Fabrication of 10 nm grained bulky material and the properties

具有低层错能的SUS304和SUS316不锈钢在室温和77K下进行了多向锻造(MDF)，较低的MDF温度会加速机械孪晶的发生，使晶粒细化到20 nm以下。随着MDF累积应变的增加，孪晶相交进行细化。温度越低，这一趋势越明显。然而，马氏体相变的发生阻碍了晶粒的细化。因此，与SUS316不锈钢相比，由于马氏体相变，SUS304不锈钢的晶粒细化和强度没有那么显著。MDFED不锈钢具有较好的强度和塑性平衡，分别为1.8 Gpa和20%。

SUS304 and SUS316 stainless steels having low stacking fault energy were multi-directionally forged (MDF) at ambient temperature and 77 K, where lower MDF temperature would accelerate occurrence of mechanical twinning to cause grain refinement down to 20 nm. As the increase in cumulative strain of MDF, grain refinement proceeded by intersection of twins. This tendency was more obvious at lower temperature. Occurrence of martensitic transformation, however, hindered the grain refinement. The grain refinement and strength in the SUS304 stainless steel, therefore, were not so notable due to martensitic transformation compared with in the SUS316 one. The MDFed stainless steels possessed superior balance of strength and ductility, i.e., 1.8 GPa and 20 %.