This paper presents an analytical solution to predict the transient temperature distribution in fillet arc welding including the effect of molten metal. The solution is obtained by solving a transient three- dimensional heat conduction equation with convection boundary conditions on the surfaces of a plate, and mapping the infinite plate onto the fillet weld geometry with energy equation. The electric heat input on the fillet weld and on the infinite plate is assumed to have a combination of two bivariate Gaussian distribution.
To check the validity of the solution, GMA welding experiments were performed under various welding conditions. The actual isotherms of the weldment cross-sections at various distances from the arc start point are compared with those of simulation result.
The temperature gradient in a weldmet changes the transit time and distorts the direction of the ultrasound beam to the higher temperature regions due to the lower sound speed in the hotter regions of the weldment. This paper describes a ray-tracing method for calculating the effects of temperature gradients on ultrasonic propagation in fillet arc welding. In the method, weldment is conceptually devided into a number of layers and the refraction and sound speed at each layer is calculated using the temperature which calculated from the analytical solution.
Calculating the time and location of echoes arrival from various interfaces around a molten weld pool determines the optimum location of ultrasonic transducers and the correct position of flaws.
To achieve the remote inspection of a weldment, this paper suggests a new method. The method is ultrasonic detection through electrode. So ultrasonic detector which can detect ultrasonic signals through electrode using immersion tank and immersion transduce installed in welding torch was developed by many experimental results.
In remote inspection the ultrasonic signal was transmitted into weldment and recieved the propagated signal using the detector during welding. And the relationship between the depth of weld pool and the distorsion of ultrasonic signal was also investigated.
