EFFECT OF Nb ON TRANSFORMATION AND MICROSTRUCTURE REFINEMENT IN MEDIUM CARBON STEEL

doi:10.3724/SP.J.1037.2013.00538

Acta Metall Sin

2014, Vol. 50

Issue (4): 400-408 DOI: 10.3724/SP.J.1037.2013.00538

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EFFECT OF Nb ON TRANSFORMATION AND MICROSTRUCTURE REFINEMENT IN MEDIUM CARBON STEEL

WU Si, LI Xiucheng, ZHANG Juan, SHANG Chengjia(

)

School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083

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WU Si, LI Xiucheng, ZHANG Juan, SHANG Chengjia. EFFECT OF Nb ON TRANSFORMATION AND MICROSTRUCTURE REFINEMENT IN MEDIUM CARBON STEEL. Acta Metall Sin, 2014, 50(4): 400-408.

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Abstract

Medium carbon steel is widely used in structural steels because of its favorable strength, but lack of toughness is a limitation in industrial applications. Among the different strengthening mechanism, grain refinement is the only method to improve both strength and toughness simultaneously. The toughness of steels can be affected by micro-alloying elements and microstructures, for medium carbon wheel steel, the fracture toughness is proportional to the square root of ferrite fraction and inversely proportional to the cube root of prior austenitic grain size. In this work, Nb micro-alloying is used to improve mechanical properties of medium carbon steel. Microstructures and mechanical properties of Nb-bearing medium carbon steel were studied in contrast with traditional Nb-free steel. The continuous cooling transformation (CCT) curves of investigated steels were drawn by adopting dilatometry and metallographic method. The typical microstructures were observed by OM and SEM with EDS. The morphologies of precipitates were obtained by TEM. The effects of cooling rates on microstructure and hardness of the steel were studied with the above experimental methods. The results showed that the typical microstructure of medium carbon steel was ferrite and pearlite and the volume fraction of ferrite was increased from 4% to 24% by adding 0.06%Nb with refined microstructure. The yield strength of Nb-bearing steel was improved from 385 to 455 MPa and the Charpy V-notch energy at -20 ℃ was increased from 7 to 19 J in the condition of almost no reduction in tensile strength. It is because of Nb addition, which makes the transformation products of medium carbon steel be composed of ferrite and pearlite in a wider region of cooling rates (≤10 ℃/s) and a broader temperature range (530~690 ℃), with the hardness lower than 300 HV. With the calculation of Thermal-Calc software and solid solubility formula, Nb exists in medium carbon steel in the form of precipitate. The result of observation by TEM indicates the size of Nb precipitates was distributed in 20~50 nm. To sum up, the grain refining and precipitation strengthening are the main mechanism of Nb to promote the ferrite-pearlite transformation and improve toughness in medium carbon steel.

Key words: medium carbon steel Nb micro-alloying microstructure refining CCT curve precipitate

Received: 30 August 2013

ZTFLH:

TG113

Fund: Supported by National Basic Research Program of China (No.2010CB630801)

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	Si WU
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	Juan ZHANG
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https://www.ams.org.cn/EN/10.3724/SP.J.1037.2013.00538 OR https://www.ams.org.cn/EN/Y2014/V50/I4/400

Table 1 Chemical compositions of medium carbon steel

Fig.1

连续冷却转变工艺示意图

Fig.2

实验钢奥氏体晶粒及正火态金相组织形貌

Fig.3

A钢在不同冷速下的OM像

表2 实验钢的力学性能

Fig.4

B钢在不同冷速下的OM像

Fig.5

实验钢的CCT曲线

Fig.6

实验钢在不同冷速下的硬度

Fig.7

B钢中铁素体相内析出物的SEM像及能谱

Fig.8

B钢中析出物的TEM像及能谱

Fig.9

析出相的体积分数随温度的变化

[1]	Zerbst U, Mädler K, Hintze H. Eng Fract Mech, 2005; 72: 163
[2]	Ekberg A, Kabo E. Wear, 2005; 258: 1288
[3]	Cui Y H, Zhang J P, Su H, Jiang B. Res Iron Steel, 2005; 114: 53
	(崔银会, 张建平, 苏航, 江波. 钢铁研究, 2005; 114: 53)
[4]	Miao C L, Shang C J, Zhang G D, Subramanian S V. Mater Sci Eng, 2010; A527: 4985
[5]	Gong W M, Yang C F, Zhang Y Q. J Iron Steel Res, 2006; 18(10): 49
	(龚维幂, 杨才福, 张永权. 钢铁研究学报, 2006; 18(10): 49)
[6]	Hansen S S, Krauss G, Banerji S K. Proc Int Conf on Welding Metallurgy of Structural Steels, Warrendale, PA: TMS-AIME, 1987: 155
[7]	Pickering F B, Garbarz B. Mater Sci Technol, 1989; 5: 227
[8]	Sakamoto H, Toyama K, Hirakawa K. Mater Sci Eng, 2000; A285: 288
[9]	Wu S, Li X C, Shang C J, Han J S, Wang Q D. Trans Mater Heat Treat, 2012; 33(7): 100
	(吴斯, 李秀程, 尚成嘉, 韩建生, 王群娣. 材料热处理学报, 2012; 33(7): 100)
[10]	Lan Y J, Li D Z, Li Y Y. Acta Mater, 2004; 56: 1721
[11]	Li X C, Xia D X, Wang X L, Wang X M, Shang C J. Sci China Technol Sci, 2013; 56(1): 66
[12]	Fu J Y. Iron Steel, 2005; 40(8): 1
	(付俊岩. 钢铁, 2005; 40(8): 1)
[13]	Tither G. Proceeding of the International Symposium Niobium 2001, Orlando: Niobium 2001 Limited, 2001: 1
[14]	GB/T 6394-2002. Metal-Methods for Estimating the Average Grain Size. Beijing: Standardization Administration of the People's Republic of China, 2002
	(国标GB/T 6394-2002. 金属平均晶粒度测定法. 6394-2002. 金属平均晶粒度测定法. 北京: 国家标准化管理委员会, 2002)
[15]	Yong Q L. Secondary Phases in Steel. Beijing: Metallurgical Industry Press, 2006: 145
	(雍岐龙. 钢铁材料中的第二相. 北京: 冶金工业出版社, 2006: 145)
[16]	Narita K. Kobe Steel Eng Rep, 1966; 16: 179
[17]	Zheng L, Yong Q L, Sun Z B. Acta Metall Sin, 1987; 23: 547
	(郑鲁, 雍岐龙, 孙珍宝. 金属学报, 1987; 23: 547)
[18]	Chi H X, Ma D S, Liu J H, Chen Z Z, Yong Q L. Acta Metall Sin, 2010; 46: 206
	(迟宏宵, 马党参, 刘建华, 陈再枝, 雍岐龙. 金属学报, 2010; 46: 206)
[19]	Gladman T. Proc Roy Soc, 1966; 294: 298
[20]	Gladman T. HSLA Steels. Warrendale, PA: TMS-AIME, 1992: 3
[21]	Gladman T. Mater Sci Technol, 1999; 15(1): 30
[22]	Lee K J, Kang K B, Lee J K, Kwon O, Chang R W. Proceedings of the International Conference in Mathematical Modelling of Hot Rolling of Steel, Hamilton, Canada: AIME, 1990: 435
[23]	Mecozzi M G, Sietsma J, Zwaag S. Acta Mater, 2006; 54: 1431
[24]	Gladman T. Recrystallization and Grain Growth of Multi-phase and Particle Containing Materials. Oskilde, Denmark: Riso National Laboratory, 1980: 183
[25]	Kop T A, Sietsma J, Zwaag S. Mater Sci Technol, 2001; 36: 1569
[26]	Wagner V, Starke P, Kerscher E, Eifler D. Int J Fatigue, 2011; 33: 69
[27]	Ahlström J, Karlsson B. Wear, 1999; 232: 1
[28]	Aglan H A, Liu Z Y, Hassan M F, Fateh M. J Mater Process Technol, 2004; 151: 268
[29]	Shang C J, Wu S, Li X C, He F, Wang X M. Chin Pat, 201210065521.6, 2012
	(尚成嘉, 吴斯, 李秀程, 贺飞, 王学敏. 中国专利, 201210065521.6, 2012)

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