Laser quenching heating surface

Laser heating surface quenching is based on high energy laser beam scanning the surface of the workpiece surface rapid heating the steel above the critical point, the use of workpiece heat transfer matrix to realize the cold hardening, phase transformation hardening of the surface. Laser heating surface quenching heating speed extremely quick ( 105 ~ 106℃/秒) Heat, it is a large, phase transformation driving force is big, austenite fit nuclear growth, diffusion homogenization too late, austenite increases carbon and alloy density inhomogeneity in the body, the carbon content in austenite micro area smaller, similar to that of the subsequent rapid cooling, 104℃/秒) Martensite formation temperature in different microscopic area have very big difference, produce fine pony austenite organization. Due to rapid heating, pearlite organization through without diffusion into austenitic organization; Due to rapid cooling, austenitic organizations through without diffusion into martensite, retained austenite content at the same time increasing, the carbon to spread, increase the carbon content of supercooled austenite, martensite in carbon content increases, the hardness increased. After laser quenching heating surface, the workpiece surface tiny lath martensite and twin martensite mixed group, with a high dislocation density and surface hardness is 20% higher than that of quenching + tempering at low temperature, even low carbon steel can improve the hardness. Laser quench hardened layer depth is commonly 0. 3 ~ 1 mm, hardening layer hardness value. With relatively normal contact friction parts movement, although be ground to surface, but the new relative movement contact surface hardness value was not decreased, wear resistance is very good, still no conventional surface quenching layer due to the contact and wear and wear away the phenomenon of increased, abrasion resistance increased by 50%, improve the working life for a few times or even dozens of times. Laser heating surface quenching the best original is quenched and tempered, after quenching parts deformation, the surface quality is very high, particularly applicable to the corner, groove, blind hole and deep hole at the bottom of the wall of the heat treatment, and these parts is very difficult to do other surface quenching method.