scholarly journals Microstructural Characterization and Mechanical Properties of Fiber Laser Welded CP-Ti and Ti-6Al-4V Similar and Dissimilar Joints

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 747 ◽  
Author(s):  
Alireza Abdollahi ◽  
Ahmed Shaheer Ahnaf Huda ◽  
Abu Syed Kabir
Keyword(s):  
Mechanical Properties ◽  
Fiber Laser ◽  
Welding Speed ◽  
Heat Input ◽  
Laser Power ◽  
Pure Titanium ◽  
Microstructural Characterization ◽  
Welding Parameters ◽  
Dissimilar Joints ◽  
Cp Ti

In this research, the microstructures and mechanical properties of similar and dissimilar autogenous joints of 3 mm thick commercially pure titanium (CP-Ti) and Ti-6Al-4V welded by ytterbium fiber laser (Yb:YAG) were investigated. Two sets of laser power and welding speed were selected in such a way that the heat input remained constant. Microstructural characterization of the joints was investigated by an optical microscope, and mechanical properties were determined by hardness and tensile tests. The only defects found were porosity and underfill, and no signs of lack of penetration and solidification cracks were observed in any of the joints. Microstructural evaluation of the fusion zone (FZ) showed that in similar Ti-6Al-4V joint, a supersaturated nonequilibrium α′ martensite was formed due to rapid cooling associated with laser welding. In similar CP-Ti, coarse equiaxed grains were observed in the FZ. Unlike the similar joints, a clear interface was observed between the heat-affected zone (HAZ) and the FZ in both the CP-Ti and Ti-6Al-4V sides in dissimilar joints. Among all the joints with different weld parameters, similar Ti-6Al-4V showed the highest strength and the lowest ductility. In similar CP-Ti and dissimilar joints, fractures took place in the CP-Ti base metal, but all the Ti-6Al-4V similar joints failed in the FZ. Significant changes in the strength and hardness with varying laser power and welding speed implied that the mechanical properties of the weld fusion zones were not entirely governed by the heat input but were also affected by individual welding parameters.

Microstructure and Mechanical Properties of Laser Welded Lap Joints of Ti-6Al-4V Alloy

2011 ◽  
Vol 311-313 ◽  
pp. 2375-2378 ◽  
Author(s):  
Yong Zhao ◽  
Jian Huang ◽  
Ying Zhao ◽  
Yi Xiong Wu
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Weld Joint ◽  
Welding Speed ◽  
Heat Input ◽  
Laser Power ◽  
Weld Zone ◽  
Lap Joints ◽  
Lap Joint ◽  
The Difference

Microstructures and mechanical properties of welded Ti-6Al-4V alloy lap joints are discussed under different parameter conditions of laser welding. The results reveal that the fusion zone consists mainly of acicular α＇martensite. The shear strength of the lap joint reaches a maximum of 836MPa at a laser power of 4kW and welding speed of 2.3m/min. When the laser power is 4kW and the welding speed is 2.1m/min, microstructures of weld joint become coarse and the shear strength falls to 736MPa. The microhardness value in the weld zone is the highest and it gradually reduces from the weld center to base metal due to the difference of microstructure. When the weld heat input is constant, larger laser power has resulted in growth of the grain and the decrease of shear strength and microhardness of lap joints.

scholarly journals Microstructural Characterization and Mechanical Properties of Laser Beam-Welded Dissimilar Joints between A6000 Aluminum Alloy and Galvanized Steel

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 543
Author(s):  
Nkopane Angelina Ramaphoko ◽  
Samuel Skhosane ◽  
Nthabiseng Maledi
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Laser Beam ◽  
Laser Welding ◽  
Heat Input ◽  
Welding Process ◽  
Galvanized Steel ◽  
Vehicle Body ◽  
Welding Parameters ◽  
Dissimilar Joints

This paper presents the laser beam welding process of a lap joint between galvanized steel (Z225) and an aluminum alloy (A6000) from an IPG fiber laser. Welding of steel to aluminum has become popular in the automotive industry as a means of reducing the total vehicle body mass. This approach reduces fuel consumption and, ultimately, carbon emissions. Laser welding parameters used to control heat input for the study were laser power ranging between 800 and 1200 W, as well as laser welding speeds between 2 and 4 m/min. Distinct features of the dissimilar joints were microscopically examined. The SEM-EDS technique was employed to study the intermetallic phases along the Fe-Al interface. The outcome revealed the presence of “needle-like phases” and “island-shaped phases” at high heat inputs. Traces of both Fe2Al5 and FeAl3 phases were detected. For low heat input, there was evidence of insufficient fusion. Weld width was influenced by welding parameters and increased with an increase in heat input. Mechanical properties of the joints indicated that the microhardness values of the weld joints were higher than those of both base metals. The maximum tensile shear strength obtained was 1.79 kN for a sample produced at 1200 W and 3 m/min.

scholarly journals Microstructure and mechanical properties of GTAW welded joints of AA6105 aluminum alloy

2016 ◽  
Vol 25 (43) ◽  
pp. 7-19 ◽  
Author(s):  
Minerva Dorta-Almenara ◽  
María Cristina Capace
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Fusion Zone ◽  
Heat Affected Zone ◽  
Welding Speed ◽  
Heat Input ◽  
Cold Work ◽  
Dendritic Morphology ◽  
Welding Parameters ◽  
Microstructure And Mechanical Properties

Gas Tungsten Arc Welding (GTAW) is one of the most used methods to weld aluminum. This work investigates the influence of welding parameters on the microstructure and mechanical properties of GTAW welded AA6105 aluminum alloy joints. AA6105 alloy plates with different percent values of cold work were joined by GTAW, using various combinations of welding current and speed. The fusion zone, in which the effects of cold work have disappeared, and the heat affected zone of the welded samples were examined under optical and scanning electron microscopes, additionally, mechanical tests and measures of Vickers microhardness were performed. Results showed dendritic morphology with solute micro- and macrosegregation in the fusion zone, which is favored by the constitutional supercooling when heat input increases. When heat input increased and welding speed increased or remained constant, greater segregation was obtained, whereas welding speed decrease produced a coarser microstructure. In the heat affected zone recrystallization, dissolution, and coarsening of precipitates occurred, which led to variations in hardness and strength.

scholarly journals Influence of the Heat Input on the Dendritic Solidification Structure and the Mechanical Properties of 2.25Cr-1Mo-0.25V Submerged-Arc Weld Metal

2021 ◽  
Author(s):  
Hannah Schönmaier ◽  
Ronny Krein ◽  
Martin Schmitz-Niederau ◽  
Ronald Schnitzer
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Heat Input ◽  
Stress Rupture ◽  
Pressure Vessels ◽  
Rupture Time ◽  
Solidification Structure ◽  
Welding Parameters ◽  
Austenite Grain Size ◽  
Submerged Arc

AbstractThe alloy 2.25Cr-1Mo-0.25V is commonly used for heavy wall pressure vessels in the petrochemical industry, such as hydrogen reactors. As these reactors are operated at elevated temperatures and high pressures, the 2.25Cr-1Mo-0.25V welding consumables require a beneficial combination of strength and toughness as well as enhanced creep properties. The mechanical properties are known to be influenced by several welding parameters. This study deals with the influence of the heat input during submerged-arc welding (SAW) on the solidification structure and mechanical properties of 2.25Cr-1Mo-0.25V multilayer metal. The heat input was found to increase the primary and secondary dendrite spacing as well as the bainitic and prior austenite grain size of the weld metal. Furthermore, it was determined that a higher heat input during SAW causes an increase in the stress rupture time and a decrease in Charpy impact energy. This is assumed to be linked to a lower number of weld layers, and therefore, a decreased amount of fine grained reheated zone if the multilayer weld metal is fabricated with higher heat input. In contrast to the stress rupture time and the toughness, the weld metal’s strength, ductility and macro-hardness remain nearly unaffected by changes of the heat input.

Numerical Analysis of Solidification Behavior during Laser Welding Nickel-Based Single-Crystal Superalloy Part: II Crystallography-Dependent Supersaturation of Liquid Aluminum

2021 ◽  
Vol 1018 ◽  
pp. 13-22
Author(s):  
Zhi Guo Gao
Keyword(s):  
Laser Welding ◽  
Single Crystal ◽  
Weld Pool ◽  
Welding Speed ◽  
Heat Input ◽  
Laser Power ◽  
Liquid Aluminum ◽  
Dendrite Growth ◽  
Solidification Cracking ◽  
Solid Liquid Interface

The thermal metallurgical modeling of liquid aluminum supersaturation was further developed through couple of heat transfer model, dendrite selection model, multicomponent dendrite growth model and nonequilibrium solidification model during three-dimensional nickel-based single-crystal superalloy weld pool solidification. The welding configuration plays more important role in supersaturation of liquid aluminum, morphology instability and nonequilibrium partition behavior. The bimodal distribution of liquid aluminum supersaturation along the solid/liquid interface is crystallographically symmetrical about the weld pool centerline in (001) and [100] welding configuration. The distribution of liquid aluminum supersaturation along the solid/liquid interface is crystallographically asymmetrical throughout the weld pool in (001) and [110] welding configuration. Optimum low heat input (low laser power and high welding speed) with (001) and [100] welding configuration is more favored to predominantly promote epitaxial [001] dendrite growth to reduce the metallurgical factors for solidification cracking than that of high heat input (high laser power and slow welding speed) with (001) and [110] welding configuration. The lower the heat input is used, the lower supersaturation of liquid aluminum is imposed, and the smaller size of vulnerable [100] dendrite growth region is incurred to ameliorate solidification cracking susceptibility and vice versa. The overall supersaturation of liquid aluminum in (001) and [100] welding configuration is beneficially smaller than that of (001) and [110] welding configuration regardless of heat input, and is not thermodynamically relieved by gamma prime γˊ phase. (001) and [110] welding configuration is detrimental to weldability and deteriorates the solidification cracking susceptibility because of unfavorable crystallographic orientations and alloying aluminum enrichment. The mechanism of asymmetrical solidification cracking because of crystallography-dependent supersaturation of liquid aluminum is proposed. The eligible solidification cracking location is particularly confined in [100] dendrite growth region. Moreover, the theoretical predictions agree well with the experiment results. The useful modeling is also applicable to other single-crystal superalloys with similar metallurgical properties for laser welding or laser cladding. The thorough numerical analyses facilitate the understanding of weld pool solidification behavior, microstructure development and solidification cracking phenomena in the primary γ phase, and thereby optimize the welding conditions (laser power, welding speed and welding configuration) for successful crack-free laser welding.

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