Mechanical and Electrochemical Properties Comparison of Additively Manufactured Ti-6Al-4V Alloys by Electron Beam Melting and Selective Laser Melting

This work involves additively manufactured Ti-6Al-4V alloys, which are widely used in automobile, biomedical, and aircraft components for a comparison of the microstructure–properties relationship between electron beam melted (EBM) and selective laser melted (SLM) alloys after hot isostatic pressing treatment. We carried out microstructural, mechanical, and electrochemical measurements on both alloys. They showed comparable α and β phase contents with slightly higher lattice parameters in the EBM sample compared to the SLM. The EBM sample showed higher yield strength and uniform elongation due to the activation of multistage defects-driven strengthening and strain hardening mechanisms. Cracking during the tensile test nucleated mainly at the α phase near high-mechanical mismatch α/β interfaces. This mechanism was consistent with the reported generation of hetero-deformation-induced strengthening and strain hardening. Both alloys showed similar electrochemical behavior, but the SLM sample was more susceptible to corrosion than the EBM alloy

Ageing behaviour of spray cast Al-Zn-Mg-Cu alloys [Sprey Dökülmüş Al-Zn-Mg-Cu Alaşimlarinin Yasşlanma Davranişi]

Three 7xxx series aluminium SS70, N707 and 7075 alloys containing copper, zinc and magnesium were spray deposited using rapid solidification. Ageing of the 7075 alloy resulted in a peak hardnesses of 147, 186 and 191 MPa after 2, 24 and 48 h at temperatures of 175°C, 130°C and 120°C respectively. The other two alloys, SS70 and N707, were aged at 120°C, and both reached peak hardness after 24 h; SS70 had a peak hardness of 229 MPa and N707 of 228 MPa. A double ageing treatment at 105°C for 5 h then at 175°C for 1 h significantly increased the peak hardness to 185.6 MPa compared to a single stage of ageing at the higher temperatures in the 7075 alloy. TEM analysis of aged specimens revealed two types of precipitate that contributed to age hardening: ?1 and ? (MgZn2)

Calorimetric and transmission electron microscopy studies of spray deposited Al-Zn-Mg-Cualloys

WOS: 000223176000008Differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) have been used to examine the precipitation process in spray cast Al - Zn - Mg - Cu alloys. The study was carried out on an Al - 5-6Zn 2-5Mg-1.6Cu alloy and an Al-11-5Zn-2-64Mg-1-16Cu alloy (wt-%). The effect of zinc on the precipitation process in the alloys was investigated. It was found that additional zinc accelerated the kinetics of formation of the precipitates

Mechanical properties of spray cast 7xxx series aluminium alloys

Mechanical properties of spray deposited and extruded 7xxx series aluminum alloys were investigated in peak aged condition. To study the influence of Zn additions on the mechanical behaviour of spray deposited materials, three alloy compositions were selected, namely: SS70 (11.5% Zn), N707 (10.9% Zn) and 7075 (5.6% Zn). After ageing treatment, notched and unnotched specimens of spray deposited alloys were subjected to tensile tests at room temperature. Experimental results showed that the SS70 alloy exhibited the highest strength. Spray deposited Al alloys showed a very high strength as compared to conventionally processed 7xxx series Al alloys. Compared with the PM processed 7xxx series A1 alloys, fracture toughness values of these alloys were higher

Investigation of secondary phase particles in spray deposited 7000 series aluminium alloys

Three 7000 series aluminium alloys, namely SS70, N707, and 7075, were produced by rapid solidification using the spray deposition process, which yields massive preforms directly from the liquid state. Optical and electron microscopy, along with energy dispersive X-ray and microprobe analysis, revealed the presence of coarse constituent phases and dispersoid particles. Constituent phases of the N707 alloy were (Al,Cu)6(Fe,Cu), Al6Fe (modified), Mg(Zn,Cu,Al)2, and amorphous silicon oxide. The same phases were present in the SS70 alloy; however, this alloy also contained an additional zirconium rich phase. In the 7075 alloy, (Al,Cu)6(Fe,Cu), (Fe,Cr,Mn)3SiAl12, Al18Mg3Cr2, an Mg-Si rich compound, and amorphous silicon oxide were observed. The dispersoid phase present in the SS70 and N707 alloys was identified as Al3Zr

Microstructure and mechanical properties of spray deposited and extruded 7000 series aluminium alloys

The microstructure and mechanical properties of spray deposited 7000 series aluminium alloys were investigated. The 7000 type alloys were produced by the spray atomisation deposition method. These alloys were hot extruded and subsequently heat treated in the T6 and T7 temper conditions. Microstructural characterisation of the alloys was carried out by transmission electron microscopy (TEM). TEM studies revealed the presence of ?' and ?(MgZn2) hardening precipitates in both temper conditions. The mechanical properties were assessed through tensile and notched tensile tests using an Instron machine. It was observed that the 0.2% proof stress of these alloys after T7 temper decreased with increased elongation to fracture values. © 2003 IoM Communications Ltd. Published by Maney for the Institute of Materials, Minerals and Mining

Influence of microstructure on tensile properties of dual phase steel [Çi•ft fazli çeli•gi•n çekme özelli•kleri•ne mi•kroyapinin etki•si•]

The influence of volume fraction of martensite and new ferrite on the tensile behaviour of dual-phase steel containing 0,0981% C, 1,653% Mn, 0,54% Si and 0,69% Ni has been studied. After intercritical annealing at 715, 725 and 752 °C, the specimens were cooled in water, oil and furnace. The formation of carbide was not observed in the optical microscope investigation even at furnace cooling rate. The results showed that after annealing at the same intercritical temperature, the highest volume fraction of martensite was obtained by water cooling among all cooling conditions. By increasing the martensite content, both yield and tensile strengths increased while uniform elongation was decreasing. It was observed that at constant volume fraction of martensite, new ferrite content was varied by using controlled cooling from intercritical annealing temperatures. The presence of new ferrite caused a decrease in strength and increase in ductility. Scanning electron microscope investigations of fracture surface showed that the specimens with new ferrite had higher densities of microvoids in the necked region and exhibited completely ductile type of fracture. In contary, it was also observed that the specimens with no new ferrite had lower densities of microvoids and exhibited mixed type of fracture which comprises both cleavage and ductile fracture together

The effect of microstructure on tensile strength of high martensite dual-phase steels

In this work, different dual phase (DP) microstructures were produced in 15CrNiMo7 steel, in order to study the effect of martensite volume fraction (MVF), martensite morphology (MM), and epitaxial ferrite (EF) on tensile strength behavior. Mechanical properties of five different DP steels have been investigated by carrying out tensile and hardness tests. By increasing the martensite content, both tensile and yield strengths increased. The presence of new ferrite caused a decrease in strength and increase in ductility. Fractography analysis after the tensile test was performed by using SEM