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采用表面机械滚压对退火态Zr-4合金进行表面纳米化处理并对其微观组织和力学性能开展了系统研究。滚压处理在Zr-4合金表面形成纳米/超细晶及变形层的厚度与滚压道次、每道次滚压深度有关;对Zr-4合金优化后的滚压参数为每道次滚压深度40μm、滚压8道次,获得从表面到心部由纳米晶、超细晶、变形组织和心部原始粗晶连续梯度变化的组织形貌,其纳米/超细晶层的厚度约为100μm,变形层的厚度约为300μm。Zr-4合金经滚压处理后,表层显微硬度显著提高;屈服强度和抗拉强度分别为352和600 MPa,各提高了7%和9%,延伸率略有降低。用混合法则计算了Zr-4合金表面滚压处理后的屈服强度,与实验值吻合。
The surface nanocrystallization of the as-annealed Zr-4 alloy was carried out by surface mechanical rolling and the microstructure and mechanical properties were systematically studied. The thickness of the nanostructured / ultrafine crystal and deformed layer formed on the surface of Zr-4 alloy by rolling is related to the rolling pass number and the rolling depth per pass. The rolling parameters optimized for Zr-4 alloy are as follows: Pressure depth of 40μm, rolling 8 times to obtain from the surface to the heart by the nanocrystalline, ultrafine crystal, deformed tissue and the heart of the original coarse grained crystalline gradient morphology, the nano / ultrafine layer thickness of about Is 100 μm, the thickness of the deformed layer is about 300 μm. After rolling, the microhardness of Zr-4 alloy was significantly improved. The yield strength and tensile strength were 352 and 600 MPa, respectively, increased by 7% and 9%, respectively, and the elongation decreased slightly. The mixing law was used to calculate the yield strength of the Zr-4 alloy after rolling, which is consistent with the experimental data.