Investigation of the effect of grain size on longitudinal critically refracted ultrasonic wave time-of-flight and speed of penetration in material

This examination investigates the influence of grain size on the time-of-flight (TOF) and velocity of longitudinal critically refracted (LCR) waves in metallic materials.L CR waves are pivotal in non-destructive assessment and material characterization due to their sensitivity to microstructural variations.We conducted experiments on typical varying grain sizes and analyzed the propagation of L CR waves.The grain size of material changes when subjected to mechanical and thermal operations.In the present study the specimens of as received material cut to 100 50 8 mm dimensions.The prepared specimens were first stress-relieved and then subjected to the heat treatments at a temperature 440 C, 480 C, 500 C, 540 C, and 560 C for 30 minute in vacuum furnace respectively.The TOF and velocity of LCR wave were measured using an ultrasonic instrument and 5 MHz frequency transducers.The grain size and structure changes with the heat treatments, At 560 C, and the grains became courser, and their size increased to 150 m.The grains get elongated at 500 C and 540 C, grains structure was equiaxed.The grain size of the specimens heated at 500 C and 540 C temperature measured as 84 m and 100 m respectively.The L CR wave speed and TOF established a linear relation with grain size effect.A negative correlation was observed between LCR wave TOF and grain size.The LCR TOF is shorter for lager grain sizes and longer for smaller grain sizes.A positive correlation was observed between LCR wave speed and grain size, with rise in grain size L CR wave speed increases and at lower grain size the L CR wave speed observed smaller.The change in 10 m grain size changes the TOF and speed wave by 0.0005 sec and 0.2411 m/s respectively.The TOF and LCR wave velocity measurements were performed with uncertainty 0.000029 and 0.010 respectively.Our results show a significant correlation between grain size, TOF, and wave velocity, emphasizing the importance of considering grain size in ultrasonic testing and material evaluation.