Origin of grain orientation during solidification of an aluminum alloy

Low-carbon steel and aluminum Alloy 5052 sheets were diffusion welded using different conditions of time, temperature, and pressure in order to understand the kinetics of diffusion and the microstructure of the interface layer. High pressures accelerated intermetallic compound formation at the interface. The interface layer consisted of aluminum-rich brittle intermetallic compounds (FeAl 3 and Fe 2 Al 5 ), which made the joints brittle. In laser roll welding, steel and aluminum sheets in a lap-joint configuration are subjected to laser heating and immediate rolling for intimate contact. Laser heating provides high temperature in a short time for melting of the aluminum alloy and diffusion. It results in formation of a thin interface layer. When the temperature is above 1473 K (1200°C), formation of iron-rich (Fe-rich) intermetallic compounds (FeAl and Fe 3 Al) is encouraged. Travel speed and roll pressure were varied and resultant joints were characterized by optical microscopy, electron-probe microanalysis (EPMA), scanning electron microscopy (SEM), X-ray diffraction, and tensile shear testing. The laser roll welded interface layer contains brittle aluminum-rich (Al-rich) intermetallic compounds on the aluminum side and slightly ductile Fe-rich intermetallic compounds on the steel side. As the travel speed increases, thinner interface layers are formed and the percentage of Fe-rich intermetallic compounds in them increases. This increases the shear strength of the joints from 11.0 to 55.9 MPa. Interface layers with a thickness of 4 to 5 μm, containing 25 to 40% Fe-rich intermetallic compounds, gave maximum shear strength.

Joining of aluminum alloy 5052 and low-carbon steel by laser roll welding

Three-dimensional modeling of grain structure evolution during welding of an aluminum alloy

New generation of selective Laser Melting (SLM) machines are evolving towards higher power lasers as well as multi laser systems in order to increase the productivity. The increase in laser power and the modification of the laser power distribution leads to microstructural and mechanical property variations that are still not well understood. This work aims at better understanding the interaction of a 1 kW top-hat power distribution laser on a well know material, 316 L stainless steel. The influence of texture and microstructure on relative density and crack density, when varying scan rotation, was evaluated. The high power (HP) laser and low power (LP) laser were compared with respect to microstructure and mechanical properties. HP leads to an increase in morphological and crystallographic texture together with a coarsening of the cell structure in contrast to the more random and finer cells found in LP processed material. Hot isostatic pressing was applied as a post-process treatment in order to close remaining pores and cracks. This helped in achieving higher elongations for LP and HP processed materials, while competitive mechanical properties to the 316 L material specifications were obtained in both cases.

Microstructure evolution of 316L produced by HP-SLM (high power selective laser melting)

In this work, successful friction stir welding of aluminum alloy 2219 using an adapted milling machine is reported. The downward or forging force was found to be dependent upon shoulder diameter and rotational speed whereas longitudinal or welding force on welding speed and pin diameter. Tensile strength of welds was significantly affected by welding speed and shoulder diameter whereas welding speed strongly affected percentage elongation. Metallographic studies revealed fine equiaxed grains in weld nugget and microstructural changes in thermo-mechanically affected zone were found to be the result of combined and interactive influences of frictional heat and deformation. A maximum joining efficiency of 75% was obtained for welds with reasonably good percentage elongation. TEM studies indicated coarsening and/or dissolving of precipitates in nugget. For the gas metal arc weld, SEM investigations revealed segregation of copper at grain boundaries in partially melted zone.

Effect of process parameters on friction stir welding of aluminum alloy 2219-T87

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Effect of Weld Solidification Mode on Tensile Properties of Aluminum Weld Metal

(1990). Quantitative investigation of heat affected zone cracking of aluminium alloy 6061. Welding International: Vol. 4, No. 8, pp. 600-609.

Quantitative investigation of heat affected zone cracking of aluminium alloy 6061

Summary This paper describes production of aluminium clad steel by vacuum roll bonding. The clad steel was heated at 560–650 °C × 0–20 sec to study the formation of intermetallic phases and the shear strength in the bond interface subjected to welding thermal cycles. The results obtained may be summarised as follows: Even under rapid heating at a temperature just under the melting point of aluminium, no intermetallic phases are formed in the bond interface of aluminium clad steel unless there is holding at this temperature. The intermetallic phases formed in the bond interface are FeAl3 and Fe2Al5. The activation energy of their formation is 41 kcal/mol. Even under rapid heating at a temperature just under the melting point of aluminium, the bond shear strength is the same as that of the as‐welded material unless there is holding at this temperature. The bond shear strength depends on the heating temperature and holding time, sharply decreasing under short‐term holding with a rising heating temperature an...

Effect of heat treatment on bond characteristics of aluminium clad steel: Production and characteristics of vacuum roll bonded clad materials (2nd Report)

A vacuum roll bonding apparatus has been developed to produce clad metals. Clad metals such as Al/SS41, A5083/SS41, Cu/SS41, Ti/SS41, SUS304/SS41, Al/Cu, Al/Ti, Cu/Ni, Cu/Ti and Nb/Ti were produced at temperature in the range 0.7-0.85 of the homologous melting temperature using the vacuum roll bonding. And bond mechanism on this method, bond microstructure and bond strength of the clad metals have been investigated. The results obtained are as follows: (1) Bondings of dissimilar metals such as aluminum clad steel, which is difficult to bond by diffusion bonding, were performed under the low reduction in thickness. (2) Though the bondings were performed at elevated temperature, interdiffusion of the elements at the bond interface which occurred during the bonding and cooling process was so little that it was not detected by EPMA analysis. (3) Bond shear strength of A5083/SS41, SUS304/SS41 and Ti/SS41 was higher than that specified by JIS. As the bond shear strength of other clad metals was very high, shear fracture at the bond interfaces did not develop on the shear test.

Development of clad metals by vacuum roll bonding and its characteristics. (Report 1). Development of vacuum roll bonding apparatus and production of clad metals.

An aluminum clad steel was produced using the vacuum roll bonding. The clad steel was heated at 560 to 650°C for 0 to 20 s to study formation of intermetallic phases and bond shear strength in the bond interface between the aluminum and the steel of the aluminum clad steel given weld thermal cycles. Main results obtained are as follows ; (1) Although the clad steel was heated at 650°C without holding, an intermetallic phase was not formed in the bond interface. (2) However, when the clad steel was heated for a certain time, intermetallic phases of FeAl3 and Fe2Al5 were formed in the bond interface and the activation energy for formation of the phases was 41 kcal/mot. (3) When the thickness of the phases was more than around 1.5μm, the bond shear strength of the clad metal was abruptly decreased in comparison with that of the clad steel in as-produced condition.

https://www.jstage.jst.go.jp/article/qjjws1983/12/4/12_4_528/_pdf

Effect of Heat Treatment on Bond Characteristics of Aluminum Clad Steel. Development of Clad Materials by Vacuum Roll Bonding and its Characteristics. (Report 2).

Shizuo Mukae

Papers

Effect of Weld Solidification Mode on Tensile Properties of Aluminum Weld Metal

Quantitative investigation of heat affected zone cracking of aluminium alloy 6061

Effect of heat treatment on bond characteristics of aluminium clad steel: Production and characteristics of vacuum roll bonded clad materials (2nd Report)

Development of clad metals by vacuum roll bonding and its characteristics. (Report 1). Development of vacuum roll bonding apparatus and production of clad metals.

Effect of Heat Treatment on Bond Characteristics of Aluminum Clad Steel. Development of Clad Materials by Vacuum Roll Bonding and its Characteristics. (Report 2).