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Influence of laser polishing on surface roughness and microstructural properties of the remelted surface boundary layer of tool steel H11
摘要： This work investigates the influence of multi-step laser polishing on microstructural properties of the remelted surface layer of tool steel H11. Four different laser polishing process parameter sets were selected that lead to a significant reduction in roughness. In a sequential process using continuous and pulsed laser radiation (Nd:YAG) a significant reduction of surface roughness was achieved on an initially annealed H11 sample. The remelted layers were analyzed using roughness measurements, white light interferometry, X-ray diffractometry, electron backscatter diffraction, glow discharge emission spectroscopy, and nanoindentation hardness measurements. Laser polishing leads to a grain refinement and a significant increase in hardness. A surface roughness of Ra 50nm was achieved in an Argon process atmosphere with an additional 6vol% CO2. In particular the carbon concentration was more than halved within the remelted layer. The lower carbon concentration is correlated with a decreased maximal surface hardness down to 366HV. High residual tensile stresses of up to 926MPa can be introduced by laser polishing. Overall, high temperature gradients and, in particular, decarburization due to carbon diffusion processes were identified to be the major driving force for significant changes in surface micro-roughness and microstructural properties.
关键词： AISI H11,micro hardness,laser polishing,decarburization,surface roughness,martensite formation
更新于2025-09-23 15:21:01
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Study for Combined Wire + Powder Laser Metal Deposition of H11 and Niobium
摘要： Laser additive manufacturing (LAM) has been proved to be a successful technique to fabricate metallic components for a number of industries; for instance, die & mold, forging and cutting tools, and aerospace. It is, however, facing multitude obstacles due to lack of maturity in terms of process knowledge, design, and qualification. This paper deals with parameters’ study and optimization of combined hot-work tool steel wire (H11) and niobium powder (Nb) deposition by laser. The process is closely analysed and compared with as well as without using Nb powder. Especially, the importance of Nb in order to refine the microstructure is discussed while taking into account the microstructure-property relationships of H11.
关键词： Laser additive manufacturing,Niobium (Nb),Hot-work tool steel,Laser metal deposition,H11
更新于2025-09-16 10:30:52