Uticaj ekvivalentnog sadržaja kiseonika u mešavini gasova na strukturu i žilavost metala šava mikrolegiranih čelika

Abstract

Ispitivanja su izvedena na dva čelika. Prvi je mikrolegiran sa Nb, a drugi sa: Ti, Nb i V. Žilavost metala šava navedenih čelika je određena na instrumentiranom Šarpijevom klatnu. Pet različitih mešavina gasova (Ar, CO2, O2) je upotrebljeno za određivanje optimalne zaštitne atmosfere pri zavarivanju ispitivanih čelika. Ekvivalentni sadržaj kiseonika je uzet kao parametar mešavine i ustanovljen je njegov uticaj na mikrostrukturu metala šava, žilavost i energiju rasta prsline. Za oba čelika, kao optimalna mešavina gasova se pokazala (5 % CO2, 0.91 % O2, ostatak Ar), koja obezbeđuje maksimalnu energiju rasta prsline, kao i dominantnu mikrostrukturu acikularnog ferita.

Testing were carried out on two steels. The first was microalloyed with Nb and second with Ti, Nb and V. The impact toughness of weld metals of these steels was evaluated using an instrumented Charpy pendulum. Five different gas mixtures (Ar, CO2, O2) were used to determine the optimal gas shielded metal arc process for both steels. The oxygen equivalent was used as a representative parameter of a mixture to follow, in particularly, its effect on the microstructure, toughness and crack propagation energy of the weld metal. For these investigated steels, the optimum gas mixture was established (5%CO2, 0.91%O2, balance Ar), which provided the maximum crack propagation energy, due to the microstructure which consisted dominantly of acicular ferrite.