SEDL / STP / STP1256-EB / STP16395S

Investigation of Fracture Mechanical Behaviour of Nodular Cast Iron and Welded Joints with Parent-Material-Like Weld Metal

Baer, W
PhD-Student, Freiberg University of Mining and Technology, Institute of Materials Engineering, Freiberg/Sachsen, G.-Zeuner-Straβe

Pusch, G
Professor, Freiberg University of Mining and Technology, Institute of Materials Engineering, Freiberg/Sachsen, G.-Zeuner-Straβe

Pages: 15    Published: Jan 1995

Download this paper for $25 PDF (344K)          View License Agreement
Abstract

The focus of the investigations was the determination of fracture mechanical characteristics and crack resistance curves of the J-Integral and CTOD concept by application of the partial unloading compliance technique and D.C. potential drop technique (four point bend) under static load.

The results show a close correlation between crack initiation values as well as crack resistance curves and graphite morphology parameters determined by means of quantitative microstructural analysis where the influence of the matrix (distance of graphite particles) dominates the crack resistance and fracture performance of ferritic nodular cast iron under consideration of the notch effect of graphite particles.

SEM in-situ tensile tests showed that due to a beneficial shielding effect of the strength overmatching parent-material-like weld metal (mis-match ratio M=1.21), cracks positioned directly in the plane of the fusion line did not deviate into the weld metal in spite of its lower toughness compared to that of the parent material. They also showed an unsymetrical formation of damage in front of the crack tip.