In investigating the properties of the developed ferritic stainless steel, it was found that the newly developed ferritic stainless steel shows higher r-values than mild steel with the same level of {1 1 1} recrystallization texture. This paper discusses the mechanism of this difference and describes the fundamental properties of the newly developed ferritic stainless steel. Three samples have been tested. Steel A was a titanium bearing high purity 18-mass-% chromium 1.2-mass-% molybdenum content ferritic stainless steel. Steel B was a titanium bearing high purity 18-mass-% chromium 1.45-mass-% molybdenum content ferritic stainless steel, which has near corrosion resistance nearly equal to that of SUS 304. Steel C was a titanium bearing mild steel. Slabs of these compositions were reheated, hot rolled, annealed as hot band, cold rolled and then annealed for recrystallization, and finally provided for experiments in the form of sheets with a thickness of 0.8 mm. Average r-values of these specimens ranged from 1.8 to 2.7. Tensile tests were performed in accordance with JIS Z 2241 using HIS 13B test specimens. Furthermore, the properties of the developed ferritic stainless steels sheets, which have excellent deep draw ability were evaluated. The following results were obtained: 1. Ferritic stainless steel and mild steel show a positive correlation between the {1 1 1} intensity and the average r-value. However, ferritic stainless steel shows higher r-values than mild steel with the same level of {1 1 1} intensity. r-values of the ferritic steels are not determined by texture alone. If it is assumed that chromium limits some slip systems in BCC metals, it is possible to explain why high r-values are easily achieved in chromium bearing ferritic steels. Ferritic stainless steel shows higher achieved r-values in comparison with high formability mild steels of the same strength level. Chromium addition contributes to property improvement in both strength and the r-value. Based on the investigation results, development of ferrite stainless steel with deep drawability which has r-value of the highest level in the world has been achieved. The newly developed ferritic stainless steel sheets are expected to be applied in a wide range of automotive parts, and applications requiring corrosion resistance and deep drawability, in which SUS 304 or high strength steel with corrosion protection treatment has been used.
Development of ferritic stainless steel sheets with excellent deep drawability by {111} recrystallization texture control
Ferritische nicht rostende Stahlbleche mit exzellenter Tiefziehfähigkeit
JSAE Review ; 24 , 4 ; 483-488
2003
6 Seiten, 7 Bilder, 2 Tabellen, 12 Quellen
Article (Journal)
English
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