基于Fe基粉末的激光熔覆及激光淬火技术研究

发布时间：2018-03-13 03:39

本文选题：Fe基合金粉末　切入点：Q235D钢　出处：《辽宁工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：本论文通过采用根据实际要求而制的Fe基合金粉末，在Q235D基体表面进行激光熔覆实验，，先后进行了激光单层熔覆、激光双层熔覆、激光多层熔覆以及激光淬火的实验探索与研究，通过反复优化实验数据，最终成功地提取出较优的激光加工工艺参数，并将提取出的较优工艺参数成功应用到实际加工中且取得了很好的效果，为该型Fe基合金粉末在实际生产中的应用奠定了非常关键的理论与实验基础。首先，利用该型Fe基合金粉末在Q235D基体的表面进行了较为关键的激光单道与单层熔覆的实验研究。通过对前期进行的大量单道、多道熔覆基础性实验得到的实验结果进行细致分析，从中选取出较优的实验数据进行了激光单层熔覆实验的探索与研究。对不同工艺参数下所得的熔覆层外观形貌、表面洛氏硬度、金相显微组织和截面显微硬度分别进行了观察测试与对比分析从而得到较优的激光单层熔覆的工艺参数。在较优工艺参数下熔覆层表面较为平整、光滑、致密均匀，基体与熔覆层两者之间发生了较成功的冶金结合，没有出现明显的裂纹痕迹，并且几乎没有发现气孔的存在，与此同时，熔覆层的显微硬度的分布也比较均匀，并且其变化不存在明显的梯度，其硬度与基体相比也得到了明显提升，为后期要进行的激光双层熔覆和多层熔覆实验也打下了牢固的基础。其次，利用之前进行的激光单层熔覆实验得到的较好的工艺参数逐步有序地进行了激光双层熔覆和激光多层熔覆实验工艺参数的探索与优化，成功提取出激光双层熔覆与激光多层熔覆的较优工艺参数。实验分析显示，较好工艺参数下熔覆层的宏观质量较好，熔覆层尺寸完全能够满足实际生产使用要求，金相显微组织的分析结果表明基本没有裂纹和气孔出现且熔覆层与基体以及各前后熔覆层之间的结合良好。此外，对层间停光时间对熔覆层的性能影响也做了深入研究分析，对实际工业生产有着非常大的指导价值。再次，在此基础上进行了激光淬火实验的探索与研究，成功的探索出了激光淬火时的较好工艺参数。实验结果显示，在较好工艺参数情况下，激光淬火后的淬硬层较为平整、光滑、分布非常均匀，其淬火后的表面硬度远远高于淬火前的基体，金相组织观察分析发现，淬火层组织主要为高硬度的片状和板条状马氏体组织，晶粒尺寸非常细小，淬火层的显微硬度分布几乎没有变化梯度，波动程度较小且明显高于传统淬火方法得到的组织硬度。实验探索了激光功率和扫描速度对淬火层深度和淬火层表面硬度的影响，为其在实际工业中的应用奠定了良好的理论与实验基础。最后，对激光熔覆与激光淬火两种加工工艺所得熔覆层与淬火层综合机械性能、加工制造成本、适用场合进行综合对比分析，为实际生产与应用都奠定了重要的理论依据。
[Abstract]:In this paper, laser cladding experiments were carried out on Q235D substrate by using Fe-base alloy powder prepared according to practical requirements. Laser cladding and double-layer laser cladding were carried out successively. The experiments of laser multilayer cladding and laser quenching are explored and studied. By repeatedly optimizing the experimental data, the better laser processing parameters are extracted successfully. The optimized process parameters were successfully applied to practical processing and good results were obtained, which laid a very important theoretical and experimental foundation for the application of the Fe-base alloy powder in practical production. First of all, the experimental study of laser single channel and single layer cladding on the surface of Q235D substrate was carried out by using the Fe-base alloy powder. The experimental results obtained from the basic experiments of multichannel cladding were analyzed in detail, from which the better experimental data were selected to explore and study the laser cladding experiments. The surface Rockwell hardness, metallographic microstructure and cross section microhardness were observed and compared to obtain the better laser cladding process parameters. The surface of the cladding layer was smooth and smooth under the optimum technological parameters. Dense and uniform, there is a successful metallurgical bonding between the matrix and the cladding layer, there is no obvious crack trace, and almost no porosity is found. At the same time, the microhardness distribution of the cladding layer is also relatively uniform. Moreover, there is no obvious gradient and its hardness is obviously improved compared with the matrix, which lays a solid foundation for the laser double-layer cladding and multi-layer cladding experiments to be carried out in the later stage. Secondly, the process parameters of laser double-layer cladding and laser multilayer cladding are explored and optimized by using the better technological parameters obtained from the previous laser cladding experiments. The optimum technological parameters of laser double-layer cladding and laser multilayer cladding are extracted successfully. The experimental analysis shows that the macroscopical quality of the cladding layer is better and the size of the cladding layer can completely meet the requirements of practical production and application. The results of metallographic microstructure analysis show that there are basically no cracks and pores, and the bonding between the cladding layer and the substrate, and between the cladding layer and the front and rear cladding layers is good. In addition, the effect of the interlayer stop time on the properties of the cladding coating is also studied. It has great guiding value to actual industrial production. Thirdly, on the basis of this, the laser quenching experiments are carried out, and the better technological parameters of laser quenching are successfully explored. The experimental results show that the hardened layer after laser quenching is relatively smooth under the better technological parameters. The surface hardness of the quenched layer is much higher than that of the matrix before quenching. The microstructure of the quenched layer is mainly sheet and strip martensite with high hardness, and the grain size is very small. The microhardness distribution of the quenched layer has almost no change gradient, the fluctuation degree is small and obviously higher than the microstructure hardness obtained by the traditional quenching method. The effects of laser power and scanning speed on the depth of the quenched layer and the hardness of the quenched layer surface are investigated experimentally. It lays a good theoretical and experimental foundation for its application in practical industry. Finally, the comprehensive mechanical properties, manufacturing cost and application of laser cladding and laser quenching are compared and analyzed, which lays an important theoretical basis for practical production and application.
【学位授予单位】：辽宁工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG174.4

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