I anneal before grinding the weld, then anneal afterwards, easy to see color. As I remember the instructions I found from Lenox say to pulse the anneal button to control the color and time to cool. I have to admit I've gotten to red, but then pulsed back to blue, and had no troubles at all.
I use the Ideal welder that's on my Powermatic 87, but only use 1/2" or narrower stock. I've welded carbon steel, bi-metallic, and carbide tipped blades with great success. I'm wondering why some people say not to weld carbide tipped blades - seems the blade body would be similar to bi-metallic, just some sort of steel?