Research On The Slag System And Toughness Of Self-shielded Flux-cored Wire For X80 Pipeline Steel

The self-shielded flux cored wire is a new type of welding materials, which has developed rapidly in recent years and used widely in oil pipelines, bridges, shipbuilding, offshore platforms, buildings and other fields. In this article, the component of the alkaline slag based on fluorides-Fe₂O₃-Al-Mg and the toughness of the deposited metal are the study objects. Then the research on self-shielded flux cored wire and the low-temperature toughness about X80 pipeline steel is carried out though the technology performance tests, mechanical properties tests and microstructure metallography analysis.The powder size used in producing the self-shielded flux cored wire is very important to the stability of the welding process. This paper indicates that pretreatment of the flux cored powder can greatly improve the welding technology performance.Slag system is an important aspect in the study of the self-shielded flux-cored wire. Because it is a primary protection to the high-temperature molten metal. In this experiment, the component of the flux core are fluorides ,Fe2O3 andAl-Mg alloy, parts of the fluorides can vaporize to formation fluoride air mass around the molten metal to isolates molten metal from the air ; Al-Mg is a good deoxidizer and denitrifier, can effectively prevent the formation of the pores. There will be a research on the adjusting of the composition and amount of the flux core, and study the impact on the technology performance of the composition, cover, viscosity, slag-detachability, wettability of the slag in welding process.The mechanical properties of the deposited metal are the important issues and raising the low-temperature toughness is the key problem. In this experiment ,adding Ni and rare earth elements to the flux core, and control Al amount at the same time, then carry out the test of yield strength, tensile strength and low-temperature impact toughness of the deposited metal, and give the analysis to the composition, structure and its inclusion, conclude that Al have a marked impact on the toughness deterioration.According to the the experimental results of the slag system and the toughenss to look for the law of the various components and the amount of the flux core. Then the quality of flux-cored wire will be further optimized through adjusting the formula rationally.