Numerical simulation of transient and residual stresses caused by laser hardening of slender elements

Phase-change heat transfer in laser transformation hardening by moving Gaussian rectangular heat source

“…A number of studies have been conducted to model the heat transfer of laser transformation hardening. The quasisteady state in a plane slab heated by a moving spot of Gaussian heat source has been considered in previous studies [1][2][3]. Laser transformation hardening using a spot beam produces high-quality treated surface, as precise controls of both the incident laser power and the traverse speed can be easily achieved.…”

“…(dS b /dy)2 (60) Based on the numerical data obtained, the left-hand side and the right-hand side of equation (60) equal 1.18 and 1.05, respectively, with a discrepancy of 11% due to numerical errors. Similar relationship about the temperature gradient change occurs ahead of the heat source at Z = 0.8 due to the heat absorption at the leading interface S a .…”

Numerical analysis and experimental validation of hardness and microstructural changes during laser transformation hardening of low alloy steel plates

“…The convective heat loss per unit area at the surface of the workpiece can be expressed as where T is the temperature of the workpiece (℃), T 0 is the room temperature (℃), q h is the convection heat flux (W/m 2 ), β is the convective heat transfer coefficient (W/m 2 ℃), value of β changes with temperature in steady condition. 11 When the rate of heat flow across a boundary is specified in terms of the emitted energy from the surface and the incident radiant thermal energy, the radiant energy emitted from the body per unit time and per unit area is σɛT 4 , while the corresponding absorbed radiant energy from the outer sides is σɛT α 4 . Therefore the net rate of heat flow per unit area as radiation energy from the body surface can be expressed as where σ is the Stefan–Boltzmann constant, and ɛ is the surface emissivity.…”

“…A mathematical and numerical model is proposed 11 to determine the size of the hardened zone after laser treatment and to estimate the phase fractions in the heat-affected zone. A numerical model is developed to analyze the thermal behavior of the material during laser hardening process.…”

“…9 The finite element modeling technique is used to simulate the steady-state and transient effects of moving beams with different beam shape (circular, rectangular and triangular) in transformation hardening of EN43A steel and it is reported that the triangular laser beam produces the best thermal history to achieve better transformation and high hardness. 10 A mathematical and numerical model is proposed 11 to determine the size of the hardened zone after laser treatment and to estimate the phase fractions in the heat-affected zone. A numerical model is developed to analyze the thermal behavior of the material during laser hardening process.…”