Copper-Nickel-Silicon Spring Hardness

Copper-nickel-silicon alloys are hardened by cold working and precipitation of silicides. This gives the material its spring force and fatigue strength under bending. When welding, you have to be careful not to lose this hardness: if you put in too much heat, the structure overages and the material becomes soft. Porosity is also an issue if you don't work clean. So keep the heat input as low as possible and let the part cool slowly after welding, then the spring effect in the core is maintained.