L415M输氢管道环焊接头氢相容性研究OA

To mitigate the hydrogen embrittlement risk of girth weld joints in high-pressure hydrogen pipelines and ensure long-term safe service of pipelines,eleven groups of L415M steel pipes with the specification of Φ813 mm×14.3 mm were taken as the research object.Welding tests were carried out by adopting three processes:GTAW+GMAW,GMAW and GTAW+SMAW.The key process parameters and process control requirements were determined,and systematic tests on conventional mechanical properties and hydrogen compatibility of the weld joints were conducted.The results show that no macroscopic defects such as cracks and pores were found in the joints fabricated by the three welding processes.At-10℃,the average Charpy impact energy of weld metal and heat-affected zone was higher than 60 J.The tensile strength of all-weld metal ranged from 530 MPa to 650 MPa,the elongation after fracture was more than 20%,and the hardness was no more than 235HV10.Under 7.2 MPa high-pressure hydrogen environment,the reduction of area loss rate was less than 45%,the fracture toughness exceeded 70 MPa·m1/2,and the fatigue life was over 5 000 cycles.After aging treatment at 200℃for 5 minutes,the fracture toughness of welded joints did not decrease.The fatigue performance of weld zones obtained by the three processes was similar.The heat-affected zones of joints welded by GTAW+GMAW and GTAW+SMAW possessed better fatigue performance than those by single GMAW.It is concluded that all the three welding processes can meet the engineering requirements for L415M hydrogen pipelines.In practical engineering,preheating temperature,interpass temperature and welding heat input shall be controlled to optimize joint performance.Technical support for the construction of hydrogen pipeline projects is provided.