喷丸对30CrMnSiNi2A合金钢表层组织性能的影响及其微观机理

Effect and Microscopic Mechanism of Shot Peening on Microstructure and Properties of 30CrMnSiNi2A Alloy Steel Surface Layer

使用气动式喷丸设备制备了30CrMnSiNi2A合金钢喷丸强化处理试样,并对试样表层的组织性能进行了综合分析。采用扫描电镜和透射电镜观察了试样表层的显微组织结构,利用纳米压痕仪和X射线应力仪测试了喷丸处理和未处理试样表层纳米显微硬度和残余应力沿厚度方向的分布。结果表明:未处理试样的组织主要为板条马氏体、少量的下贝氏体、孪晶及残余奥氏体,喷丸处理在试样表面形成了厚度约为30μm的致密塑性变形层,该层内晶粒平均直径约为46 nm,纳米显微硬度值达到6.8 GPa,加工硬化量提高了4.9%;同时,喷丸处理在试样表面引入了深度约为280μm的残余压应力层,最大值为-1050 MPa。最后,分析了喷丸处理晶粒细化机制及其对材料加工硬化和残余应力的影响。

The strengthening treated samples of 30CrMnSiNi2A alloy steel were prepared by pneumatic shot peening equipments, and microstructure and mechanical properties of the samples surface layer were analyzed. Microstructures of the samples surface layer were investigated by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The surface layers＇ hardness and residual stress distributions along the thickness direction of the samples with and without shot peening treatment were measured by nano- indention and X-ray diffraction method. The results showed that the organization of untreated sample is lath martensite and a small a- mount of bainite, twinning, and retained austcnite. A plastic deformation layer was formed by the shot peening treatment, and the depth extended up to about 30 p,m. The average grain size was about 46 nm in this layer which hardness average values was up to 6.83 GPa, and increased 4.9% than the untreated sample. At the same time, a residual compressive stress layer was also produced by shot peening treatment, and the depth was close to 300 p,m. The maximum compressive residual stress was - 1050 MPa. At last, the grain refinement mechanism of shot peening treatment and effect on work hardening, compressive residual stress were discussed.