Title: Effect of laser shock processing and heat treatment sequence on surface layer characteristics of high strength Ni-Co-Mo steel

Authors: Luca Petan; José Luis Ocaña; Juan Antonio Porro; Janez Grum

Addresses: Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana, Slovenia ' Centro Láser UPM, Universidad Politécnica de Madrid, Campus Sur UPM. Ctra. de Valencia, km. 7.3, Madrid 28031, Spain ' Centro Láser UPM, Universidad Politécnica de Madrid, Campus Sur UPM. Ctra. de Valencia, km. 7.3, Madrid 28031, Spain ' Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana, Slovenia

Abstract: Tool steels operate in demanding environments since they are usually exposed to chemical, mechanical, and thermal detrimental phenomena. Therefore, there is an interest in investigating surface engineering techniques that can improve their surface characteristics. This paper presents the results our research, where the effects of laser shock peening (LSP) on Ni-Co-Mo maraging steel were investigated by analysing the surface integrity. Maraging steels do not achieve their maximum strength after quenching, but after precipitation hardening. Consequently, there is a distinct difference in the mechanical properties between the solution-annealed condition and precipitation-hardened condition. Because of their particular heat treatment process, the effects of LSP were analysed before and after different sequences of laser peening and heat treatment stages to determine whether the choice of order significantly influences the surface integrity.

Keywords: die casting; thermal fatigue; cracking; LSP; laser shock peening; residual stress; maraging steel.

DOI: 10.1504/IJMMP.2017.092168

International Journal of Microstructure and Materials Properties, 2017 Vol.12 No.5/6, pp.427 - 435

Received: 09 Jun 2017
Accepted: 12 Feb 2018
Published online: 06 Jun 2018 *

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