40CrMnSiB钢圆柱壳体膨胀断裂中间状态回收试验研究

针对回火温度条件对金属圆柱壳体膨胀断裂动态过程的影响问题，设计了冻结回收试验，用于回收处于膨胀断裂状态的金属壳体断裂形貌。以200 ℃、350 ℃、500 ℃和600 ℃ 4种回火温度处理下的40CrMnSiB钢为研究对象，通过冻结回收试验获得了4种回火温度状态下壳体断裂中间状态，分析了不同回火温度对壳体断裂、裂纹萌生、扩展及分布的影响，揭示了回火温度对40CrMnSiB钢圆柱壳体宏观断裂特性的影响规律。研究结果表明：随着回火温度从200 ℃上升到600 ℃，初期受动态塑性及断裂韧性改善的影响,壳体的断裂相关参量变化明显，后期材料动态强度减小造成的影响更突出，断裂相关参量基本不变；在500 ℃回火状态下的壳体断裂应变最大，相对于200 ℃回火状态提高了48.1%.

Recovery Experiment Study of Cylindrical 40CrMnSiB Steel Shell in Intermediate Phase of Expanding Fracture Processes

To understand the influence of tempering temperature on the dynamic process of expansion and fracture of cylindrical metal shell, a recovery experiment is designed to recover the fracture morphologies of metal shells at the intermediate phase of explosion. The 40CrMnSiB steels tempered at 200 ℃, 350 ℃, 500 ℃, and 600 ℃ are used as the research objects. The intermediate states of fractures of cylindrical metal shells at four different tempering temperatures were obtained through the recovery experiment. On this basis, the effects of different tempering temperatures on the fracture pattern, crack initiation, propagation and distribution are analyzed, and the influence rule of tempering temperatures on the macroscopic fracture characteristics of cylindrical 40CrMnSiB steel shells is revealed. The result shows that, as the tempering temperature is increased from 200 ℃ to 600 ℃, the fracture characteristic parameters of shell are influenced by the improvement in dynamic plasticity and fracture toughness and change significantly at the initial stage; at the later stage, the effect caused by the decrease in the dynamic strength of material is more prominent, so these parameters are essentially constant. The fracture strain of metal shell tempered at 500 ℃ is maximal, which is increased by 48.1% compared with that tempered at 200 ℃.