奥氏体不锈钢氢损伤表面波检测的有限元模拟

摘要

奥氏体不锈钢通常比铁素体和马氏体钢具有更好的抗氢损伤性能,因此广泛地用于核能、化工等临氢环境中,但是仍然会发生可逆塑性损失和滞后开裂等相关的失效.宏观裂纹形成前,氢原子分布在金属的近表层中,而表面波在介质表层传播,且包含了超声波的大部分能量,所以表面波特别适用于早期氢损伤的检测.由于氢原子会降低了金属原子的结合力从而导致金属弹性模量的减小,因此通过检测表面波波传播时间的滞后可以检测出金属的氢损伤.本文采用ABAQUS有限元分析软件模拟了表面波在早期氢损伤以及未损伤试样中的传播过程,研究了表面波第一个波峰抵达试样上表面中间节点的时刻与氢损伤的关系.早期氢损伤造成的表面波传播时间的滞后为10-7 s数量级,对仪器精度、分辨率提出很高的要求.频率越低,对仪器的要求越高.%The austenite stainless steel is commonly considered to have a better anti-hydrogen property than martensite steel,as a result,it is extensively used in hydrogen environment of nuclear energy and chemical industry.However,the failure caused by hydrogen,mainly reversible loss of plasticity and delayed fracture,still happen.The hydrogen atoms are distributed in the near surface region of metal before the crack is formed.The surface wave travels in the near surface region of the medium.In addition,the surface wave carries most of the energy of ultrasonic wave.Thus,the surface wave can be used to discover the hydrogen damage of metal.Hydrogen atom can reduce the bonding force between metal atoms,so as to reduce the elastic modulus.As a result,hydrogen damage of metal can be discovered by evaluate the delay of surface wave travelling.The finite element analysis software ABAQUS was adopted to simulate the travelling process of surface wave in the test piece which is damaged or not.The relationship between the moment when the first crest of surface wave arrived at the middle node of the top surface of the test piece and hydrogen damage was studied.The delaying time caused by hydrogen damage is on the scale of 10-7 s,so the instrument should have high precision and resolution.The signal with higher frequency is more suitable than the one with lower frequency.