Improvement of weld quality of AISI 304 pipes welded by TIG method

AISI 304 steel is one of the most familiar steel type which is used especially as transition and cooling system pipes. The reason of this, AISI 304 steel has important mechanical and corrosion properties. However, welding AISI 304 has some limitations which causes weld decay problem during tungsten inert gas (TIG) weld process. During the solidification stage temperature transition between 850 °C and 450°C which is the sensitivity range during welding, chromium and carbon elements precipitates at grain boundaries in heat affected zone (HAZ). It is a vital failure particularly in AISI 304 stainless pipes due to their required resistivity to corrosion, high temperature and pressure. The longer the heat affect zone remains in this critical temperature range during the welding process, the more precipitation will occur in this zone. Main focus of this thesis is to concentrate on the improvement of weld quality of AISI 304 pipes welded by TIG method. During welding process with the help of the continuous cooling method, the sensitive temperature range is passed quickly. In this study, it has been shown positive effects on microstructural, mechanical and corrosion properties by passing the sensitization temperature range quickly.