Development of technologies to produce the very fine structure is currently very intensively accelerated. Even in scientific research, it is recognized that precisely controlled forming processes, including special processes, enabling control of technological parameters with regard to the structure refinement, and tied with the strengthening of materials, currently had the highest gradient of utilization efficiency of the scientific research findings in practice. Severe plastic deformation (SPD) processes have been extensively investigated in the last decade to facilitate the production processes on nano-structured or ultrafine-grained (UFG) materials with unique utility properties. This work deals with analysis of utilization the forming equipment that uses a method of metal forming -DRECE (Dual Rolling Equal Channel Extrusion), which was designed to produce a material with ultra-fine grain structure. Increasing the mechanical properties of the formed sheet metal strip is primary. It has demonstrated that the forming method leads to an increase of strength characteristics (Yield strength and Ultimate tensile strength) of the investigated medium carbon steel Ck55, while a slight decrease in plasticity of the formed steel. DRECE forming method has a positive effect on the microhardness distribution. With the increasing number of passes was observed that a HV0.1 difference between lower and upper sheet surface decreases to the minimum value, which depends on the processing of the initial state of the investigated sheet. The increasing dislocation density of cold severely deformed medium carbon steel resulted in an increase of the tensile properties and hardness.
This article presents a study on the influence of temperature and time of multi-variant heat treatment on the structure and properties of materials produced in direct metal laser sintering (DMLS) and casting technology. The materials were manufactured in the form of cuboidal elements with a cross-section of 1.5 mm × 15 mm and a length of 60 mm. The samples prepared in this way had a similar volume, but due to the production technology the metal crystallization took place at different rates and directions. In the cast, the direction of heat transfer was toward the mold, and the DMLS was directed locally layer by layer. The small thickness of the cast material allowed reaching conditions similar to the DMLS cooling process. Both DMLS and cast samples show similar mechanical properties (hardness) achieved after long ageing time, i.e., 16 h at 170 °C. The maximum hardness was observed for 8 h. In the DMLS samples, in contrast to cast samples, no lamellar precipitates of silicon were observed, which indicates their better resistance to cracking
The DRECE method is a very promising method for forming sheet metal sheet using the severe plastic deformations (SPD) principle. The DRECE method is characterized by the continuous extrusion of the sheet metal strip by the forming die, which creates a forming angle of 108 ° in the deformation zone. In the case of materials formed by a given method, there is a substantial increase in the mechanical properties, in particular the yield strength, already after the first pass through the forming device, while maintaining sufficient ductility of the materials. This fact is very important for the subsequent use of the method in industrial practice. In order to study the possibility of applying the DRECE method in industrial practice, this work presents proposals for design solutions for industrial use. The proposed design solution is also supplemented by mathematical simulations of the forming process.
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