Quenching Media Commonly Used In Steel Heat Probe Evaluation And Quenching Media Database

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.