In this investigation steel P355NH was successfully clad with Inconel 625 through the method of explosive welding. Explosively welded bimetal was subjected to the two separated heat treatment ...processes: stress relief annealing (at 620oC for 90 minutes) and normalizing (at 910oC for 30 minutes). In order to identify the microstructure of the joint and to investigate the influence of the heat treatment on it, the light and scanning electron microscope observations and microhardness analysis have been performed. In order to investigate the diffusion zone microstructure the scanning transmission electron microscope observation have been performed. It was stated that obtained joint has characteristic wavy-shape geometry with the presence of the melted zones and severe deformed grains of both joined materials. Strengthening of materials in joint zone was established with microhardness analysis. In both of the heat treatments the changes in the grain structure have been observed. The normalizing heat treatment has the most significant impact on the microstructure of the joint as well as the concentration of the chemical elements in the joint zone. It was reported that due to normalizing the diffusion zone has been formed together with precipitates in the joint zone.
In this research the three different FSW joints of Titanium Grade 1 have been performed by using tool made of W25Re alloy with different welding velocity values. In order to investigate the influence ...of FSW process on microstructure of joined material the light microscope observations have been performed on the etched samples. It has been reported that significant grain refinement occurs in the stir zone in all analyzed samples. On the other hand, occurrence of weld defects, such as tunneling defect and kissing bond has been noticed. The microhardness analysis of the cross-section of the obtained joints indicates on microhardness increasing in the stir zone by 40-60 HV0,1 compared to the base material. Peak hardness of stir zone in the researched samples has tendency to decrease along with increasing of welding velocity. The strength of obtained joints was designated in the uniaxial tensile tests and confronted with strength of base material. Despite the occurrence of weld defects the established joints efficiency contains in range 92-94%. It has been stated that Young’s modulus of Titanium Grade 1 FSW joints is 15-19% lower in comparison to the base material. At the same time, no significant influence of FSW on the ductility of material were observed.
In this investigation the friction stir welded joint of 5 mm thick AA7075-T651 alloy have been subjected to the post-weld explosive treatment. To assess the influence of the proposed treatment on the ...joint properties, a comprehensive analysis was conducted, including microstructural examination, microhardness testing, static tensile tests, low-cycle fatigue testing, and fracture surface observations. The strain amplitudes of 0.35 %, 0.4 %, 0.5 %, and 0.6 % with asymmetry coefficient R = 0.1, were used for the examined samples. It was concluded that the explosively treated FSW joints are characterized by a lower amplitude of plastic deformation, a reduced number of cycles to failure and show a tendency for cyclic softening. The differences in the fatigue crack propagation primarily concern the initiation area of the crack near the hardened surface. Explosive treatment did not influence the location of material decohesion, which occurs in the low-hardness zone.
Industries that rely on additive manufacturing of metallic parts, especially biomedical companies, require material science-based knowledge of how process parameters and methods affect the properties ...of manufactured elements, but such phenomena are incompletely understood. In this study, we investigated the influence of selective laser melting (SLM) process parameters and additional heat treatment on mechanical properties. The research included structural analysis of residual stress, microstructure, and scleronomic hardness in low-depth measurements. Tensile tests with specimen deformation analysis using digital image correlation (DIC) were performed as well. Experiment results showed it was possible to observe the porosity growth mechanism and its influence on the material strength. Specimens manufactured with 20% lower energy density had almost half the elongation, which was directly connected with the porosity growth during energy density reduction. Hot isostatic pressing (HIP) treatment allowed for a significant reduction of porosity and helped achieve properties similar to specimens manufactured using different levels of energy density.
In this paper, the microstructure of laser beam welded Sc-modified AA2519-F has been taken under investigation. The welded joint has been produced using Fanuc 710i industrial robot equipped with ...YLS-6000 6 kW laser beam source. The welding speed and laser power were equal to 0.75 m/min and 3.2 kW, respectively. The investigation involved microstructure observations with the use of both light microscope and scanning electron microscope with energy dispersive spectroscopy (EDS) analysis of chemical composition and microhardness distribution measurements. It has been stated that laser beam welding allows to obtain Sc-modified AA2519-F weld of good quality, characterized by the presence of an equiaxed grain zone containing scandium-rich precipitates adjacent to the fusion boundary.
The aim of the work was to produce laminated structures consisting of Ti–6Al–4V alloy and AA2519 plates and to investigate their microstructure and mechanical properties with an emphasis on the role ...of an additional AA1050 interlayer. Explosive welding was selected as a joining technology. The microstructure and chemical composition of the explosively joined samples were investigated. Mechanical properties were evaluated in the tensile testing and by microhardness analysis.
The results demonstrated that explosive welding is an effective way to produce Ti/Al laminates. Both Ti6Al4V/AA2519 and Ti6Al4V/AA1050/AA2519 laminated plates exhibit good quality of bonding without voids and major delamination. The explosive welding produced metallurgical bonding with a nanostructured zone consisting of Al3Ti and Al2Ti phases. This zone is thicker in the joint with additional AA1050 interlayer when compared to direct AA2519/Ti6Al4V bonding. In the latter, SEM and STEM analysis reviled the presence of net-like structure in the collision zone. Advanced EDX analysis shows the enrichment of grain boundaries in copper. The formation of this structure is widely discussed. In addition, the explosive welding introduces large plastic deformation which induces the process of grain refinement in aluminium plates. Tensile testing confirms that joining section is not the weakest element of the cladded plates.
Display omitted
•The microstructure and strength of interface joints strongly depends on the presence of additional AA1050 plate•Good quality of joints was confirmed in tensile testing, as the joints have never been the weakest element of the laminates•Ti6Al4V/AA2519 and Ti6Al4V/AA1050/AA2519 laminate plates were successfully obtained through explosive welding;•EXW introduces into both aluminium plates a highly localized plastic deformation, which causes significant grain refinement
This paper presents new experimental data concerning the effect of the complex combined loading mode on changes in the mechanical properties of titanium alloys of different classes subjected to ...static stretching. The complex combined loading mode consists in the application of additional pulse loads for given degrees of static pre-loading followed by quenching of titanium alloys at a temperature of liquid nitrogen under a pre-set scheme. The authors used a new method for studying the material fracture kinetics, the so-called method of complete stress-strain diagrams, to explore a full range of mechanical properties of titanium alloys subjected to the combined loading mode, including the crack resistance.
•Mechanical properties of the of high-strength titanium alloys after DNP were studied.•A method that allows for a significant increase in the plasticity of a material is proposed, with a minimum loss of its strength.
This paper presents the results of experimental studies of propagation of the semi-elliptical cracks in 1.4541 austenitic steel commonly used for the construction of the industrial pipelines. The ...work includes the results of studies of the structure and mechanical properties of 1.4541 steel used to build new pipeline sections and steel after many years of service. Fatigue crack growth analysis was performed by using the method of electrical potential drop (EPD). In order to confirm correctness of the electrical potential drop measurement method a two other experimental methods were used in comparative studies, staining of fatigue fracture and using a strain propagation gauge. Elaborated EPD measurement methodology enables a continuous recording of the dimensions of propagating semi-elliptical cracks, both under variable tension and under constant bending, which was confirmed during the tests.
•Comparative fatigue studies of 1.4541 steel in three states were conducted.•We determined influence of operation environment on structure and mechanical properties.•Fatigue tests were conducted under load conditions of real chemical pipeline.•There was proposed modified measurement method of two-dimensional fatigue cracks.
PDF
