Lu Ruilong, Han Jingtao, Li Zhanhua, Zhang Congfa, Liu Jiawei, Liu Cheng, Lang Zhenqian, Ma Xiaoyan
School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
Guangzhou Sino Precision Steel Tube Industry Research Institute Co., Ltd., Guangzhou 511300, China.
Materials (Basel). 2023 Oct 17;16(20):6719. doi: 10.3390/ma16206719.
QBe2.0 strips were used to fabricate spiral tubes and actuators for controlled extension (STACERs) through the winding and stabilization method, which is a novel technique for obtaining STACERs. The raw strips and the STACERs were investigated using tensile tests and SEM for the mechanical properties and fractography observation, employing specialized test equipment for service performance, and via XRD, EBSD, and TEM were used to test the residual stress and microstructure evolution. The tensile strength/elongation for raw strips was 485.8 MPa/60%, while for STACERs, tensile strength increased by 834.67 MPa to 646 MPa, and the elongation rate decreased by 12% to 19.3%. The fractography showed that the fracture mode was ductile. The service performance tests indicated that STACERs obtained under 320 °C had a higher driving force, good pointing accuracy, and high bending stiffness, while the residual stress of raw strips was τ = -6 MPa; for STACERs obtained between 290 °C and 350 °C, τ decreased from -5 MPa to -74 MPa, then increased from -74 MPa to 21 MPa, and the optimum fabricating parameter was 320 °C + 2 h. The EBSD results showed that LABs and HABs for raw strips and STACERs at 320 °C + 2 h accounted for 3-97% and 24.5-75.5%, the grain sizes were 7.07 μm and 3.67 μm, and the twin fraction decreased from 57.3% to 31.8%, respectively. The KAM and Schmid factor maps indicated that the STACER was prone to recovering and recrystallizing. Coupled with the EBSD results, the TEM results indicated that the strengthening mechanism for raw strips is twinning strengthening, while that for STACER is grain-refining strengthening with a precipitation of the γ″ phase. It is a meaningful novelty that the relationship between the macro properties and microstructure has been elucidated.
采用QBe2.0带材通过缠绕和稳定化方法制造用于控制延伸的螺旋管和致动器（STACER），这是一种获得STACER的新技术。使用拉伸试验和扫描电子显微镜对原始带材和STACER进行了机械性能和断口形貌观察研究，采用专门的测试设备测试其服役性能，并通过X射线衍射、电子背散射衍射和透射电子显微镜测试残余应力和微观结构演变。原始带材的抗拉强度/伸长率为485.8MPa/60%，而STACER的抗拉强度增加到646MPa，增加了834.67MPa，伸长率降低了12%，降至19.3%。断口形貌表明断裂模式为韧性断裂。服役性能测试表明，在320℃下获得的STACER具有更高的驱动力、良好的指向精度和高弯曲刚度，而原始带材的残余应力为τ = -6MPa；对于在290℃至350℃之间获得的STACER，τ从-5MPa降至-74MPa，然后从-74MPa升至21MPa，最佳制造参数为320℃ + 2h。电子背散射衍射结果表明，原始带材以及在320℃ + 2h条件下的STACER中低角度晶界和高角度晶界分别占3 - 97%和24.5 - 75.5%，晶粒尺寸分别为7.07μm和3.67μm，孪晶分数分别从57.3%降至31.8%。取向差角平均值和施密德因子图表明STACER易于回复和再结晶。结合电子背散射衍射结果，透射电子显微镜结果表明原始带材的强化机制是孪生强化，而STACER的强化机制是晶粒细化强化并伴有γ″相析出。阐明宏观性能与微观结构之间的关系是一项有意义的新发现。
