40Cr钢表面纳米化组织与性能的研究

Study on Microstructure and Properties of 40Cr Steel Surface Nanocrystallization

采用超音速微粒轰击技术(SFPB)对40Cr调质钢进行表面纳米晶结构层的制备,利用TEM、XRD、GX-71型金相显微镜和TUKON2100显微/维氏硬度计等对表面纳米层的组织结构、硬度以及耐磨性进行了分析研究。结果表明:经过SFPB表面处理后,40Cr调质钢表面晶粒细化,形成了随机取向的铁素体和渗碳体纳米晶粒构成,晶粒尺寸达到10nm,纳米层厚度为40μm。纳米晶粒尺寸随着距表面距离的增加而增大,纳米化主要是位错运动的结果。经SFPB处理后,表层的显微硬度提高到526HV,且随着深度的增加,硬度迅速降低,表面的耐磨性也明显提高。

By means of supersonic fine particles bombarding （SFPB）, nanostructured surface layer was fabricated on 40Cr steel plate. The microstructure features of various sections in the surface layer were characterized by using XRD, TEM and optical microscope observation. The micro-hardness was measured by micro-hardness instrument. The result shows that after SFPB treatment, in the surface layer, nano-sized grains are observed and composed of ferrite and cementite phases, the the mean grain size in the surface layer is about 10 nm and the depth is about 40μm; The grain size increases depending upon distance from the treated surface. Experimental evidence and analysis indicate grain refinement could be mainly attributed to the movement of dislocation. The surface micro-hardness is increased to 526HV, and decreases rapidly with the increase of the depth from the surface. At the same time, its wear resistance also is greatly improved.