Microstructure and Mechanical Properties of Medium Carbon Steel with Ultrafine-Grained Ferrite-Pearlite Lamellar Structure

doi:10.12068/j.issn.1005-3026.2025.20240048

Abstract

Abstract:

Using the warm rolling process in the two-phase region，ultrafine-grained ferrite-pearlite lamellar microstructures were obtained in a 0.41%C medium carbon steel. The microstructures and mechanical properties of the warm rolled steel sheets were characterized using scanning electron microscopy（SEM），electron backscatter diffraction（EBSD），quasi-static tensile tests，and a series of low-temperature impact tests at three different temperatures（770，800 and 830 ℃）for comparative analysis. The results reveal that in the steel sheets rolled at temperatures of 770，800，and 830 ℃，the average grain size of ferrite is measured to be 0.82，0.89，and 1.14 μm，the proportion of pearlite is 16.4%，36.2%，43.5%，with the size of 0.9，1.3，1.8 μm，respectively. Furthermore， the yield strength is（696±3），（733±7）and（776±5）MPa，the elongation after fracture is 16.5%，16.1% and 13.8%，and the impact energy at -60 °C is 119，114，and 89 J，respectively.The proportion and size of ultrafine-grained ferrite-pearlite in the lamellar structure of medium carbon steel can be changed by warm rolling at different temperatures in the two-phase region.As a result， a remarkable improvement in the low-temperature impact toughness of the medium carbon steel with high pearlite content is achieved. This leads to a synergistic enhancement of strength， ductility， and low-temperature impact toughness.

Key words: medium carbon steel, warm rolling in two-phase region, ultrafine-grained, lamellar structure, strength, low-temperature toughness

CLC Number:

TG 142.1

Hao WEI, Yang ZHANG, Xiao-ning XU, Qi-bin YE. Microstructure and Mechanical Properties of Medium Carbon Steel with Ultrafine-Grained Ferrite-Pearlite Lamellar Structure[J]. Journal of Northeastern University(Natural Science), 2025, 46(9): 81-86.

Figures/Tables 7

Fig.1 Schematic illustration of rolling process for ultrafine-grained medium carbon steel

Fig.2 Optical micrographs of steel sheet samples in direct-quenched and warm-rolled states at various temperatures

Fig.3 SEM micrographs of direct-quenched and warm-rolled steel sheets at various subcritical temperatures

Fig.4 IPF micrographs, grain boundary maps and KAM distribution for WA770, WA800, and WA830 steels

Fig.5 Distribution of grain size of WA770，WA800， and WA830 steels

Fig.6 Tensile and work hardening rate curves of WA770, WA800 and WA830 steels

Fig.7 Variation of impact absorbed energy with temperature of WA770，WA800 and WA830 steels

References 17

[1]	Jia N N， Guo K， He Y M， et al. A thermomechanical process to achieve mechanical properties comparable to those of quenched-tempered medium-C steel［J］. Materials Science and Engineering： A， 2017， 700（17）： 175-182.
[2]	全国钢标准化技术委员会. 工程机械用高强度耐磨钢板和钢带［S］. 北京：中国标准出版社，2022.
	National Steel Standardisation Technical Committee. High-strength wear-resistant steel plates and strips for construction machinery ［S］. Beijing： China Standard Press， 2022.
[3]	王昭东，邓想涛，曹艺，等. 新型低成本超高强低合金耐磨钢研究及其工业化应用［J］. 钢铁， 2010， 45（8）： 61-64， 69.
	Wang Zhao-dong， Deng Xiang-tao， Cao Yi， et al. Development and industrial application of new low alloy abrasion steel with low cost and ultra-high strength［J］. Iron & Steel， 2010， 45（8）： 61-64， 69.
[4]	郑东升，范才河，蹇海根，等. 工程机械用超高强钢的弯曲性能及弯曲过程中的微观组织演变［J］.材料热处理学报，2022，43（3）：81-88.
	Zheng Dong-sheng， Fan Cai-he， Qian Hai-gen， et al. Bending properties and microstructure evolution during bending of ultra-high strength steel for construction machinery［J］. Journal of Heat Treatment of Materials， 2022， 43（3）： 81-88.
[5]	蒋月月，王昭东，邓想涛. 铈对低合金超高强钢马氏体相变行为的影响［J］. 钢铁， 2020， 55（6）： 84-90.
	Jiang Yue-yue， Wang Zhao-dong， Deng Xiang-tao. Effect of trace rare earth Ce on martensitic transformation behavior of ultra-high strength low alloy steel［J］. Iron & Steel， 2020， 55（6）： 84-90.
[6]	Inoue T， Ueji R. Improvement of strength， toughness and ductility in ultrafine-grained low-carbon steel processed by warm bi-axial rolling［J］. Materials Science and Engineering： A， 2020， 786： 139415.
[7]	Song R， Ponge D， Raabe D， et al. Microstructure and crystallographic texture of an ultrafine grained C-Mn steel and their evolution during warm deformation and annealing［J］. Acta Materialia， 2005， 53（3）： 845 -858.
[8]	Mojtaba D， Fathallah Q， Mahdi G， et al. Effect of inter-cycle heat treatment in accumulative roll-bonding （ARB） process on planar isotropy of mechanical properties of AA1050 sheets［J］. Transactions of Nonferrous Metals Society of China， 2020， 30（9）： 2381-2393.
[9]	Ovid’ko I A， Valiev R Z， Zhu Y T. Review on superior strength and enhanced ductility of metallic nanomaterials［J］. Progress in Materials Science， 2018， 94： 462-540.
[10]	Shaeri M H， Shaeri M， Salehi M T， et al. Microstructure and texture evolution of Al-7075 alloy processed by equal channel angular pressing［J］. Transactions of Nonferrous Metals Society of China， 2015， 25（5）： 1367-1375.
[11]	Duan J Q， Quadir M Z， Xu W， et al. Texture balancing in a FCC/BCC multilayered composite produced by accumulative roll bonding［J］. Acta Materialia， 2017， 123： 11-23.
[12]	苏元飞，李慧杰，徐晓宁，等. 温轧对DP590钢层状超细晶双相组织与拉伸性能的影响［J］. 东北大学学报（自然科学版）， 2023， 44（3）： 357-362， 369.
	Su Yuan-fei， Li Hui-jie， Xu Xiao-ning， et al. Effect of warm rolling on laminated ultra-fine grained dual-phase microstructure and tensile properties of DP590 steel［J］. Journal of Northeastern University （Natural Science）， 2023， 44（3）： 357-362， 369.
[13]	Zhao X， Yang X L. Ultrafine-grained steel produced by warm rolling and annealing of lath martensite［J］. Materials Science Forum， 2010， 667/668/669： 863-866.
[14]	Hanamura T， Yin F， Nagai K. Ductile-brittle transition temperature of ultrafine ferrite/cementite microstructure in a low carbon steel controlled by effective grain size［J］. ISIJ International， 2004， 44（3）： 610-617.
[15]	Zhou Y H， Xiao Y， Li R， et al. In situ investigation on plastic deformation behaviors in austenite-ferrite heterostructured stainless steel［J］. Materials Science and Engineering： A， 2022， 857： 144111.
[16]	Zhao L J， Park N， Tian Y Z， et al. Dynamic transformation mechanism for producing ultrafine grained steels［J］. Advanced Engineering Materials， 2018， 20（7）： 1701016.
[17]	Wang P F， Li Z D， Lin G B， et al. Influence of vanadium on the microstructure and mechanical properties of medium-carbon steels for wheels［J］. Metals， 2018， 8（12）： 978.