Research On Welding Of Extremely Thick High Strength Steel EH47BCA With Brittle Crack Arrestibility

With the increasing demand of Mega container carriers of international shipping industry,and the newly enforced requirements for use of EH47extremely thick steel plates should design with brittle crack arrestibility,this paper is based on actually request of production for the shipyard recently contracted 14k TEUs container carrier new building projects to take the research on the welding procedure of EH47BCA steel plates.Discussed about the 60mm thickness EH47BCA butt welding procedure in horizontal position（2G）and vertical position（3G）.The research of the procedure was mainly followed the rules of Lloyd’s Register,also refer to IACS URW28/S33/AWS and other classes’rule and standards for welding parameters’design,welding of the test plates and analysis the properties of the welding joints.During the process of the welding parameter design,with refer to the value of Carbon equivalent and Pcm of base metals and also the previous experiences on the similar type of steel of subject steel,investigated the weldability of the base metal and decided to apply the low hydrogen welding consumable,choosed the V shape as the joints bevel,established the preheat temperature should be controlled within 100¹50℃,inter-pass temperature within 100²50℃,the welding process with multiple layers by passes to properly control of the heat input to assure the sound quality of the welding joints.Found the multiple lays specially featured“heat treatment”was effectively assure the toughness and other mechanically properties of the welding joints without post welding heat treatment.Through the monitoring the accuracy of welding parameters during the test plates’welding processing,confirmed the welding was carried out adhere with the preliminary designed parameter.Following the welding joints properties testing according to classes’rule,Results of the tests indicating:the adopting of the multiple layers by passes welding technic and processing the welding with Low hydrogen of CO₂ gas shield welding consumable of class numbered as 5YQ460SA H5,controlling of the preheat temperature not more than 150℃and the inter-pass temperature not more than 250℃,Confirmed the properties of EH47BCA welding joints that the HAZ,deposited metal and base metal closed to joints were complied with rules requirements as well as the request of the projects.