淬火介质的常用钢热探头评价和淬火介质数据库

【作者】 王宇挺；

【导师】 王富岗； 张立文；

【作者基本信息】 大连理工大学 ， 材料学， 2004， 硕士

【摘要】 淬火介质的正确选择和使用一直是热处理的重要课题之一。淬火介质评价方法中，冷却曲线法应用最广。它能描述冷却过程中淬火介质与工件间的传热行为，而且已发展出若干定量的评价方法。但热探头材料和测温点的选择等方面存在的局限，使现有冷却曲线既无法正确表征淬火介质对实际工件的冷却效果，又无法据此准确预测工件的淬后性能。 本文提出设计常用钢热探头评价淬火介质并建立淬火介质数据库。常用钢热探头在尺寸、材料、热电偶布置等方面不同于以往的评价方法中使用的热探头。选择有代表性的钢材制造热探头并依照热处理工艺进行淬火，可以模拟工件的冷却过程。通过采集热探头内典型部位的冷却曲线、淬火组织和硬度，可以表征淬火介质的冷却能力和硬化能力。 开发淬火过程温度采集系统，实现了较高的采样速率，使用数字滤波消除了数据的噪声干扰。利用温度采集系统测量了20CrMnTi、GCr15、H13等10种常用钢热探头在9种油基和水基淬火介质中淬火的冷却曲线。研究了热探头中央横截面的淬后组织分布和硬度分布，对淬火开裂的热探头，采集了开裂部位的形貌。 开发了淬火介质数据库，可以实现常用钢热探头淬火过程的冷却曲线、冷速曲线及热探头淬后组织分布、硬度分布和淬裂形貌的查询。数据库在设计中对易用性和数据规模的可扩展性进行了充分考虑。更多还原

【Abstract】 Correct selection and usage of quenchants is one of the key issues in heat treatment. Among the evaluation methods of quenchants, cooling curve method is the most popular. This method is able to describe heat transfer between quenchant and workpiece during quenching. Although many quantitative analysis methods were developed from cooling curve method, it is still a problem to select proper material for thermal probe manufacturing and to select locations in probe for temperature measurement. This prevents cooling curve method from presentation of quenchants’ cooling effect on practical workpieces and results in incorrect prediction of enhanced performance.In this thesis, it is put forward to design a probe of typical steels and to establish a quenchant database by quenching tests. The probe of typical steels has specific features in measurement, material, thermal couple arrangement, etc. With the tests in accordance with standard quenching technology, practical quenching process of workpiece can be simulated. This method gives cooling power and hardening power of quenchants with the results of cooling curves, microstructure and hardness collected at several representative locations in the probes.A temperature acquisition system was developed to carry out high-speed acquisition of temperature signals. Probes made of 10 kinds of typical steels such as 20CrMnTi, GCr15 and H13 were quenched in 9 different quenchants, and cooling curves were recorded with the acquisition system. In this work, microstructure distribution and hardness distribution along cross-section in the middle of the length of quenched probes were investigated, and the photographs of cracked probes were taken.The quenchant database provides users with access to the data of cooling curves and cooling rate curves of quenching tests. It also restores microstructure distribution and hardness distribution of all the quenched probes as well as photographs of the cracked probes. Extensibility and user-friendly characteristics are involved in design philosophy.更多还原