engleski

Weldability of nickel and nickel-based alloys

Nickel is strategic metal due to its importance for aerospace, military, power and chemical industry. Commercially pure (CP) nickel and three different nickel-based alloys — solid-solution strengthened (SSS), precipitation strengthened (PS) and specialty alloys — are broadly used, usually at very high temperatures, in corrosive environments and in cryogenic applications. Nickel or nickel alloys often need to be welded. All electric arc and beam power welding processes have been applied on nickel and its alloys. TIG and EBW have been most frequently used. Friction stir welding (FSW) is the most promising solid state welding process for joining nickel and its alloys. Porosity, hot and warm cracking are the main weldability problems associated with nickel and its alloys. CP nickel has the best weldability. It is susceptible to porosity and weld metal solidification cracking. Generally, SSS alloys have better weldability compared to PS nickel alloys but both can exhibit weld metal solidification cracking, liquation cracking in partially melted and heat-affected zone and ductility-dip cracking (DDC). Additionaly, PS alloys are susceptible to strain-age cracking (SAC). Weldability of speciality nickel alloys is poor and brazing could be the solution. Using suitable filler metal, welding parameters and low restraint can minimize or prevent cracking.

Nickel ; Nickel-based Alloys ; Weldability ; Hot Cracking ; Weld Metal Solidification Cracking ; Liquation Cracking ; Ductility Dip Cracking (DDC) ; Strain Age Cracking (SAC) ; Porosity ; Welding Processes

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