An investigation on hot tearing cracks in nodular cast iron with hot tensile tests near the melting point

摘要

Hot cracks in cast iron are often due to the stress that develops in the mushy zone or in the solidified shell when close to the freezing temperature. There can be various causes for the stress; however, the material is more sensitive to cracks at temperatures where the material becomes brittle. When this condition is met, not only hot cracks but also internal microcracks can develop in the material. These microcracks considerably reduce the strength of the material. In this work, hot tensile tests were performed on nodular cast iron samples near the melting point to find the temperature at which brittle fractures occur. The microstructures of the samples were also studied to understand the fracture mechanism at high temperatures.