微合金元素對鋼材抗氫引誘破裂的效應

Effects of Microalloying Elements on HIC Resistant Property of HSLA Steels

本文主要研究鈮、銅、鉻、鉬及鈦等五種常添加於高強度低合金鋼（HSLA）的合金元素與鋼材抗氫引裂（HIC）的關係，以作為開發耐蝕HSLA的參考。實驗依NACE TM-02-84規定進行HIC試驗，浸泡溶液為BP及NACE溶液，試驗後並分別利用OM、SEM、EPMA、AES及影像解析儀來進行分析。結果發現：(1)提高鈮含量會增加介在物的長寛比、不利於HIC的抵抗。(2)含銅鋼於BP溶液中，會生成避免HIC發生的保護膜，其外側為γ-Fe2O3且富含銅，內側為FeS。(3)鉻、鉬共同添加，具有加成作用，易生成低溫相，增加HIC的敏感性，且鉬的效應約為鉻的3倍。(4)粗大TiN與MnS相似，均扮演HIC的起始源，且會彼此結合而導致HIC的發生。

The effects of alloying elements (including: niobium, copper, chromium, molybdenum, and titanium) in high strength low alloy (HSLA) steels on hydrogen induced cracking (HIC) have been investigated. The HIC test method is performed by NACE TM-02-84 in BP and NACE solution. After test, OM, SEM, EPMA, AES, and image analyzer were chosen to analyze the data. The results show that addition of niobium increases the aspect ratio of inclusion and results in decrease of HIC resistance. In BP solution, copper-bearing steel can form a protective film whose outside is γ-Fe2O3, enriched Cu and inside is FeS. Alloying chromium and molybdcnum has synthetic effect on formation of low temperature transformation phase and increase of the sensitivity of HIC. This detrimental effect of molybdenum is three times that of chromium. Additionally coarse TiN precipitates, as well as elongated MnS inclusions, are the initiation sites of HIC, and both can cooperate to result in occurrence of HIC.