Investigation of the Effect of Modifying the AlSi7Mg0.3 Alloy with a Fast-Cooled Master Alloy Using Heat Treatment

The development of modern high-tech industries of industrial production is impossible without the development of new methods for processing materials with high mechanical characteristics. There is a growing need for an increase in the proportion of parts made of aluminum alloys, a more complex configuration of cast parts, an increase in their reliability and durability in operation, etc. All this poses for metallurgists and foundry workers the task of creating new technologies for producing alloys, improving the technical and economic characteristics of structural materials, improving the quality and reducing the cost of castings.Hypoeutectic silumins have good casting properties, good weldability, machinability and corrosion resistance. However, they are prone to the formation of a coarse needle-like state, which reduces their useful characteristics. To eliminate this phenomenon, it is necessary to apply special technologies and the most common is their modification, which provides grain refinement. This makes it possible to use silumins for the manufacture of castings of complex shapes with increased density and low shrinkage porosity. Such parts can withstand average loads in critical units. Aluminum-silicon alloy AK7 or (ASi7Mg0.3) is a typical silumin, which is in demand in the automotive industry, construction, aircraft construction, machine, automobile and tractor production. It is appreciated for its good casting properties, weldability, machinability and corrosion resistance.

Sand Casting Implementation of Two-Dimensional Digital Code Direct-Part-Marking Using Additively Manufactured Tags

Statistical quality control is used in foundries to identify special cause defects and root causes by correlating process input variations with casting defects. A difficulty exists in associating process data collected with individual cast parts as the parts are processed through the foundry and then out into the supply chain. Typically, alphanumeric labels for marking castings and manual identification of the castings with route-paper based tracing approaches have been used. Such manual-based systems make root cause analysis of quality defect issues tedious. This study presents the development of a semi-automated approach using 3D printed sand mold inserts shaped as 2D matrix codes which thereby permit directly cast identification code into the parts. This enables automated part tracking at the very beginning of the casting process including mold making. Automated scan based tracking of parts through a foundry and subsequent supply chain allows for statistical process data collected to also be associated with each part processed with unique identification, building upon the part history and pedigree.

Comparative Evaluation of Marking Methods on Cast Parts of Al–Si Alloy with Image Processing

Quality issues caused by casting defects are commonly complicated to solve, because the part-specific process parameters are not traced to the individual cast part. This problem can be mitigated by the traceability of each cast part with an identifier code. Therefore, a study of the influence of marked surface topography and post-treatments on code symbol quality is desirable for a well-designed traceability system. In this work, the code symbol quality of laser, dot peen, and electrolytic marking methods on three as-cast surfaces of Al–Si alloy, after sandblasting and heat treatment, is evaluated comparatively with a customized image processing software. The result shows that the laser marking method produces the highest performance for different as-cast surfaces; electrolytic marking provides acceptable results only on the smooth surfaces of high-pressure die casting; dot peen marking produces the codes of high symbol contrasts, which are similar to those of laser marking, especially for rough as-cast surfaces of sand casting. However, for all marking methods, the code qualities of all surface topographies decrease substantially after post-treatments. Considering that dot peen marking has satisfying performances as well as low equipment and maintenance costs, this method is more suitable for small- and medium-size foundries to start to trace each cast part in an economical manner.

The Repair of Defects in High-Manganese Steel Castings by Welding Technology

Welding technologies are used to repair defects in cast parts of high - manganese austenitic steel (Hadfield steel). These include repair welding for newly manufactured castings, welding the formed defects in the old operating cast parts and, finally, for cladding layer of wear-resistant metal on the surface of the cast parts. Manual metal arc welding (MMAW) are used as often as gas metal arc welding (GMAW) and of flux-core wire welding (FCAW-S). These welding processes make possible to obtain a weld metal with the expected quality of the restored surface and a slight distortion of the base metal structure. The article presents methods of the casting repair by welding and surfacing. The parameters of welding and surfacing procedures are given, welding materials are recommended, and the methods for nondestructive testing of welds are prescribed.

Minimization of Internal Shrinkage Defects in Cast Parts Using 5VA Powder Solder Application

The article presents a method for eliminating the crystallization of thermal nodes and shrinkage defects in the form of micro-friable cavities. The method of soldering on castings from steel grades VNL-1 and VNL-6 using 5VA powder solder has been investigated. Also, the optimal soldering modes were determined, the effects of soldering modes on the properties of the base material and the soldered joint were studied, the corrosion resistance was investigated, the corrosion resistance of the soldered joints in corrosive environments. The conducted studies of sealing by soldering cast parts with microdefects lead to the following results: increased corrosion resistance; ensuring increased tightness; improving the presentation; elimination of surface microdefects.

Possibility for Replicating Mechanoscopic Surface Marks in the Hybrid Vacuum-Pressure Casting Process

Vacuum-pressure casting technology allows small batches of components to be manufactured from polymer materials, mainly from thermosetting plastics such as polyurethane and epoxy resins. Apart from being very simple, the process is also advantageous in that it offers a very accurately reproduced geometrical structure of the surfaces of master patterns used in mold manufacturing. This article presents the results of analyses performed for the process of replicating mechanoscopic marks with the use of three vacuum casting variants, including a hybrid vacuum-pressure casting process developed in particular for the replication purposes. The main research objective was to analyze and evaluate the influence of the parameters of the individual process variants on the quality of the obtained cast parts and on the replication accuracy without introducing additional artifacts on their surfaces. The article discusses the individual stages of the process and provides an analysis of their parameters. The replicas were evaluated for their porosity and reproduction quality with the use of CT methods and comparative photographs obtained from a light microscope.

Analytical method of calculation of thermal fields of cast parts during crystallization

The aim of the work is to create a mathematical method that allows to calculate the distribution of thermal fields in cast parts during crystallization using a system of analytical formulas. During the calculations, a combination of known analytical formulas GF was used. Balandin, AY Weinik, S. Schwartz with their own original mathematical solutions created on the basis of the analysis of thermophysical processes in castings in the process of their crystallization. Computer simulation of thermal fields using the LVMFlow program was used to compare the results. According to the created mathematical method, examples of calculation of thermal fields for two castings made of steel 25L of hollow cylindrical shape, the wall thickness of which is 100 mm and 4 mm, respectively, are given. Calculations were performed for the conditions of crystallization of castings in a single sand form. The comparison of results of calculations by the developed method and with use of the existing software is presented. For the first time, based on our own mathematical and thermophysical developments, a comprehensive calculation method for determining the thermal field of the casting during crystallization and cooling was developed. casting. The technique is expressed in a number of analytical formulas, each of which describes a specific thermal process that occurs in the casting. This takes into account the features of the casting configuration. The created complex method of calculation of thermal fields of cast parts is a mathematical basis for determining the thermal fields of molds and rods, which allows to predict their properties and select the optimal molding materials. The created technique can also be offered as a mathematical basis for refining applied computer programs for foundry production. CASTING, TEMPERATURE, THERMAL FIELD, COOLING DYNAMICS, COOLING DURATION, MATHEMATICAL LAW, COLORING FRONT, CALCULATION

Development of a Laser Powder Bed Fusion Process Tailored for the Additive Manufacturing of High-Quality Components Made of the Commercial Magnesium Alloy WE43

Additive manufacturing (AM) has become increasingly important over the last decade and the quality of the products generated with AM technology has strongly improved. The most common metals that are processed by AM techniques are steel, titanium (Ti) or aluminum (Al) alloys. However, the proportion of magnesium (Mg) in AM is still negligible, possibly due to the poor processability of Mg in comparison to other metals. Mg parts are usually produced by various casting processes and the experiences in additive manufacturing of Mg are still limited. To address this issue, a parameter screening was conducted in the present study with experiments designed to find the most influential process parameters. In a second step, these parameters were optimized in order to fabricate parts with the highest relative density. This experiment led to processing parameters with which specimens with relative densities above 99.9% could be created. These high-density specimens were then utilized in the fabrication of test pieces with several different geometries, in order to compare the material properties resulting from both the casting process and the powder bed fusion (PBF-LB) process. In this comparison, the compositions of the occurring phases and the alloys’ microstructures as well as the mechanical properties were investigated. Typically, the microstructure of metal parts, produced by PBF-LB, consisted of much finer grains compared to as-cast parts. Consequently, the strength of Mg parts generated by PBF-LB could be further increased.

OPTIMAL HARDENING TREATMENT OF CAST PARTS OF MACHINES WITH A HARD-ALLOY WEAR-RESISTANT COATING

The article presents research materials on thestructure and properties of hard-alloy coatings obtained in the process of casting products using gasified models. The composition and properties of steel were studied, as well as the hardness and microhardness of the surface and subsurface layers of castparts. The relative wear resistance of tests performed in laboratory and field conditions is analyzed. The final modes of heat treatment with double phase recrystallization for cast parts are carried out. It is shown that heat treatment with double phase recrystallization increases the wear resistance of hard-alloy coatings and finished products by 3-4 times.Keywords: gasified model Casting, hard-alloy coating, high-carbon steel, hardness and microhardness, microstructure, heat treatment with double phase recrystallization, abrasive wear resistance and durability

PRODUCTIVITY INCREASE OF EQUIPMENT FOR CASTING OF THERMOSETS THROUGH THE INTRODUCTION OF HEATED INJECTION MOLD

The results of the introduction of a heated injection mold into the equipment for automated casting of parts from thermosets are presented. The results of the influence of injection mold heating on the polymerization rate of cast parts are obtained.