Thus, for the sake of serviceability and economic benefits, the strategy that internal crack in heavy forgings could be healed has attracted much attention. Even small-sized defects could aggregate and provoke catastrophic failures. The microstructural evolution of the crack zone in the SA 508–3 steel was sketched.ĭuring the manufacturing process of heavy forgings, cavity-type defects, such as cracks and voids, are inevitable. When the temperature was above 1150 ☌, the impact properties began to deteriorate because of grain coarsening and larger MA (martensite–austenite) constituents. The recovery degrees of mechanical properties in crack healing zones increased with increasing the healing temperature and reduction ratio in the temperature range of 950–1050 ☌. The tensile properties of crack healing zones could be fully restored, while their impact and low cycle fatigue properties could only be partially achieved. The results showed that the internal cracks in SA 508–3 steel disappeared and were replaced by newly formed grains, achieved by recrystallization and abnormal grain growth. Microstructures of the crack healing zones were observed using an optical microscope (OM) and electron back scattered diffraction (EBSD) technology, and the recovery degrees of mechanical properties in the crack healing zones with the healing temperature and a reduction ratio were tested systematically. In this study, mechanical properties recovery after crack healing in SA 508–3 steel were investigated. Internal cracks could be healed under the process of hot plastic deformation.
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