| Abstract: | Hastelloy alloy B-42 weld overlay welding Alloy NiMo 28, Mat. No. 2.4617 (HASTELLOY alloy B-2), is known for its excellent corrosion resistance in hydrochloric and sulfuric acids over a wide range of concentrations and temperatures. Under critical conditions, however, severe corrosion can occur in welds (weld deposit and HAZ). This is attributed to molybdenum depletion of the microstructure. The properties of a filler material were investigated which contained an excessive amount of molybdenum over the parent alloy. This filler is called HASTELLOY alloy B-42, a nickel alloy having about 42% molybdenum. The much less ductile HASTELLOY alloy B-42 weld deposit is more corrosion resistant in hydrochloric and sulfuric acids than wrought HASTELLOY alloy B-2 and Hastelloyalloy B-2 filler. It can therefore be applied as weld overlay of HASTELLOY alloy B-2 welds subject to critical corrosion conditions. In field testing promising results were obtained. Currently only TIG rod having a diameter of not less than 4.76 mm (0.187”?) are available which are causing handling problems. Tube wire with a diameter of 2.5 mm (0.098”?) is under development and will be available shortly. |
