Schematic of the striation generation process. (MA: melt accumulation, CF: central flow, LB: laser beam).
The 2D model of kerf front profiles. Evolution of the profile depends on the sign of the stability function S(α) [see Eq. (7)], where α is the local inclination angle of the front. (a) When S(α) > 0, a concave mode can develop: the node B moves to the left from the line AC, and then the node D to the left from the line BC. (b) When S(α) < 0, an inversed convex mode develops as from the line AC to AB’C and then to AB’D’C.
The angular dependences of the stability function S(α) [defined by Eq. (7)] for the two wavelengths of 1.06 and 10.6 μm.
(a) The angular dependences of the absorptivity A(α) for the two wavelengths of 1.06 and 10.6 μm at T = T m (Ref. 18). (b) A model kerf profile in the case of the regime of humps.
The 2D model of the striation generation process. The solid part is melted due to heat transfer from the MA sliding down along the kerf side wall.
Temperature field inside the solid.
Calculated R z ′ and u′ as a function of T′ for different values of b.
The complex refractive indices (n + ik) used in the calculation of the stability function S(α) (Ref. 18).
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