Abstract
The first study of thin-walled aluminum-alloy tubes with underwater-laser-nozzle in situ melting technology was carried out. The study mainly covered the influence of the water environment on the laser melting process, melting appearance, geometric characteristics, microstructure, regional segregation and microhardness. During the transfer of the cladding environment from air to water, the uniformity of the cladding layer became poor, but excellent metallurgical bonding was still obtained. The dilution rate (D) decreased from 0.46 to 0.33, while the shape factor (S) increased from 4.38 to 5.98. For the in-air and underwater samples, the microstructure of the melting zone (MZ) and the cladding zone (CZ) were columnar dendrites and equiaxed grains, respectively. In addition, the microstructure of the overlapping zone (OZ) was composed of columnar dendrites and equiaxed grains. The underwater average grain size was smaller than that of in-air. In addition, the water environment was beneficial for reducing the positive segregation in the columnar dendrite region. Compared with the in-air cladding sample, the precipitated phases in the OZ of the underwater cladding sample reduced. Under the combined action of grain refinement and precipitated phase reduction, the microhardness value of the underwater OZ was higher than that of the in-air OZ.
Highlights
IntroductionWith the overexploitation of land resources, the development and transportation of marine resources in marine engineering have developed rapidly in recent years [1,2]
Accepted: 18 August 2021With the overexploitation of land resources, the development and transportation of marine resources in marine engineering have developed rapidly in recent years [1,2].underwater structures serve in the extreme oceanic environment, and they are vulnerable to corrosion failure [3]
In order to to study study the the effect effect of of the the water water environment environment on on wire-feed wire-feed laser laser cladding cladding of of the aluminum alloy, we compared the quality of in-air and underwater laser cladding the 5052 aluminum alloy, we compared the quality of in-air and underwater laser cladunderunder the same process parameters, and the conclusions were drawn: ding the same process parameters, andfollowing the following conclusions were drawn: (1)
Summary
With the overexploitation of land resources, the development and transportation of marine resources in marine engineering have developed rapidly in recent years [1,2]. Underwater structures serve in the extreme oceanic environment, and they are vulnerable to corrosion failure [3]. Due to the increase in water depth and the wide use of new materials, the in situ remediation of underwater components and structures began to face serious challenges [4]. There is a variety of underwater repair technologies for corroded components and structures. The most widely used is underwater arc welding, but its process stability is poor, and it is still very difficult to achieve precise and high-quality underwater repair [5,6]. High-quality, efficient and precise underwater in situ repair technologies are urgently needed. Feng et al [7] and
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