摘要
在微塑性成形过程中,虽然零件的宏观尺寸达到了毫米或微米级,但其微观组织却没有发生明显的变化,材料的表层晶粒尺寸也就越来越趋近零件的几何尺寸,导致塑性成形规律呈现出与宏观大尺寸零件不同的尺寸效应现象。对四种厚度的304不锈钢薄板试样进行了单向拉伸试验和微弯曲试验,测量了薄板的厚度。结果表明,随着薄板厚度的减小,塑性变形区内表层晶粒的位错滑移变化对力学性能和无量纲弯矩的影响越来越显著,表现出"越薄越强"的尺寸效应现象。引入修正的Hall-Petch公式与修正的Nix-Gao应变梯度模型,使力学性能和无量纲弯矩的预测和试验结果吻合。
In the process of micro-plastic forming, although the macroscopic sizes of the parts reach the millimeter or micron grade, its microstructure has not changed significantly. The surface of the grain size of the material is more and more closer to the geometry of the part, so that the plastic forming law presents the different size effect phenomenon of the macro-size parts. The uniaxial tensile test and micro-bending test of 304 stainless steel sheet samples with four thicknesses were carried out. The thickness of the sheet was measured. The results show that with the decrease of the thickness of the sheet, the influence of dislocation slip of the surface grain size in plastic deformation zone on the mechanical properties and dimensionless moment is more and more remarkable. It shows the size effect of ＂the thinner, the stronger＂. Introducing the modified Hall-Petch formula and modified Nix-Gao strain gradient model, it makes prediction results of mechanical properties and the dimensionless moment in good agreement with the experimental results.
出处
《热加工工艺》
CSCD
北大核心
2015年第23期35-37,41,共4页
Hot Working Technology
关键词
304不锈钢
表层晶粒
应变梯度
304 stainless steel
surface grain
strain gradient
