硅对高铬铸铁高频感应堆焊层组织和性能的影响

发布时间：2018-05-13 19:56

本文选题：硅 + 高铬铸铁　；参考：《郑州大学》2017年硕士论文

【摘要】：高频感应堆焊作为一种金属材料表面强化工艺,具有升温快、热影响区小、操作简单等优点,在工业领域中有着广泛的应用。高铬铸铁作为一种常用的耐磨材料,具有性价比高、适应性广等优点。本文通过在高铬铸铁合金中添加一定量的硅元素,研究高频感应堆焊工艺条件下合金粉末中硅加入量对高铬铸铁堆焊层组织和性能的影响。通过正交试验,研究了工作电流、加热时间、熔剂添加量对堆焊层成型工艺的影响,得到最佳堆焊工艺参数为:工作电流70A、加热时间50s、熔剂添加量14%。采用上述工艺参数,研究了粉末中硅加入量对堆焊层成型性的影响,结果表明堆焊粉末中硅加入量超过7%时成型性不佳。采用优化工艺制备粉末中硅加入量为0.6%、1%、2%、3%、4%、5%、6%、7%的高频感应堆焊层,并采用金相显微镜、扫描电镜、能谱仪、X射线衍射仪、洛氏硬度计、维氏硬度计、磨损试验机等对堆焊层组织性能进行测试分析,试验结果如下:堆焊层组织为初生碳化物+共晶组织的过共晶高铬铸铁组织。初生碳化物与共晶碳化物均为M7C3型碳化物,基体由马氏体、奥氏体与铁素体组成。堆焊粉末中硅含量从0.6%增加到7%,高频感应堆焊层中的硅含量从0.286%变化到2.083%。随堆焊粉末中硅加入量的增多,堆焊层中初生碳化物的数量增加,形态细化;共晶碳化物数量减少,共晶碳化物间距缩小;固溶于基体中的硅原子数量增加,基体中奥氏体含量减少,马氏体含量增加。对堆焊层宏观和显微硬度进行检测分析,高铬铸铁堆焊层的洛氏硬度为59.2~63.7HRC,随着硅加入量的增加,堆焊层硬度升高,当硅加入量超过5%时,堆焊层硬度增加趋于平缓。高铬铸铁堆焊层中初生碳化物显微硬度值为1310.6~1383.1HV,显微硬度值不随硅加入量的变化而变化;共晶团显微硬度为590.5~691.6HV,随着硅加入量的增加共晶团显微硬度值升高,当硅加入量超过4%时,共晶团显微硬度值的增加趋于平缓。对堆焊层断裂韧性进行分析,随着堆焊粉末中硅加入量的增加,堆焊层的断裂韧性值先升高后降低。当硅加入量在0.6%~5%时,随硅加入量的增加,堆焊层的断裂韧性值升高,在硅加入量为5%时堆焊层的断裂韧性值最高;当硅加入量在6%~7%时,随硅加入量的增加,堆焊层的断裂韧性值降低。对堆焊层的耐磨性进行分析,以相对耐磨性来表征堆焊层的耐磨能力。当载荷为10N时,随着硅加入量的增加,堆焊层的相对耐磨性升高,最高值为1.14,在硅加入量超过5%时,相对耐磨性增加趋于平缓;当载荷为40N时,随着硅加入量的增加,堆焊层的耐磨性先升高后降低,在硅加入量为4%时相对耐磨性达到最高为1.11。根据上述试验结果,综合考虑堆焊工艺的经济性能和耐磨性能,确认在高频感应堆焊工艺下高铬铸铁粉末中硅的适宜加入量为4%左右。
[Abstract]:High frequency induction surfacing, as a kind of metal material surface strengthening technology, has the advantages of fast heating, small heat affected zone, simple operation and so on. It is widely used in industrial field. High-chromium cast iron, as a common wear-resistant material, has the advantages of high cost-performance ratio and wide adaptability. In this paper, the effect of silicon content in alloy powder on the microstructure and properties of high chromium cast iron surfacing layer under the condition of high frequency induction surfacing welding was studied by adding a certain amount of silicon into high chromium cast iron alloy. The effects of working current, heating time and flux addition on the forming process of surfacing layer were studied by orthogonal test. The optimum surfacing process parameters were as follows: working current 70 A, heating time 50 s, flux addition 14 s. The influence of silicon content in the powder on the forming property of the surfacing layer was studied by using the above process parameters. The results showed that the molding property of the surfacing powder was not good when the amount of silicon added in the powder was more than 7. The optimized process was used to prepare the high frequency induction surfacing layer with the addition amount of 0.6% silicon in the powder and 3% of the silicon content in the powder. The layer was composed of metallographic microscope, scanning electron microscope, energy spectrometer, X-ray diffractometer, Rockwell hardness meter, Vickers hardness meter, metallographic microscope, scanning electron microscope, X-ray diffractometer, Rockwell hardness meter, Vickers hardness meter. The results are as follows: the microstructure of the surfacing layer is hypereutectic high chromium cast iron with primary carbides eutectic structure. The primary carbides and eutectic carbides are both M7C3 carbides, and the matrix consists of martensite, austenite and ferrite. The silicon content in the surfacing powder increased from 0.6% to 7%, and the silicon content in the high-frequency induction surfacing layer changed from 0.286% to 2.0833%. With the increase of silicon content in the surfacing powder, the number of primary carbides in the surfacing layer increases, the morphology is refined, the amount of eutectic carbides decreases, the distance between eutectic carbides decreases, and the number of silicon atoms dissolved in the matrix increases. The content of austenite in matrix decreases and the content of martensite increases. The microhardness and macroscopic hardness of the surfacing layer were tested and analyzed. The Rockwell hardness of the surfacing layer of high chromium cast iron was 59.2or 63.7 HRC. With the increase of silicon content, the hardness of the surfacing layer increased, and the hardness of the surfacing layer tended to increase slowly when the addition amount of silicon exceeded 5%. The microhardness of primary carbides in high chromium cast iron surfacing layer is 1310.6 / 1383.1 HVV, and the microhardness of eutectic cluster is 590.5 / 691.6HV. the microhardness of eutectic cluster increases with the increase of silicon content, and the microhardness of eutectic group increases with the increase of silicon content, when the addition amount of silicon is more than 4, the microhardness of eutectic cluster increases with the increase of silicon content. The increase of microhardness value of eutectic clusters tends to be gentle. The fracture toughness of the surfacing layer was analyzed. With the increase of silicon content in the surfacing powder, the fracture toughness of the surfacing layer first increased and then decreased. When the amount of silicon is between 0.6 and 5, the fracture toughness of the surfacing layer increases with the increase of the amount of silicon, and the fracture toughness of the surfacing layer is the highest when the amount of silicon is 5, and when the amount of silicon is in the range of 6 ~ 7, the fracture toughness of the surfacing layer increases with the increase of the amount of silicon. The fracture toughness of the surfacing layer decreases. The wear resistance of the surfacing layer is analyzed and the wear resistance of the surfacing layer is characterized by the relative wear resistance. When the load is 10 N, the relative wear resistance of the surfacing layer increases with the increase of silicon content, and the maximum value is 1.14. When the silicon addition is more than 5 N, the relative wear resistance increases slightly, and when the load is 40 N, the relative wear resistance increases with the increase of silicon content. The wear resistance of the surfacing layer first increased and then decreased, and the relative wear resistance reached the maximum of 1.11 when the silicon content was 4. According to the above test results, considering the economic properties and wear resistance of surfacing technology, it is confirmed that the suitable addition amount of silicon in high chromium cast iron powder under high frequency induction surfacing technology is about 4%.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG455

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