J507堆焊层超声冲击表面纳米化

采用在工程上获得广泛应用的超声冲击技术在J507堆焊层上制备纳米结构表层,利用金相显微镜、x射线衍射和透射电子显微镜表征了表面纳米晶层的结构,并对超声冲击表面纳米化处理前后表面层显微硬度的变化进行了分析.结果表明,经过超声冲击处理后,试样表层的晶粒可细化至21.25 nm.在超声冲击载荷作用下,粗晶粒内部形成高密度的位错墙和位错缠结,位错墙和位错缠结逐渐演变成小角度亚晶界,小角度亚晶界继续吸收位错而转变成大角度晶界,亚晶内部不断重复上述过程,使晶粒尺寸不断减小,最终形成纳米晶.表面强化层的厚度为100 um.与样品的心部相比,表面纳米晶层的显微硬度提高1.4倍.

Fabrication and characterization of nanocrystructured surface layer of J507 weld by ultrasonic impact peening

A nanostructured surface layer was fabricated on a J507 weld metal by. ultrasonic impact peening (UIP). The refined microstructure in the top surface layer was characterized by means of X-ray diffraction and transmission electron microscopy (TEM), and the microhardness variation along the depth of the treated sample was examined. Experimental results show that, after the UIP treatment, the microstructure of the surface layer may be refined into 21.25 nm. Grains refinement involves formation of dense disloca...