Fatigue Properties of Maraging Steel after Laser Peening

Abstract

Maraging steels are precipitation hardening steels used for highly loaded components in aeronautical and tooling industry. They are subjected to thermomechanical loads and wear, which significantly shorten their service life. Improvements of their surface mechanical properties to overcome such phenomena are of great interest. The purpose of our research was to investigate the influence of pulse density and spot size of a laser shock peening (LSP) process on the surface integrity with the fatigue resistance of X2NiCoMo18-9-5 maraging steel. Surface integrity was analyzed through roughness, residual stress, and microhardness measurements. The tests performed on resonant testing machine confirmed LSP is a promising process for increasing fatigue resistance of a component. Fatigue crack occurs, when the resonance frequency decreases. This moment, when the fatigue crack initiation phase ends and the fatigue crack propagation phase starts, was chosen as the moment of failure. We have proved LSP is a successful method in improving fatigue resistance of maraging steel by appropriate combination of laser spot size and pulse density tested in our research.

Laser Shock Processing and Related Phenomena

“…In the second section (comprising nine full research papers), we aimed to compile as representative as possible coverage of the different key aspects leading the present-day research in LSP technology and related disciplines. The result has been a collection of articles ranging from the study of fundamental physics aspects (mostly laser-plasma interaction diagnosis and plasma pressure development, respectively represented by the articles of Colón et al [3] and Sadeh et al [4]); passing through the application of numerical modelling to the predictive assessment of the results of the application of LSP to the most relevant present-day materials (represented by the articles of Langer et al [5] and Angulo et al [6]); continuing on to the theoretical and experimental analysis of the parametric space of LSP in view of realistic applications (represented by the articles of Kallien et al [7], Troiani and Zavatta [8], and Petan et al [9]); and, finally, arriving at two of the most advanced developments at present day in the industrial application of LSP (i.e., the articles of Le Bras et al [10] and T. Sano et al [11]). In short, a collection of first-rank articles covering fundamental processes, numerical modelling, microstructural and material-related issues, materials and standard specimens testing, parametric applications design, advanced LSP applications, and implementation issues has been obtained.…”

Influence of reverted austenite on fatigue life of 18 % nickel maraging steel

“…Large‐sized inclusions decrease the fatigue life and aluminate‐type inclusions are least damaging compared to titanium nitride inclusions which are the most damaging concerning the fatigue life of 18 % nickel maraging steel. Carbonitride‐type inclusions were found to be more damaging to fatigue life in 18 % nickel maraging steel than aluminate‐type [8–11].…”

“…Shot peening increases the high cycle fatigue life and helps to reduce the sensitivity to humid environments [2,18,24,27]. Laser shock peening helps in delaying both crack initiation and propagation [8,9]. Nitriding increases the hardness of the surface and induces compressive residual stress in the surface layer which improves the fatigue life [25,28].…”