PSI - Issue 23

Golta Khatibi et al. / Procedia Structural Integrity 23 (2019) 475–480 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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breakouts or spalling visible for both wires and the edge is wearing evenly without large single defects in both cases. The mean volume loss values for C-series and E-series were 8.4 ± 1.0 mm³ and 9.0 ± 1.2 mm³ and the mean wear rates were 750 ± 102 dm³/s .kg.10 11 and 704 ± 86 dm³/s .kg.10 11 respectively indicating an improvement of about ~8% in the wear resistance of the C-series. Furthermore, a comparison of the obtained results with the wear volume losses of Hardox 500 and X120Mn12 wear resistance steels which is in the range of 7.5-8 mm³ confirms the excellent properties of the both welding consumables for hardfacing applications against impact and abrasion.

Fig. 5. (a) Comparison of the wear rate and volume loss of the two sample series after impeller/tumbler tests and (b, c) macroscopic views of the weld samples prior and after the wear test.

3.3. Fatigue tests The results of ultrasonic fatigue tests of the two sample series are presented as stress amplitude against loading cycles to failure plots in Fig. 6a. High cycle fatigue tests for each sample series were conducted at a constant stress level in which the samples endured up to 1e8 loading cycles. The selected stress amplitude for each sample type was determined by using a step test technique and was found to be 460 MPa and 600 MPa for E- and C-series respectively. Thus it is evident that the high cycle fatigue resistance of the weld overlays prepared by C- wires is considerably higher than that found for the E-type material.

Fig. 6. Comparison of the fatigue data (stress amplitude against loading cycles to failure) for E and C welded samples series (a). Typical overview images and details of the fatigue fracture surfaces of (b,d) E- and (c,e) C- weld samples series.

The lifetime of the 42CrMo4 base material was not obtained in this study, however relevant literature studies report fatigue data in the range or above those obtained for the C-series weldments. High cycle fatigue experiments at a testing frequency of 20 kHz revealed a fatigue resistance of 650 to ~780 MPa at 1e8 cycles, depending on the pre treatment conditions of the tested 42CrMo4 steel (Sun 2008). Furthermore, the strain-life curve of the material