Ultrasonic Propagation Characteristics Of 65Mn Plate Specimens Under Different Heat Treatment

Heat treatment is an important metal heat processing, which controls its performance by changing the microstructure of the metal surface or internal, different heat treatment processes will lead directly to the different metal properties, whether The heat treatment process is correct directly determine the use of meta, therefore, how to evaluate heat treatment effect quickly and accurately, and how to effectively evaluate the damage in use for metal which adopt different heat treatments, there is an important theoretical and practical engineering significance.65Mn steel is a popular spring steel with good toughness and ductility. Due to different requirements,it often has different heat treatment. Generally,the method of heat treatment of 65 Mn spring steel is quenching and tempering. Through heat treatment,the crystal structure and mechanical properties of 65 Mn spring steel will be changed. In order not to undermine the integrity of the steel,we use non-destructive testing methods to study it.The purpose of this paper is the effect of heat treatment and ultrasonic propagation characteristics combine to 65 Mn steel for the study, experiments were launched around the heat treatment, Specimens after different heat load analysis of different times, nonlinear changes observed specimen,and it is necessary to test the quality of its heat treatment performance The main contents are as follows:(1) Through a common method of non-destructive testing- Ultrasonic testing,a brief introduction of propagation of ultrasonic has been made,including about an understanding of reflection, scattering, attenuation propagation characteristics of ultrasound in the steel structure.(2) Moreover,it describes a theory of nonlinear ultrasonic of solid material. According to this theory we can evaluate the impact of different treatment methods on the specimen.(3) 65 Mn steel heat treatment for different specimens were taken not fatigue loads, fatigue loads 100,000 and 250,000 times fatigue loading experiments. For different heat treatment but the same number of specimens loaded, compare the waveform chart, amplitude-frequency power spectrum and FFT comparison chart. Observe the changes of different magnitudes, plasticity and toughness properties.(4) For each specimen by a Fast Fourier amplitude of the fundamental and second harmonic amplitudes are compared transform, to prove the feasibility of the theory of nonlinear ultrasound,besides a series of theories has been made to evaluate the performance of 65 Mn spring steel after different heat treatment process by nonlinear ultrasonic method.