Production of super steel by multi directional forging

研究了大变形量弥散相对超细晶演变的影响。为此，可使用含有约1体积%的奥氏体不锈钢。在637和873 K温度下，对半径为30 ~ 70 nm的第二相粒子进行了多轴压缩，最大压缩应变ε=6.0。随着应变的增加，位错壁或位错边界节点的组织逐渐发展。然而，细晶粒的演变似乎是停滞的细颗粒的存在下相比，没有沉淀物的普通304不锈钢的结果。即使在ε=6.0时，超细晶演化也不明显，但在变形带和微带附近，超细晶的平均晶粒尺寸约为0.5μm。这种微观结构的演变看起来更明显的样品中含有更细的颗粒。这一结果表明，回复过程是影响剧烈塑性变形过程中超细晶演变的重要因素之一。

Effect of large amount of dispersed particles on ultra-fine grain evolution severe deformation was investigated. For that purpose, austenitic stainless steels containing about 1 vol.% of second phase particles, which radii ranged from 30 to 70 nm, were multi-axially compressed at 637 and 873 K to a strain of ε=6.0 at maximum. Microstructure with nodes of dislocation walls or boundaries was gradually developed as strain increased. However, fine-grain evolution seemed to be stagnated by the presence of the fine particles when compared with the result of plain 304 stainless steel with no precipitates. Though ultra-fine grain evolution was not sharply took place even at ε=6.0, the grain size of the ultra-fine grains specifically evolved around deformation bands and microbands was about 0.5μm in average. Such microstructural evolution looked to be more obvious in the samples containing finer particles. This result suggests that recovery process is one of the most important factors on the ultra-fine grain evolution by severe plastic deformation.