INFLUENCE OF PULSED MAGNETIC TREATMENT ON MICROSTRUCTURES AND MECHANICAL PROPERTIES OF M42 HIGH SPEED STEEL TOOL
MA Liping, LIANG Zhiqiang(), WANG Xibin, ZHAO Wenxiang, JIAO Li, LIU Zhibing
Key Laboratory of Fundamental Science for Advanced Machining, Beijing Institute of Technology, Beijing 100081
Cite this article:
MA Liping, LIANG Zhiqiang, WANG Xibin, ZHAO Wenxiang, JIAO Li, LIU Zhibing. INFLUENCE OF PULSED MAGNETIC TREATMENT ON MICROSTRUCTURES AND MECHANICAL PROPERTIES OF M42 HIGH SPEED STEEL TOOL. Acta Metall Sin, 2015, 51(3): 307-314.
Magnetic treatment of tools is a novel method to increase tool life in which the tool is magnetized before cutting or the cutting is performed in a magnetic field. The method has many attractive features, such as short treatment time and no pollution. However, this approach has not been widely applied yet, since the mechanism of magnetic treatment of tools is not clear and treatment results are affected by many factors. Therefore, it is important to study the mechanism of magnetic treatment of tools. This work aims to study the influence of pulsed magnetic treatment on microstructures and mechanical properties of M42 (W2Mo9Cr4VCo8) high speed steel, which is a typical tool material which contains high amounts of cobalt. So it can show a stronger magnetism in the process of pulsed magnetic treatment. Changes of dislocation configuration, carbide distribution and microstructure before and after magnetic treatment were characterized by TEM and laser scanning confocal microscope. Moreover, Rockwell hardness and micro-hardness were measured to quantitatively investigate the influence of magnetic treatment on the mechanical properties. Results showed that after pulsed magnetic treatment the lattice of material was distorted, the carbide was precipitated, and the microstructure and crystalline grain were refined. The changes of microstructure led to changes of mechanical properties, of which the Rockwell hardness and micro-hardness were significantly increased. The maximum increase of Rockwell hardness was 2.9 HRC. Ultimately, the strengthening mechanisms of high speed steel were analyzed based on dislocation theory. It was shown that the subjected force of dislocations due to the magnetic treatment could overcome the centripetal restoring force and the Peierls stress of dislocations. Therefore, dislocations proliferated by the Orowan dislocation strengthening mechanism, and dislocation density increased. The dislocation configuration determined from TEM micrographs was in good agreement with the discussion of dislocation mechanisms.
Fig.1 Schematic diagram of pulsed magnetic treatment system
Fig.2 TEM images of M42 high speed steel before (a) and after (b) pulsed magnetic treatment
Fig.3 Schematics of magnetic domain in ferromagnetic material before (a) and after (b) magnetization (The arrows indicate the directions of spontaneous magnetization)
Fig.4 HRTEM image of M42 high speed steel after pulsed magnetic treatment
Fig.5 Morphologies of carbide in M42 high speed steel before (a) and after (b) pulsed magnetic treatment at low magnification
Fig.6 Morphologies of carbide in M42 high speed steel before (a) and after (b) pulsed magnetic treatment at high magnification
Fig.7 Microstructures of M42 high speed steel before (a) and after (b) pulsed magnetic treatment
Fig.8 Effect of pulsed magnetic treatment on Rockwell hardness of M42 high speed steel
Fig.9 Effect of pulsed magnetic treatment on micro-hardness for M42 high speed steel
Fig.10 Variation of surface temperature with pulsed magnetization time for M42 high speed steel
Fig.11 Analysis of subjected force on dislocations in the presence of a magnetic field (M—magnetization vector of domain, H—magnetic field, q—angle between the magnetic field direction and the magnetization vector, L—length of dislocation)
Fig.12 Schematic of Orowan dislocation strengthening mechanism (a) and TEM image of typical dislocation circles (b) (t —subjected force of dislocation, tc—critical stress to drive the dislocation, sc—Peierls-Nabarro force)
[1]
Li G R, Zhao Y T, Dai Q X, Zhang H J, Wang H M. J Univ Sci Technol Beijing, 2007; 14: 460
[2]
Miller P C. Tool Prod, 1990; 55: 100
[3]
Batainech O, Klamecki B, Koepke B G. J Mater Process Technol, 2003; 134: 190
[4]
E1 Mansori M, Pierron F, Paulmier D. Surf Coat Technol, 2003; 163: 472
[5]
E1 Mansori M, Lordache V, Seitier P, Paulmier D. Surf Coat Technol, 2004; 188: 566
[6]
Mkaddem A, Benabou A, E1 Mansori M, Clenet S. Int J Solids Struct, 2013; 50: 2078
[7]
E1 Mansori M, Schmitt M, Paulmier D. Surf Coat Technol, 1998; 108-109: 479
[8]
E1 Mansori M, Paulmier D. Appl Surf Sci, 1999; 144-145: 233
[9]
Chin K J, Zaidi H, Nguyen M T, Renault P O. Wear, 2001; 250: 470
[10]
Chin K J, Zaidi H, Mathia T. Wear, 2005; 259: 477
[11]
Singh S, Shan H S, Kumar P. J Mater Process Technol, 2002; 128: 155
[12]
Klamecki B E. J Mater Process Technol, 2003; 141: 385
[13]
Tang F, Lu A L, Fang H Z, Mei J F. Mater Sci Eng, 1998; A248: 98
[14]
Cai Z P, Huang X Q. Mater Sci Eng, 2011; A528: 6287
[15]
Zaidi H, Pan L, Paulmier D, Robert F. Wear, 1995; 181: 799
[16]
Jiang J L, Tian Y, Meng Y G. Wear, 2011; 271: 2991
[17]
Fahmy Y, Hare T, Tooke R, Conrad H. Scr Mater, 1998; 38: 1355
[18]
Bose M S C. Phys Status Solidi, 1984; 86A: 649
[19]
Zhong W D. Ferromagnetics. Beijing: Science Press, 1987: 7
(钟文定.铁磁学. 北京: 科学出版社, 1987: 7)
[20]
Li G R, Wang H M, Yuan X T, Cai Y. Chin J Mater Res, 2013; 27: 397
(李桂荣, 王宏明, 袁雪婷, 蔡 云. 材料研究学报, 2013; 27: 397)
[21]
Lei T Q,Yao Z K,Yang D Z. Thermomechanical Treatment of Steel. Beijing: China Machine Press, 1979: 135
(雷廷权,姚忠开,杨德庄. 钢的形变热处理. 北京: 机械工业出版社, 1979: 135)
[22]
Xu B J, Gu N J, Yan D R, Yin F X. Acta Metall Sin, 1989; 25: 352
(徐伯钧, 谷南驹, 阎殿然, 殷福星. 金属学报, 1989; 25: 352)
[23]
Sun Z J. Heat Treat, 2002; 17(1): 37
(孙忠继. 热处理, 2002; 17(1): 37 )
[24]
Ferreira P J, Vander S J B. Scr Mater, 1999; 41: 117
[25]
Wang Y N,Chen S J,Dong X C. Dislocation Theory and its Applications. Beijing: Metallurgical Industry Press, 2007: 35
(王亚男,陈树江,董希淳. 位错理论及其应用. 北京: 冶金工业出版社, 2007: 35)
[26]
Li H Q, Chen Q Z, Wang Y B, Chu W Y. Chin Sci Bull, 1997; 42: 2282
