Influence of ns-Laser Cleaning Parameters on the Removal of the Painted Layer and Selected Properties of the Base Metal.

Xinyan Li,Yucheng Lei,Juming Gao,Canyang Li,Dan Wang,Nianzheng Wang,Weiwei Zhang

doi:10.3390/ma13235363

Xinyan Li, Yucheng Lei + Show 5 more

Open Access

https://doi.org/10.3390/ma13235363

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Abstract

The removal of the surface paint of Q345 (Gr·B) steel, as well as microstructure and hardness of the cleaned surface were investigated. The laser source used in this study is a nanosecond pulsed Gaussian light source. The surface morphology and microstructure were characterized by a scanning electron microscope and electron back-scattered diffraction. A hardness test was used for capturing variations of the parameter of the cleaned region in comparison to the base metal. The results show that when the X-scanning speed was 1500 mm/s and Y-moving speeds was 7 mm/s during ns-laser cleaning, respectively, the cleaned surface was relatively flat and there was only a few small residual paint. In addition, the contents of Fe and C elements on the cleaned surface reached to 89% and 9%, respectively. Moreover, the roughness was the lowest of 0.5 μm through the observation of the three-dimensional topography. In addition, a fine grain layer appeared on the cleaned surface after laser cleaning at the X-scanning speeds of 500 mm/s and 1000 mm/s. The maximum hardness of the fine grain layer was more than 400 HV, higher than the base metal.

Highlights

Structural steels, having a high fracture toughness, beneficial fundamental mechanical properties, and good weldability, are widely used in manufacturing ships, airplanes, automobiles, bridges, railways, and oil and gas pipeline industries [1,2,3]
The optical microscope (OM) image of the surface covered by the black paint layer is presented in Figure 1a, and the paint layer was distributed uniformly and densely as it was investigated by the scanning electron microscope (SEM, FEI, Hillsboro, OR, USA), Figure 1b
In order to investigate the effect of speed parameter on Q345 surface paint laser removal, the surface morphology of the cleaned material be observed by means of OM and SEM

Summary

Introduction

Structural steels, having a high fracture toughness, beneficial fundamental mechanical properties, and good weldability, are widely used in manufacturing ships, airplanes, automobiles, bridges, railways, and oil and gas pipeline industries [1,2,3]. For the purpose of preventing materials from rusting and improving the service life of structural parts, the surface of components is always covered in paint layer. Some surfaces still need to be overhauled over a period of time, since part of the paint layers could fall off. The commonly used methods to clean the surface paint layer include mechanical process [5], chemical stages [6], and ultrasonic methods [7] etc. Shot blasting is a common type of operation in mechanical equipment, but if the flow of impacted abrasive particles is not controlled, it will cause certain damage to the surface [5,8,9]. Pickling is one of the main methods in chemical cleaning

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