MANUFACTURE OF SI-CONTAINING HIGH STRENGTH HOT-DIP GALVANIZING CARBON STEEL SHEETS AND ALLOY HOT-DIP GALYANNEALED STEEL SHEETS

摘要

PURPOSE: To eliminate generation of non-plated parts and promote Zn-alloying by applying the specific aqueous solution of sulfur compound, thereby realizing annealing in the non-oxidizing atmosphere after preliminarily executing the degreasing of a steel plate surface on executing the hot-dip galvanizing the surface of the Si-containing high strength steel sheet. ;CONSTITUTION: After oils and fats sticked on the surface of a high strength steel sheet containing Si0.2% are degreased with NaOH aqueous solution, the aqueous solution having a concentration of ≥0.1% sulfur compound such as thiourea is applied on the surface of a steel sheet following the spray process, the dipping process or the like, then the steel sheet is dried by the hot air. Successively, hot-dip galvanizing is executed after this steel sheet is heated and annealed in the non-oxidizing atmosphere. Non-plated parts are generated, and the alloying speed is improved in executing alloying of the plated Zn and Fe of the steel sheet.;COPYRIGHT: (C)1993,JPO&Japio