EFFECTS OF SOLUTION TREATMENT ON MICRO-STRUCTURE AND WEAR-RESISTANT PROPERTIES OF CoCrW ALLOYS
Bo HE1,Qingwu NIE1,Hongyu Zhang2,Hua WEI2()
1 School of Mechatronics Engineering, Shenyang Aerospace University, Shenyang 110136, China 2 Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
Cite this article:
Bo HE,Qingwu NIE,Hongyu Zhang,Hua WEI. EFFECTS OF SOLUTION TREATMENT ON MICRO-STRUCTURE AND WEAR-RESISTANT PROPERTIES OF CoCrW ALLOYS. Acta Metall Sin, 2016, 52(4): 484-490.
CoCrW alloy is a kind of stellite alloy, which has high strength, good wear resistance, and is widely used in aviation industry, nuclear industry and other fields. For a long time, the CoCrW alloy is mainly used as coating to have an effect on wear and the corrosion resistance. With the development of the industry, the conventional cast CoCrW alloy has been widely studied. The mechanical properties of the cast CoCrW alloy can be changed by heat treatment, which is of high hardness and great brittleness. In this work, hardness and wear-resistant properties of the CoCrW alloys as-cast and after solution treatment were studied by combining XRD, SEM, EDS, hardness test and wear resistance test, and effects of the solution temperature on the microstructure and wear-resistant properties were also investigated. The results showed that the microstructures of the CoCrW alloys as-cast and after solution treatment were both composed of M23C6, M6C and γ-Co matrix, but the size, morphology and distribution of carbides occurred in the alloy changed obviously by solution treatment. The dissolution of a large amount of carbides in the alloy after solution treatment was mainly responsible for the decrease in hardness and wear resistance of the alloy compared with that of the as-cast one. With the increase of the solution temperature, the Cr, W and other alloying elements in the carbides were dissolved into the γ-Co matrix so as to strengthen the matrix resulting in the improvement of the hardness and the associated wear resistance of the alloy. The mechanism that controlling the wear-resistant property of CoCrW alloys as-cast and after solution treatment was the interaction of abrasive wear, adhesive wear and oxidation wear.
Fig.1 SEM images of CoCrW alloys as-cast (a) and after solution treatment at 1150 ℃ (b), 1200 ℃ (c) and 1250 ℃ (d) for 4 h, and EDS results of W-rich phase (e), Cr-rich phase (f) and matrix (g)
Fig.2 XRD spectra of CoCrW alloys as-cast and after solution treatment
Fig.3 Area fractions of phases in CoCrW alloys as-cast and after solution treatment
Fig.4 Friction coefficient curves of CoCrW alloys as-cast and after solution treatment
Fig.5 Three-dimensional shapes (a1~d1) and SEM images at low (a2~d2) and high (a3~d3) magnification of wear tracks of CoCrW alloys as-cast (a1~a3) and after solution treatment at 1150 ℃ (b1~b3), 1200 ℃ (c1~c3) and 1250 ℃ (d1~d3) for 4 h
Fig.6 SEM images (a1, b1) and EDS results (a2, b2) of wear tracks of CoCrW alloys as-cast (a1, a2) and after solution treatment at 1250 ℃ for 4 h (b1, b2)
[1]
Alireza K, Liu R, Liang M, Yang Q.Mater Des, 2014; 56: 487
[2]
Yamanaka K, Mori M, Kuramoto K J, Chiba A.Mater Des, 2014; 55: 987
[3]
Yamanaka K, Mori M, Chiba A.Mater Sci Eng, 2014; C40: 127
[4]
Malayoglu U, Neville A.Wear, 2003; 255: 181
[5]
Wang Q L, Zhang L, Dong J D, Sun Y M.J Xuzhou Inst Technol, 2010; 25(3): 7
[5]
(王庆良, 张磊, 董建东, 孙彦敏. 徐州工程学院学报, 2010; 25(3): 7)
[6]
Zhong M L, Liu W J.Acta Metall Sin, 2002; 38: 495
[6]
(钟敏霖, 刘文今. 金属学报, 2002; 38: 495)
[7]
Li F, Hu K A, Li J L, Zhao B Y.Wear, 2002; 249: 877
