对低碳钢板材进行表面球磨处理，利用电子显微术研究剪切变形方式下深度方向的组织演变。结果表明，低碳钢的纳米化过程包括：位错通过增殖、运动、湮灭和重组形成位错墙；位错墙逐渐转变成小角度和大角度晶界，将原始粗晶分割成亚微晶；亚微晶内重复上述过程使晶粒继续细化，最终形成等轴状、取向接近随机分布的纳米晶组织。外力作用方向并未改变纳米化过程，但会影响变形层的厚度。当晶粒处于有利于滑移系开动的取向时，可以加快纳米化进程。
A low carbon steel was treated by means of ball milling, and the shear-stress induced microstructural evolution along the depth was examined by using electron microscopy. The grain refinement process of low carbon steel includes: formation of dislocation walls through propagation, slip, annihilation and recombination of the dislocations; transformation of dislocation walls into small to large angle boundaries to refine the initial coarse grains into submicro-grains; further subdivision of submicro-grains by means of dislocation activities leads to the formation of equiaxed grains with random orientations. The directions of external loads can not affect the grain refinement process, but can change the thickness of deformation layer, and the grain refinement process can be promoted in those grains with more active slip systems.
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