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金属的氢损伤是个老问题,早期合金钢中出现的白点(或发纹)及后来高强度钢的电镀和焊接中的裂纹问题,都是钢中氢作用的结果。五十年代以来,美国航空工业采用的超高强度钢(σ_s>140kg/mm~2)也出现了水解质中的应力腐蚀开裂。以 Troiano 为代表,提出了这些开裂及几乎所有的应力腐蚀开裂,除少数例外都与氢有关。近年来无论是金属加工工业、化学工业还是石油工业及新近发展起来的核动力工业等,都遇到氢损伤问题。它已成为国际上活跃学术领域之一。金属材料的氢损伤通常分为两类:一类是在高温(一般为220℃以上)高压下,钢中氢和碳及 Fe_3C 反应,生成甲烷。结果造成材料内裂纹和鼓泡,称之为氢腐蚀(简称 HA);另一类为由于扩散到金属中位错处的氢或生成金属氢化物所造成的材料脆化现象称为氢脆(简称 HE)。1.氢损伤的分类及其特征
Hydrogen damage to metals is an old problem. The appearance of white spots (or hair lines) in early alloy steels and subsequent cracking in the electroplating and welding of high-strength steels are the result of hydrogen in steel. Since the 1950s, the ultra-high strength steels (σ_s> 140 kg / mm ~ 2) used by the U.S. aeronautic industry also show stress corrosion cracking in the hydrolyzate. Troiano as the representative of these cracks and almost all of the stress corrosion cracking, with a few exceptions are related to hydrogen. In recent years, both the metal processing industry, the chemical industry or the oil industry and the newly developed nuclear power industry, have encountered the problem of hydrogen damage. It has become one of the most active academic fields in the world. Hydrogen damage of metal materials are usually divided into two categories: one is at high temperature (usually above 220 ℃), the steel hydrogen and carbon and Fe_3C reaction to generate methane. The result is cracks and bubbling in the material, known as hydrogen corrosion (HA); the other is due to diffusion into the metal at the dislocation of hydrogen or metal hydride caused by material embrittlement phenomenon known as hydrogen embrittlement (referred to as HE). 1. Classification of hydrogen damage and its characteristics