Rationale

Both Ferritic Stainless Steel Types 409 and 439 were first introduced to ASTM A463 in 1999. The molybdenum requirement was intended to be Mo 0.60 % maximum, for both Types. Unfortunately, when ASTM A463-99a was issued, the molybdenum requirement for FSS Type 439 was incorrectly published as Mo 0.06 % max versus the correct value of Mo 0.60 % max. This error was recently identified and needs to be corrected. This ballot item corrects this error.