Effect of Material Characteristics of zinc-based coatings on hydrogen embrittlement of steel fasteners

锌基涂层材料特性对钢紧固件氢脆的影响

• 批准号: 428422-2011
• 负责人: Yue, Stephen
• 金额: $ 6.46万
• 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: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=552319
• 关键词: Effect; Material; Characteristics; zinc; based

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. The aim of this project is to better understand the effect of coating materiel characteristics on hydrogen embrittlement of high strength fasteners. The importance of the coating material is related to the degree that it is permeable to hydrogen. The more permeable the coating, the more likely hydrogen can be extracted from the substrate steel to reduce the risk of HE. On the other hand, the same coating material can allow external hydrogen to be absorbed more easily, consequently increasing the risk of environmental HE. The proposed methodology will rigorously characterize the coating material. The results will be used initially to understand and quantify the permeability of a number of selected coating materials and, ultimately, to guide the evolution of plating processes aimed at obtaining coatings with compositions and characteristics that minimize the propensity for hydrogen embrittlement failure of coated fasteners. The fastener industry is part of the lucrative automotive and aerospace parts sectors, which are of considerable economic importance in Canada.

高强度和超高强度机械紧固件的广泛特点是抗拉强度在1,000至2,000 MPa之间，经常用于关键应用。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，氢脆造成的损伤可能会发生。故障的后果可以从最小的到灾难性的，甚至导致生命损失。氢脆（HE）是高强度钢中常见的问题，是由单质氢吸收到材料基体中引起的。高强度钢紧固件中的氢损伤可以概括为可移动氢从晶格点向应力集中点的迁移，导致裂纹萌生，裂纹尖端的原子键解聚导致裂纹扩展。氢脆对材料的影响通常以各种类型的慢应变速率试验和增量阶跃载荷试验为特征，这些试验量化了强度和延性等力学性能的损失。本项目旨在更好地了解涂层材料特性对高强度紧固件氢脆的影响。涂层材料的重要性与它对氢的渗透程度有关。涂层渗透性越强，就越有可能从基体钢中提取氢，从而降低HE的风险。另一方面，同样的涂层材料可以使外部氢更容易被吸收，从而增加了环境HE的风险。所提出的方法将严格表征涂层材料。这些结果最初将用于了解和量化一些选定涂层材料的渗透率，并最终指导电镀工艺的发展，旨在获得具有最小化涂层紧固件氢脆失效倾向的成分和特性的涂层。紧固件行业是利润丰厚的汽车和航空航天零部件行业的一部分，这两个行业在加拿大具有相当大的经济重要性。