Tensile strength and fatigue crack growth rate of chamfered and clamped A6061 friction weld joints

Yudy Surya Irawan,Wahyono Suprapto,Bayu Satria Wardana,Fakhri Razaq

doi:10.15587/1729-4061.2019.154384

Yudy Surya Irawan, Wahyono Suprapto + Show 2 more

Open Access

https://doi.org/10.15587/1729-4061.2019.154384

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Abstract

Friction welding is a solid-state joining technique. It is suitable to be used to join a round bar of aluminum that has problems in joining. This paper reports measurements of the tensile strength and fatigue crack growth rate of a continuous drive friction welding (CDFW) joint of aluminum alloys A6061. The CDFW process was conducted by using the round bar A6061 machined to form a chamfer angle and applying a clamping process before the upset stage. Various chamfer angles of 0, 30, 45, and 60 degrees were machined on the stationary round bar. In order to increase the tensile strength and to reduce the fatigue crack growth rate of the CDFW joint, round clamps were applied on the CDFW joint. CDFW process was conducted with the revolution speed of 1,100 rpm, the initial compression force of 3.9 kN during friction stage for 4 seconds, and an upset force of 28 kN for 60 seconds. The specimens of friction weld joints were machined to shape the specimens of tensile strength testing and fatigue crack growth testing. Fatigue crack growth testing was performed using a cantilever rotary bending machine. The testing results show that using a small chamfer angle together with the round clamp produced a CDFW joint that exhibited higher tensile strength than the joint without chamfer or clamping. The specimen created with a chamfer angle of 30 degrees and the clamping method had the highest tensile strength and the lowest fatigue crack growth rate among the samples studied. This result was caused by smaller heat input as a result of using a small one-sided chamfer together with two stages of plastic deformation from the clamping process and upset process during CDFW. The fatigue crack growth rate is also confirmed by macro and scanning electron microscope imaging of the fracture surfaces. The area of fatigue crack growth of the specimen with high tensile strength is wider than the specimen with lower tensile strength. The striations are also observed more clearly in the fracture surface of the specimen with the highest tensile strength and the lowest fatigue crack growth rate, namely the specimen, which has a chamfer angle of 30 degrees with clamping

Highlights

Friction welding is one of solid-state joining methods
This paper reports the effects of a one-sided chamfer angle and a clamping process on the tensile strength and fatigue crack growth rate of friction weld joints of A6061, based on the tensile strength test, fatigue crack growth test, temperature measurement and fractography of the fracture surface of the specimens
The flash did not surround the weld joint but instead was moved to the two sides of the weld joint, making easier to remove compared to the specimen without clamping

Summary

Introduction

Friction welding is one of solid-state joining methods. The friction welding method was first patented in the 1890s [1]. In the continuous drive friction welding (CDFW) method, the energy to produce friction at the interface is continuously supplied by an electric motor with a constant rotational speed. CDFW is a type of friction welding process for joining a round metal bar in the solid-state, which uses friction at the surface contact to gene rate heat and produce metallic joint. When the compression force is applied to the stationary part, the coalescence of the rotating and the stationary parts yields friction and generates heat at the interface. As the flash formed, the rotating part is stopped, and a higher final compressive force is applied to form a metallic joint at the interface of the specimens [2, 3]

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