One-sided friction stir welding of 1565сhM alloy plates

Abstract

The results of experimental studies of the features of the structure of butt joints of 1565chM alloy plates with a thickness of 25 mm obtained by one-sided friction stir welding are presented. It is established that the structure of the mixing zone (weld metal) is a dynamically and primarily recrystallized region. The grain size in the weld metal varies depending on the distance from the front surface of the weld from 5.16 μm (upper part of the joint) to 2.93 μm (root part of the joint). The separation of intermetallic compounds in the mixing zone for Al—Mg system alloys helps to reduce the average grain size. In the bodies of grains at the level of half the thickness of the plate, there are both chaotically distributed dislocations and dislocation clusters mainly in the form of dislocation walls. In this case, the scalar density of dislocations at this level exceeds the values of the scalar density of dislocations in the upper and root parts of the weld. In the mixing zone of the joints of the 1565chM alloy plates the microstructure at different levels of horizontal sections along the thickness of the plate is very homogeneous, which indicates the mechanism of layer-by-layer transfer, which is macroscopic.