Analysis on the physical mechanism of laser cladding crack and its influence factors

Crack Behavior of Ni60A Coating Prepared by Laser Cladding on a Tilted Substrate

“…The main reasons for cracks in a Ni60A coating prepared by laser cladding are excessive residual tensile stress and nonuniformly distributed Cr-rich precipitates. When the residual tensile stress exceeds the fracture strength of the coating, cracks are formed [6]. Due to the difference in thermophysical properties between the substrate and the coating, thermal stress is the main source of residual tensile stress.…”

“…However, laser cladding is a non-equilibrium metallurgical process, which increases the inhomogeneity of the local temperature field and results in a great residual stress in the specimen. Especially, the residual tensile stress significantly reduces the static load strength and fatigue strength of the specimens, and even leads to cracking [5][6][7]. The residual stress and crack behavior are always the focus of laser cladding.…”

“…Yu et al [14] found that thermal stress was the main source of residual stress, and the low plasticity caused by the high hard brittle phase and the excessive residual tensile stress were the main reasons for the cracking of Ni60A coating. Based on the temperature gradient in laser cladding, Fu et al [6] established a thermal stress analytical model and analyzed the factors affecting cracking, including laser power, scanning speed, laser diameter and the properties of the material. By summarizing the existing research, Song and Lin et al [15,16] proposed a variety of crack control methods for Ni60A coating, such as preheating the substrate, optimizing process parameters, adding pure nickel powder or rare earth elements, introducing ultrasonic vibration or an electric-magnetic compound field, et al…”

Numerical Simulation of Convex Shape Beam Spot on Stress Field of Plasma-sprayed MCrAlY Coating During Laser Cladding Process

“…In comparison with other surface machining technologies, the laser cladding technology integrates the merits of broad scope of application, strong practicability and exible application, so it has aroused extensive attention and attracted great importance and has been widely used [1][2][3][4][5][6][7][8]. At present the major problem in laser cladding is high coating brittleness and great cracking tendency [9][10][11][12][13][14][15][16], which considerably restricts its scope of application in key components, so cracking inhibition in the laser cladding is of great realistic signi cance to the application of the laser cladding technology in production.…”

Effect of the Average Energy on WC Grain Growth of WC-10Co-4Cr Composite by Laser Cladding

“…It has been established that the key processing parameters in LC are the laser power, the scanning speed, and the powder feeding rate, which strongly influence the geometrical characteristics of LC tracks, including aspects such as dilution, width, and wetting angle [7][8][9]. With the purpose of establishing a relationship among three different processing parameters, that is, laser power, scanning speed and laser spot diameter, the concept of Metals 2019, 9,1245; doi:10.3390/met9121245 www.mdpi.com/journal/metals Metals 2019, 9,1245 2 of 12 average energy (E a ) [10], also called average energy per unit area [8,10,11], specific energy [12][13][14][15][16], effective energy [13,17,18] and/or energy density [10,[19][20][21][22], is frequently used in the literature; thereby, E a is basically set by adjusting the corresponding parameters. WC-Co alloys have been commonly deposited utilizing laser cladding [7,8,10,11,[23][24][25].…”