African Fusion August 2018

Hybrid electro slag cladding

Depth from top

Bead location Centre Overlap Centre Centre Centre Centre

C Mn Si

S

P

Cr

Ni

Mo

Nb

Al

Ti

Fe

On top On top 1.0 mm 2.0 mm 3.0 mm 4.0 mm

0.031 0.18 0.30 0.012 0.010 22.46 60.37 8.99 0.030 0.19 0.34 0.013 0.011 22.35 60.02 8.88 0.029 0.18 0.29 0.009 0.010 22.14 60.66 9.06 0.023 0.18 0.32 0.013 0.009 22.16 60.70 9.04 0.027 0.18 0.33 0.012 0.008 22.15 60.58 9.12 0.029 0.18 0.31 0.013 0.009 22.11 60.60 9.17

4.037 0.043 0.053 3.27 3.945 0.049 0.056 3.49 3.965 0.041 0.049 3.34 4.030 0.049 0.059 3.23 4.087 0.046 0.057 3.50 4.126 0.047 0.058 3.67

ASME AWS SFA5.1

0.1 0.5 0.5 0.015 0.02 20.0-23.0 >58.0 8.0-10.0 3.15-4.15 0.4 0.4 5.0

Table 4: Chemical analysis of single layer Ni-625 H-ESC cladding deposits.

Depth from top Bead location C Mn Si N On top Centre 0.030 1.34 0.53 0.0092 0.02 18.98 10.24 0.109 0.598 0.083 .019 0.008 .0369 On top Overlap 0.029 1.28 0.51 0.0091 0.02 19.06 10.20 0.108 0.656 0.085 .019 0.008 .0341 1.0 mm Centre 0.031 1.29 0.55 0.0130 0.018 18.80 10.07 0.113 0.658 0.093 .016 0.008 .0385 2.0 mm Centre 0.028 1.34 0.56 0.0100 0.018 18.74 10.18 0.111 0.704 0.088 .016 0.008 .0385 3.0 mm Centre 0.029 1.37 0.57 0.0100 0.019 18.67 10.02 0.109 0.682 0.09 .017 0.007 .0385 4.0 mm Centre 0.029 1.37 0.59 0.0079 0.018 18.63 10.04 0.109 0.657 0.086 .019 0.008 .0309 ASME AWS SFA5.4 0.08 0.5-2.5 0.9 0.03 0.04 18.0-21.0 9.0-11.0 0.75 0.8-1.0 0.75 S P Cr Ni Mo Nb Cu Al Ti

Table 5: Chemical analysis of single layer SS 347 H-ESC cladding deposits.

• Cladding of all major austenitic stainless steel grades (SS 308L/ 316L/347) can be achieved using a single stan- dard strip composition and a single high-speed neutral flux. Only the MCW composition needs to be changed to produce corresponding stainless grade weld chemistry. Extensive tests have been carried out using this technique for different Ni alloys and austenitic stainless steels, which conclude the following: • Chemical analysis revealed that the weldmetal chemistry is fully homogeneous across the width and height, since there is only a single molten pool. SEM analysis has con- firmed that undiluted clean cladding chemistry is achieved nearly throughout the clad thickness (Figures 7 & 8 for Ni‑625 and SS 347 deposits respectively). Delta Ferrite control of between 5-8 FN can be achieved for austenitic stainless steel welds as per customer requirements. • Sound bonding between the clad and base material as well as between the weld beads was confirmed using ultrasonic testing.

comfortably in single layer cladding applications, includ- ing the <5% Fe requirement for Ni 625 deposits and >40% Ni in Ni-825 deposits. • The introduction of hot MCW into the hottest spot of molten pool produces amore homogeneous weld deposit across the width and depth of the weld bead. • The use of an automatic weld controller guarantees con- stant strip-to-wire-feed ratios according to pre-set values, which ensures the same chemistry is achieved throughout the weld deposit. • The melting of both consumable strip and multiple hot MCWs makes this technique much more productive as compared to conventional or high-speed ESW cladding. Deposit rates at least 50-90% higher can be achieved. • The higher melting rate coupled with use of high-speed neutral flux helps this technique to run with at least 50-100% higher welding speeds than conventional ESW cladding.

• Satisfactory 180° side bend tests were performed as per ASME Sect IX in the ‘as-welded’ and after PWHT condition (Figure 9). • Theweldmetal is fully corrosion resistant. The corrosion rate of Ni‑625 cladweldwas tested at 0.66 mm/yr as per ASTM G-28A; and bend tests as per ASTM A 262 Prac- tice E for austenitic stainless steel grades were free from any indications in the as- welded and PWHT condition (Figure 10). • Tests conducted on C-Mn steel and low- alloy steel (2.25Cr‑1Mo/1.25Cr-0.5Mo) base materials confirmed that the hardness val- ues in the weld metal and HAZ of the clad layer were well within acceptance limits. An application A top global fabricator, Walter Tosto SpA (WT)

Figure 7: Side bend test samples for H-ESC cladding of (a) Ni-625, (b) Ni-825 and (c) SS 347.

Figure 8: IGC test samples for H-ESC cladding of (a) SS 308L, (b) SS 316L and (c) SS 347.

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August 2018

AFRICAN FUSION