Nickel electrodes are used to weld cast iron of different forms – grey, ductile and malleable. The nickel material is high in demand because it has properties such as heat resistance and corrosion resistance. It is one of the toughest metals with high thermal and electrical conductivity.
Is Nickel an Active Electrode?
Yes. It takes part in electrolytic relations. It largely uses nickel hydroxide as an active material.
Is Nickel an Inert Electrode?
Inert electrodes transfer electrons instead of exchanging ions and do not take part in any chemical reaction. It means that inert electrodes non-reactive. However, a nickel welding rod is chemically reactive and can dissolve chemically. Hence, nickel is not an inert electrode.
What is Nickel Mesh Electrode?
This is made by using high purity nickel wire and then weaving it into platting nickel later. It has high strength and good electrical properties.
What is Nickel Electroplating?
Nickel electrodes for electroplating are extensively used for superior ductility, hardness and corrosion resistance. The technique electroplates a thin layer of nickel on a metal object.
There is also a nickel electro less plating process used to deposit nickel-alloy coating by chemical reduction. It doesn’t require an electric current, unlike nickel electroplating.
When you weld nickel electrodes, you need to bear the following tips in mind:
Filler composition should usually match the parent metal. Always use nickel base fillers when using nickel base alloys, especially when joining stainless steel. Or else, there is a risk of the weld developing cracks.
Limiting the Heat Input
Nickel alloy welding electrodes have low thermal productivity due to which heat builds up quickly. Hence, the welder should always limit the heat input. Allow the weld to cool down between the beads or passes.
Before starting the welding, it is necessary to clean corrosion, scale, grease, oil, dirt, paints, marking inks and other sources of contamination. Welders can use cleaning methods such as rubbing by abrasive cloth, machining, grinding, chemically by pickling or sandblasting.
Porosity occurs when unwanted gases like oxygen, nitrogen or hydrogen get trapped in the molten weld puddle during the solidification process. As a result, pockets or pores appear on the surface or within the bead. Hence, welders should use either helium, argon or a mixture of both for the nickel electrodes process to avoid porosity.
Post Welding Imperfection
Nickel is vulnerable to post-weld heat treatment cracking and stress corrosion cracking. Welders can address these issues through pre-heat weld treatment and applying for thermal stress relief after welding.
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