关键词：挤压-切削；可控厚度；双层梯度结构；梯度超细晶带材；机械性能中图分类号：TG376DOI：10.3969/j.issn.1004-132X.2025.04.010 开放科学（资源服务）标识码（OSID）：

New Process and Mechanism of Squeeze-machining for Preparing Bilateral Gradient Structure Sheets with Controllable Thickness

PANG Xueqin1，² ZHAO Junyu1 DENG Wenjun² ZENG Yuning² ZHONG Peixuan2* 1.Faculty of Electrical and Mechanical Engineering，Kunming University of Science and Technology， Kunming，650500 2.School of Mechanical and Automotive Engineering，South China University of Technology， Guangzhou，510641

Abstract ： To address the issues of high strength but low ductility in ultrafine-grained materials，a unique squeeze tool and extrusion channel design was developed. This design enabled the one-step fabrication of ultrafine-grained sheets with a controllable thickness and a bilateral gradient structure through the combined effects of squeeze，friction and cutting. The numerical simulation and experimental methods were combined to analyze the forming processes of bilateral gradient structured pure copper sheets. The mechanism of squeeze-machining machining and the influences of processing parameters on the formations of the bilateral gradient microstructure were explored. The results show that，compared to the original pure copper samples，the maximum hardness of the pure copper sheets prepared using the squeeze-cutting method is increased by approximately threefold. Additionall，the sheets exhibit an excellent strength-ductility synergy： while some ductility is sacrificed， the yield strength nearly is of doubles，and the ultimate tensile strength increases by a factor of four.

Key words： squeeze-machining； controllble thickness； bilateral gradient structure; gradientultra-fine-grained sheet；mechanical property

0 引言

强度-延展性的协同是金属材料发展和应用中的一大障碍[1]。近年来，研究人员提出了有希望解决强度和延展性协同性问题的策略，即异质结构设计，其中梯度结构作为异质结构的典型代表，既可有效改善超细晶/纳米晶材料的强度-塑性“倒置\"矛盾，又可使不同特征尺寸的结构相互协调，避免结构尺寸突变引起的性能突变，使材料使役行为和整体性能得到优化提高[2]。目前，制备梯度结构材料的工艺主要有电化学沉积以及大塑性变形方法。

电化学沉积可通过改变试剂浓度、流压密度、催化强度等，诱导基材产生梯度结构[3]，但沉积的控制过程可控性差且往往存在不确定性，易使梯度结构内部产生应力及偏析杂质，影响材料性能的稳定[4]。另外，电化学沉积的过程中还会产生大量有毒废液，这与当下强调的绿色发展理念相悖，因此电化学沉积法在实际应用中并不广泛。

大塑性变形法制备梯度结构的主要工艺有表面机械碾压[5]、表面机械研磨[6、表面机械滚压[7]、滑动摩擦[8]、喷丸[9]等。WU等[10]通过表面机械滚压工艺在商业纯钛上制备了梯度纳米结构层，相比于粗晶试样，其强度提高1.8倍后延展性只下降了 22% 。CHENG等[11]通过调整表面机械研磨时间来制备梯度结构的纯铜，其屈服强度可达粗晶纯铜的2.3倍。ZHANG等[12]通过超声喷丸的方法制备了新型轴承钢材料的梯度结构超细晶，相比于粗晶，虽然其抗磨损性大幅提高却也牺牲了部分韧性。……