Significance of Material Antisepsis

 

Corrosion-resistant material is used for many applications where the working conditions and requirement for corrosion resistance are ramified. Corrosion is an intrinsic problem for utility metals. In case of steel, stainless steel, galvanizing, electro galvanizing, and weathering steel of which corrosion can be prevented or moderated have been put to practical use. This has led to an increase in the volume of steel used along with the improvement in performance for corrosion resistance.

 

Japan has constructed and accumulated large-scale social and industrial infrastructures since the post-war high economic growth period. Thirty years have already passed since then, and the demand is growing for effective maintenance and a long service life of those infrastructures. On the other hand, in the fields of durable consumer goods and daily necessaries, public attention has been focused on 3 R (Reduce, Reuse, and Recycle) aiming at the improvement of a recycling rate and the reduction of wastes as a consequence of the enforcement of various environment-related laws, including the law for recycling of specified kinds of household electric appliances, and the green purchase law. Furthermore, in anticipation of the directive of EU (European Union), a move is rapidly being made toward the reduction in and the ban on the use of the environmental affecting substances, particularly lead and hexavalent chromium. As abovedescribed, the changes in social needs and the progress of industrial technology have asked high technology for corrosion protection over a broad range of fields along with the request for high performance under severer working conditions.

 

Fig. 1 shows the outline of the market needs and the progresses in technology in respective fields. The horizontal-axis shows the applications in a variety of fields from daily necessaries and durable consumer goods with a comparatively short service life (in the order of several to 15 years) to social infrastructures for which a service life of over 100 years is required. In the field of daily necessaries and durable consumer goods, anti-rusting carries weight, and coating is applied. In the field of social and industrial infrastructures, a target is set for a long service life of over 50 years, and corrosion-resistant steel is mainly used. The main technical issue is how to make a service life longer, including how to maintain. Compliance with the en-vironment applies to all fields. Nippon Steel has so far succeeded in developing many corrosion-resistant steel and coated steel.

 

This paper, after supplementing the working environment and requirements for corrosion resistance, introduces the important development in corrosion-resistant materials and corrosion protection technology together with typical commercialized new products in recent years in Nippon Steel.