Analiza otpornosti ka lomu ZUT-a u zavarenim spojevima mikrolegiranih čelika povećane čvrstoće

Abstract

Ispitivane su karakteristike otpornosti ka lomu u ZUT zavarenog spoja mikrolegiranog čelika povećane čvrstoće koji se koristi za izradu posuda pod pritiskom. S obzirom na namenu zavareni spoj treba da ima veliku otpornost ka pojavi i rastu prslina. Analiza je obuhvatila udarnu žilavost uzoraka simuliranih mikrostruktura koje su tipične za ZUT, žilavost loma nestandardnih uzoraka sa simuliranim mikrostrukturama i konačno standardne zavarene SENB uzorke. Analiza je pokazala da tip prsline (erozimatna i zamorna) na početak stabilnog rasta prsline ima veći uticaj kod duktilnijih mikrostruktura, a manji ili skoro nikakav kod krtijih. Takođe, komparativna analiza simuliranih uzoraka i zavarenih uzoraka pokazala je uticaj odnosa i veličine mikrostrukturnih regiona u ZUT-u na rast prsline t.j. uticaj mismeča na otpornost ka lomu.

The HAZ fracture behavior of the weldments of HSLA steel for pressure vessels has been investigated. Having in mind the purpose of such structure, the welded joint should poses sufficient resistance towards crack occurrence as well its propagation. The analysis encompassed impact toughness testing of Charpy specimens and fracture toughness determination of SENB specimens of base metal and simulated microstructures of HAZ, and finally fracture toughness testing of welded specimens with crack located in the very narrow HAZ regions. The analysis revealed the effect of the crack tip (electro eroded or fatigued) on the onset of the stabile crack growth for the different microstructures. The comparative analysis between the testings showed the influence of the mismatch towards the fracture behavior of real welded joint in respect of simulated microstructures.