Abstract
The composition distribution can influence the performances of laser cladding layers. Hence, the technology of rthe eal-time monitoring of chemical composition is required to apply on laser cladding process. In this experiment, four kinds of Ni-based alloy powders were used to prepare laser cladding layers on AISI (American Iron and Steel Institute) 4140 steel. At the same time, emission spectra were collected during real-time laser cladding process. The intensity of spectral lines were revised with a corrected number deduced with evaporation rate of elements. By correlating the weight ratios of elements with the intensity ratios of spectral lines, four calibration curves were established to monitor composition distribution. The main results are shown as following: Weight ratios among elements in the laser cladding layers changed versus input energy density due to different saturated vapor pressures among elements; the dilution amount of substrate showed weak relations under the different manufacturing parameters, and the main reason for this can be attributed to the change of thermo–physical properties among different Ni-based alloy powders; the predicted results showed that when the composition concentration was higher than 3 wt.%, the relative error was lower than 8%, compared with EDS (Energy-dispersive X-ray spectroscopy) testing data.
Highlights
The technology of laser cladding is capable of fabricating a wide range of surface alloys and composites of required properties
Because of the Stark effect, the spectral lines were typically broadened to the Lorentz profile; the original data were firstly removed the baseline, and they were processed by the Lorentz fitting [30,31,32,33]
Four kinds of Nickel-based laser cladding layers were prepared on AISI 4140 steel with different manufacturing parameters
Summary
The technology of laser cladding is capable of fabricating a wide range of surface alloys and composites of required properties. Laser induced breakdown spectroscopy (LIBS) is a kind of emission spectroscopy applied to chemical analysis [9] It can measure composition during interactions between a laser pulse and a material surface. To improve the accuracy of the monitoring system used in real time laser processing, Song et al completed lots of work regarding the calculation method of calibration curves [17]. The analysis method used for real time composition monitoring was always cited by LIBS, but there is little research about the error revision of composition between the liqiud state and the gas state. The emission spectra were collected during the laser cladding process, and the spectral lines emitted by the atoms of substrate and alloy elements were selected in spectra. The prediction results analyzed by the monitoring system were compared with that measured by energy dispersive spectrometry (EDS)
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