Effect of Different Ultrasonic Power on the Properties of RHA Steel Welded Joints

Peng Yin,Qinxue Pan,Chunguang Xu,Wenjun Zhang,Xiaowei Jiang

doi:10.3390/ma15030768

Peng Yin, Qinxue Pan + Show 3 more

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https://doi.org/10.3390/ma15030768

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Abstract

Based on the changes of microhardness, tensile strength, and impact resistance caused by the difference of macroscopic morphology and microstructure of welded joints, this paper studied the effect of different ultrasonic power on the properties of welded joints during the welding of homogeneous armor steel. It is experimentally found that the macroscopic morphology of those joints is very different. Compared with conventional welding, ultrasonic welding can increase the weld depth and the width of the heat-affected zone (HAZ) on either side of the weld. However, only the ultrasonic wave at an appropriate power level can increase the weld width. In addition, appropriate ultrasonic power can significantly improve the grain state of the weld. With the increase of ultrasonic power, the grain size in HAZ will decrease. The microhardness of the weld will first increase and then decrease, while the microhardness of the HAZ will increase. This is basically consistent with the changing trend of impact resistance. An ultrasonic wave can also increase the tensile strength of a welded joint up to 802 MPa, 12.4% higher than that in conventional welding. However, a high-power ultrasonic wave will bring down the tensile strength. This study provides guidance for the selection of ultrasonic-assisted regulation power to achieve the different properties of homogeneous armor steel joints.

Highlights

Since the formal development of armor protection technology in the late 19th century, rolled homogeneous armor (RHA) steel has been widely used in the main components of tanks and armored vehicles due to its excellent mechanical properties, such as high hardness and high strength
High hardness and wear resistance is required for some parts, while high strength and impact resistance or good comprehensive performance is required for the other parts
This is true especially when the ultrasonic power increases to U5, at which the melted metal will flow to the unmelted base metal outside the weld and form an overlap

Summary

Introduction

Since the formal development of armor protection technology in the late 19th century, rolled homogeneous armor (RHA) steel has been widely used in the main components of tanks and armored vehicles due to its excellent mechanical properties, such as high hardness and high strength. How to quickly and conveniently produce the RHA steel welds with specific welding performance at low cost and develop an efficient welding process to solve the above problems has always been a hot spot in the field of weapon research in various countries. Due to the influence of welding heat transfer, the grain state of each region of a welded joint is poor. These problems seriously affect the welding performance and reduce the service reliability of weapons, becoming the difficulties in the research of RHA welding performance. The research on RHA welding performance control is mainly focused on the optimization of process parameters and fixtures [3,4,5,6,7]. Different welding conditions and fixtures have different effects on the welding performance, so a good unified control method is currently unavailable

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Results

Conclusion