超高强度不锈钢冷轧薄带材拉伸变形特征

Investigation on Tensile Deformation Characteristics of the Cold Rolled Thin Strip of a Maraging Stainless Steel

借助于板拉伸试验,研究了0.3mm厚马氏体时效不锈钢冷轧薄带材的拉伸变形特征。结果表明薄带材板拉伸试样较高的宽厚比(w/t)强烈约束拉伸变形过程中的漫缩颈变形,降低了总的断后伸长率。拉伸试样最终形成局部缩颈带,局部缩颈充分扩展后通过微孔聚合形成裂纹,裂纹扩展到临界尺寸后沿最大剪应力面断裂。试样局部缩颈区累积较高的应变后断裂证明薄带材具有良好的宏观塑性。此外,微孔聚合型的微塑性断裂也证明超高强度薄钢带具有足够的可靠性。

By means of sheet tensile test, the plastic deformation characteristics of 0.3mm-thick cold rolled strip of a maraging stainless steel have been investigated. The results have indicated that the very high width to thickness (w/t) ratio in sheet tensile specimen developed a constraint to diffuse neck growth in the width direction, lowering the gross elongation and resulting in the formation of a local neck, which is the dominant failure mode. With the local neck strain accumulation, microvoids initiated, grew, and coalesced to develop the final fracture along the maximum shear stressplane. Due to considerable strain accumulation prior to fracture initiation in the local neck bands, it was confirmed that thin steel strip possess good ductility. Moreover, the microscale ductile fracture by microvoid coalescence has also demonstrated that structural components fabricated from the thin steel strip has sufficient reliability.