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The additive manufacturing (AM) 3D printing technique is the most feasible, advanced technology for metal parts that have attracted great attention in the manufacturing industry. AM of titanium alloys by selective laser melting (SLM) is one of the most recent research developments in this field because of its benefits and wide applicability in manufacturing sectors. SLM is an efficient, convenient AM technology that can quickly form complex structures. A well-known titanium alloy named Ti6Al4V, manufactured by SLM, has several practical applications in engineering technology, including cars, space shuttles, and aeronautics. This paper demonstrates the density, sectional morphology, microstructure, and mechanical properties before and after heat treatment of Ti6Al4V alloy sample due to laser power, exposure time, and line spacing. A selective laser melting technology was used to fabricate the Ti6Al4V samples. The results show that the sample defects decreased with the increase in laser power. Moreover, when the laser power was 400 W combined with an exposure time of 30 µs, the sample's tensile strength reached 1203 MPa, almost 300MPa greater than that of ordinary forged Ti6Al4V titanium alloy after annealing. The continuous variation in the line spacing within a certain limit (50-65 µm) could increase the relative density up to 99.59%, which is much better than previously reported results. The tensile fracture of the sample presents a brittle crack. [ABSTRACT FROM AUTHOR]

A dense Cu-10Sn alloy bulk specimen was obtained by optimizing the laser powder bed fusion (L-PBF) processing, and the relative density of the specimen reached 99.7%. The grain morphology was mainly the columnar dendrite and inter-dendritic phases generated along the solidification direction. Tensile testing and detailed microstructural characterization were carried out on specimens in the as-built and heat-treated condition. Under the quasi-static tensile condition, the yield strength (σ0.2), ultimate tensile strength (UTS), and the elongation of the as-built Cu-10Sn specimen were 392 MPa, 749 MPa and 29%, respectively. After the solution treatment at 800 °C for 4 h, and aging treatment at 400 °C for 2 hours, the microstructure of the specimen transformed from the columnar grain to equiaxed grain, the dislocation density decrease, and numerous annealing twins were observed in the heat-treated state. Therefore, the quasi-static tensile yield strength (σ0.2) of the specimen was reduced to 245 MPa. However, the UTS and the elongation were increased to 840 MPa and 56%, respectively, due to the interaction between annealing twins and equiaxed grain. [ABSTRACT FROM AUTHOR]

Nowadays, wire-arc spraying is an attractive technique to deposit coatings for oxidation and corrosion protection. In this study, a new FeCrSiB-cored wire was designed to produce protective coatings for the components used in high temperature environment by wire-arc spraying. The microstructure, phase composition, microhardness, and high temperature corrosion behavior of the new coating were investigated in comparison with a FeCr coating and a commercial NiCrTi coating. The results showed that the FeCrSiB coating was composed of dense lamella with much fewer oxide inclusions than the FeCr and NiCrTi coatings. The microhardness of the FeCrSiB coating was the highest of the three coatings. Thermogravimetric analysis was used to evaluate the high temperature corrosion behavior of the coatings in mixed salt NaSO-25% KSO environment at 650 °C under cyclic condition. It showed that the high temperature corrosion resistance of the FeCrSiB coating is significantly better than that of the FeCr coating and approaching to the commercial NiCrTi coating. [ABSTRACT FROM AUTHOR]

In the present article, the wrought magnesium alloy AZ31B sheets were soldered by means of high-frequency induction heating device using a novel binary Zn-based solder alloy in argon gas shield condition. The interfacial microstructure, phase constitution, and fracture morphology of the soldered joint were studied. The microhardness and shear strength of the soldered joint were tested. The experimental results exhibit that α-Mg solid solution and γ-MgZn phase were formed in soldering region. Moreover, the β-MgZn phase in the original Zn-based solder alloy disappeared completely after the soldering process due to the fierce alloying between the molten binary Zn-based solder alloy and the base metal AZ31B during soldering. Test results show that the shear strength of the soldered joint is 28 MPa. The fracture morphology of the soldered joint displays an intergranular fracture mode, and the crack originates from α-Mg + γ-MgZn eutectoid structure. The interaction between the molten Zn-based solder alloy and the base metal AZ31B leads the Zn-based solder alloy to be transformed into Mg-based soldering metal during soldering. [ABSTRACT FROM AUTHOR]

In this paper, a novel Al-Mg-Zn filler metal was designed to join magnesium alloy AZ31B plates by means of high-frequency induction brazing in argon gas shield condition. The microstructure and the mechanical properties of the brazed joint were investigated. The experimental results showed that the brazed joint contained large amount of α-Mg and β-Mg(Al, Zn) phases. The homogeneous Mg(Al, Zn) phase in the original filler metal was consumed due to the intensive alloying during the brazing process. The results indicate that the shear strength of the brazed joint is 35 MPa. The fracture morphology of the brazed joint exhibits intergranular fracture mode, and the fracture originates from the hard β-Mg(Al, Zn) phase. [ABSTRACT FROM AUTHOR]

In the present study, a cored wire of 304 L stainless steel as sheath material and NiB and WC-12Co as filler materials was designed and deposited to produce a new wear resistant coating containing amorphous phase by arc spraying. The microstructure of the coating was investigated. The porosity and hardness of the coating were determined. The wear performance of the coating was evaluated. The XRD and TEM analyses showed that there are high volume of amorphous phase and very fine crystalline grains in the coating. DTA measurements revealed that the crystallization of the amorphous phase occurred at 579.2°C. Because metallurgical processes for single droplets were non-homogenous during spraying, the lamellae in the coating have different hardness values, which lie between about 700 and 1250 HV100 g. The abrasive wear test showed that the new Fe-based coating was very wear resistant. [ABSTRACT FROM AUTHOR]

In this study, nickel-base cored wires were prepared by using NiCr strip to wrap metal powders of nickel (Ni), chromium (Cr), molybdenum (Mo), and chromium boron (CrB). Nickel-base coatings were prepared by electric arc spraying. Microstructures of Ni-Cr-Mo and Ni-Cr-B coatings were investigated using scanning electron microscopy (SEM), energy-dispersive analysis (EDAX), and x-ray diffraction (XRD) analysis. The coatings have a compact surface and presented a bonding strength higher than 40 MPa. Potentiodynamic polarization measurements and salt-spray test were carried out to determine the corrosion behavior of the coatings. The results showed that Ni-base coatings containing Mo (5%) or B (2-4%) had better antichlorine ion corrosion performance than that of Ni-base coatings without Mo element, and PS45 (Ni-Cr-Ti) coating. The antichlorine ion corrosion coatings could be used for resolving the corrosion protection problem of the equipment and piping contacting sour, alkali, salt liquid in petrochemical engineering applications. [ABSTRACT FROM AUTHOR]