Ponašanje pri zamoru i lomu zavarenih spojeva čelika NIOMOL 490K

Abstract

Cilj rada je ispitivanje epruveta radi analize ponašanja prslina u zavarenim spojevima posuda pod pritiskom izrađenim od mikrolegiranog čelika, primenom parametara mehanike loma. Čelik NIOMOL 490K je namenjen za izradu zavarenih konstrukcija izloženih dinamičkom opterećenju i niskoj temperaturi, zbog čega, osim dovoljne čvrstoće, mora imati i prihvatljivu žilavost. U cilju razumevanja uzroka i načina pojave i rasta prslina u zavarenim spojevi-ma čelika povišene čvrstoće potrebno je da se utvrdi kako heterogenost mikrostrukture i mehaničkih svojstava zavarenog spoja, a pre svega HAZ, utiču na pojavu i rast prsline kao i na parametre rasta zamorne prsline. Ovaj rad treba da doprinese razvoju osnovnih parametara i kriterijuma prihvatljivosti grešaka tipa prslina kod posuda pod pritiskom namenjenih za rad u uslovima niskih temperatura i agresivnih sredina. .

The aim of this paper is testing specimens for analyzing crack behavior in welded joints of pressure vessels, made of micro alloyed steel, by applying fracture mechanics parameters. Steel NIOMOL 490 K is designed for welded structures exposed to dynamic loads and low temperature, and in respect to this, apart to sufficient strength, it must also have acceptable toughness. In the course of under-standing causes and modes of crack initiation and growth in welded joints of high strength steels, it is necessary to establish how the heterogeneity of microstructure and mechanical properties, primarily in HAZ, affect crack initiation and growth, as well as fatigue crack growth parameters. This paper should contribute to the development of basic parameters and criteria for the acceptance of crack-like defects in pressure vessels aimed to operate at conditions of low temperature and aggressive environment. .