We describe here the aging characteristics and strengthening behavior of a low-carbon medium-Mn Cu precipitation-strengthened steel. Atom probe tomography (APT) was employed to characterize the evolution of Cu-rich precipitates in terms of mean radius, number density and volume fraction. Aging at 500 °C and 550 °C for 1 h resulted in substantial coherent body-centered cubic (bcc) Cu-rich precipitates with mean radius of 1.35 and 2.59 nm, respectively. The precipitation strengthening mechanism for these two aging conditions was shearing mechanism and the corresponding strengthening contribution was ~ 266 and ~ 312 MPa, respectively. Here, coherency strengthening and modulus strengthening played a major role, while the contribution of chemical strengthening was relatively small. With increased aging temperature to 600 °C, the precipitates grew and coarsened to elongated shape with incoherent face-centered cubic (fcc) structure, and the strengthening mechanism was Orowan mechanism with a contribution of ~ 232 MPa. Increasing the aging temperature also facilitated the formation of retained austenite, which was of great benefit to plasticity without pronounced deterioration on precipitation strengthening. Ultra-high yield strength of 1020 MPa with superior total elongation of 25.8% was obtained in the sample aged at 600 °C for 1 h. The excellent mechanical properties derived from the combination of precipitation strengthening by Cu-rich precipitates and plasticity effect of retained austenite can be considered as a design principle to simultaneously optimize strength and ductility.

我们在这里描述了低碳中锰Mn析出强化钢的时效特性和强化行为。原子探针层析成像（APT）用于通过平均半径，数量密度和体积分数表征富铜沉淀物的演变。在500°C和550°C时效1 h会导致大量凝聚体中心立方（bcc）富铜沉淀，平均半径分别为1.35 nm和2.59 nm。在这两个时效条件下的沉淀强化机制是剪切机制，相应的强化贡献分别为〜266和〜312 MPa。在此，相干强化和模量强化起主要作用，而化学强化的贡献相对较小。随着老化温度增加到600°C，析出物长大并粗化为具有不连贯面心立方（fcc）结构的拉长形状，强化机制为Orowan机制，贡献度约为232 MPa。时效温度的升高也促进了残余奥氏体的形成，这对塑性有很大的好处，而在沉淀强化方面没有明显的恶化。在600°C时效1 h的样品中，获得了1020 MPa的超高屈服强度和25.8％的优良总伸长率。富铜沉淀物的沉淀强化与残余奥氏体的塑性作用相结合而获得的优异的机械性能可以被视为同时优化强度和延展性的设计原理。加强机制为Orowan机制，贡献量约为232 MPa。时效温度的升高也促进了残余奥氏体的形成，这对塑性有很大的好处，而在沉淀强化方面没有明显的恶化。在600°C时效1 h的样品中，获得了1020 MPa的超高屈服强度和25.8％的优良总伸长率。富铜沉淀物的沉淀强化与残余奥氏体的塑性效应相结合而获得的优异的机械性能可以被视为同时优化强度和延展性的设计原理。强化机制为Orowan机制，贡献量约为232 MPa。时效温度的升高也促进了残余奥氏体的形成，这对塑性有很大的好处，而在沉淀强化方面没有明显的恶化。在600°C时效1 h的样品中，获得了1020 MPa的超高屈服强度和25.8％的优良总伸长率。富铜沉淀物的沉淀强化与残余奥氏体的塑性效应相结合而获得的优异的机械性能可以被视为同时优化强度和延展性的设计原理。这对可塑性有很大的好处，而沉淀强化不会明显恶化。在600°C时效1 h的样品中，获得了1020 MPa的超高屈服强度和25.8％的优良总伸长率。富铜沉淀物的沉淀强化与残余奥氏体的塑性效应相结合而获得的优异的机械性能可以被视为同时优化强度和延展性的设计原理。这对可塑性有很大的好处，而沉淀强化不会明显恶化。在600°C时效1 h的样品中，获得了1020 MPa的超高屈服强度和25.8％的优良总伸长率。富铜沉淀物的沉淀强化与残余奥氏体的塑性效应相结合而获得的优异的机械性能可以被视为同时优化强度和延展性的设计原理。