PSI - Issue 14

P D Gosavi et al. / Procedia Structural Integrity 14 (2019) 304–313 P D Gosavi et al./ Structural Integrity Procedia 00 (2018) 000 – 000

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3. RESULTS AND DISCUSSION 3.1. Weld metal chemistry

The weld metal chemistry of different alloying elements was observed to vary to a certain with different welding processes. The variation of weld chemistry was calculated in terms of P cm values (wt %) for different weld joints, as given in table 4.The P cm values were calculated as per the following formula.

Table 4. P cm Values of weld joints Welding Process

No. of passes

P cm

W1 W2 W3 W4

44 49 63 46

0.23 0.27 0.22 0.24

3.2. Weld microstructure and phase analysis

The microstructure of base was mostly bainitic type as shown in Fig.4. The weld microstructure was predominantly consist of acicular ferrite, with presence of other phases like grain boundary ferrite (GBF) + Widmanstatten Ferrite (WF) +Polyogonal Ferrite (PF) to a limited but extent, fig.5 to fig.8 Quantitative metallography was carried out to determine the volume fraction of different micro constituents in weld metal at different locations (at least four) across the weld cross sections. quantitative metallography was carried out with respect to two phases (i) phase 1containing acicular ferrite (af - red colour) and (ii) phase 1containing grain boundary ferrite (gbf) + widmanstatten ferrite (wf) + polyogonal ferrite (pf) (green colour) as shown in fig.9 for the joints w1, w2, w3 and w4 respectively. The phase analysis for different weld joints is given in table 5.

Fig.4. Microstructure of base steel 200X