缺陷类型对FGH95粉末高温合金界面开裂行为影响的模拟

Simulation of influence of defect types on interface cracking behavior of FGH95 P/M superalloy

为了研究缺陷类型对粉末高温合金缺陷处应力应变分布的影响,通过弹性模量表征,将缺陷分为硬夹杂(弹性模量大于基体)、软夹杂(弹性模量小于基体)、孔洞(弹性模量为0)。用有限元模型模拟了弹塑性条件下不同类型缺陷对缺陷/基体界面应力应变分布的影响。结果表明,缺陷类型对界面附近应力应变分布影响明显。在该研究的基础上,分析了不同类型缺陷的致裂机制,即:当界面粘接强度较低时,界面应力是评价界面附近破坏的主要参量,当界面粘接强度较高时,基体最大主应力和基体最大塑性应变是评价界面附近破坏的主要参量。分析了当界面结合强度较强、较弱(相对于基体)两种情况下,硬夹杂和软夹杂的界面裂纹在外加载荷作用下的演变过程。从断口上观察分析了源区含不同类别夹杂开裂形貌,其开裂行为与模拟结果一致,验证了模拟的有效性。

In order to study the effect of defect types on the distribution of stress and strain in powder superalloy defect sites,the defects were deemed as hard inclusions(elastic modulus greater than matrix),soft inclusions(elastic modulus less than matrix)and hole(elastic modulus of 0).The effects of different types of defects on the stress-strain distribution at the interface between the defects and the matrix were simulated by using the finite element model.The results show that the type of defects has an obvious effect on the distribution of stress and strain near the interface.On the basis of this study,the fracture mechanism of different types of defects is analyzed,and it is found that when the bonding strength of the interface is low,the interface stress is the main parameter to evaluate the failure near the interface,and when the bonding strength of the interface is high,the maximum main stress of matrix and the maximum plastic strain of matrix are the main parameters to evaluate the failure near the interface.The evolution process of interfacial cracks of hard inclusions and soft inclusions under the external loads is analyzed when the interface bonding strength is strong and weak(relative to the matrix).The fracture morphology of the source region with different type of inclusions was observed and analyzed.It shows that the cracking behavior is consistent with the simulation results,which verifies the effectiveness of the simulation.