Effects of Hot Isostatic Pressing and Heat Treatments on Structural and Corrosion Properties of Direct Metal Laser Sintered Parts

Purpose – This paper aims to investigate the effects of various heat treatments on microstructure, hardness, porosity and corrosion properties of the parts. Design/methodology/approach – Hot isostatic pressing (HIP) process, various heat treatments and their combinations were applied to the AlSi10Mg parts produced by direct laser metal sintering (DMLS). Findings – It has been found that the HIP process, which is a post-processing process, reduces the amount of porosity in DMLS-AlSi10Mg material, thus improves corrosion resistance significantly. Originality/value – In this study, the HIP process and subsequent T6 heat treatments were applied to AlSi10Mg parts produced by the DMLS technique. The study aims to increase the corrosion resistance of AlSi10Mg parts by reducing porosity with the HIP process and by altering the microstructure with the T6 process

Applying High Voltage Cathodic Pulse with Various Pulse Durations on Aluminium Via Micro-Arc Oxidation (MAO)

The present study is an investigation of the effect of pulse duration on properties of coatings formed on aluminium alloy (Al) in alkaline solution via using of high voltage cathodic pulses. Nine different anodic-cathodic pulse couples with various durations were selected for processing. In order to find out the effect of pulse duration on coating: duty cycle, anodic voltage, cathodic voltage, processing time, electrolyte temperature and electrolyte composition were kept constant. Scanning electron microscope (SEM), profilometer, X-ray diffractometer and indenter were employed to investigate the microstructure, surface roughness, phase distribution and hardness of the coatings. Also, coating thickness measurement was carried out to find out the effect of pulse duration on productivity. Varying of pulse duration caused significant differences among thickness of coating layers. Coating layers with thickness between 45-75 μm and surface roughness between 2.5-5.5 μm were obtained. Coatings consist of two layers, outer porous layer and inner dense layer. The outer porous layer was γ-Al2O3 and the inner dense layer was a mixture of γ-Al2O3 and α-Al2O3. The hardness of inner dense layers was between 1100-1600 Vickers

Corrosion Behaviour of Additive Manufactured Metals

Additive manufacturing is the production process in which a 3D CAD model is combined into layers, and the material is turned into a physical part. Additive manufacturing is an important technology that is very popular and expected to take a more important place in our future lives. Additive manufacturing is a revolutionary method in automotive, aviation, aerospace, health construction, and energy. Therefore, understanding additive manufacturing technology is a very strategic issue for today. Corrosion is the phenomenon of metal or metal alloys being damaged by oxidation or other chemical effects. Corrosion is the most harmful type of damage in parts working in the industry today, corrosion studies of metal parts (such as aluminum, maraging steel, stainless steel, and titanium) are essential. Therefore, if additive manufacturing technologies want to find widespread application, corrosion behavior should be considered. Additive manufacturing parts have a unique microstructure. This microstructure affects the corrosion behavior of the parts. Hence, corrosion behavior of metallic parts produced by additive manufacturing becomes a more important field. This section will explain the corrosion behavior and protection methods of important metal alloys produced by additive manufacturing

Heat Treatment of Additive Manufactured Metals

Additive manufacturing systems, which have strict control processes before and after manufacturing, are used in many industries. The quality of the machine’s equipment and raw materials used directly affect the production parts characteristics and quality. Additive manufacturing parts, which give properties close to traditional production methods, require secondary processing mostly. Due to the nature of the process, AM parts have weaknesses. Although postproduction processes help correct some of these defects, it should be remembered that irreversible damage will occur by malicious applications. The most widely used and most reliable process after the production is heat treatment. In this section, the most commonly used additive manufacturing processes and heat treatments (as a postprocess) for metals (titanium, aluminum, steel, etc.) and the effects (microstructure, mechanical properties, corrosive properties, thermal properties) of the heat treatment processes on the material will be discussed. The most used heat treatments in additive manufactured metal product, stress-relieving annealing, solution annealing, ageing, over-ageing, etc., processes are examined in detail. Different heat treatment applications (atmospheric control, impurity level, pressure, etc.) may be required depending on the type of material used, production conditions and place of use (there are many rules in aviation and medical services). In some cases, second/third heat treatment applications may be required

Investigation of the Effect of Heat Treatment Conditions on Hardness Properties of Maraging Steels Produced by Additive Manufacturing

Additive Manufacturing (AM) technology produces parts in layers and offers design freedom (3D design), zero waste, reduced expensive tool material requirements, and improved mechanical properties. Maraging steels have superior strength and toughness with adequate ductility. The effect of aging process parameters on the final properties of AM Maraging steels is enormous. In this study, the effects of heat treatment atmospheres and temperatures to the direct metal laser sintered (DMLS) maraging steels were examined. Aging heat treatment was applied in different atmospheres(Ar/H2 and air) and temperatures(4900C,5200C,5500C,5800C). SEM and XRD devices were used to examine the microstructure properties, and Vickers hardness device was used to determine the mechanical properties. When the results are evaluated, it was observed that the increased temperature after 490 0C adversely affected the hardness value. XRD analysis showed martensite and austenite phases in air and Ar/H2 atmospheres. According to the SEM images, it can be said that the traces of the melt pool remaining from the AM disappear with the increasing temperature in general

Post-Processing in Additive Manufacturing Requirements, Theories, and Methods

3D printing has always been seen as a promising technology for creating small, lowquality prototypes. As it is getting faster and more dependable, its applications are becoming more diversified. 3D printing involves adding components layer by layer using only raw material and energy source, which is more economical and efficient with materials than cutting a shape from a larger block or pouring molten material into a mold [1–3]. In recent years, the commercial market for 3D printers has rapidly expanded thanks to an unprecedented development in materials and printing techniques, making it more diversified and highly competitive [3, 4]. With 3D printing’s quick and simple design process, it is now possible to customize a wide variety of materials for different applications, making the development of unique products a reality that was previously only a pipe dream with milling or casting. The schematic representation of an LPBF operation is given in Figure 4.1

Investigation of the Effects of Different Retrogression and Re-Aging Parameters Applied to the 7075 Alloy on the Micro-Arc Oxidation Process

In this paper, retrogression and re-aging (RRA) heat treatment was applied to 7075 aluminum alloy in T6 condition at di®erent times (30 and 90 min) and temperatures (180 C and 240 C). While RRA heat treatments increase the corrosion resistance of the material, it does not harm its mechanical properties. On the other hand, the surface resistance of aluminum is low. Surface modi¯cations are applied to overcome this de¯ciency. Among these, the micro-arc oxidation (MAO) method increases the corrosion resistance and attains excellent values in surface hardness. To better understand the RRA/MAOrelationship, heat-treated (RRA) samples with four di®erent parameters were coated with the MAO method. In this way, a ceramic oxide coating layer was created on the material surfaces. In order to determine the RRA parameter e®ect, the MAO process parameters are kept constant (anode voltage (Va): 500V, cathode voltage (Vk): 300 V, anode voltage open time (ta Þ: 300 s, cathode voltage open time (tk): 200 s, frequency: 160 coating with Hz, and process time: 20 min). Surface properties (coating thickness, surface roughness, surface arc duct's structure, etc.), phase analysis (X-ray diffraction (XRD)) and microstructures (coating cross-section studies: distance-dependent hardness, coating/backing material interface character, coating porosity ratio) were examined. XRD analysis showed that the main phase of the coatings is -Al2O3. A coating layer of around 125 m was achieved with the growth rate of 6 m/min. Surface roughness was between 5.5 m and 8 m for di®erent RRA parameters. RRA/MAO relation with the characterization made was detailed, and predictions were made for the surface properties of the material (hardness, corrosion resistance, wear, etc.)

Characterization of O/W model system meat emulsions using shear creep and creep recovery tests based on mechanical simulation models and their correlation with texture profile analysis (TPA) parameters

The effects of different oil and temperature levels on the viscoelastic behavior of O/W model system meat emulsions were assessed using creep and creep recovery tests. The viscoelastic behavior of such emulsions was characterized using the Burgers model parameters. In addition, texture profile analysis (TPA) of cooked meat emulsions was carried out to find a possible relationship between the creep and creep recovery data and TPA parameters. The final percentage recovery of the emulsions remarkably increased with oil content, but decreased with temperature level. Significant correlations among the creep-recovery data and TPA parameters were observed, this enabling meat processor to predict TPA parameters by resorting to shorter and less material consuming creep and creep recovery tests. (C) 2011 Elsevier Ltd. All rights reserved.The effects of different oil and temperature levels on the viscoelastic behavior of O/W model system meat emulsions were assessed using creep and creep recovery tests. The viscoelastic behavior of such emulsions was characterized using the Burgers model parameters. In addition, texture profile analysis (TPA) of cooked meat emulsions was carried out to find a possible relationship between the creep and creep recovery data and TPA parameters. The final percentage recovery of the emulsions remarkably increased with oil content, but decreased with temperature level. Significant correlations among the creep-recovery data and TPA parameters were observed, this enabling meat processor to predict TPA parameters by resorting to shorter and less material consuming creep and creep recovery tests. (C) 2011 Elsevier Ltd. All rights reserved