Influence of welding current intensity on susceptibility to intergranular corrosion in welded joints of stainless steel

Abstract

Susceptibility to intergranular corrosion in welded joints of austenitic stainless steel X5Cr-Ni18-10 was tested. The welding was performed with different intensity of welding current (110 A, 130 A and 150 A). The tests were performed using electrochemical potentiokinetic reactivation method with double loop (DL EPR method) on the base metal and in the heat affected zone. The results obtained by the DL EPR method show that the heat affected zone formed by welding with 150 A has the highest susceptibility to intergranular corrosion. The susceptibility to intergranular corrosion is considerably lower when applying smaller welding current. The base metal is resistant to intergranular corrosion. The indicator of susceptibility to intergranular corrosion (Qr/Qp)GBA is ~ 6 times higher for the heat affected zone (at 150 A welding current intensity) than for the base metal. Obtained testing results show that the welding current intensity greatly influences the susceptibility to intergranular corrosion in welded joints of stainless steel X5Cr-Ni18-10.

Ispitana je sklonost prema interkristalnoj koroziji zavarenog spoja austenitnog nerđajućeg čelika X5Cr-Ni18-10. Zavareni spoj je formiran pri različitim jačinama struje zavarivanja (110 A, 130 A i 150 A). Ispitivanja su vršena metodom elektrohemijske potenciokinetičke reaktivacije sa dvostrukom petljom (DL EPR metoda), na osnovnom metalu i u zoni uticaja toplote (ZUT). Osnovni metal je otporan prema interkristalnoj koroziji. Zona uticaja toplote formirana pri zavarivanju strujom jačine 150 A pokazuje najveću sklonost prema interkristalnoj koroziji. Sklonost prema interkristalnoj koroziji je znatno niža pri zavarivanju manjim jačinama struje. Pokazatelj sklonosti prema interkristalnoj koroziji (Qr/Qp)GBA je ~ 6 puta veći za zonu uticaja toplote (pri jačini struje zavarivanja od 150 A) nego za osnovni metal. Na osnovu prikazanih rezultata može se zaključiti da jačina struje zavarivanja u velikoj meri utiče na sklonost zavarenog spoja nerđajućeg čelika X5CrNi18-10 prema interkristalnoj koroziji. .