Formation of Carbide Dispersion Type Overlay Weld by Plasma Arc

Study on Hardfacing Process Using Extremely Hard Material (Ist Report)

Abstract

A new plasma arc hardfacing process has been developed for the overlay weld with excellent wear resistance.
In this process, the powder mixture, transition metal carbide NbC or VC with austenitic stainless steel SUS304L, is used as hardfacing material, and the overlay weld consisted of matrix alloy and unmelted carbide particles dispersed uniformly is formed.
The main results obtained are summarized as follows:
1) In the bead-on-plate welding with oscillation of 10 mm width, the overlay weld having good shape and low penetration is obtained by powder feeding rate of 10-15 g/min, welding current of 100-120 A and travelling speed of 3-6 cm/min.
2) Mean hardness of the overlay weld is adjustable from Hv 400 to 1000 according to the carbide content in powder mixture fed.
3) In spite of high hardness, the weld crack sensitivity of this process is less than conventional hardfacing materials such as Co-Cr-W alloy.
4) Abrasive and adhesive wear tests show that the wear resistance of this weld metal is excellent in comparison with other hardfacing materials and wear resistant materials.