PSI - Issue 42

Pavel Doubek et al. / Procedia Structural Integrity 42 (2022) 1529–1536 Pavel Doubek et al./ Structural Integrity Procedia 00 (2019) 000 – 000

1531

3

(a)

(b)

Fig. 2. Real specimens composed of high strength steel S960 substrate coated with (a) an aluminium bronze layer and (b) a hard chrome layer applied via laser cladding technology In the vicinity of the transition zone, the semi-melted material of substrate is mixed with melted powder. For detection of microscopical stress concentrators and for describing the microstructure of the interphase between the surface layer and the steel substrate (including the heat-affected area and bonding zone), two samples for each type of layer have been prepared for metallographic analysis by electron microscope, see an example in Fig. 3.

(a)

(b) Fig. 3. 500× zoomed detail of the vicinity of the transition zone S960 with (a) an aluminium bronze layer and (b) a hard chrome layer applied via laser cladding technology (Lens: Z5200 : X500) An analysis to identify the real chemical composition of the cladded layers was carried out by X-ray fluorescence spectrometry (XRF spectrometry) in which the material interacts with high-energy X-rays. The results of Metco 51NS and Rockit 401 recorded with Delta Professional hand spectrometer are shown in Tabs. 2 and 3, respectively. It needs to be emphasized that not all elements of the Mendeleev Periodic Table can be determined by XRF spectrometry. Elements with atomic numbers 1 to 11 are not recognizable by this method. Table 2. Chemical composition of the aluminium bronze layer Metco 51NS

Chemical elements

Parameter

Unit

Cu

Al

Fe

Si

Cr

Mn

C

Mo

Ni

V –

–

–

–

–

–

Declared content [%]

Bal.

8.5 – 10.8 0.5 – 2.0

0.15

–

Real content

[%] 68.50

23.84

5.24

1.78 0.28 0.20

0.05 0.03 0.08

Table 3. Chemical composition of the hard chrome layer Rockit 401

Chemical elements

Parameter

Unit

Fe

Cr

Ni

Si

Mo 0.5

Mn

V –

–

–

Declared content [%]

Bal.

18.0

2.5

Real content 0.22 During the laser cladding process of the layers of the additive material, defects may occur in the cladded layers, see Fig. 4. Some defects could be minor but others could have a significant impact on the durability of structural [%] 78.83 17.22 2.05 1.04 0.49 0.15