method for heisstauch coating without alloying steel plate with a low content of zwischengitteratomen

摘要

Interstitial free steel sheet is coated with Al, Zn or Al Zn alloy by dipping the heated steel into a relatively cool bath of molten Al, Zn or alloy and subjecting the dipped steel to a heat treatment of less than 5 mins., pref. around 2 mins., duration where it is first heated quickly to a temp. above 300 degrees C but below the temp. at which the coating would alloy with the steel and then quickly cooling to ambient temp. The heat treatment temp. is 550-625 degrees C for Al or Al alloy, 320-390 degrees C for Zn or Zn alloy and 390-550 degrees C for an alloy of Al and Zn. Prior to dipping the steel is cleaned and recrystallised by heating in a non-oxidising atmosphere. The Al based coating provides a base for subsequent enamelling and the Zn based coating for a paint coating which needs to be baked at over 100 degrees C.