Assessment of the behaviour of fatigue loaded HSLA steel welded joint by applying fracture mechanics parameters

Abstract

From a fracture mechanics point of view on welded joints, it is assumed that the welded joint is pre-cracked such as that the fatigue life of the pre-cracked structure is then determined by the period of crack growth under variable load. Experimental data obtained by testing provide a substantial basis for a better understanding and an explanation of the phenomenon of material fatigue. Low cycle fatigue (LCF) occurs during the process of charging and discharging of reactors, pressure vessels and pipelines; the fatigue can be accelerated by an additional negative effect of temperature variation and the aggressive effect of the media contained inside the vessel, and during the exploitation of the equipment in the processing industry. In the present paper the results are presented of J-integral measurements at LCF of a low-alloyed high strength steel (HSLA) weld metal used in the submerged arc welding process in the manufacture of pressure vessels.

U zavarenim spojevima, sa gledišta mehanike loma, se pretpostavlja prisustvo prslina, gde se onda vek s obzirom na zamor takvih konstrukcija sa prslinama procenjuje vremenom rasta prsline pod promenljivim opterećenjem. Eksperimentalni podaci dobijeni ispitivanjem pružaju značajnu osnovu za bolje razumevanje i objašnjenje fenomena zamora materijala. Niskociklični zamor (LCF) se javlja u procesu punjenja i pražnjenja reaktora, posuda pod pritiskom i cevovoda; proces zamora može ubrzati dodatni negativan efekat promene temperature i efekat agresivne sredine sadržane u posudi, kao i tokom perioda eksploatacije opreme u procesnoj industriji. U ovom radu prikazani su rezultati merenja J integrala pri niskocikličnom zamoru (LCF) metala šava niskolegiranog čelika povišene čvrstoće (HSLA), koji se koristi u proizvodnji posuda pod pritiskom postupkom zavarivanja pod praškom.