Heat Treatment Quality Evaluation Study Of 2Cr13 Sample Based On The Magnetic Memory Technology

Heat treatment is a kind of technology that modifying the solid metal or alloy through heating, insulation and cooling with appropriate ways to obtain the wanted organizational structure and performance. Compared with other processing techniques, heat treatment generally does not change the shape of the part and its chemical composition, but changes its microstructure, or the surface chemical composition, or improves the mechanics performance. The purpose is to improve the immanent quality of the treated part. As the saying goes, "do a good job in heat treatment, the part will have ten times life", shows the important effect of heat treatment on mechanical manufacturing. Heat treatment control is the key in the quality assurance system, including crafts control, process control, subcontract control, etc. But most plants often have many problems in the quality control system, so the heat treatment quality is not ideal as in the handbooks. Also, for there is no effective means to fulfill quickly and easily inspection, the heat treatment components often cause catastrophic failures in service. In this thesis, metal magnetic memory technology is adopted to quickly evaluate the artifacts after heat treatment and forecast their performance. All of these efforts are valuable, whether for metal magnetic memory theory research, or its application study in engineering field.2Cr13 steel is selected as the research material for its common application in steam turbine blades which are key parts in petroleum, chemical industry. The research details are listed below.1、Quenching 2Cr13 specimens under different temperatures and cooling in oil, analyzing microstructure and grain size effect on the mechanical properties, magnetic, magnetic memory. The relationship is found between magnetic memory amplitude and mechanical performance parameters, the magnetic parameters for them.2、Putting 2Cr13 specimens under isothermal heat treatment with different cooling medium, analyzing microstructure and quenching stress on effect of mechanical properties, magnetic, magnetic memory. The relationship between magnetic memory amplitude, mechanical performance parameters and magnetic parameters of different cooling specimens is advanced.3、Treating 2Cr13 samples under different tempering temperature, analyzing microstructure on effect of mechanical properties, magnetic, magnetic memory. The relationship between magnetic memory amplitude, mechanical performance parameters and magnetic parameters of different tempering specimens is found.4、Three groups of samples after heat treatment are tested with tensile testing and magnetic memory testing, The changing law of magnetic memory features is obtained in tensile test, also the tensile damage evaluation method.5、2Cr13 samples after quenching at different temperature and cooling in oil are tested under fatigue testing and magnetic memory testing. The relationship between grain size, tensile strength, magnetic features and fatigue life is studied. Also the changing law of magnetic memory signal feature is achieved along with the time under fatigue load. Last, the evaluation method of fatigue damage is advanced with metal magnetic memory.