Micropores in G20Mn5N cast steel and their influence on stress distribution

To accurately analyze the impact of casting pores in steel, high-resolution 3D X-ray tomography technology was used to gather detailed statistical information about micropores. These micropores were classified as gas, shrinkage, and gas-shrinkage pores depending on their formation origin and morphology. Clustering tendencies and affinity parameters were defined to characterize the spatial correlations among these three types of pores. The 3D data from X-ray tomography scans were then integrated into finite element analysis (FEA) software to predict how micropore shape, size, and distribution influence stress distribution within the material. The results show that certain inflection points with small local radii within the cast pores are major contributors to stress concentration. Therefore, cast pores cannot be simply modeled as ideal spherical pores. The sphericity and volume of pores have a significant impact on the stress concentration of the model. Specifically, lower sphericity and larger pore volumes result in higher stress concentrations. Moreover, the internal pores of steel castings exhibit specific global distribution characteristics. Pores located on the surface of the specimen lead to significantly higher stress concentrations compared to those located inside the specimen. Cast steel is extensively used in civil engineering structures owing to its excellent strength, toughness, and impact resistance. Sand casting is the preferred manufacturing process for many applications involving low-alloy cast steel[ 1] . However, various production processes such as casting design, molding sand, welding repair, and heat treatment can introduce certain micro defects in steel castings[ 2-3] . These micro defects can cause discontinuities in the cast steel, adversely affecting steel casting durability[ 4-6]. © 2024 Southeast University. All rights reserved.