Evaluation of the mechanical properties of Inconel 718 to SCM 440 dissimilar friction welding through real-time monitoring of the acoustic emission system

Abstract

Friction welding was chosen for its versatility in the joining of dissimilar materials with high quality. The aim of this study is to determine the optimal welding conditions for attaining quality joints by using online monitoring of acoustic emission system signals. During friction welding, the formation of cracks, defects, or any abnormalities in the joining process which have a detrimental effect on the joints quality was identified. The most widely used materials in the aerospace industry—Inconel 718 and molybdenum steel—were joined by friction welding. The precision of the joints, internal defects, and quality are major concerns for aerospace parts. The results of the present research determined the optimal welding conditions for high tensile strength by nondestructively inducing acoustic emission signals. During friction time and upset time periods, the typical waveforms and frequency spectrum of the acoustic emission signals were recorded, and their energy level, average frequency, cumulative count, and amplitude were analyzed. Both cumulative count and amplitude were found to be useful parameters for deriving the optimal welding conditions. In the initial stage of friction welding, a very high voltage of continuous form was generated with frequency characteristics of 0.44 MHz and 0.54 MHz. The signals generated during the upset stage had a low voltage, but a very high frequency of 1.56 MHz and 1.74 MHz with a burst-type signal. The amplitude of the signal generated for the optimally welded joints was about 100 dB at the friction time and about 45 dB at the upset time.

Experimental Investigation on Microstructure and Mechanical Properties of Friction Welded Dissimilar Alloys

“…Tis is attributed to reduced joint strength. It is consistent with the previous researcher [29,30]. Te change in tensile strength as a function of rotating speed is shown in Table 4.…”

Microstructure and Mechanical Properties of Solid-State Rotary Friction Welded Inconel 713C and 32CrMo4 Steel Joints Used in a Turbocharger Rotor

“…Increasing the friction pressure causes martensite formation and thus increases the hardness in the joint zone. The interface of the weld is intensively mixed, and a strong bonding line between joined materials is formed, as also observed by Kong et al [ 50 ]. After RFW, the welds have three zones: the thermo-mechanically affected zone, the heat-affected zone, and the BM zone.…”

Combined analysis of acoustic emission and vibration signals in monitoring tool wear, surface quality and chip formation when turning SCM440 steel using MQL

“…Many studies on milling SCM440 steel aimed to investigate the technological parameters affecting the surface quality as well as the tool life [7,8]. Studies on machining SCM440 steel are mainly applied to cool studies with conventional cooling solutions, showing that cutting fluid benefits temperature reduction and productivity improvement [9,10]. However, using a large amount of cutting fluid will adversely affect the environment and the operator's health.…”