淬火与回火工艺对WC-20%Co硬质合金微观结构和性能的影响
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摘要
WC-Co硬质合金在刀具材料中被广泛应用,热处理可以有效地改善WC-Co硬质合金的综合性能。本文采用扫描电镜(SEM)、X射线衍射(XRD)和电子探针(EMPA)等分析手段,研究了淬火和回火处理对WC-20%Co硬质合金的微观结构与力学性能的影响。结果表明:随着淬火温度升高,WC晶粒尺寸呈现先增大后减小的变化趋势。在一定温度范围内,淬火温度越高,材料的硬度和抗弯强度也越高;抗弯强度在1 250℃淬火时达到最大值3 090 MPa,相对于未处理样品增加了13.2%。但当淬火温度达到1 350℃时,其硬度和抗弯强度开始下降,分别为985.0 HV和2 810 MPa。在淬火温度一定的条件下,回火温度越高,钴相中保留的高温相α-Co分数和固溶的W含量越低,材料的力学性能也随之降低。对比不同淬火介质后发现,相比于油淬,水淬处理更有助于提高材料的综合性能。
WC-Co cemented carbides have been widely used in tool materials, and heat treatment can effectively improve the comprehensive properties of WC-Co cemented carbides. In this paper, the effects of quenching and tempering on microstructure and mechanical properties of WC-20%Co cemented carbides were studied by scanning electron microscopy(SEM), X-ray diffractometry(XRD), electron probe microanalysis(EMPA) and other analytical methods.The results show that : with the increasing of quenching temperatures, the mean grain size of WC increased firstly and then decreased. within a certain temperature range, the hardness and bending strength of the alloy increase with the increase of the quenching temperature. The bending strength can reach a maximum of 3 090 MPa after quenching at 1 250 ℃, which is 13.2% higher than the untreated samples. When the quenching temperature reaches 1 350 ℃, the hardness and bending strength decline to985.0 HV and 2 810 MPa, respectively. Meanwhile, the fraction of high-temperature phase ɑ-Co and W dissolved in the cobalt phase is decreased with the increase of the tempering temperature after quenching at 1 250 ℃, resulting in poor mechanical properties of the material. Comparing with different quenching media, it has been found that water quenching is more efficientto improve the comprehensive properties of the materialthan oil quenching.
WC-Co cemented carbides have been widely used in tool materials, and heat treatment can effectively improve the comprehensive properties of WC-Co cemented carbides. In this paper, the effects of quenching and tempering on microstructure and mechanical properties of WC-20%Co cemented carbides were studied by scanning electron microscopy(SEM), X-ray diffractometry(XRD), electron probe microanalysis(EMPA) and other analytical methods.The results show that : with the increasing of quenching temperatures, the mean grain size of WC increased firstly and then decreased. within a certain temperature range, the hardness and bending strength of the alloy increase with the increase of the quenching temperature. The bending strength can reach a maximum of 3 090 MPa after quenching at 1 250 ℃, which is 13.2% higher than the untreated samples. When the quenching temperature reaches 1 350 ℃, the hardness and bending strength decline to985.0 HV and 2 810 MPa, respectively. Meanwhile, the fraction of high-temperature phase ɑ-Co and W dissolved in the cobalt phase is decreased with the increase of the tempering temperature after quenching at 1 250 ℃, resulting in poor mechanical properties of the material. Comparing with different quenching media, it has been found that water quenching is more efficientto improve the comprehensive properties of the materialthan oil quenching.
引文
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[17]Konyashin,Hlawatschek,Ries,et al.On the mechanism of WCcoarsening in WC-Co hardmetals with various carbon contents[J].International Journal of Refractory Metals&Hard Materials,2009,27(2):234-243.
[18]]Kawakami M,Terada O,Hayashi K.HRTEM microstructure and segregation amount of dopants at WC/Co interfaces in TiC and TaCmono-doped WC-Co submicro-grained hardmetals[J].J Jpn Soc Powder Powder Metall,2006,53:166-71.
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[20]李广生.超细WC-Co硬质合金的磁性能和金相分析[J].中国钨业,2008,23(2):33-35.Li Guangsheng.Magnetic and metallographic analysis of ultra-fine WC-Co cemented carbide[J].China tungsten industry,2008,23(2):33-35
[21]刘寿荣.WC-Co硬质合金中钴相的磁性研究[J].中国有色金属学报,1992,(3):66-68.Liu Shourong.Study on the magnetism of cobalt phase in WC-Co cemented carbide[J].Transactions of Nonferrous Metals Society of China,1992,(3):66-68.
[22]谢浩,李锐.淬火温度对不同钴含量中、粗晶粒硬质合金组织与性能的影响[J].硬质合金,2016,33(3):169-175.Xie Hao,Li Rui.Effect of quenching temperature on microstructure and properties of coarse grain cemented carbides with different cobalt contents[J].Cemented Carbide,2016,33(3):169-175.
[23]胡保全.金属热处理原理与工艺[M].中国铁道出版社,2017.Hu Baoquan.Principle and technology of metal heat treatment[M].China Railway Press,2017.
[24]尹超,郭建中,任跃.油淬温度对YG11C和YG20C硬质合金组织及性能的影响[J].硬质合金,2016,33(5):291-299.Yin Chao,Guo Jianzhong,Ren Yue.The effect of oil quenching temperature on the performance and microstructure of YG 1 1 C and YG20C cemented carbide[J].Cemented Carbide,2016,33(5):291-299.
[2]张卫兵,刘向中,陈鼎,等.WC-Co硬质合金最新进展[J].稀有金属,2015,39(2):178-186.Zhang Weibing,Liu Xiangzhong,Chen Ding,et al.The latest development of WC-Co cemented carbide[J].Rare metal,2015,39(2):178-186.
[3]Ponomarev S S,Shatov A V,Mikhailov A A,et al.Carbon distribution in WC based cemented carbides[J].International Journal of Refractory Metals&Hard Materials,2015,49:42-56.
[4]Gu Lining,Huang Jiwu,Tang Yunfeng,et al.Influence of different post treatments on microstructure and properties of WC-Co cemented carbides[J].Journal of Alloys and Compounds,2015,620:116-119.
[5]王荣滨.硬质合金的热处理与应用研究[J].有色金属与稀土应用,2007,34(1):18-22.Wang Rongbin.Study on heat treatment and application of cemented carbide[J].Non-ferrous Metals and Rare Earth,2007,34(1):18-22.
[6]吴冲浒,陈杉杉.热处理对超细晶硬质合金性能的影响[J].热处理技术与装备,2014,35(6):7-10.Wu Chonghu,Chen Shanshan.Effect of heat treatment on properties of superfine cemented carbide[J].Heat Treatment Technology and Equipment,2014,35(6):7-10.
[7]王忆民,李锐,曹群.淬火回火热处理对WC-25%Co硬质合金组织与性能的影响[J].硬质合金,2014,31(3).Wang Yiming,Li Rui,Cao Qun.Effect of quenching and tempering heat treatment on microstructure and properties of WC-25%Co cemented carbide[J].Cemented Carbide,2014,31(3).
[8]严永林.热处理工艺对硬质合金性能的影响[C].全国硬质合金学术会议,2010.Yan Yonglin.Effect of heat treatment process on the properties of cemented carbide[C].National Academic Conference on Cemented Carbides,2010.
[9]周书助.硬质合金生产原理和质量控制[M].冶金工业出版社,2014.Zhou Shuzhu.Production principle and quality control of cemented carbide[M].Metallurgical Industry Press,2014.
[10]陈向明,杨金辉.硬质合金热处理和钴粘结相转度温度的研究[J].硬质合金,1999,(1):1-7.Chen Xiangming,Yang Minghui.Study on the phase transition temperature of cemented carbide heat treatment and cobalt bonding[J].Cemented Carbide,1999,(1):1-7.
[11]赵步青,张丹宁,刘春菱.硬质合金的热处理[J].金属加工:热加工,2018,(2):30-33.Zhao Buqing,Zhang Danning,Liu Chunling.The heat tretments of cemented carbide[J].Metal Forming:the Heat Treatment,2018,(2):30-33.
[12]朱骥飞,张立,徐涛,等.基于体视学原理的硬质合金显微组织参数化定量分析[J].粉末冶金材料科学与工程,2015,(1):26-31.Zhu Jifei,Zhang Li,Xu Tao,et al.Parametric quantitative analysis of microstructure of cemented carbide based on stereoscopic principle[J].Powder Metallurgical Materials Science and Engineering,2015,(1):26-31.
[13]谢晨辉,周华堂,彭宇.粘结相Co的切变机制及微观结构的研究[J].硬质合金,2013,30(5):242-248.Xie Chenhui,Zhou Huatang,Pengyu.Shear mechanism and microstructure of bonded phase Co[J].Cemented Carbide,2013,30(5):242-248.
[14]陈楚轩.硬质合金质量控制原理[M].自贡:中国钨业协会硬质合金分会&自贡硬质合金有限责任公司,2007:43-45.Chen Chuxuan.Quality control principle of cemented carbide[M].ZiGong:Cemented Carbide Association in Ctia&Zigong Cemented Carbide Corp.,Ltd,2007:43-45.
[15]Gu L,Huang J,Xie C.Effects of carbon content on microstructure and properties of WC-20Co cemented carbides[J].International Journal of Refractory Metals&Hard Materials,2014,42(1):228-232.
[16]Hans-Olof Andrén.Microstructure development during sintering and heat-treatment of cemented carbides and cermets[J].Materials Chemistry&Physics,2001,67(1):209-213.
[17]Konyashin,Hlawatschek,Ries,et al.On the mechanism of WCcoarsening in WC-Co hardmetals with various carbon contents[J].International Journal of Refractory Metals&Hard Materials,2009,27(2):234-243.
[18]]Kawakami M,Terada O,Hayashi K.HRTEM microstructure and segregation amount of dopants at WC/Co interfaces in TiC and TaCmono-doped WC-Co submicro-grained hardmetals[J].J Jpn Soc Powder Powder Metall,2006,53:166-71.
[19]刘寿荣.WC-Co硬质合金成分的磁性测定原理[J].硬质合金,1999,(3):129-136.Liu Shourong.Principle of magnetic determination of WC-Co cemented carbide components[J].Cemented Carbide,1999,(3):129-136.
[20]李广生.超细WC-Co硬质合金的磁性能和金相分析[J].中国钨业,2008,23(2):33-35.Li Guangsheng.Magnetic and metallographic analysis of ultra-fine WC-Co cemented carbide[J].China tungsten industry,2008,23(2):33-35
[21]刘寿荣.WC-Co硬质合金中钴相的磁性研究[J].中国有色金属学报,1992,(3):66-68.Liu Shourong.Study on the magnetism of cobalt phase in WC-Co cemented carbide[J].Transactions of Nonferrous Metals Society of China,1992,(3):66-68.
[22]谢浩,李锐.淬火温度对不同钴含量中、粗晶粒硬质合金组织与性能的影响[J].硬质合金,2016,33(3):169-175.Xie Hao,Li Rui.Effect of quenching temperature on microstructure and properties of coarse grain cemented carbides with different cobalt contents[J].Cemented Carbide,2016,33(3):169-175.
[23]胡保全.金属热处理原理与工艺[M].中国铁道出版社,2017.Hu Baoquan.Principle and technology of metal heat treatment[M].China Railway Press,2017.
[24]尹超,郭建中,任跃.油淬温度对YG11C和YG20C硬质合金组织及性能的影响[J].硬质合金,2016,33(5):291-299.Yin Chao,Guo Jianzhong,Ren Yue.The effect of oil quenching temperature on the performance and microstructure of YG 1 1 C and YG20C cemented carbide[J].Cemented Carbide,2016,33(5):291-299.