摘要本文研究了18CrNiMo7-6固体渗硼和渗碳后渗硼的组织与性能。用金相显微镜观察了渗硼层的金相组织，用显微硬度计测试了渗硼层的硬度分布，用XRD进行了渗硼层的物相分析。结果表明通过使用预渗碳后渗硼的方法对18CrNiMo7-6的渗硼层，与原本单一渗硼后的渗层相比，渗硼层厚度增加，最大硬度由1732HV0.3降低到1453HV0.3，基体平均硬度由513HV0.3升高到了687HV0.3，很大程度上缓和了硬度曲线，降低了渗硼层脆性，明显优化了渗硼层的性能。另一方面，对单一渗硼处理研究发现温度和时间的升高，也会引起渗硼层厚度和最大硬度的增加，对渗硼层的性能和组织也有一定影响。30418
关键词：18CrNiMo7-6钢;复合渗;渗硼层;硬度曲线;厚度
毕业论文设计外文摘要
Title The Microstructure and Properties of Boronizing Layer after Carburizing of Low-Carbon Steel
Abstract The microstructure and properties of 18CrNiMo7-6 pack boronizing and boronizing after carburizing were studied in this paper. The metallographic structure of boronizing layer is observed with metallographic microscope, the hardness distribution of boronizing layer was tested with microhardness tester and the phase analysis of boronizing layer is conducted with XRD. The results show that compared with the boronizing layer after originally single boronizing, for the boronizing layer of 18CrNiMo7-6 after pre-carburizing, the thickness of boronizing layer increases, the maximum hardness decreases from 1732HV0.3 to 1453HV0.3, average hardness of matrix increases from 513HV0.3 to 687HV0.3, which greatly eases the hardness curve, reduces the fragility of boronizing layer and obviously optimizes the performance of boronizing layer. On the other hand, it is found in the single boronizing treatment and research that the rise of temperature and time will cause the increase of the thickness and maximum hardness of boronizing layer and poses certain influence on the performance and organization of boronizing layer.
Keyword：18CrNiMo7-6;carbon multiboronizing;The boronized layer;Hardness curve； Thickness
目 次
1 引言 1
1.1 复合渗硼技术 1
1.2 碳硼复合渗的组织与性能 2
1.3 本课题研究内容 4
2 实验方法 5
2.1 实验材料与设备 5
2.2 实验过程与实验方案 6
3实验结果与讨论 8
3.1 渗硼层的金相组织分析 8
3.2 渗层厚度分析 10
3.3 渗硼层硬度测量 13
3.4 渗硼层的物相分析 15
结论 19
致谢 20
参考文献 21
1 引言
渗硼技术是一种近些年来发展的较为热门的热处理工艺方法，其本质上是通过让硼元素进入铁以及一些非金属的表面中来改善表面性能的一种化学热处理的方法。通过硼在基质中扩散，从而与基质材料在某些特定温度下形成一个或者多个金属间相组成的化合物层，即为渗硼层。而相对与普通表面层，渗硼使得原本材料表面拥有了很高的硬度以及耐磨性，良好的抗腐蚀性，红硬性和表面抗氧化性，从而可以使零件更适应于摩擦和腐蚀的环境中[1]。但由于渗硼层在使用的过程中相对容易剥落以及脆裂，这也很大程度上使得渗硼技术的使用受到限制，所以迫切需要新技术来改善现状。 低碳钢渗碳后渗硼层的组织和性能:http://www.751com.cn/cailiao/lunwen_26111.html