Metode za izračunavanje temperatura predgrevanja pri zavarivanju čelika povišene i visoke čvrstoće

Abstract

Predgrevanjem čelika se smanjuje brzina hlađenja zone uticaja toplote, čime se izbegava pojava struktura sklonih nastanku hladnih prslina. Sa druge strane suviše mala brzina hlađenja, u ovoj zoni, dovodi do porasta metalnog zrna što, takođe, ima za posledicu povećanje skonosti ka nastanku prslina. Za izračunavanje temperatura predgrevanja čelika povišenih i visokih čvrstoća koriste se metode Itto - Bessyo i metoda data u standardu SRPS EN 1011-2. U radu su navedene metode primenjene na izračunavanje temperature predgrevanja mikrolegiranog čelika P460 NL1. Analiza rezultata proračuna po obe metode pokazuje značajne razlike u visini izračunatih temperatura predgrevanja. Zaključeno je da obe metode imaju ograničenja, koja se moraju imati u vidu pri njihovoj primeni u praksi.

With preheating of steel the cooling speed of a heat affected zone decreases, which prevents appearance of structure prone to cold cracks. On the other hand, too small cooling speed, in this area, results with growth the metal grains which, also, leads as to the higher prone to cracks. Common used method for calculation of preheating temperature for high strength steels ar Itto - Bessyo method, and method by standard SRPS EN 1011-2. This paper presents the methods for calculating the preheating temperature of micro aloyed steel P460 NL1. Analysis of the results obtained from both methods shows significant differences in the amounts calculated preheat temperature. It was concluded that both methods have limitations that must be taken into account in their application in practice.