Microstructure and properties of 1050A/AZ31 bimetallic bars produced by explosive cladding and subsequent groove rolling process

Abstract

Within the framework of this study, the 1050A/AZ31 round bimetal bars were produced by the explosive cladding method and subsequent groove rolling process. LM/SEM investigation shown that by proper selection of the explosive cladding parameters (mainly initial distance between 1050A tube and AZ31 core and detonation velocity) it is possible to produce 1050A/AZ31 feedstocks without a continuous layer of Mg–Al intermetallic phases on the interface between joined materials. The experimental tests of the groove rolling process of 1050A/AZ31 bars were supplemented with a theoretical analysis using FEM-based numerical modelling. Based on the test results obtained, it was found that the interface of the 1050A/AZ31 bar rolling at a temperature (300 °C) was characterized by the generation of a thin continuous intermetallic layer without cracks. Applying a higher rolling temperature of 400 °C, which is usually used in hot forming processes of Mg alloys, led to the production of a thicker intermetallic layer, which cracked during the rolling process as a result of deformation. Strength of the fabricated bimetal joints was high, they did not delaminate during shear tests.

Effect of the Shape of Rolling Passes and the Temperature on the Corrosion Protection of the Mg/Al Bimetallic Bars

“…Additionally, in this case, some of the mentioned methods do not guarantee the right quality of the joint, the required thickness of the plating layer, and, in addition, in the case of round bimetallic bars, even distribution of the plating layer around the core perimeter [29,30]. The most frequently used methods to produce round bimetallic bars include extrusion [18,19,31] and rolling in grooves [23,30,32]. The feedstock for these processes is made directly in the processes themselves, as in the case of extrusion [18,19] or with the possibility of earlier use of the casting method [22] or explosive welding [30,32].…”

“…The most frequently used methods to produce round bimetallic bars include extrusion [18,19,31] and rolling in grooves [23,30,32]. The feedstock for these processes is made directly in the processes themselves, as in the case of extrusion [18,19] or with the possibility of earlier use of the casting method [22] or explosive welding [30,32]. One of the methods ensuring the right thickness and even distribution on the perimeter of the round bar of the plating layer is the combination of the explosive welding method to produce a bimetallic feedstock, and then rolling in elongating grooves [32,33].…”

“…The feedstock for these processes is made directly in the processes themselves, as in the case of extrusion [18,19] or with the possibility of earlier use of the casting method [22] or explosive welding [30,32]. One of the methods ensuring the right thickness and even distribution on the perimeter of the round bar of the plating layer is the combination of the explosive welding method to produce a bimetallic feedstock, and then rolling in elongating grooves [32,33]. A combination of these methods was used to produce bimetallic bars of steel/Cu [29,34], Al/Cu [30], and, recently, also Mg/Al [22,23,32].…”

“…One of the methods ensuring the right thickness and even distribution on the perimeter of the round bar of the plating layer is the combination of the explosive welding method to produce a bimetallic feedstock, and then rolling in elongating grooves [32,33]. A combination of these methods was used to produce bimetallic bars of steel/Cu [29,34], Al/Cu [30], and, recently, also Mg/Al [22,23,32]. Although the method of explosion welding guarantees obtaining a bimetallic feedstock marked by a high quality of the joint [32], it does not always guarantee obtaining high-quality bimetallic bars while rolling in grooves.…”

“…A combination of these methods was used to produce bimetallic bars of steel/Cu [29,34], Al/Cu [30], and, recently, also Mg/Al [22,23,32]. Although the method of explosion welding guarantees obtaining a bimetallic feedstock marked by a high quality of the joint [32], it does not always guarantee obtaining high-quality bimetallic bars while rolling in grooves. Due to the fact that the process of rolling bars in the grooves is marked by a spatial state of deformation and a large inhomogeneity of metal flow in the rolling gap, the distribution of deformations is inhomogeneous [29,34].…”