發(fā)布時間：2018-09-16 21:44

【摘要】：鐵素體(α)和奧氏體(γ)兩相組成的2205雙相不銹鋼由于鐵素體相的存在而具備優(yōu)良的機械性能,由于奧氏體相的存在而具備很好的耐蝕性能。這種優(yōu)良的綜合性能使之廣泛應用于海洋建筑、儲酸設備、輸油輸氣管道等領域。然而在其服役的過程中,由于服役環(huán)境中雜質離子的存在以及人為施加的保護措施,如陰極保護過程,導致氫等雜質離子進入內部,在應力的共同作用下,導致2205雙相不銹鋼出現(xiàn)脆性開裂,造成嚴重的后果,帶來不可預估的損失。材料的組織決定其性能,因此,對2205雙相不銹鋼微觀組織與腐蝕行為和氫脆敏感性關系的研究具有很大的理論與實際意義。本文通過改變固溶溫度的方式控制2205雙相不銹鋼的微觀組織,利用顯微組織和顯微硬度分析、電化學分析測試(極化曲線,電化學阻抗)、慢應變速率拉伸、氫滲透以及掃描電鏡觀測的方法研究微觀組織對2205雙相不銹鋼的腐蝕行為以及氫脆敏感性的影響。固溶處理實驗結果表明:當固溶溫度處于1000℃至1200℃之間時,2205雙相不銹鋼組織中只存在鐵素體相與奧氏體相,不存在σ、CrN等第二相,鐵素體相比例隨固溶溫度的升高呈線性升高關系,而奧氏體相則呈相反規(guī)律。當固溶溫度為1050℃時,兩相比例最接近1:1,此時材料顯微硬度最低,并且隨著固溶溫度的升高,顯微硬度增大。硫酸溶液電化學測試結果表明:2205雙相不銹鋼在0.5M硫酸溶液中具有明顯的鈍化區(qū)間,且當溫度為1050℃時,材料耐蝕性最好,鈍化膜致密度最高,2205雙相不銹鋼在0.5M硫酸溶液中的整個陽極過程都不存在應力腐蝕敏感性。應力腐蝕拉伸結合拉伸過程阻抗譜結果表明:陰極充氫導致2205雙相不銹鋼表面鈍化膜惡化,其氫脆敏感性也大大增加;氫脆敏感性與相比例密切相關,當兩相比例接近1:1時,材料的氫脆敏感性最低,且隨著兩相比例差異的變大,氫脆敏感性大大增加;在0.5M硫酸溶液的慢應變拉伸過程中氫脆裂紋經歷萌生-發(fā)展-鈍化的過程,奧氏體相作為“氫陷阱”阻礙氫擴散。單一相耐蝕性能實驗結果表明:2205雙相不銹鋼兩相耐蝕性能與各自相組成元素的含量密切相關,當溫度為1050℃時,鐵素體單相與奧氏體單相的耐蝕性能達到最佳。在3.5%氯化鈉溶液中,鐵素體相耐蝕性高于奧氏體相,奧氏體相優(yōu)先腐蝕,在0.5M硫酸溶液中,兩相耐蝕性差異不明顯,趨于均勻腐蝕。氫滲透結果表明:隨著固溶溫度的升高,2205雙相不銹鋼整體的氫擴散系數增加,單相鐵素體的氫擴散系數增加以及鐵素體含量的升高導致2205雙相不銹鋼氫脆敏感性變大。
[Abstract]:The 2205 duplex stainless steel composed of ferrite (偽) and austenite (緯) has excellent mechanical properties due to the existence of ferrite phase and good corrosion resistance due to the existence of austenite phase. This excellent comprehensive performance makes it widely used in ocean building, acid storage equipment, oil and gas pipeline and other fields. However, in the course of service, due to the presence of impurity ions in the service environment and artificial protective measures, such as cathodic protection, impurity ions such as hydrogen enter into the interior, under the joint action of stress. It leads to brittle cracking of 2205 duplex stainless steel, resulting in serious consequences and unpredictable losses. The microstructure of 2205 duplex stainless steel depends on its properties. Therefore, it is of great theoretical and practical significance to study the relationship between microstructure and corrosion behavior and hydrogen embrittlement sensitivity of 2205 duplex stainless steel. In this paper, the microstructure of 2205 duplex stainless steel was controlled by changing the solution temperature. The microstructures and microhardness were analyzed, electrochemical analysis (polarization curve, electrochemical impedance), slow strain rate stretching, The effect of microstructures on corrosion behavior and hydrogen embrittlement sensitivity of 2205 duplex stainless steel was investigated by hydrogen permeation and scanning electron microscopy. The experimental results of solution treatment show that there are only ferrite phase and austenite phase in the microstructure of T2205 duplex stainless steel when the solution temperature is between 1000 鈩，

本文編號：2244904