PSI - Issue 43

Pavel Doubek et al. / Procedia Structural Integrity 43 (2023) 101–106

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Pavel Doubek et al./ Structural Integrity Procedia 00 (2022) 000 – 000

There are many ways of applying the surface layers. One of the increasingly used methods is laser cladding, in which a thin layer of additional material, providing better utility and protective properties, is applied to the base material with the required properties, see e.g. Zhu et al. (2021). The method is suitable for the creation of functional surfaces with specific properties as well as for carrying out quality repairs of damaged components due to manufacturing errors, accidents or operational wear, see e.g. Li et al. (2020). The principle of laser cladding is a method in which a metal powder or wire is fed to a laser beam. This powder/wire is melted together with the base material and a deposition layer is formed on the surface of the structure. A strong metallurgical bond is formed between the new metallic surface layer and the substrate material, see Fig. 1 and Fig. 2. The advantage of laser cladding is an excellent adhesion between the surface layer and the original structure and the relatively small HAZ, see e.g. Laser Therm (2021). Due to a high variability of functional layers, this method could replace some older, often ecologically disadvantageous technologies, see e.g. Optic.org (2017).

Fig. 2. Laser cladding of CuAl layer on a steel substrate.

Fig. 1. The principle of laser cladding.

A sufficient number of samples of different material combinations have been obtained by laser cladding (where the Young's modulus ratio is E 1/ E 2≠1) during an experimental campaign. A part of these samples was subsequently subjected to the Vickers microhardness tests. The aim was to analyse structural changes in the vicinity of the material interface to describe the effect on the fracture-mechanical behavior of the samples. The parameters of deposition are shown in Tab.1.

Table 1. Parameters of deposition. Power

Transport gas flow rate

Protective gas flow rate

Gas

Feed speed Lateral shift

P [W]

v [cm/min]

l [mm]

Q 1 [l/min]

Q 2 [l/min]

[ – ]

1050 - 1200

28 – 35

1.1 – 1.4

10

12

Argon 5.0

2. Material and methods for determining selected fracture-mechanical parameters The S960 high-strength steel was chosen as the material of the substrate. Two variants of materials – aluminum bronze Metco 51NS and hard chrome Rockit 401 – have been used as the materials of the cladded layers, see. Fig. 3. The parameters are given in Tab. 2.

Table 2. Material of the substrate, laser-cladded layers and their parameters. Designation Description E [GPa] ν [-]

Hardness HV 0.5

Type

S960

High Strength Steel Aluminum bronze

202 117 104

0.27 0.32 0.22

346 158 620

substrate

Metco 51NS Rockit 401

laser-cladded layer laser-cladded layer

Hard chrome