(1. 江蘇科技大學(xué) 材料科學(xué)與工程學(xué)院，鎮(zhèn)江 212003；2. 中國石油天然氣管道局 海洋工程分公司，廊坊 065000)
摘 要: 采用D-S雙電解池研究7075-T6鋁合金的表觀氫滲透系數(shù)，對表面鍍鎳厚度、充氫電流和循環(huán)次數(shù)對表觀氫滲透系數(shù)的影響進(jìn)行研究，進(jìn)一步研究表面鍍鎳充氫試樣的應(yīng)力腐蝕敏感性。結(jié)果表明：表面鍍鎳厚度為220 nm時，鈍化電流最為穩(wěn)定，鍍鎳層厚度對氫滲透電流的影響主要體現(xiàn)在對氫原子的氧化能力和對鋁合金基體的保護(hù)能力上。表觀氫滲透系數(shù)隨充氫電流增大有增大的趨勢，主要與表面氫原子深度增大、深度梯度增大以及加速氫向鋁合金的滲透相關(guān)。但是增大幅度表觀氫滲透系數(shù)有減小的趨勢，主要原因是由于氫的表面覆蓋度增大后，大部分的氫原子開始結(jié)合為氫氣而脫離鋁合金表面。隨著循環(huán)次數(shù)的增加，表觀氫滲透系數(shù)也隨之增大，主要原因是隨著循環(huán)次數(shù)增加，鋁合金內(nèi)部的不可擴(kuò)散氫深度趨于穩(wěn)定，可擴(kuò)散氫的滲透速度增大。SSRT實驗分析和SEM電鏡照片結(jié)果表明：隨充氫時間的增長，SSRT敏感性增大，氫能夠滲入鋁合金內(nèi)部，并使其脆性增大，且其脆性隨著充氫時間延長而有所增大。
關(guān)鍵字: 7075-T6鋁合金；表觀氫滲透系數(shù)；D-S雙電解池； SSRT實驗
（1. School of Materials Science and Engineering, Jiangsu University of Science and Technology,
Zhenjiang 212003, China;
2. China Petroleum Pipeline Bureau Offshore Engineering Company, Langfang 065000, China）
Abstract:The apparent hydrogen diffusivity was studied by D-S double cell. The effect of thickness of plated Ni, charging current density and charging-uncharging cycles on apparent hydrogen diffusivity was studied. And the stress corrosion cracking (SCC) sensitivity of constant charging specimens was studied. The results show that the passivation current is steady while the thickness of plated Ni is 220 nm. The plated Ni can provide protection from pitting corrosion and catalysis effect on hydrogen. The apparent hydrogen diffusivity increases with the increase of charging current density. The surface hydrogen concentration increases with the increase of charging current density, and the concentration gradient also increases, the hydrogen permeation rate increases, while the increase trend becomes slow due to the surface coverage. The apparent hydrogen diffusivity increases with the increase of charging-uncharging cycles at the beginning, and then reaches a steady value due to the overflow of non-diffuse hydrogen and the increase of hydrogen permeation rate. And the SCC sensitivity of constant charging specimens increases with the increase of charging time.
Key words: 7075-T6 Al alloy; apparent hydrogen diffusivity; D-S double cell; SSRT experiment
