期刊
MATERIALS & DESIGN
卷 192, 期 -, 页码 -出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.matdes.2020.108689
关键词
Laser polishing; AISI H11; Surface roughness; Decarburization; Micro hardness; Martensite formation
资金
- Volkswagen Stiftung [I/83252]
- Fraunhofer Institute for Laser Technology
- RWTH Aachen University
- German Federal State of North-Rhine Westphalia within the Center for Nanophotonics [290047022]
- State Key Laboratory for Tribology at Tsinghua University
- National Natural Science Foundation of China [51527901, 51575298, 51705284, 51705285, 11890672]
This work investigates the influence of multi-step laser polishing on microstructural properties of the remelted surface layer of tool steel H11. Four different sets of process parameters were selected for laser polishing of ini-tially annealed samples made from tool steel H11. In a sequential, multi-step process using continuous and pulsed laser radiation (Nd:YAG) a significant reduction of surface roughness was achieved.. The remelted layers were analyzed using roughness measurements, white light interferometry, X-ray diffractometry, electron back-scatter diffraction, glow discharge emission spectroscopy, and nanoindentation hardness measurements. Laser polishing leads to a grain refinement and a significant increase in hardness. A minimal surface roughness of Ra = 50 nm was achieved in an Argon process atmosphere with an additional 6 vol% CO2. In particular the carbon concentration was significantly reduced within the remelted layer. The lower carbon concentration is correlated with a decreased maximal surface hardness down to 366 HV. High residual tensile stresses of up to 926 MPa 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 rough-ness and microstructural properties. (C) 2020 The Author(s). Published by Elsevier Ltd.
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