Development of Automatic Ultrasonic System for NDE Characterization on the Heat Treatment in Piston Rods for a Use of Shock Absorbers

In general, piston rods can absorb both the shock and vibration to maintain the stability of moving automotive wheels; a high-frequency heat treatment is performed to guarantee their quality. Appropriate nondestructive techniques are required to monitor the degrees of this treatment. It is possible to quantitatively predict the beam profile behavior and the degree of heat treatment for the outer diameter of the piston rods by measuring the ultrasonic behavior of the rods through an automated ultrasonic system.BRThe results of this study demonstrated that the specimens underwent this treatment had a longer time-of-flight (TOF) than the specimens without it, indicating that it is possible to lower the surface ultrasound velocity. It was determined that the shock observer piston rod surface particles become both enlarged and oxidized owing to this treatment and that the surface wave velocity is affected by thermal oxidation.