Determination of Optimal Temperature of Heating upon Local Normalizing of Welded Seam in Pipes Made of Low-Alloyed Steels

Abstract

Processes that occur in heat affected zone (HAZ) upon heating and cooling of metal ofwelded joint upon local heat treatment (LHT) in normalizing mode are simulated. For cooling rates used in workshop conditions critical points are determined for steels of different chemical composition. Novel LHT modes are developed for different pipe steels capable of increasing the impact toughness due to formation of small austenitic grains after heating and uniform fine-grained ferrite-pearlite microstructure in welded joint after cooling. The results are tested and imlemented in production of electric-welded tubes 114 - 530 mm in diameter (K50 - K60 pipe grades, according to API standard) at the JSC “Vyksa Steel Works.”