The effect of microstructure on the shock response of 1045 steel is investigated via plate impact experiments and postmortem characterization. Three unique microstructures are explored: ferrite-pearlite, martensite, and ferrite with spheroidal cementite (i.e. spheroidized). Two spall recovery experiments, at approximate peak pressures of 3.2 and 3.5 GPa, are conducted to assess the Hugoniot elastic limit (HEL), spall strength, and damage morphology of the various microstructures. The ferrite-pearlite and martensite microstructures exhibit continuous yielding at both quasi-static and dynamic rates, while the spheroidized condition displays discontinuous yielding. Discontinuous yielding of the spheroidized microstructure is attributed to a combined low initial dislocation density coupled with a low dislocation nucleation rate. The spall strength of ferrite-pearlite is consistently lower than the spheroidized microstructure, attributed to elongated cementite that is more susceptible to cracking than more spherical cementite precipitates. Despite a high density of boundaries, martensite exhibits the highest spall strength. A large percentage of the boundaries within the martensite microstructure are found to be low energy (i.e. Σ3 or low angle), and are thus less susceptible to spall damage. Overall, the high spall strength of martensite is likely linked to traditional strengthening mechanisms that limit dislocation motion.

通过板冲击实验和事后表征研究微观结构对 1045 钢冲击响应的影响。探索了三种独特的微观结构：铁素体-珠光体、马氏体和具有球状渗碳体（即球化）的铁素体。在大约 3.2 和 3.5 GPa 的峰值压力下进行了两次剥落恢复实验，以评估 Hugoniot 弹性极限 (HEL)、剥落强度和各种微结构的损伤形态。铁素体-珠光体和马氏体微观结构在准静态和动态速率下均表现出连续屈服，而球化条件下表现出不连续屈服。球化微观结构的不连续屈服归因于较低的初始位错密度和较低的位错成核率。铁素体-珠光体的剥落强度始终低于球化微观结构，这是由于伸长的渗碳体比球形渗碳体沉淀物更容易开裂。尽管边界密度高，但马氏体具有最高的抗剥落强度。马氏体微观结构内的大部分边界被发现是低能量的（即 Σ3 或低角度），因此不易受到剥落损坏。总的来说，马氏体的高散裂强度可能与限制位错运动的传统强化机制有关。马氏体具有最高的抗剥落强度。马氏体微观结构内的大部分边界被发现是低能量的（即 Σ3 或低角度），因此不易受到剥落损坏。总的来说，马氏体的高散裂强度可能与限制位错运动的传统强化机制有关。马氏体具有最高的抗剥落强度。马氏体微观结构内的大部分边界被发现是低能量的（即 Σ3 或低角度），因此不易受到剥落损坏。总的来说，马氏体的高散裂强度可能与限制位错运动的传统强化机制有关。