Intergranular fracture of low-alloy cast steel

A series of microstructural, macrostructural, and fracture observations, mechanical properties tests, and analyses of electroextracted nonmetallic inclusions have been made on samples from two high-carbon Cr and Cr-Mo cast-steel rolls. The fracture comparison test at 950 °C and room temperature showed that intercrystalline fracture occurs at high temperatures. AlN precipitates were extracted from the surfaces of rock-candy-type fractures. Welldefined dendrites are seen in some places in the cracked area. Close to them, coarse carbide needles and ledeburites, which are rich in Cr and Mn, are precipitated along the primary austenite grain boundaries. An explanation is given for the occurrence of the intercrystalline fracture in accordance with the test results, and measures are suggested to eliminate this kind of defect.