Method for measuring surface layer oxide film thickness of galvanized steel plate

Abstract

A major object is to provide a technique of measuring the thickness of a 10 to 100 nm-thick oxide film formed on the surface of a zinc-based plated steel sheet in a quick and highly precise manner. Another major object is to evaluate the press formability of a plated steel sheet having an oxide film on the basis of the measured oxide film thickness. A method of measuring the film thickness of an oxide film formed on the surface of a zinc-based plated steel sheet is characterized by applying an electron beam accelerated to 3 to 6 kV using a scanning electron microscope having an electron probemicro-analyzer or wavelength dispersive X-ray detector and measuring the intensity of the oxygen Ka-line generated by the application through the detector and a pulse height analyzer at the succeeding stage to exclude the influence of the secondary line of the zinc L-line.

Description

technical field The present invention relates to a technique for quickly measuring the thickness of an oxide film with a thickness of 10nm to 100nm formed on the surface of a galvanized steel sheet. Background technique In the product fields of steel, semiconductors, and displays, surface coatings with a thickness of tens to hundreds of nm sometimes become factors that determine product characteristics. In the field of iron and steel products, the surface layer film with a thickness of tens to hundreds of nm sometimes becomes a factor that determines the stamping characteristics of the product. In recent years, steel sheets used for automobiles and home appliances have been frequently plated with zinc from the viewpoint of high corrosion resistance. When manufacturing difficult-to-form parts by press-forming galvanized steel sheets, there is a problem that press cracks in the steel sheets tend to occur at difficult-to-work locations. There is known a method of improving th...

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Problems solved by technology

However, for example, when there are unevenness caused by temper rolling and fine unevenness caused by alloying reaction on the base plated steel sheet, such as alloyed hot-dip galvanized steel sheet, it is difficult to ensure the measurement accuracy of the film thickness.

As mentioned above, there is no technology that can accurately measure the thickness of the ultra-thin oxide film formed on the surface layer of hot-dip galvanized steel sheets at a minimum speed that does not delay shipments.

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