Effect of cold rolling reduction ratio on microstructure and properties of 439L ferritic stainless steel
The cold rolling process has an important impact on the subsequent annealing structure of ferritic stainless steel,and is also the key to obtaining good surface quality,mechanical properties and formability.In this paper,Nb+Ti dual-stabilized 439L ferritic stainless steel was used as the experimental material.By means of X-ray diffraction,microstructure characterization and performance testing,the effects of different cold rolling reduction ratios(60%～85%)on the evolution of microstructure and texture during the annealing process(1000℃×2 min)of the stainless steel and on its mechanical properties and formability were studied.The results show that with the increase of cold rolling reduction ratio,γ-fiber texture in 439L ferritic stainless steel after annealing continues to strengthen,while the α-fiber texture gradually disappears.This means that α→γ texture transformation occurs during annealing.Moreover,with the increase of cold rolling reduction ratio,the peak intensity of annealing texture gradually increases and moves to γ-fiber orientation line.In such a case,the average plastic strain ratio(rm)of cold-rolled and annealed 439L steel sheet continuously increases,and the sheet steel has the minimum absolute value of the planar anisotropy(|Δr|)when the cold rolling reduction ratio is 80%.
ferritic stainless steelcold rolling reduction ratioannealingtextureformability
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