PROCESS FOR PRODUCING AUSTENITE STAINLESS STEEL, SOLDER MELTING VESSEL AND AUTOSOLDERING APPARATUS

摘要

A passivated coating including a nitriding modified layer wherein no chromium nitride (CrN) is contained is formed on a surface of austenite stainless steel. The passivated coating constituted of chromium oxide acts as a protective film against lead-free solder. As a result, the surface of stainless steel even when brought into contact with a lead-free solder bath becomes resistant to corrosion, thereby exhibiting a strikingly enhanced anticorrosion, and also has abrasion resistance. With respect to a SUS316 stainless steel having a passivated coating provided on its outermost surface, as shown by line Le in Fig. 4, the time up to corrosion start is prolonged (about 500 hr), and the depth of corrosion becomes less than the conventional (about 20 to 25 mum). Thus, it is foreseen that the durable years can be improved to those of the same level as exhibited in the use of lead solder, so that a highly anticorrosive stainless steel can be obtained.