后處理對粗晶WC-10Co硬質(zhì)合金的影響研究
發(fā)布時間：2018-09-11 09:31
【摘要】：隨著礦山、油氣資源開發(fā)和基礎(chǔ)設(shè)施建設(shè)的迅速發(fā)展,對新一代高效、長壽命粗晶超粗晶礦用硬質(zhì)合金的需求量日益增加�，F(xiàn)代采掘業(yè)高沖擊載荷、熱沖擊以及強烈磨料磨損的工況條件,對硬質(zhì)合金礦用工具材料的性能要求非常高。深冷處理和時效處理是能有效改變金屬材料組織結(jié)構(gòu)與合金性能的后處理工藝。將深冷處理和時效處理工藝應用于粗晶超粗晶礦用硬質(zhì)合金有重大的研究價值和應用前景。本論文以粗晶WC-10Co硬質(zhì)合金為研究對象,制備了四種不同碳含量的粗晶WC-10Co硬質(zhì)合金樣品,并對試樣進行了空白對照、深冷處理以及回火+深冷處理三種處理工藝后,采用電解選擇性腐蝕法溶除WC-Co硬質(zhì)合金表層中的WC硬質(zhì)相,研究了腐蝕時間、WC粒度、Co相含量對WC選擇性腐蝕速度的影響;研究了不同處理工藝對不同碳含量硬質(zhì)合金樣品的力學性能、飽和磁化強度、相結(jié)構(gòu)、顯微組織和沖擊磨粒磨損性能的影響,并結(jié)合實驗結(jié)果討論了影響機理;通過與國內(nèi)外相關(guān)研究進行對比,得出以下結(jié)論:(1)對于WC-6Co～WC-14Co的粗晶硬質(zhì)合金,合金中WC硬質(zhì)相的電解腐蝕速率與腐蝕時間、WC粒度以及Co含量密切相關(guān)。在常規(guī)電解腐蝕條件下,當選擇性電解腐蝕9h時,可獲得最佳的合金表層中WC相溶除效果;(2)硬質(zhì)合金的耐沖擊磨粒磨損性能與硬質(zhì)合金的含碳量以及后處理方式密切相關(guān):通過降低含碳量,可使燒結(jié)合金的沖擊磨粒磨損量降低60%以上;通過回火+深冷處理,可使合金的沖擊磨粒磨損量進一步降低20%以上;(3)深冷處理以及回火+深冷處理后硬質(zhì)合金的顯微組織結(jié)構(gòu)未發(fā)生明顯改變。但HRTEM觀察發(fā)現(xiàn):燒結(jié)態(tài)低碳WC-10Co硬質(zhì)合金的Co相中存在著少量成分為WxCoyCz、尺寸為3～5nm、與Co相基體形成完全共格界面的球狀彌散相;回火+深冷處理后,由于回火(時效)處理時產(chǎn)生原位沉淀析出效應,納米WxCouCz彌散相的數(shù)量明顯增加,使合金的維氏硬度(HV30)輕微上升。(4)在不產(chǎn)生η相的前提下,粗晶WC-10Co硬質(zhì)合金采用較低碳含量和回火(時效)+深冷處理工藝可獲得最佳的耐沖擊磨粒磨損性能。對于粗晶合金磨粒磨損性能的提升,Co粘結(jié)相中原位析出的納米彌散相的沉淀強化作用至關(guān)重要;合金中WC硬質(zhì)相鄰接度的降低對避免應力集中起到了重要作用;深冷處理后合金表面宏觀壓應力增加有利于抑制合金表面微裂紋的生成與擴展導致的合金早期失效,從而有利于提高粗晶WC-Co合金的耐磨壽命。
[Abstract]:With the rapid development of mining, oil and gas resources development and infrastructure construction, the demand for the new generation of high efficiency, long life coarse crystal cemented carbide is increasing day by day. The working conditions of high impact load, thermal shock and strong abrasive wear in modern mining industry require very high performance of cemented carbide mining tools. Cryogenic treatment and aging treatment are post-treatment processes which can effectively change the microstructure and properties of metallic materials. The application of cryogenic treatment and aging treatment to coarse ultracoarse cemented carbide has great research value and application prospect. In this paper, four samples of coarse crystalline WC-10Co cemented carbide with different carbon content were prepared, and the samples were treated with blank control, cryogenic treatment and tempering cryogenic treatment. The WC hard phase in the surface layer of WC-Co cemented carbide was dissolved by electrolysis selective corrosion method. The effect of corrosion time and content of WC particle size and Co phase on the selective corrosion rate of WC was studied. The effects of different treatment processes on the mechanical properties, saturation magnetization, phase structure, microstructure and impact abrasive wear properties of cemented carbide samples with different carbon content were studied. The conclusions are as follows: (1) the electrolysis corrosion rate of the WC hard phase in WC-6Co~WC-14Co cemented carbide is closely related to the corrosion time and the content of WC and the content of Co. Under the condition of conventional electrolytic corrosion, when the selective electrolytic corrosion is 9 h, The best solution effect of WC in the alloy surface can be obtained. (2) the abrasive wear resistance of the cemented carbide is closely related to the carbon content of the cemented carbide and the way of post-treatment: by reducing the carbon content, The impact abrasive wear of the sintered alloy can be reduced by more than 60%. The impact abrasive wear of the alloy can be further reduced by more than 20%; (3) the microstructure of cemented carbide after cryogenic treatment and tempering cryogenic treatment has not changed significantly. However, HRTEM observation shows that there is a spherical dispersion phase in the Co phase of sintered low carbon WC-10Co cemented carbides with a WxCoyCz, size of 3 ~ 5 nm, which forms a complete coherent interface with the Co matrix, and is treated by tempering at low temperature. Due to the precipitation effect of in-situ precipitation during tempering (aging) treatment, the amount of nanometer WxCouCz dispersion phase increases obviously, and the Vickers hardness (HV30) of the alloy increases slightly. (4) without 畏 phase, the Vickers hardness (HV30) of the alloy increases slightly. Low carbon content and tempering (aging) cryogenic treatment were used to obtain the best impact wear resistance of coarse WC-10Co cemented carbides. It is very important to enhance the abrasive wear properties of coarse grained alloy by precipitation strengthening of nano-dispersed phase precipitated in situ in Co bonded phase, and the reduction of WC hard adjacent joint in alloy plays an important role in avoiding stress concentration. The increase of macroscopic compressive stress on the alloy surface after cryogenic treatment is helpful to restrain the early failure of the alloy caused by the formation and propagation of microcracks on the surface of the alloy and thus to improve the wear resistance life of the coarse grain WC-Co alloy.
【學位授予單位】：北京有色金屬研究總院
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG135.5
本文編號：2236306
[Abstract]:With the rapid development of mining, oil and gas resources development and infrastructure construction, the demand for the new generation of high efficiency, long life coarse crystal cemented carbide is increasing day by day. The working conditions of high impact load, thermal shock and strong abrasive wear in modern mining industry require very high performance of cemented carbide mining tools. Cryogenic treatment and aging treatment are post-treatment processes which can effectively change the microstructure and properties of metallic materials. The application of cryogenic treatment and aging treatment to coarse ultracoarse cemented carbide has great research value and application prospect. In this paper, four samples of coarse crystalline WC-10Co cemented carbide with different carbon content were prepared, and the samples were treated with blank control, cryogenic treatment and tempering cryogenic treatment. The WC hard phase in the surface layer of WC-Co cemented carbide was dissolved by electrolysis selective corrosion method. The effect of corrosion time and content of WC particle size and Co phase on the selective corrosion rate of WC was studied. The effects of different treatment processes on the mechanical properties, saturation magnetization, phase structure, microstructure and impact abrasive wear properties of cemented carbide samples with different carbon content were studied. The conclusions are as follows: (1) the electrolysis corrosion rate of the WC hard phase in WC-6Co~WC-14Co cemented carbide is closely related to the corrosion time and the content of WC and the content of Co. Under the condition of conventional electrolytic corrosion, when the selective electrolytic corrosion is 9 h, The best solution effect of WC in the alloy surface can be obtained. (2) the abrasive wear resistance of the cemented carbide is closely related to the carbon content of the cemented carbide and the way of post-treatment: by reducing the carbon content, The impact abrasive wear of the sintered alloy can be reduced by more than 60%. The impact abrasive wear of the alloy can be further reduced by more than 20%; (3) the microstructure of cemented carbide after cryogenic treatment and tempering cryogenic treatment has not changed significantly. However, HRTEM observation shows that there is a spherical dispersion phase in the Co phase of sintered low carbon WC-10Co cemented carbides with a WxCoyCz, size of 3 ~ 5 nm, which forms a complete coherent interface with the Co matrix, and is treated by tempering at low temperature. Due to the precipitation effect of in-situ precipitation during tempering (aging) treatment, the amount of nanometer WxCouCz dispersion phase increases obviously, and the Vickers hardness (HV30) of the alloy increases slightly. (4) without 畏 phase, the Vickers hardness (HV30) of the alloy increases slightly. Low carbon content and tempering (aging) cryogenic treatment were used to obtain the best impact wear resistance of coarse WC-10Co cemented carbides. It is very important to enhance the abrasive wear properties of coarse grained alloy by precipitation strengthening of nano-dispersed phase precipitated in situ in Co bonded phase, and the reduction of WC hard adjacent joint in alloy plays an important role in avoiding stress concentration. The increase of macroscopic compressive stress on the alloy surface after cryogenic treatment is helpful to restrain the early failure of the alloy caused by the formation and propagation of microcracks on the surface of the alloy and thus to improve the wear resistance life of the coarse grain WC-Co alloy.
【學位授予單位】：北京有色金屬研究總院
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG135.5
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