Techalloy 99 description: Techalloy 99 is used for welding of cast irons to other cast irons as well as for joining cast irons to mild steels and stainless steels. It is also readily used for the repair of castings. The welds produced are generally more machinable than a Tech-Rod 55 deposit. A preheat and inter-pass temperature of not less than 350F (175C) is required during welding to prevent cracking.