Study on Prevention of Brittle Fracture in Weld Bond for High Tensile Steel (Report 1)

Fracture Characteristics of High Heat Input Submerged-Arc Weld Bond for 80kg/mm² HTS

Abstract

A study was made on prevention of brittle fracture in a high heat input welded joint for 80kg/mm² high tensile steel and a metallurgical investigation into the improvement of cleavage fracture strength of weld bond was carried out.
In this report the fracture characteristics of conventional HT80 steels' welded joints welded with 80 KJ/cm heat input are clarified. They fracture at weld bond in a brittle manner at 15-20°C.
And the clue to prevention of brittle fracture is discussed according to fracture analysis diagram.
It is stressed that the solution to this problem lies in the fact that the compound microstructure of low carbon bainite and low .carbon martensite has superior notch toughness and higher yeild stress.
Namely, the higher the notch toughness and the higher the yield stress are in weld bond, the tendency of weld bond brittle fracture becomes the lis less conspicuous.