Applying a Traditional Casting Defect Classification to Categorize Casting Defects in Metal Matrix Composites with Saturated Reinforcement

Traditional casting defects in metal-matrix composites with saturated reinforcement. This classification forms a casting defect group called “structure defects,” while the remaining defect groups (shape defects and raw surface defects) under this new classification method include groups present in casting defects in traditionally cast materials. This group (structure defects) contains 5 subgroups, including both structural defects in traditionally cast materials, which correspond to structural defects in saturated composite castings, as well as defects specific to these castings. The proposed classification is still being refined. Introduction Metal composites are increasingly replacing traditional construction materials used in aviation and in the construction of machinery and equipment. This is due to the ability to obtain virtually any desirable functional properties using a composite material, such as a high damping factor, high resistance to abrasion, high Young's modulus, low specific weight, and low coefficient of thermal expansion which was generally widely described in classic books [1, 2], and detailed issues in conference papers, earlier [3, 4] and recently [5-8]. A composite is defined [1, 2] as an ideal material with a perfect structure; however, real composite materials, especially cast composites, usually have imperfect structures because they contain various defects [4, 5, 9-12]. These defects arise because castings have specific structures that are affected by the manufacturing process sequence. Classifying such material irregularities makes it possible to: – identify them precisely, – determine why they form, – determine which manufacturing stage causes their formation, – promptly take countermeasures. For metal composite castings, especially those produced by saturation, there is no such classification [13-16]. The classification of casting defects of traditional materials (cast iron, cast steel, and non-ferrous metal alloys) is insufficient and must be supplemented with specific defects for metal composites. This problem, noticed during the manufacturing of castings from saturated metal composites, was the reason for creating such a classification in this paper. Terotechnology XI Materials Research Forum LLC Materials Research Proceedings 17 (2020) 57-64 https://doi.org/10.21741/9781644901038-9 58 Findings and discussion All metal castings have defects of various types and origins. We define a casting defect as a deviation in a material’s structure and mechanical or physicochemical properties from its specifications [16]. Defects can be identified based on their features, which in turn leads to the creation of a casting defect classification. This classification is useful for: 1) transferring information in research work, during an educational process, or in a manufacturing process; 2) eliminating defective castings from further stages of a manufacturing process; 3) intervention aimed at removing the causes of defects from the manufacturing process. As for the second case, the classification criteria of casting defects can be divided into three casting groups [14-19]: a) good castings (without defects) or with acceptable defects, b) castings with repairable defects, c) castings with disqualifying defects. • Casting defect classification systems For castings made from traditional materials, there are standards, atlases or catalogues of defects [2, 14-21], which: – enable unambiguous identification of defects; – provide methods to detect them; – determine why they form; – suggest technological measures to prevent their formation. Classification diagrams for casting defects are shown in Figure 1.