Influence of Zinc Chloride Exposure on Microstructure and Mechanical Behavior of Age-Hardened AZ91 Magnesium Alloy.

The AZ91 magnesium alloy was subjected to a complex treatment involving age hardening (supersaturation and artificial aging) and simultaneous surface layer modification. The specimens were supersaturated in contact with a mixture containing varying concentrations of zinc chloride, followed by cooling either in air or water. After supersaturation, the specimens were subjected to artificial aging and then air-cooled.

A Review on Additive Manufacturing Methods for NiTi Shape Memory Alloy Production.

The NiTi alloy, known as Nitinol, represents one of the most investigated smart alloys, exhibiting a shape memory effect and superelasticity. These, among many other remarkable attributes, enable its utilization in various applications, encompassing the automotive industry, aviation, space exploration, and, notably, medicine. Conventionally, Nitinol is predominantly produced in the form of wire or thin sheets that allow producing many required components.

In-situ directed energy deposition of Al based low density steel for automotive applications.

This work deals with the fabrication of one low density steel by mixing AISI S2 tool steel and AlSi10Mg powders using powder-based directed energy deposition (P-DED) technique. Two approaches of mixing powders were compared-continuous mixing during the process (in-situ) and mixing the powder prior to the process (premixed). The P-DED sample was characterised by a variety of techniques such as optical microscopy, scanning electron microscopy, electron backscatter diffraction, X-ray diffraction, and hardness measurement.

Kinetics of Austenite Decomposition in 54SiCr6 Steel during Continuous Slow Cooling Conditions.

In this study, dilatometry and metallography were used to investigate the effect of silicon and copper alloying on the decomposition kinetics of 54SiCr6 steel during continuous slow cooling. It is different from the published literature for using the approach of the local activation energy of the austenite decomposition and the local Avrami exponent of the volume fraction of the transformed phase to study the kinetics of austenite-pearlitic transformation in cooled 54SiCr steel at slow cooling rates. The Johnson-Mehl-Avrami equation was used to determine the dependence of the local activation energy for austenite decomposition and the local Avrami exponent on the volume fraction of the transformed phase .

Effect of Heat Treatment on Creep Deformation and Fracture Properties for a Coarse-Grained Inconel 718 Manufactured by Directed Energy Deposition.

The creep properties of a laser-directed energy deposition (L-DED) technique manufactured Inconel 718 (IN718) was investigated at 650 °C/700 MPa. Microstructure and creep properties of L-DED IN718 samples were tailored by various post heat treatments involving homogenization heat treatment with temperature ranging from 1080 to 1180 °C + double aging and hot isostatic pressing (HIP). Microstructural changes and their influence on the creep behavior and fracture mechanism were observed and discussed.

Fatigue in an AZ31 Alloy Subjected to Rotary Swaging.

The magnesium AZ31 alloy was swaged with rotary pressure with the aim of redefining the microstructure and improving mechanical and fatigue properties. The rotary swaging process and subsequent ageing improved the yield stress in tension and compression. In the present study, the investigation was focused on fatigue behaviour.

Enhanced Spring Steel's Strength Using Strain Assisted Tempering.

Spring steels are typical materials where enhancement of mechanical properties can save considerable mass for transport vehicles, in this way the consumption of fuel or electric energy can be decreased. A drastic change in both the resulting microstructure and mechanical properties could be achieved due to the inclusion of strain into the tempering process after quenching. The strain assisted tempering (SAT) technology was applied, i.

The Use of Miniature Specimens to Determine Local Properties and Fracture Behavior of LPBF-Processed Inconel 718 in as-Deposited and Post-Treated States.

This paper summarizes the assessment of directional anisotropy in local mechanical properties for Laser Powder Bed Fusion (LPBF) IN-718 bulk samples via the use of miniature samples excised from the bulk for both as-deposited and post-treated states. The quasi-static tensile properties at room temperature are investigated at several different locations along the build direction and at different orientations for both considered states. A comparison between the excised miniature tensile specimens and standard-sized sample results have also been conducted and exhibit very good agreement.

Elevated Temperature Baseplate Effect on Microstructure, Mechanical Properties, and Thermal Stress Evaluation by Numerical Simulation for Austenite Stainless Steel 316L Fabricated by Directed Energy Deposition.

In the present study, the effect of material deposition at the elevated temperature baseplate on the microstructure and mechanical properties was investigated and correlated to the unique thermal history by using numerical simulation. Numerical results agreed well with the experimental results of microstructure and mechanical properties. Numerical results revealed a significant decrease in temperature gradient and a 40% decrease in thermal stress due to material deposition on the elevated temperature baseplate.

Extended Continuous Cooling Transformation (CCT) Diagrams Determination for Additive Manufacturing Deposited Steels.

Continuous cooling transformation (CCT) diagrams are widely used when heat treating steels and represent which type of phase will occur in a material as it is cooled at different cooling rates. CCT diagrams are constructed on the basis of dilatometry measurements on relatively small testing samples (cylindrical shape with diameter of 4mm and length of 11 mm in this study). The main aim of this work was to demonstrate the possibility of evaluating the tensile test properties using mini-tensile tests from miniature volumes (1.

Heat Source Modeling and Residual Stress Analysis for Metal Directed Energy Deposition Additive Manufacturing.

The advancement in additive manufacturing encourages the development of simplified tools for deep and swift research of the technology. Several approaches were developed to reduce the complexity of multi-track modeling for additive manufacturing. In the present work, a simple heat source model called concentrated heat source was evaluated for single- and multi-track deposition for directed energy deposition.

Additive Manufacturing of Honeycomb Lattice Structure-From Theoretical Models to Polymer and Metal Products.

The study aims to compare mechanical properties of polymer and metal honeycomb lattice structures between a computational model and an experiment. Specimens with regular honeycomb lattice structures made of Stratasys Vero PureWhite polymer were produced using PolyJet technology while identical specimens from stainless steel 316L and titanium alloy Ti6Al4V were produced by laser powder bed fusion. These structures were tested in tension at quasi-static rates of strain, and their effective Young's modulus was determined.

Prediction of Behaviour of Thin-Walled DED-Processed Structure: Experimental-Numerical Approach.

Additive manufacturing (AM) becomes a more and more standard process in different fields of industry. There is still only limited knowledge of the relationship between measured material data and the overall behaviour of directed energy deposition (DED)-processed complex structures. The understanding of the structural performance, including flow curves and local damage properties of additively manufactured parts by DED, becomes increasingly important.

Base Plate Preheating Effect on Microstructure of 316L Stainless Steel Single Track Deposition by Directed Energy Deposition.

The microstructural morphology in additive manufacturing (AM) has a significant influence on the building structure. High-energy concentric heat source scanning leads to rapid heating and cooling during material deposition. This results in a unique microstructure.

Damage tolerant design of additively manufactured metallic components subjected to cyclic loading: State of the art and challenges.

Undoubtedly, a better understanding and the further development of approaches for damage tolerant component design of AM parts are among the most significant challenges currently facing the use of these new technologies. This article presents a thorough overview of the workshop discussions. It aims to provide a review of the parameters affecting the damage tolerance of parts produced by additive manufacturing (shortly, AM parts) with special emphasis on the process parameters intrinsic to the AM technologies, the resulting defects and the residual stresses.

Copper-Induced Strengthening in 0.2 C Bainite Steel.

Bainitic steels were the focus of this study. These steels have the potential to obtain a good combination of strength, ductility, and edge stretchability, which is a very desirable characteristic in the automotive industry. Cu precipitation potential was investigated during prolonged isothermal bainitization treatment.

Strain Hardening in an AZ31 Alloy Submitted to Rotary Swaging.

An extruded magnesium AZ31 magnesium alloy was processed by rotary swaging (RSW) and then deformed by tension and compression at room temperature. The work-hardening behaviour of 1-5 times swaged samples was analysed using Kocks-Mecking plots. Accumulation of dislocations on dislocation obstacles and twin boundaries is the deciding factor for the strain hardening.

Post-Processing Treatment Impact on Mechanical Properties of SLM Deposited Ti-6Al-4 V Porous Structure for Biomedical Application.

Additive manufacturing technologies allow producing a regular three-dimensional mesh of interconnected struts that form an open-cell porous structure. Regular porous structures have been used in the orthopedic industry due to outstanding bone anchoring. The aim of the study was to determine how the postprocessing influences the mechanical properties of porous structures made of titanium alloy CL 41TI ELI.

Numerical Simulation Development and Computational Optimization for Directed Energy Deposition Additive Manufacturing Process.

The rapid growth of Additive Manufacturing (AM) in the past decade has demonstrated a significant potential in cost-effective production with a superior quality product. A numerical simulation is a steep way to learn and improve the product quality, life cycle, and production cost. To cope with the growing AM field, researchers are exploring different techniques, methods, models to simulate the AM process efficiently.

Structure and Properties of High‑Strength Ti Grade 4 Prepared by Severe Plastic Deformation and Subsequent Heat Treatment.

Severe plastic deformation represented by three passes in Conform SPD and subsequent rotary swaging was applied on Ti grade 4. This process caused extreme strengthening of material, accompanied by reduction of ductility. Mechanical properties of such material were then tuned by a suitable heat treatment.

Magnesium Reinforced with Inconel 718 Particles Prepared Ex Situ-Microstructure and Properties.

Magnesium samples reinforced with 0.7, 1.4, and 2.

Continuous Production of Pure Titanium with Ultrafine to Nanocrystalline Microstructure.

This work deals with the application of the Conform SPD (Severe Plastic Deformation) continuous extrusion process for ultrafine to nanostructured pure titanium production. The process has been derived from the Equal Channel Angular Pressing (ECAP) technique but, unlike ECAP, it offers continuous production of high-strength wire. This study describes the Conform SPD process combined with subsequent cold working (rotary swaging technique), its potential for commercial application, and the properties of high-strength wires of pure titanium.

The Effect of Hot Working on the Mechanical Properties of High Strength Biomedical Ti-Nb-Ta-Zr-O Alloy.

Beta titanium alloy Ti-35Nb-6Ta-7Zr-0.7O (wt%) was developed as a material intended for the manufacturing of a stem of a hip joint replacement. This alloy contains only biocompatible elements and possesses a very high yield strength already in the cast condition (900 MPa).

Strengthening from Cu Addition in 0.2C-(1-2)Mn Steels during Tempering.

The strengthening effects of Cu and Mn were studied in steels, which contained 0.2% C and were micro-alloyed with B and Ti. The experimental steels were austenitized and quenched in order to take Mn and Cu into solid solution.

Comprehensive Evaluation of the Properties of Ultrafine to Nanocrystalline Grade 2 Titanium Wires.

This paper describes the mechanical properties and microstructure of commercially pure titanium (Grade 2) processed with Conform severe plastic deformation (SPD) and rotary swaging techniques. This technology enables ultrafine-grained to nanocrystalline wires to be produced in a continuous process. A comprehensive description is given of those properties which should enable straightforward implementation of the material in medical applications.