SPV50Q钢焊接接头腐蚀和氢渗透性能分析

Analysis on properties of corrosion and hydrogen-permeation for weldment of SPV50Q steel

具有不同组织结构的焊接接头是腐蚀环境中服役焊接设备或管道的薄弱环节,这与焊接接头处发生的非均匀腐蚀密切相关.利用动电位极化、交流阻抗技术和氢渗透技术,研究了液化石油气(LPG,liquefied petroleum gas)球罐用SPV50Q钢焊接接头在含H2S溶液中的腐蚀和氢渗透特性.结果表明,具有不同组织结构的SPV50Q钢焊接接头各区金属(母材、热影响区和焊缝),在含H2S溶液中的耐腐蚀性和氢渗透性能都具有一定的差异性,母材的耐蚀性最好,热影响区次之,焊缝金属的最差;对氢渗透性能而言,焊缝金属的氢扩散速度和扩散系数最大,热影响区的次之,母材的最小.

The difference in microstructures of the base metal(BM),weld metal(WM) and heat-affected zone(HAZ) of the weldment is one of the major causes for the failure of the welded equipments and pipelines serviced in corrosion environment,which would be essentially attributed to the non-homogeneous corrosion reaction occurred electrochemically on the weldment.Using potentiodynamic polarization measurement,electrochemical impedance spectroscopy(EIS) and hydrogen-permeation technique,the properties of corrosion and hydrogen-permeation for the weldment of SPV50Q steel used to fabricate LPG spherical tank were performed in H2S-containing solution.The results show that the difference in the various zones of weldment for SPV50Q steel affects the properties of corrosion and hydrogen-permeation in H2S-containing solution.BM has the best resistantomce compared wich HAZ and WM,and the resistance of WM is the poorest among them.As for the hydrogen-permeation properties,the diffusion efficient and rate for hydrogen increase in the order of BM,HAZ and WM.