The main defects in heavy steel castings are related to hot tear formation during solidification. Depending on the steel grade, design, and local solidification conditions, it is possible to predict regions with higher risk of hot tear formation during the casting process. However, steels containing Boron show more complex crack and defect patterns compared to common steel casting alloys. The mechanisms behind the Boron induced hot tearing is investigated in this work to understand the influence of Boron enrichment during solidification and the influence on hot tearing. The experimental work includes the investigation of phase diagrams and the corresponding fractions of the solid and liquid phases depending on temperature using thermal analysis e.g. DSC and HT-LSCM. The hot tearing sensitivity and mechanical properties during solidification are obtained in the Submerged Split Chill Test, SSCT. In addition IMC-B 3-point bending tests are performed to determine high-temperature material properties in the solid state. The work is part of a research project where the final goal is to improve the hot tear predictions based on experimental work and carry out a benchmark simulation of a real sized casting and use it to show the agreement between the numerical results and extensive non-destructive testing from industrial observations.
Inorganic bonded sand cores are getting increasing attention in industry due to their environmental advantages, and they are now widely used for series production in automotive applications. The advantages of these binder systems are nevertheless associated with a greater sensitivity of the core quality in relation to the manufacturing and storage process before casting, which is also having a major impact on the core strength. This paper presents the current work in integrating the modelling of the binder decomposition and evaporation of binder water with the mechanical performance of partially hardened and dried sand cores. This allows a local description of mechanical properties, considering different behaviour in compression and tension which depends on temperature and different levels of moisture content through the core. Recent work has shown the importance of including creep effects in the numerical modelling of 3D Printed (3DP) inorganic sand cores. Measurements of the mechanical behaviour of 3DP cores compared to shot cores have shown some fundamental differences in strength due to different density and binder content. This has been investigated in detail in collaboration with a major automotive manufacturer and the application of the model extension was done on a complex water jacket core.
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