, Lotter U. Formation of Pearlitic Banded Structures in Ferritic-pearlitic Steels[J]. Steel Research, 1992, 63(8): 331-336.

DOI: 10.1002/srin.199200529

[7] Wang Bin, Hu Hongmei, Zhou Cui. The Method of Eliminating Banded Structure and the Effects of Banded structure on the Transverse Properties in 20G Steel[J]. Applied Mechanics and Materials , 2013, Vols. 347-350 : 1171-1175.

DOI: 10.4028/www.scientific.net/amm.347-350.1171

[8] Chao Yang, Yongan Min, et al. Study of identifying the banded structure of 8620 steel bars[J]. Advanced Materials Research, 2014Vols. 915-916: 643-649.

DOI: 10.4028/www.scientific.net/amr.915-916.643

[9] Wang Fang, Yuan Shuqiang, et al. Current Research Situation of Alleviating or Eliminating Band Structure in Steel[J]. Hot Working Technology, 2013, 42(5): 52-57.

[10] Thompson W S, Howell R P. Factors Influencing Ferrite/Pearlite Banding and Origin of Large Pearlite Nodules in a Hypoeutectoid Plate Steel[J]. Material Science and Technology, 1992(8): 777.

DOI: 10.1179/mst.1992.8.9.777

[11] Liu Yuan, Xu Leilei, et al. Effect of Cooling Rate and Cooling Temperature on the Formation of Banded Structure inSA-210Gr. C Steel[J]. Journalof Iron and Steel Research, 2014, 26(6): 57-60.

[12] Gu Zhiji, Xu Luoping, Min Yongan, et al. Controlling the heat treatment of an as-forged gear of 20CrNi2Mo Steel to improve its banded structure[J]. Shanghai Metals, 1999, 21(4): 15-19.

[13] Xie Wenxin, Li Guozhong, Cao Hongfu. Effect of Heat Treatment Process on Banding Structure of Low Carbon Gear Steel SAE8620H[J]. Special Steel, 2009, 30(1): 58-59.

[14] Zhang Yanling, Liu Haiying, et al. Microsegregation behaviors of alloy elements and their effects on the formation of banded structure in pinion steels[J]. Journal of University of Science and Technology Beijing, 2009, 31(1): 199-205.

[15] Xu Shangxin, Zhou Lixin, ectal. G20CrNi2MoA Banded Structure Formation Mechanism and Methods to Eliminate[J]. Physics Examination and Testing, 2012, 30(5): 18-22.