چكيده به لاتين
Sand casting is an extremely practical and economical way to produce. Along with the economic advantages of this method, technical and metallurgical deficiency have led to the development of more advanced methods. Ablation casting is a new method for improving the mold casting imperfections. In Ablation method, the mold is washed with a coolant fluid and the part quickly cools down. Due to the arrival of the washing method, some of the parameters, such as waterjet begining time, have not been properly identified. In this research, the effect of waterjet begining time on mechanical properties and structure of steel parts has been investigated. The results show that waterjet begining time has a great influence on the mechanical properties of steel parts. The effect of waterjet begining time depends on the dendrites coherency point (DCP). The evaluation of the results of the tensile test and the thermal analysis together showed that the waterjet begining time before the DCP point would improve the mechanical properties. Washing the mold after the DCP point will cause toughness. Thus, by optimizing the immersion time, in the samples with carbon at 0.258%, the final strength was up to 71.27% (from 638.75 Mpa to 1094 Mpa) and the total strain 32.63% (from 11.9% to 15.88%) increased. The yield strength in some part decreased by about 12%, which increased by about 6% as the cooling regiem changed, the yield strength improved. The structure of the ablated parts has changed dramatically over the parts. The microstructure of parts was changed from ferrite and perlite to acicular ferrite, widmanstatten ferrite, bainite and martensite.
