I have a job on the farm to weld brackets of mild steel (10mm thick) to a high carbon steel (tool steel) (20mm thick). I have experience of basic welding, but would appreciate some advice as I know this can't be done with standard rods. I have googled the subject and although a little wiser am still a little confused. From what I've gathered, I think I will use 312-16 rods, I have seen reference to pre-heating, but also other advice saying with a 312 rod this is unnecessary? Is there any particular technique for welding with 312 rods? TIA.