Influence of homogenizing annealing on reducing the content of δ-ferrite in high-strength high-chromium martensitic steel grade 07Kh15N5D4B obtained by selective laser alloying

The work studies effects of temperature – time parameters of homogenizing annealing and related structural changes on the content of δ-ferrite in high-chromium martensitic steel grade 07Kh15N5D4B, obtained by selective laser alloying. It is shown that homogenizing annealing at a temperature of 1150°C with a holding time for 8 hours reduces the content of δ-ferrite, eliminates the cellular structure, and also increases the strength properties of the above-mentioned steel.

Control of the chemical composition of heat-resistant nickel alloys upon manufacturing products from these alloys using additive technologies

Heat-resistant alloys (superalloys) widely used for manufacturing parts of various components of aircraft engines are complex nickel-based systems which contain apart from alloying (Al, Cr, Co, Ti, Mo, W, etc.) and microalloying additives (B, Mg, REM, etc.) different amounts of the impurities (Mn, Fe, Si, Pb, As, Sn), including gas-forming (O, N, C, S) ones. The use of additive technologies (AT) in manufacturing of complex-shaped parts made of these alloys makes it possible to increase the material utilization coefficient and shorten the technological process. However, the use of AT requires real-time control of the composition of semi-products and finished products at all stages of production. Study of various stages of manufacturing parts from ZhS6K and VZh159 alloys using an AT of selective laser alloying (SLA) is carried out using analytical control systems of the laboratory of the Testing Center (TC) of FSUE «VIAM». A complex of methods for atomic emission, mass spectrometric and X-ray fluorescence determination of different groups of elements was used for the analysis of charge materials, cast bar blanks, metal-powder compositions (MPC) and synthesized parts. The results of analysis of nickel N-1u and chromium Kh99N1 used upon and after smelting of cast billets, as well as analysis of MPC of these alloys carried out by different methods are presented (gas analyzers were used to determine the gas-forming impurities). Monitoring on the chemical composition of materials throughout the process of additive manufacturing ensure their compliance with the regulatory requirements and predict the properties of finished products. The work was carried out within the framework of complex scientific direction 2.1 «Fundamental research» («Strategic directions for the development of materials and technologies for their processing for the period up to 2030»).

Study of the structure and mechanical properties of samples obtained by the selective laser alloying technology from the Inconel 738 heat-resistant alloy powder

The technology of selective laser melting of heat-resistant alloys is of great interest in the aerospace industry, because it allows you to implement a more complex geometry of parts in comparison with traditional technologies. This paper presents the results of determining the rational technological parameters of scanning a metal powder of a heat-resistant alloy Inconel 738. By statistical processing of experimental data to determine the effect of technological parameters of scanning on the tensile strength of a material, rational technological parameters of scanning are established, namely, the laser radiation power is 325 W, the scanning step is 0,12 mm, scanning speed of 677 mm/s, which corresponds to a bulk energy density of 80 J/mm3. The results of tests of cylindrical samples manufactured at angles of 0°, 30°, 45°, 60° and 90° to the uniaxial tension building platform are presented. A study of the microstructure of the samples was executed.

INVESTIGATION OF HOT ISOSTATIC PRESSING AND HEAT TREATMENT EFFECT ON STRUCTURE AND MECHANICAL PROPERTIES OF 3D-PRINTED SAMPLES MADE FROM VT6-PS GRADE MATERIAL

Presents the results of the investigation of the influence of hot isostatic pressing and heat treatment on the structure and mechanical properties during tension of synthesized workpieces obtained by selective laser alloying from a metal-powder composition of VT6 alloy. The blanks were subjected to heat treatment at various temperatures in the state after synthesis, as well after HIP. The influence of different heat treatment modes was assessed by the results of tensile tests and structural researches.

Researching structire and properties of metal-powdered compositions made of corrosion-resistant steels obtained by gas atomization of alloy and intended for detail production by selective laser alloying

Investigations of the microstructure and technological properties (such as flow ability, bulk density, tapped density etc.) of novel Fe–Cr–Ni, Fe–Cr–Ni–Mo and Fe–Cr–Ni–Co–Mo stainless steel metal powders were carried on. These powders are intended for use in additive manufacturing processes. Morphology of the powders was researched and the dendritic parameter was estimated for powder particles with various sizes (diameters). Dependence of gas impurities contamination on particles size was determined. Complex of these investigations allows confirming high quality of metal powders for additive manufacturing processes. In particular, minimal value of flow ability was determined as 14 sec while standard requirements for additive technologies are within 20 sec.