Control of crack propagation on SUS316 plate by laser-induced patterning: heat treatment and cladding

A practical method is proposed to control the direction of crack propagation and to generate a crack-growth-proof (CGP) zone on a metal plate using laser induced line patterns: heat treatment and cladding. To evaluate the effect on crack propagation by the line patterns, we fabricated and tested diverse line-pattern shapes on a thin SUS316 plate of 1 mm thickness, such as single vertical line; one, three, and five horizontal lines; one and three 45°-tilted lines; X-shaped lines; and rectangular box lines by both laser heat treatment and cladding process. For description of metallurgical change via the pattern and its effect on the crack growth, we did a microstructural analysis of the treated SUS316 specimen. For example, ultimate tensile stress (σu) and fracture strain changed according to the pattern shapes. A specimen treatiing a rectangular line pattern of 4×20 mm showed an increase of σu to about 8.8 %, and fracture strain also increased by 10 % compared to that of a SUS316 plate. Through this work, we verified that the CGP zone could be controlled on a thin metal plate using the proposed method for protection of highly valuable mechanical parts mounted on it.