Fundamental examinations for quality evaluation of gas pressure welds: Non‐destructive inspection method for gas pressure welds with bulge removal by hot shearing (1st Report)

Summary

The authors have given serious consideration to key problems facing quality evaluation of gas pressure welds and have developed a non‐destructive method for 100% quality inspection of gas pressure welds just after welding has been performed. The method is based on bulge removal by hot shearing. The present paper describes the results obtained during quality evaluation of gas pressure welds based on this method. The results obtained may be summarised as follows:

1. The quality (joint interfacial strength and properties) of steel gas pressure welds is controlled by the area expansion factor of the gas pressure welds and gas pressure welding temperature. Within the range avoiding any melting of the surfaces being welded, the quality improves with increasing values of both factors.

2. The quality of gas pressure welds can be evaluated by whether or not flat fracture occurs on the fracture surface under mechanical test and its proportion.

3. The effects of the area expansion factor and gas pressure welding temperature on improvement of the quality of gas pressure welds vary depending on the carbon content of the base metal, their effects being more pronounced with a greater carbon content. This is due to reduction of the interfacial oxides by the carbon contained in the base metal.