Effect of Al-B₄C nanocomposite filler manufactured by accumulative roll bonding (ARB) method on the microstructure and mechanical properties of weldings prepared by tungsten inert gas welding

In this research Al/B 4 C nanocomposite was manufactured by accumulative roll bonding (ARB) method. Straps with a width of 5 mm were used as the filler metal. To manufacture the composite by ARB method first the surface of the sheets were prepared then the nanoparticles were sprayed by atomic spray on the entire surface of one sheet and subsequently the rolling process was applied after sandwiching two sheets. The spraying of the nanoparticles was only done for the first two cycles to obtain 0.5 and 1 volume percent Al/B 4 C nanocomposite. Finally in order to reach the optimized dispersion of nanoparticles the accumulative roll bonding was done for seven cycles. TIG welding was applied on sheets with 10 mm thickness having a one directional V shaped groove with 60 degree angle and a filler of 30 mm × 5 mm using AC current at room temperature. The welding was done under a current of 160 A and 24 volts. SEM and elemental map was used in order to study on the microstructure and dispersion of the particles in the matrix for each cycle. The results showed improvement in the dispersions of the particles with the increase in the number of the rolling cycles. Furthermore SEM image and elemental map was prepared for the samples after the welding procedure which indicated the dispersion of particles in the matrix and also the absence of agglomerated particles. In order to study on the mechanical properties, tensile and hardness tests were applied. The results showed increased hardness for the TIG welding with the increase in the number of cycles and also increased hardness with the increase in the volume percent of the nanoparticles. In the welded samples, the hardness of the base metal was 36 Vickers which reduced at the heat affected region. The hardness at the welding metal region of the 0.5 and 1 volume percent sample increased to 46 and 58 Vickers respectively showing significant improvement in the hardness. Furthermore the increase in the yield and tensile strength is directly related to the addition of the nanoparticles and the decrease in the size of the grains. The tensile strength of the weld metal with pure aluminum was reported to be 90 MPa while for samples with 0.5 and 1 volume percent nanoparticles the increase in tensile strength was 130 and 160 MPa respectively.