Abstract: A welding method for improving quality of 5G all-position welding of a marine riser and a product thereof are provided, and the disclosure belongs to the technical field of welding. The welding method specifically includes the following. welding the marine riser in 5G all positions using a unified welding mode; reducing a predetermined voltage or reducing predetermined inductance in an overhead welding position to improve directivity and stability of an arc; and meanwhile increasing an arc swing width in the overhead welding position to eliminate a lack-of-fusion defect. In the disclosure, a unified welding mode suitable for flat welding is applied to marine riser welding. The process of 5G all-position welding of the marine riser is effectively simplified. The welding quality of 5G all-position welding of the marine riser is thereby effectively improved.

Abstract: A simplified method for welding a 5G position filler layer of a marine riser and a product thereof are provided, and the disclosure belongs to the technical field of welding. The method specifically includes the following. performing filler welding on the marine riser using an oscillation scanning laser-GMAW hybrid welding process; performing welding on each layer using same process parameters, then reducing gravity of a molten pool and increasing an arc force through interaction between laser and an arc, meanwhile expanding a range of a welding molten pool through an oscillation scanning behavior of the laser beam. A lack-of-fusion defect is prevented from being generated. A 5G position filler layer welding process of the marine riser is effectively simplified in the disclosure. Further, laser beam scanning also expands the range of the welding molten pool and prevents generation of the lack-of-fusion defect on a side wall.

Abstract: The present disclosure relates to a method and system for predicting the critical floating time of a reinforcing phase. According to the method, a particle concentration processing model, a half-life processing model, an agglomeration kinetics model, and a floating time processing model are combined to obtain the critical floating time of a reinforcing phase particle according to an initial particle size of the reinforcing phase particle, a density of the reinforcing phase particle, a mass fraction of the reinforcing phase of a composite soldering material, and a density of the composite soldering material. The method and system can accurately predict the critical floating time of the reinforcing phase particle.

Abstract: The present invention discloses a quantitative evaluation method for sensitivity of welding transverse cold cracks in a typical joint of a jacket, including following steps: S1, performing macroscopic analysis, metallographic analysis, fracture analysis and hardness analysis on cracks of a failed component to obtain main causes of cold crack failure; and S2, designing and processing a dedicated sample, and performing rigid restraint crack tests on the dedicated sample at different preheating temperatures to obtain a cracking/non-cracking critical restraint stress ?1cr of the sample.

Abstract: The present invention discloses a quantitative evaluation method for sensitivity of welding transverse cold cracks in a typical joint of a jacket, including following steps: S1, performing macroscopic analysis, metallographic analysis, fracture analysis and hardness analysis on cracks of a failed component to obtain main causes of cold crack failure; and S2, designing and processing a dedicated sample, and performing rigid restraint crack tests on the dedicated sample at different preheating temperatures to obtain a cracking/non-cracking critical restraint stress ?1cr of the sample.

Abstract: The present disclosure relates to a method and system for predicting the critical floating time of a reinforcing phase. According to the method, a particle concentration processing model, a half-life processing model, an agglomeration kinetics model, and a floating time processing model are combined to obtain the critical floating time of a reinforcing phase particle according to an initial particle size of the reinforcing phase particle, a density of the reinforcing phase particle, a mass fraction of the reinforcing phase of a composite soldering material, and a density of the composite soldering material. The method and system can accurately predict the critical floating time of the reinforcing phase particle.

Abstract: This invention discloses a method for preparing a kind of Sn-based silver-graphene lead-free composite solder, including mixing a certain amount of graphene with sodium dodecyl sulfate, then adding a certain amount of dimethylformamide, sonicating for 2 hours, adding a certain amount of silver nitrate to the mixture, continuing the sonication and finally obtaining the homemade. The solders matrix powder is weighed according to different silver-graphene mass fraction required, then poured into a ball-milling tank milling for 5 h. The powder is poured into a stainless steel mold after drying, then placed under hydraulic pressure to 500 Mpa for pressure forming. Later, the cold-pressed cylinder is placed in a high vacuum tube resistance furnace and sintered at 175° C. for 2 hours. After cooling to room temperature, it is formed into a cylinder under the hydraulic press.