Characterization of hydrogen embrittlement in high-strength fastener steels: mechanical testing and numerical modeling

高强度紧固件钢的氢脆特征：机械测试和数值模拟

• 批准号: 492103-2015
• 负责人: Yue, Stephen
• 金额: $ 8.03万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=618373
• 关键词: Characterization; hydrogen; embrittlement; strength; fastener

High strength and ultrahigh strength mechanical fasteners are broadly characterized by tensile strengths ranging from 1,000 to 2,000 MPa, and are often used in critical applications. Damage resulting from hydrogen embrittlement can occur by a complex interaction of material characteristics, environmental conditions, manufacturing flaws, installation conditions, and joint design criteria. The consequences of failures can range from minimal to catastrophic, even resulting in loss of life. Hydrogen embrittlement (HE) is a common problem in high strength steel caused by the absorption of elemental hydrogen into the material matrix. Hydrogen damage in high strength steel fasteners can be summarized as a migration of mobile hydrogen from lattice sites to points of stress concentration, resulting in crack initiation followed by crack propagation by atomic bond decohesion at the crack tip. The effect of hydrogen embrittlement in materials is generally characterized by various types of slow strain rate tests and incremental step load tests which quantify the loss of mechanical properties such as strength and ductility.This project builds on previous work as it aims to characterize and quantify the individual effects ofmicrostructural defects in hydrogen transport of high strength steel components such as fasteners. A multiscale modeling approach that combines atomistic and continuum numerical simulations will be employed, creatively bridging nanoscale trapping energetics with macroscopic hydrogen diffusion. In parallel to the modeling, dedicated experiments such as measurements of hydrogen in bulk materials by thermal desorption are being explored to validate and parameterize the model. The above modeling and experimental efforts will be further integrated with measurements from incremental step load tests to provide predictive assessments on the HE susceptibility of the material based on the trapping and transport characteristics of hydrogen.

高强度和高抗拉强度机械紧固件的广泛特征在于拉伸强度范围为1，000至2，000 MPa，并且通常用于关键应用中。氢脆导致的损坏可能是由于材料特性、环境条件、制造缺陷、安装条件和接头设计标准的复杂相互作用而发生的。故障的后果可能很小，也可能是灾难性的，甚至会导致生命损失。氢脆（HE）是高强度钢中常见的问题，其原因是元素氢被吸收到材料基体中。高强度钢紧固件中的氢损伤可以概括为移动的氢从晶格位置向应力集中点的迁移，导致裂纹萌生，随后通过裂纹尖端处的原子键脱粘导致裂纹扩展。材料氢脆效应的特征通常是通过各种类型的慢应变速率试验和增量阶跃载荷试验来量化强度和延展性等机械性能的损失，本项目建立在以前的工作基础上，旨在表征和量化微观结构缺陷对高强度钢部件（如紧固件）氢传输的影响。一个多尺度的建模方法，结合原子和连续数值模拟将采用，创造性地桥接纳米级捕获能量与宏观氢扩散。在建模的同时，正在探索专用实验，如通过热解吸测量散装材料中的氢，以验证和参数化模型。上述建模和实验工作将进一步与增量阶跃载荷试验的测量结果相结合，以根据氢的捕获和传输特性对材料的HE敏感性进行预测评估。