CORROSION TESTING OF HYBRID WELDED STAINLESS STEEL POT.

摘要

This article describes the investigation of the use of hybrid welding by preparation of tailored blanks for the manufacturing of a deep drawn pot. The specific design of the two-piece circular tailored blanks was initiated by the demand that the pot should be used in connection with an induction cooker. A study of the corrosion properties was necessary due to the importance of this in the manufacturing of food-related equipment. A 2,6 kW CO CO2 laser/TIG welding process was used to combine 4 mm ferritic and 2 mm austenitic stainless steel plates. In a number of systematic laboratory experiments, the gap has been varied between 0 and 0,9 mm along with the TIG current between 15 and 105 Amp. A quality assessment has been performed on welds in order to understand the effects of the welding process in respect to gap influence, metallurgy and corrosion resistance. The gap influence on the weld quality has been measured according to ISO 13.919-1. Corrosion testing in saline vapor chamber and metallurgical analysis have been carried out on welds with TIG currents between 15 and 75 Amp, in order to identify the effect of the secondary energy source on the weld structure and on the properties of the weld. The corrosion test elapsed for 720 h according to ISO 3768. In order to bridge gaps above 0,1 mm, TIG currents of 15 Amp or higher are necessary in order to secure a stable welding process, and to obtain a weld profile with minimum sagging. The corrosion resistance is highly affected by the augmented TIG current. Increasing the current worsens the corrosion resistance in the HAZ, but it is possible to maintain an acceptable corrosion resistance along with the gap bridging capabilities. The acceptance of the level of corrosion depends on the requirements to a specific product.