Test Study On Hydrogen Induced Cracking And Stress Corrosion Of Q345(R-HIC) Steel Welding Joint

Q345(R-HIC) steel is a kind of anti hydrogen steels. It is mainly used in themanufacture of pressure vessel. Now the pressure vessel is all welded structure. Weldingbecome the main process for manufacture of pressure vessels. But the welding technologywith heating, fast cooling and add the characteristics of welding materials. So themicrostructure and properties of welded joints have no uniformity. Working environment ofa lot of pressure vessel is very bad. It work in the hydrogen sulfide corrosion solution. Sowelded joint will become the weak link and corrosion parts. It prone to stress corrosion andhydrogen induced cracking. Because the problem of pressure vessel corrosion cracking inH2S environment become increasingly serious, and caused a great loss. So research stresscorrosion and hydrogen cracking of welded joints in wet H2S solution has greatsignificance. Object of study in this article is Q345(R-HIC) steel. It is used in themanufacture of low pressure separator. The low separator working environment in wet H2Ssolution. It use of five kinds of welding process. In order to ensure its corrosion resistanceproperties and prevent the occurrence of safety accidents. Five kinds of welding process tobe tested for stress corrosion and hydrogen. Stress corrosion cracking test using four pointbending method of GB/T4157-2006and ASTM in the G39-2005Standard. Hydrogeninduced Cracking test in accordance with GB/T8650-2006standard. The main researchwork and results are as follow.1. The first is component analysis and performance test of base metal，judge weldingperformance and select welding material. Then conduct component analysis andperformance test for welding material.2. Analyzing the structure of low pressure separator. To determine the number ofwelding procedure qualification. Organization pre welding process specification. Conductthe mechanical performance test and bending test for welding test plate.3. According to the welding process, welding test plate. Through metallographicobservation on welded joint of parent material and product test plate. Welded jointeliminate the banded structure of base mental. Its grain is tiny, closely spaced, and evenlydistributed. To observe the fracture morphologies of tensile sample. All samples are visiblenecking on macroscopically. Observation by scanning electron microscope, the fracture isdimple morphology, on inclusions in dimples and dimple depth is bigger. That explain thewelded joints has good plasticity.4. Sampling the product test plate. To test corrosion and hydrogen induced cracking in accordance with standard. The results show that there are no hydrogen bubbling andcracking. That explain the corrosion resistant performance is good, the welding procedureis qualified.