In industries such as aerospace, petrochemistry and automobile, many parts of different machines are under environment which shows high temperature and high pressure, and have their proneness to wear and corrosion. Therefore, the wear resistibility and stability under high temperature need to be further improved. Nowadays, Laser cladding (LC) is widely used in machine parts repairing and functional coating due to its advantages such as lower dilution rate, small heat-affected zone and good metallurgical bonding between coating and substrate. In this paper, LC is introduced in detail from aspects of process simulation, monitoring and parameter optimization. At the same time, the paper gives a comprehensive review over LC material system as high entropy alloys (HEAs), amorphous alloy and single crystal alloy have been gradually showing their advantages over traditional metal materials in LC. In addition, the applications of LC in functional coatings and in maintenance of machine parts are also outlined. Also, the existing problems and the development trend of LC is discussed then.

Recent research and development status of laser cladding: A review

Investigation of metal mixing in laser keyhole welding of dissimilar metals

Investigation of formation and microstructure of Ti-6Al-4V weld bead during pulse ultrasound assisted TIG welding

Additive manufacturing of Ti6Al4V parts using ultrasonic assisted direct energy deposition

Ultrasonic effects on gas tungsten arc based wire additive manufacturing of aluminum matrix nanocomposite

The paper shows the possibilities of using ultrasonic vibrations in the processes of laser welding and cladding. Optical and electron microscopy, local elemental analysis, X-ray tomography, and series of tensile tests were used to investigate the effect of vibrations on the respective processes. It is shown that ultrasonic vibrations can be used in two different ways: ultrasonic online processing during welding and surfacing and post processing of the finished weld seam and cladded metal. In the first case, ultrasonic effect leads to reduction of the weld seam thickness and an increase of the depth of weld penetration. In the second case, ultrasonic post-treatment of the samples produced by layer-by-layer direct laser wire deposition results in an increase of tensile strength of the cladded material up to 1.3 times. It is shown that the effect is caused by formation of an oriented thin-plate structures on the surface of the samples.

Investigation of microstructure and properties of low-carbon steel during ultrasonic-assisted laser welding and cladding

The key features of laser acoustic welding (LAW) of AISI 321 stainless steel samples are investigated in the paper. It is found that the microstructure and the quality of the welds depend strongly on the frequency of the applied acoustic waves, which were selected at sonic (15 kHz) and ultrasonic (22, 40, 80, and 100 kHz) levels. The impact on the molten alloy acoustic vibrations with a frequency of 80 kHz provides weld joints with a uniform structure without detectable pores and homogeneous chemical composition in the cross-section. This results in noticeable improvements in mechanical properties of the weld. The pronounced displacement of the metal from the melting zone and highly inhomogeneous structure of the weld observed at 15 kHz is attributed to the sonocapillary effect.

O. A. Nyukhlaev

Papers

Investigation of microstructure and properties of low-carbon steel during ultrasonic-assisted laser welding and cladding

Investigations of the sound frequency effect on laser acoustic welding of stainless steel