宽带激光熔覆铁基涂层工艺参数及性能研究北大核心CSCD

27SiMn钢液压支架在恶劣的工作条件下长期使用后,其表面容易形成腐蚀,磨损和疲劳损坏等缺陷。为提升其使用寿命,本文利用宽带激光熔覆技术在27SiMn钢表面进行制备铁基涂层的实验研究。基于控制变量的方法来依次调整激光功率、送粉速度、载气流量及扫描速度开展单道单因素熔覆试验,并以表面粗糙度为熔覆层质量评价指标初选工艺参数。基于单因素试验进一步开展4因素3水平正交试验,终选显微硬度为熔覆层质量评价指标。利用极差分析考察数据发现扫描速度对熔覆层显微硬度影响最大,其后依次为激光功率、载气流量和送粉速度,最优工艺参数为熔覆处在激光焦点位置且激光功率、送粉速度、在其流量和扫描速度分别为4000 W、2.50 rpm、6.9 L/min和600 rpm。同时对熔覆层进行了摩擦磨损试验,分析了摩擦因素、磨损率及磨损形貌,验证了工艺参数优化的可行性。最终,熔覆层平均硬度较基体提升2.2倍,磨损率较基体提升27%。工艺参数优化能够实现铁基合金粉末熔覆层表面硬度及耐磨性的显著提升,对熔覆修复27SiMn液压支架大有帮助。

Research on process parameters and performance of broadband laser cladding iron based coatings

27SiMn steel hydraulic support is prone to defects such as corrosion,abrasion and fatigue damage on their surface after long time use under harsh working conditions.In order to improve its service life,broadband laser cladding technology is used on the surface of 27SiMn Steel for the preparation of iron based coatings in this paper.Based on the method of control variables,the laser power,powder feeding speed,carrier gas flow rate and scanning speed were adjusted in sequence to carry out single pass single factor cladding test,and the surface roughness was used as the initial selection process parameter of the cladding layer quality evaluation index.The 4 factor 3 level orthogonal test was further conducted based on the single factor test,and the microhardness was finally selected as the quality evaluation index of the cladding layer.It is found that the scanning speed has the greatest impact on the microhardness of the cladding layer,followed by laser power,gas flow and powder delivery speed through the range analysis of the research data.The optimal process parameters are cladding at the laser focal point and laser power,powder feeding speed,carrier gas flow and scanning speed are 4000W,2.50 rpm,6.9 L/min and 600 rpm,respectively.At the same time,a friction and wear test was carried out on the cladding layer,and the friction coefficient,wear rate and wear form were analyzed to verify the feasibility of optimization of process parameters.Finally,it is concluded that the average hardness of the cladding layer is 2.2 times that of the matrix,and the wear rate is 27% of that of the matrix.Through the optimization of the process parameters,the surface hardness and wear resistance of the iron based alloy cladding layer can be significantly improved,which is very beneficial to the cladding repair of the 27SiMn hydraulic support.