Plasma Welding of Thermo-Mechanically Processed Steel

The article presents the course and results of tests involving the technological plasma welding of 3 mm thick butt joints made of steel S700MC using the melt-in welding technique and the key-hole welding technique. The technological tests made it possible to determine parameters enabling the obtainment of joints representing quality level B in accordance with the PN-EN ISO 5817:2014 standard. The tests discussed in the article included tensile tests, bend tests, hardness tests as well as macro and microscopic metallographic tests involving the use of light microscopy. The test results were subjected to detailed analysis performed to identify the effect of high arc energy used in plasma welding on the structure and properties of the test joints. The test results revealed that the melt-in welding technique (characteristic of the TIG method) did not ensure the obtainment of minimum tensile strength.