新型奥氏体耐热钢C-HRA-5原位拉伸断裂机理

 断裂机理是材料力学性能研究的主要方向之一。为了阐明C-HRA-5钢单轴拉伸断裂机理,通过原位SEM观察拉伸全过程,对该耐热钢内部微裂纹萌生—扩展—断裂进行了深入分析。结果表明,C-HRA-5钢在室温和700 ℃下都表现出典型的韧性断裂特征。材料断裂主要受到M₂₃C₆相和MX相的影响,微裂纹由M₂₃C₆相聚集的三叉晶界处萌生。室温时,微裂纹与晶内MX相处裂纹相连,形成穿晶裂纹;高温时,微裂纹在剪应力的作用下形成局部穿晶裂纹,导致材料最终失效。

In-situ tensile fracture mechanism of new type austenitic heat-resistant steel C-HRA-5

Fracture mechanism is one of the main research directions of mechanical properties of materials. In order to clarify the uniaxial tensile fracture mechanism of C-HRA-5 steel,the entire tensile process was observed by in-situ SEM,and the initiation-propagation-fracture of microcracks in this heat-resistant steel was analyzed deeply.The results show that C-HRA-5 steel exhibits typical ductile fracture characteristics at room temperature and 700 ℃.The fracture of the material is mainly affected by the M₂₃C₆ phase and the MX phase,and microcracks originate from the trigeminal grain boundaries where the M₂₃C₆ phase aggregates. At room temperature,microcracks are connected to the cracks in the MX phase of the crystal,forming transgranular cracks. At high temperatures,micro-cracks form local transgranular cracks under the action of shear stress,resulting in the ultimate failure of the material.