E. V. Borisov

Microstructure and Mechanical Properties of Ti-6Al-4V Manufactured by SLM

The article presents results of a study of phase composition and microstructure of initial material and samples obtained by selective laser melting of titanium-based alloy, as well as samples after heat treatment. The effect of heat treatment on microstructure and mechanical properties of specimens was shown. It was studied mechanical behavior of manufactured specimens before and after heat treatment at room and elevated temperatures as well. The heat treatment allows obtaining sufficient mechanical properties of material at room and elevated temperatures such as increase in ductility of material. The fractography of samples showed that they feature ductile fracture with brittle elements.

Microstructure and Mechanical Properties of Inconel 718 Produced by SLM and Subsequent Heat Treatment

The article presents results of selective laser melting of Inconel 718 superalloy. It was studied phase microstructure of the material obtained by selective laser melting and also the material after heat treatment. The phase composition of the initial powder material, the specimens after selective laser melting before and after heat treatment was studied. The effect of heat treatment on microstructure and mechanical properties of the specimens was shown. It was studied the mechanical behavior of the manufactured specimens before and after heat treatment at room and elevated temperatures as well. The results of impact tests and fractography of the specimens are presented. Mechanical tests showed that the specimens after heat treatment have decent mechanical properties comparable to hot-rolled material. Fractography showed that the obtained material is characterized by ductile failure mode with local elements of brittle fracture.

Selective Laser Melting of the Inconel 718 Nickel Superalloy

The results of the research on selective laser melting process of the Inconel 718 superalloy powder under conditions of additive manufacturing of parts for special purposes are presented. The influence of process parameters on the quality of manufactured parts is shown. Process parameters which allow manufacturing parts with the density close to 100%, are determined. Also, the results of mechanical tests and investigation of microstructure are presented.

Anisotropy of mechanical properties of products manufactured using selective laser melting of powdered materials

Causes of the appearance of anisotropy of properties in products manufactured according to the technology of selective laser melting of metallic powder materials are investigated. The results of an evaluation of mechanical properties of the samples made of Ti–6Al–4V and VT6 titanium-based alloys and Inconel 718 refractory nickel alloy in various directions are presented. The dependence of their mechanical properties on the orientation of billets relative to the working platform of the installation is presented. An analysis of microslices of the Ti–6Al–4V alloy showed that the direction of the granular structure for a rectangular sample corresponds to the growth direction, while, when manufacturing thin elements of a net construction, other thermal processes flow due to their smaller cross section, which affects the crystallization conditions and microstructure being formed. Grain directions and shapes change depending on the slope angle of the element of the net structure.

Producing Hip Implants Of Titanium Alloys By Additive Manufacturing

Additive manufacturing (AM) technologies, in particular selective laser melting (SLM) allows the production of complex-shaped individual implants from titanium alloys with high biocompatibility, mechanical properties, and improved osseointegration by surface texturing. In this work, the possibility of producing a custom-made hip implant from Ti-6Al-4V powder according to the data acquired via computed tomography of the patient is shown. Different heat treatments were applied in order to achieve better combination of tensile strength and elongation by partial decomposition of the martensitic phase. The implant was installed to the patient, postoperative supervision has shown good results, and the patient is able to move with the installed implant. A successful case of applying AM for producing custom hip implant is demonstrated in the paper. Using AM allowed the production of a custom-made hip implant in a short time and decreases the operation time and lessens the risk of infection ingress.

A laser ultrasonic technique for studying the properties of products manufactured by additive technologies

Study of the possibility for using a laser ultrasonic technique in nondestructive testing of products that are manufactured by selective laser melting is presented. Procedures of producing samples and carrying out nondestructive testing by the laser ultrasonic technique are described. Mechanical properties of samples that were grown in vertical and horizontal directions have been measured, as well as the speed of ultrasound in these samples. It has been established that the laser-ultrasonic technique is a promising technology for the quality control of products that are obtained by selective laser melting.

Creep and Thermomechanical Fatigue of Functionally Graded Inconel 718 Produced by Additive Manufacturing

Inconel 718 is a nickel-based superalloy commonly used in aircraft engine and nuclear applications, where components experience severe mechanical stresses. Due to the typical high temperature applications, Thermo-Mechanical Fatigue (TMF) and creep tests are common benchmarks for such applications. Additive manufacturing offers a unique way of manufacturing Inconel 718 with high degree of design freedom. However, limited knowledge exists regarding the resulting high temperature properties. The objective of this work is to evaluate creep and TMF behaviour of Inconel 718, produced by selective laser melting (SLM). A novel microstructural design, allowing for grain size control was employed in this study. The obtained functionally graded Inconel 718, exhibiting core with coarse and outside shell with fine grained microstructure, allowed for the best trade-off between creep and fatigue performance. The post heat-treatment regimens and resulting microstructures are also evaluated and its influence on creep and TMF is discussed.