Abstract
Ingot forging processes often consist of several successive deformation steps with high interpass times, during which metadynamic recrystallization (MDRX) occurs. Two-stage isothermal compression tests were carried out at 1150°C and 1200°C with strain rates of 0.25-2s −1 and interpass times of 5-25s. Based on the experimental results, a material model for MDRX is proposed. The constitutive model was implemented in Forge NxT 1.1 ® software to simulate the multistage compression. Results from the material model are consistent with the numerical analysis and experimental results.
Highlights
Forging of ingot after casting process starts with ingot breakdown process which is generally performed at very high temperatures (0.75 of melting point ′′MP′′) so as to breakdown the chemical and microstructural structure inhomogeneity [1]
Despite large efforts being made on the development of kinetic equations for wrought ferrous alloys, little information is available on the flow behavior of as-cast structures at very high temperature (~0.7Mp) and prolonged interpass times
The objective of this study is to investigate the influence of strain rate, temperature and interpass time on compressive deformation characteristics of as-cast 42CrMo using double hit hot compressive tests
Summary
Forging of ingot after casting process starts with ingot breakdown process which is generally performed at very high temperatures (0.75 of melting point ′′MP′′) so as to breakdown the chemical (macrosegregation) and microstructural structure (as-cast dendritic) inhomogeneity [1]. Hot workability is defined as the amount of deformation that a material can undergo without cracking and reach desirable mechanical properties and microstructure at a given temperature and strain rate It is generally evaluated by various parameters like strain rate, strain, temperature and interpass time. Despite large efforts being made on the development of kinetic equations for wrought ferrous alloys, little information is available on the flow behavior of as-cast structures at very high temperature (~0.7Mp) and prolonged interpass times. This corresponds to the ingot breakdown process during which the porosities inherited from solidification are close, macrosegregation levels are reduced and the ascast structure is converted into a much finer and more isotropic wrought structure. Avrami equation describing the relationship of flow stress, strain rate, strain, interpass time and temperature was investigated and used to simulate real time analysis of the ingot breakdown process using FEM analysis
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