核电结构材料应力腐蚀开裂初始阶段裂尖驱动力的研究

Invesitigation of Crack Growth Driving Force at Tip of Stress Corrosion Cracking in Nuclear Structural Materials in Initial Stage

摘要:

裂尖力学状态是影响核电结构材料应力腐蚀开裂(SCC)扩展速率的主要因素之一。为了搞清SCC不同扩展阶段裂尖驱动力的变化及其对SCC扩展速率的影响,本文建立了SCC扩展不同阶段的有限元模型,详细分析了裂纹初始阶段影响裂尖应力状态的工作载荷、残余应力,以及氧化膜形成过程中产生的膜致应力。结果表明,在SCC裂纹初始阶段,裂尖氧化膜形成所产生的“锲入张力”是SCC的主要驱动力；随着裂纹的扩展,工作载荷和残余应力逐渐成为SCC裂纹扩展的主要驱动力。

Abstract:

The mechanical state at the crack tip is one of the major factors affecting the stress corrosion cracking (SCC) growth rate in structural materials of the nuclear power plant. To understand the crack growth driving forces and their effects on SCC growth rate in the whole process of SCC, a finite element model of the growth process of SCC was built by using a commercial software ABAQUS, sequentially the working load, residual stress, and the film induced stress produced by the oxide film formationin front of the crack tip during SCC initial stage were discussed in this paper. The results indicate that the film induced stress produced by the formation of oxide film is the main crack growth driving force during the initial stage of SCC. While the working load and residual stress gradually become the main crack growth driving force as SCC crack advances.