Advance of Researches on the Cold Cracking of the Gray Cast Iron Cold-welding with Homogenous Welding Consumables

In this paper, the advance of researches on the cold cracking of the gray cast iron cold-welding with homgenous consumables both at home and abroad is summarized in four aspects including:(1) the effect of the graphite morphology and microsturcture of the weld on the cold cracking; (2) the mechanism of the cold cracking, and its initiation and propagation in the cast iron welds; (3)the research on the HAZ cold crack; (4)the development of the cold crack testing methods for the cast iron welded joints. These researches revealed: the crack resistance is much improved when the graphite is turned spheroidal from flake in the weld; the crack suscept ibility of the gray cast iron weld can also be de-creased by the twice stress-relaxation effecl of both bainitic and martensitic transformations; the crack is easily initiating and propagating at the narrow ferrite matrix bridge between neighbouring graphites; the effect of the diffusive hydrogen on the HAZ cold crack is less strong than that of the martensite transformation. The cold crack testing methods both the re-straint cracking test and the plate rigid restraint cracking (PRRC) test for cast iron welds are emphasized because they can quantitatively evaluate the cracking resistance of the cast iron welds.