Thanks all for your comments. Lofty, higher temperature hard silver soldering needs such a high temperature that the temper of the blade will be ruined.

The solder I use is 4 % silver content Eutectic brand and solders at 198 degrees centigrade. It does not corrode over time. I know that because I occasionally see knives I 've made that are over 20 years old. Still bright and shiny, also after intensive use.