FINITE-ELEMENT STUDY ON THE ROLE OF CONVECTION IN LASER-SURFACE MELTING

The surface-tension-driven convection in laser melting has been simula ted by the Galerkin finite element method. The governing laminar, axis ymmetric convection equations are solved in a sequential manner by an explicit projection method. The numerical results show a strong depend ence of the flow pattern on the value of the temperature coefficient o f surface tension (sigma(T)). Results are presented for a range of sig ma(T) values typical in steel, -10(-4) less-than-or-equal-to sigma(T) less-than-or-equal-to + 10(-4) N / mK. As the melt depth is more affec ted than the width, the melt aspect ratio changes due to convection. T he melt pool is broad and shallow when sigma(T) < 0, and deep and narr ow when sigma(T) > 0.