20G和Cr5Mo的高温环烷酸腐蚀行为

Naphthenic Acid Corrosion Behavior of 20G and Cr5Mo under High Temperature

使用高温高流速环烷酸腐蚀模拟装置对20G低碳钢和Cr5Mo低合金钢在不同温度和冲刷角下的环烷酸腐蚀行为进行了研究。结果表明温度对两种材料的环烷酸腐蚀速率有较为显著的影响;在240℃、280℃、360℃三个温度下冲刷角0°及90°的腐蚀速率差在20%内,在320℃下的高腐蚀速率时冲刷角影响可达46%。在温度高于320℃时由于环烷酸的分解导致腐蚀速率下降。使用Fluent软件对两种冲刷角下湍流状态的模拟表明平行试样迎液流冲刷区及垂直试样中部具有最大的湍流强度,而这些区域的环烷酸腐蚀最为严重,这证明湍流状态对环烷酸腐蚀具有显著的影响。对腐蚀形貌的分析表明环烷酸腐蚀时两种材料均发生珠光体优先溶解现象,在表层珠光体腐蚀完后再由晶界向晶内腐蚀铁素体,从而整体上保持局部均匀腐蚀形貌。

High temperature and high flow rate naphthenic acid corrosion（NAC） simulation device is applied to investigate NAC behavior of 20G low carbon steel and Cr5Mo steel under various temperature and flushing angle.The results show that temperature and flushing angle could influence the corrosion rate of both steels in naphthenic acid.Under temperature of 240 ℃、280℃ and 360 ℃ the difference of corrosion rate between flushing angle of 0° and 90° is less than 20%,but at 320 ℃ the difference could reach 46%.Corrosion rate would decrease above 320 ℃ due to the decomposition of naphthenic acid.The software of Fluent is applied to simulate the turbulence on the surface of specimens and the results indicate that the areas along the flushing direction of fluid on the specimens of 0° and the central regions on the specimens of 90° are the places that maximum turbulence and maximum naphthenic corrosion existed,this fact indicate that turbulence influenced NAC behavior distinctly.The corrosion morphology analysis of both materials indicate that the perlites in 20G and Cr5Mo dissoluted preferentially,the ferrites corrode from the grain boundary to intracristalline only after the perlite dissoluted.