Evolution law of corona bond of non-magnetic drill rod weld by friction welding

In this paper, experiments and numerical simulations were conducted to study the evolution law of the corona bond at the interface of non-magnetic steel by continuous drive friction welding and the reasons for the appearance of banded structures at the weld. The nucleation position of the corona bond gradually moved from a position close to the edge to the center of the weld as the rotational speed increased, and the width of the corona bond gradually increased. During the evolution of the corona bond in non-magnetic steel, the corona bond underwent rapid nucleation and rapid expansion. As the plasticized metal was extruded, the corona bond concentrated at the interface center. The evolution process of the interface temperature field was basically consistent with the nucleation of the corona bond and its extended evolution law. With the increase in rotational speed, the maximum value of equivalent strain gradually decreased, while the maximum value of equivalent stress slightly increased. When the corona bond was 0.12 r₁ ~ r₁ away from the center of the weld, and the width of the corona bond was less than r₁, the corona bond expanded. When the position of the corona-bond is close to the distance from the weld center is 0 ~ 0.12r₁ away from the weld center, and the plasticized metal was extruded, the corona bond no longer expanded. In addition, since the corona bond had no driving force for expansion, and the temperature at the interface center was lower than that at the outer edge, the corona bond could no longer expand at the interface center. This non-expansion phenomenon caused the weld to present a spindle-shaped heat flow pattern, resulting in the formation of a banded structure in the weld and further leading to a decrease in strength.