Brief description of the pre - chemical treatment before galvanization of toles of steel is distinguished by a content of silicon and phosphorus particular.

摘要

Process for chemical pretreatment, before galvanising, of steel sheets distinguished by a particular silicon and phosphorus content, characterised in that the article to be treated, pickled and degreased beforehand, is immersed for approximately 15 to 30 minutes in a nickel bath containing an alkali metal or alkaline-earth metal hypophosphite at a temperature of between 80 and 100 DEG C, preferably between 85 and 95 DEG C, so as to coat this article with a pretreatment layer which has a maximum thickness of approximately 10 mu m and a phosphorus content of between 1 and 20 %.