This paper studies the weld interface microstructure and mechanical properties of AlMg6-stainless steel and AlMg6-titanium bimetals produced using explosive welding. The microhardness (HV), tear strength, and microstructure of the weld seams were evaluated. The interface of the weld zones had a flat profile. No structural disturbances or heterogeneity in the AlMg6-titanium weld interface were observed. On the other hand, the bimetal AlMg6-stainless steel had extensive zones of cast inclusions in the 10–30 µm range. SEM/energy-dispersive X-ray spectroscopy (EDS) analysis showed the presence of a hard and brittle intermetallic compound of Al and FeAl₃ (with 770–800 HV). The microhardness of the AlMg6-titanium bimetal grew higher closer to the weld interface and reached 207 HV (for AlMg6) and 340 HV (for titanium). Both bimetals had average tear strength below 100 MPa. However, the tear strength of some specimens reached 186 and 154 MPa for AlMg6-titanium and AlMg6-stainless steel, respectively. It is also worth mentioning that heat treatment at 200 °C for one hour led to a uniform distribution of tear strength along the entire length of the bimetals. The study shows that one of the possible solutions to the problem of the formation of the brittle intermetallic compounds would be the use of intermediate layers of refractory metals.

This work is devoted to the study of the processes that take place in the welding gap during explosive welding (EW). In the welding gap, when plates collide, a shock-compressed gas (SCG) region is formed, which moves at supersonic speed and has a high temperature that can affect the quality of the weld joint. Therefore, this work focuses on a detailed study of the parameters of the SCG. A complex method of determining the SCG parameters included: determination of the detonation velocity using electrical contact probes, ceramic probes, and an oscilloscope; calculation of the SCG parameters; high-speed photography of the SCG region; measurement of the SCG temperature using optical pyrometry. As a result, it was found that the head front of the SCG region moved ahead of the collision point at a velocity of 3000 ± 100 m/s, while the collision point moved with a velocity of 2500 m/s. The calculation of the SCG temperature showed that the gas was heated up to 2832 K by the shock compression, while the measured temperature was in the range of 4100–4400 K. This is presumably due to the fact that small metal particles that broke off from the welded surfaces transferred their heat to the SCG region. Thus, the results of this study can be used to optimize the EW parameters and improve the weld joint quality.

Due to their low density, high strength, and resistance to corrosion, Al-Mg alloys are widely used in the railcar construction and shipbuilding, and other industries. The aim of this study was to carry out a detailed analysis of the microstructure of the AlMg6-AlMg6 weld interface after explosive welding (EW). The results of this study are important for a better understanding of the joint formation process in EW of AlMg6 with other metals and alloys. The study included optical and electron microscopy of metallographic specimens with etched surfaces. Vickers hardness tests and tear strength tests were carried out to determine the mechanical properties of the joint. Optical and electron microscopy revealed a large number of adiabatic shear bands (ASBs) formed during EW and dark-etching structures formed after etching. An increase in explosive welding parameters leads to an increase in ASBs in the flyer plate and parent plate. The dark-etching structures are most likely the accumulations of structural defects and intermetallic compound fragments. The tear testing of the weld joint showed that higher EW parameters lead to much higher tear strength with a non-uniform distribution along the length of the plates. It was concluded that in order to achieve a joint between AlMg6 and other alloys and metals with the highest strength, plastic deformation in the weld interface must be sufficiently high, while heating must be minimal. The maximum joint strength was 150 MPa in mode 2 and 242 MPa in mode 3, respectively.

Multilayer composite materials, consisting of layers of aluminum alloy and steel, are used in the manufacturing of large engineering structures, including in the shipbuilding and railcar industries. Due to the different properties of aluminum alloys and steels, it is difficult to achieve high-strength joints by conventional welding. Therefore, these joints are produced by explosive welding. In the present work, the structure of a multilayer material, AA1070-AlMg6-AA1070 (aluminum alloys)-VT1-0-08Cr18Ni10Ti (steel), was investigated after explosive welding and heat treatments were performed under different conditions. The microstructure of the AlMg6 layer at the AlMg6-AA1070 interface consists of shaped anisotropic grains extending along the weld interface. The AA1070 layer is enriched with magnesium due to its diffusive influx from AlMg6. In the AlMg6 and VT1-0 layers, adiabatic shear bands are found that start at the weld interface and propagate deep into the material. The optimal temperature for the heat treatment is 450–500 °C, as internal stresses are reduced at this temperature and the grain structure of the AlMg6 layer is not coarse. Tear strength testing revealed that the tear strength of the composite material after explosive welding was 130 ± 10 MPa, which exceeded the strength of the AA1070 alloy.