【作者】 张迪；

【导师】 周桂莲；

【作者基本信息】 青岛科技大学 ， 机械制造及其自动化， 2010， 硕士

【摘要】 不锈钢具有高硬度、耐高温以及耐腐蚀性等优良特性,广泛应用于化工设备、管道、汽轮机叶片、医用器械等诸多领域。尤其是马氏体不锈钢以及半马氏体不锈钢在汽轮机叶片领域发挥着超强的实用价值。由于叶片形状较为复杂且叶片材料硬度较大,用传统的机械加工,成本会比较大,另一方面由于电火花线切割具有“以柔克刚、精密微细、仿型逼真”的加工特点,所以电火花线切割加工叶片也行正在逐步受到人们的重视,并呈现进一步扩大的趋势。青岛捷能汽轮机集团叶片分厂对叶型的加工采用的正是高速走丝线切割加工,而在加工过程中叶片表面粗糙度以及电加工产生的裂纹等表面质量问题对叶片的使用寿命产生了很大影响,时常会使叶片在使用过程中产生开裂或者叶片装配精度不够。基于此,捷能集团叶片分厂与青岛科技大学采取校企联合方式,对高速走丝线切割加工叶片材料表面质量问题展开了深入研究和探讨。本文通过电火花线切割加工1Cr13钢正交试验,分析了个电参数对加工表面粗糙度的影响,并且对数据进行了方差和显著性分析,最后得到了一组最优的粗糙度电参数组合。从而为企业进一步研究汽轮机叶片材料的电加工表面粗糙度工艺提供了参考。电极丝对汽轮机叶片加工表面质量的影响主要体现在:电极丝的直径大小、走丝速度、变频进给速度、张力、换向次数、垂直度以及走丝机构的传动精度。下面根据这些具体因素,对高速走丝线切割加工汽轮机叶片的表面质量进行了分析。并结合生产实际,介绍了如何合理的选用电极丝的各参数。本文利用带有能谱的扫描电子显微镜对变质层的成分变化进行了分析;利用X射线衍射实验分析了变质层加工前后化合物的变化情况;又用变质层在高温电阻炉分布长加热情况下,分析得到了其变化规律大致符合1Cr13钢的低温加高温回火规律的结论;接着对变质层的形貌进行了扫描电镜分析,以及对凝固层、再回火层、再淬火区进行了金相分析;对1Cr13钢变质层的硬度、耐磨性两个机械性能指标进行了研究;对线切割加工的白亮层的厚度变化规律进行了总结;分析了表面变质层显微裂纹的形成;最后对线切割加工1Cr13钢变质层的改善方法进行了归纳。根据X射线衍射测定电火花线切割变质层残余应力的基本原理及方法,以及在此基础上分析研究了汽轮机叶片材料1Cr13钢电火花线切割加工表面残余拉应力随各电参数的变化规律。并研究出变质层表面的残余拉应力并不是影响零件开裂的因素。更多还原

【Abstract】 Martensite stainless steel owns lots of good features, for example: hardness, high temperature, corrosion and so on. In view of these advantages, Martensite stainless steel and semi-martensitic stainless steel were used more and more in chemical equipment, pipeline, turbine blade and medical devices. Especially, in the field of turbine blade, it`s merit is very outstanding. Because the shape of blade is rather complex,stainless steel`s hardness is very high, the cost of traditional machining process is very big, and WEDM owons the feature, as follows:“dealt with gently, precision fine, profiling realistic”, processing turbine blade with WEDM is being paid attention more and more. Blade Factory of Qing Dao Jie Neng Group uses methold of WEDM to product turbine blade. In this process, the life of blade is affected by surface quality——surface roughness, crack and so on. These factors usually make the blade crack and reduce the assembiy precision. Basing on these problems, enterprise coalition was taked Blade Factory of Qing Dao Jie Neng Group and Qing Dao University of Science and Technology. This paper analyzes the surface quality of turbine blade 1Cr13 by WEDM.Basing on making orthogonal experiment in machining 1Cr13 by WEDM, the influence of main electrical parameters on maching surface roughness, variance and saliency was analyzed. Finally,the best optimal electrical parameters combination was got. It provides some reference for roughness research of processing turbine blade with WEDM.The factor of influencing surface quality of the electrode wire is an imprtant factor of influencing surface quality of WEDM. Diameter size, takeup speed, frequency conversion feeding speed, tension, reversing times, uprightness of electrode wire and driving accuracy wire-walkingwere analyzed for the influence of electrode wire on machining surface roughness in high-speed wire cutting process. The methods of choosing and using each parameter of electrode wire was introduced.Basing on the scanning electron microscope with energy spectrum, the chemical composition of 1Cr13 was analyzed; Basing on X-ray diffraction experiments, the compounds of metamorphic layer was analyzed; Under the condition of putting the test sample in the high temperature resistance furnance, the law of metamorphic layer in accordance with tempering of 1Cr13 was found; With the help of SEM and metallurgical microscope, the morphology of metamorphic layer, solidified layer, tempering layer, and quenching layer were analyzed; The law of white layer`s thickness was generalized; the micro crack of metamorphic layer was analyzed with the help of SEM; finally, the process of the WEDMed blade material- 1Cr13 was improved and generalized.Basing on the principle and method of residnal stress determination by X-ray, the residual stress of WEDMed turbine blade material- 1Cr13 was revealed. Finally, the factor of causing cracking is not residual stress.更多还原