Ti-CONTAINING FERRITIC STAINLESS STEEL SHEET, MANUFACTURING METHOD, AND FLANGE

Abstract

A Ti-containing ferritic stainless steel sheet having a large gauge thickness and excellent toughness has a chemical composition containing, in terms of percentage by mass, from 0.003 to 0.030% of C, 2.0% or less of Si, 2.0% or less of Mn, 0.050% or less of P, 0.040% or less of S, from 10.0 to 19.0% of Cr, 0.030% or less of N, from 0.07 to 0.50% of Ti, from 0.010 to 0.20% of Al, from 0 to 1.50% of Mo, and from 0 to 0.0030% of B, the balance of Fe and unavoidable impurities. The steel has a K value defined by the following expression of 150 or more: K value=−0.07′Cr−6790′Free(C+N)−1.44′d+267, and having a sheet thickness of from 5.0 to 11.0 mm. Herein, Free(C+N) corresponds to the solid-dissolved (C+N) concentration (% by mass), and d represents an average crystal grain diameter (μm).

Description

TECHNICAL FIELD[0001]The present invention relates to a Ti-containing ferritic stainless steel sheet having a large gauge thickness excellent in toughness, and a method for manufacturing the same. The invention also relates to a flange using the Ti-containing ferritic stainless steel sheet.BACKGROUND ART[0002]Members for an automobile exhaust gas flow path are demanded to have such characteristics as corrosion resistance, heat resistance, strength, and the like. As a material that is excellent in these characteristics, an austenitic stainless steel sheet has been frequently used. In recent years, there is an increasing need to use a ferritic type steel, which has a small thermal expansion coefficient and a small raw material cost, instead of an austenitic type steel. Examples of the alternate material therefor include a Ti-containing ferritic stainless steel sheet.[0003]Members for an automobile exhaust gas flow path are generally produced by subjecting a cold rolled and annealed st...

AI Technical Summary

Benefits of technology

[0021]According to the invention, a steel sheet having a large gauge thickness of a Ti-containing ferritic stainless steel excellent in toughness can be stably achieved. The steel sheet is enhanced particularly in low temperature toughness, and thus the restrictions in the passing condition to the line and the production condition can be alleviated. The steel sheet having a large gauge thickness has high reliability in toughness even in the case where the steel sheet having a large gauge thickness as a material is worked into various members (such as a flange for an automobile exhaust gas flow path.

Problems solved by technology

These measures involve deterioration of the productivity and increase of the production cost.