The metallographic analysis shows that the metallurgical structure is proper. The results of internal pressure test indicate that the hot tap structure can work safely.

Tensile tests, metallographic analyses and micro-Vickers tests were carried out to evaluate the mechanical properties of the joints as a function of the process parameters.

The effects of welding time on the property of the joins were researched by using macroscopically mechanical property testing and microcosmic crystalline phase analyses. The reasonable welding …