## 1 Introduction
Therefore, the use of weld wire to alloy the weld metal with nickel is restricted to a limited number of weld wire formulations. Matched alloying of the weld metal may be better accomplished if the metal powder is applied to the welding process to achieve the aim weld metal composition [14; 15]. Furthermore, efforts are made to develop flux cored wire for weld metal nickel alloying due to work hardening of the solid weld wire in manufacturing and in feeding the weld wire through the SAW wire feeding mechanism [16]. In this reported study two flux formulations of different basicity were tested under the same welding conditions, at BI of 1.4 and 2.8. Flux basicity affected the deposition rate and weld metal oxygen content, however, insignificant differences were reported on Ni yield from the flux cored wire to the weld metal, despite high weld metal ppm O values of 628 to 835 ppm O. Similarly, Ni-containing pre-alloyed powders were applied in SAW to better control the required chemistry of coating applications via SAW [14]. The claimed benefits of using pre-alloyed powders for alloying in cladding, compared to alloying via the weld wire, are that weld metal dilution from the iron contained in the weld wire and dilution from the substrate steel are limited because the weld pool is cooled due to the melting of the added powders. Overall deposition productivity is also improved due to the application of metal powders. However, conversion of the reported analyses values to Ni yield values confirms that the Ni yield is less than 100%. Nickel yield values ranged from 57 to 78% from iron based alloy powders containing 27-29% Cr, 5-8% Ni, and 2-4% Mo. These nickel yield values appear to be much lower than the typical values of 100% nickel yield reported when solid weld wire is used in SAW [12; 17]. In comparison, in conventional SAW with solid weld wire, some nickel and chromium loss values were reported as influenced by slag chemistry, although the base metal alloying element values were low: 0.3% Ni loss and 0.3% Cr loss from the welding base plate containing 1.65% Ni and 0.76% Cr when solid weld wire containing 0% Ni and 1.25% Cr was used. These values represent 81% Ni yield and 61% Cr yield in the presence of a highly oxidising flux of 40% SiO\({}_{2}\)-MnO-CaO [18]. Although comparative welding tests with more oxidising flux (40% SiO\({}_{2}\)-FeO-CaO) showed smaller element loss values for Ni and Cr,and welding with a highly reducing basic flux (40% SiO\({}_{2}\)-MnO-CaF\({}_{2}\)) showed the lowest element loss values for Ni and Cr. Therefore, even when solid wire alloying is applied in SAW, the extent of the de-oxidiser effect of Cr on Ni yield, and its importance, are not clear. Nickel is used as an alloying element in low-alloy steels and as an austenite stabiliser in stainless steels to counter the ferrite stabiliser effect of chromium. Nickel is added at levels up to 10% in aluminium killed cryogenic steels. Nickel may be used in combination with copper or cobalt as precipitation hardening agents [13]. Although aluminium is traditionally not added in large quantities in steel, the more recent development of low density/high-entropy steels and low density stainless steels requires high quantities of aluminium in the steel [19; 20]. Therefore, the application of combinations of alloying elements with aluminium in SAW is an important contribution to expanding the application of SAW to these newer steel grades. Addition of Fe powders in SAW is used to increase welding productivity in cladding applications and in weld joining of metal plates [15; 21; 22]. Significant productivity gains were achieved in the form of increased metal deposition rates, when iron metal powder was added in SAW [15; 21; 22]. This is possible because only 20% of the arc energy is used to melt the weld wire in conventional SAW which uses only solid weld wire [15].