Papers by Keyword: Investment Casting

Abstract: The research focuses on cored blades made from the MAR-M247® Ni-based superalloy, which were manufactured through directional solidification with varying withdrawal rates of either 3.4 mm/min or 5.0 mm/min, and shell mold temperatures of 1510 °C or 1566 °C after undergoing solution heat treatment. The characterization of four variants of the cored blades was conducted using several analytical techniques: X-ray diffraction (XRD), light microscopy (LM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The XRD analysis identified the presence of the γ matrix, the intermetallic γ' phase, MC carbides, and M₅B₃ phases. The dendritic regions of the cored blades consist of secondary γ' precipitates surrounded by a γ matrix, with a mean size ranging from 0.264 to 0.272 μm, depending on the fabrication parameters.

Abstract: Ti-6Al-7Nb is commonly used as orthopedic implant, especially for total hip arthroplasty application, due to its excellency in biocompatibility and surface feature. This study investigates the effects of varying solution treatment temperatures on the mechanical properties and corrosion resistance of the biomedical Ti-6Al-7Nb alloy fabricated using centrifugal investment casting. Solution treatment was performed at 850°C, 970°C, and 1050°C, and the results were evaluated through tensile tests, hardness measurements, microstructural observations, and potentiodynamic polarization tests. The treatment at 970°C produced the optimal combination of mechanical strength and corrosion resistance, achieving a tensile strength of 690 MPa and the lowest corrosion rate of 0.00826 mmpy. The superior performance at 970°C is attributed to the formation of fine α precipitates in the microstructure. These findings highlight the effectiveness of suitable solution treatment temperature in enhancing Ti-6Al-7Nb’s properties for potential use in biomedical applications.

Abstract: In this article, the possibility of using investment casting technology to produce high-quality shaped and thin-walled castings of magnesium alloys (Mg-Al based alloy - AZ91E and Mg-Zr-based alloy WE43B) at ALUCAST s.r.o. (the Czech based precision castings foundry) is described. The paper briefly focuses on using suitable and available protective atmospheres for the safe processing of magnesium alloys, considering the current European legislation. The casting process and the best arrangement of the gating system were optimized by software simulation of the casting process using "ProCast" software by the ESI group. Microstructures and mechanical properties of magnesium alloys AZ91E and WE43B within the scope of this article were investigated by light microscopy (LM), hardness tests, and tensile tests. In addition, radiography inspections and chemical composition analyses were performed. The experiments show that good mastery of magnesium melt processing technology (including knowledge of methods for reducing reactions between melt and ceramic shell, the porosity of real castings around 0.04%, etc.) allows high quality and precise magnesium castings with high mechanical properties corresponding to castings from AZ91E and WE43B alloys produced by sand casting.

Abstract: Damage and fracture processes in high temperature creep of an investment cast B1914 Ni-based superalloy with the increased amount of boron to 0.08wt.% for high temperature applications were analysed. Constant load creep tests in tension were conducted at temperatures from 800 to under applied stress ranging from 150 to 700 MPa. The microstructure of fractured specimens was investigated by scanning electron microscope Tescan equipped with an electron-back scatter diffraction. Microstructure investigation showed that the microstructure of the B1941 superalloy consists of a gamma (γ) phase with a dendritic structure and gamma prime (γ ́) phase with a cuboidal shape. Precipitates of γ ́and a lamellar eutectic, composed of γ/(Mo,Cr,Ni)₃B_2, were identified in the interdendritic region. Creep damage and fracture are closely connected with decohesion of the interface between M₃B₂ boride and matrix.

Abstract: This article deals with the problematics of the production of small castings using gravitational investment casting. These are castings with a relatively complex shape, which are used as parts of trigger assembly for musical wind instruments. During their production, various defects occur which are connected with the casting process. The aim of this article is to describe the defects and suggest possible methods for removing them. The first step was to find and identify these defects using metallographic and EDX microanalysis. Furthermore, a simulation calculation of the casting process was used to determine the influence of the casting geometry on casting quality. Based on these analyses, the most suitable alloy and casting system geometry were proposed for the production of the casting.

Abstract: At present the production paradigm undergoes a fundamental change when testing of actual units involving castings manufacturing gives way to digital simulation which allows to overcome constraints intrinsic to the traditional methods of trials and errors. This article presents the work on numerical study and prediction of shrinkage porosity in Nickel alloys castings made by precision casting method for further comparison of simulation results with the size of flaws produced during actual hardware testing.

Abstract: A comparative study of the surface contaminated layer formed by chemical reaction between ceramic-mold and titanium aluminum alloy castings or titanium alloy castings were carried out. The morphology, thickness and hardness of the surface contaminated layer were characterized by means of metalloscopy and microhardness measurement. The results show that surface contaminated layers formed between Ti-Al alloy castings and ceramic-mold, also formed between Ti alloy castings and ceramic-mold. The surface contaminated layers of Ti-Al alloy castings were continuous and compact, their thickness was about 0~90 μm. The surface contaminated layers of titanium alloy castings were not even, their thickness was 0~900 μm. Titanium alloy is more liable to react with the ceramic -mold than the Ti-Al alloy.

Abstract: Investment casting of an orthopedic implant plate based on stainless steel 316L was considered an economical process. Nevertheless, the mechanical properties of the investment casting product were found to be inferior as compared to the implant plate fabricated with other methods such as forging due to their differences in the microstructure. Investment casting mostly produced coarser grain as compared to those with forging or rolled process. In order to improve their mechanical properties, cold-rolling followed by a repetitive thermal cycling process is proposed. The goal is to generate finer grain size through recrystallization process leading to nucleation of new grain during the thermal cycling process thus increasing their strength. Stainless steel 316L was cold-rolled to 52% reduction in thickness and this process generate stored strain energy in the form of dislocation density in the material. The thermal cycling treatment performed within several cycles after cold rolling enabling gradual disperse of stored strain energy that facilitates the recrystallization process that initiates new grain formation. The short holding time within several cycles limits the grain growth that normally occurs during annealing. It was found that thermal cycling treatment at a temperature of 950 °C for 35 seconds within four cycles led to the formation of finer grain size of 22 µm on average as compared to the initial investment casting average grain size of 290 µm. The hardness also increases to 253 HV_0.3 in this condition as compared to 155 HV_0.3 of investment casting products. Lower thermal cycling temperature than 950 °C during the test did not result in grain refinement thus indicating that strain energy relieves were not enough to aid the recrystallization process.

Abstract: The use of local raw materials for the manufacturing of import substitution casting products on investment casting technology has been done. Compared to the conventional casting process, investment casting has the advantage of being able to create a sophisticated casting product and produce a product that is near net shape, so it is no need machining process. The objective is as an effort to find an alternative method of making a quality casting product, has high added value with the utilization of local raw materials which available in Indonesia so that it can reduce the cost of production and dependence on imports of industrial raw materials which are very expensive in the investment casting process. The method of making casting products with investment casting process, including: pattern making, mould making, dewaxing, melting, pouring, finishing and testing. Investment casting technology has been successfully applied to the manufacture of rocker arm, impeller pump and turbine blade with the utilization of local raw materials ie: epoxy resin as a substitute for metal pattern, mixture wax of paraffin, and celo resin for the pattern of wax and zircon sand of Bangka island as coating slurry for ceramic mould. The discussion of this paper is expected to be a case of developing other casting products needed by Indonesia for industry such as: medical equipment, agricultural equipment, textile equipment, gun and small armaments, electronics, automotive and electrical components etc.

Abstract: 316L stainless steel is used in various industrial applications including chemical, biomedical and mechanical industries due to its good mechanical properties and corrosion resistance. Recycling of 316L stainless steel scrap without significantly reducing its value has received recently great attention because of the environmental regulations. In the current work, 316L stainless steel scrap was recycled via casting using Skull induction melting technique. The casted products subsequently subjected to laser surface melting process to improve its surface properties to be used for harsh environment. The results showed defect free surfaces with homogeneous microstructures. Nano size grains were also obtained due to rapid solidification process. Such nano size grains are preferred for extending the usage of the 316L stainless steel in new applications.Corresponding author: E-Mail: elgazzar.ha@gmail.com