Research On Weldability Of The High Strength Low Alloy Steels For The Boom Of The Crawler Crane

In order to improve the lifting performance of the machine performance and enforce thelightweight design of the implementation work device, the comprehensive mechanicsperformance of the high strength steel and its welding joint for higher requirements were putforward for the crawler crane boom. The weld strength and the weld material selectioncombination of FGS90WV-FGS90WV and FGS90WV-20CrMnTi was discussed respectivelyin this paper, for they were used by the crawler crane boom the string tube and connector. Andthe carbon equivalent, cold crack sensitivity indexes and Y-groove creaking tests wereperformed to evaluate the weldability of the two kinds of identity of combination. Thewelding heat input impacts on the multilayer multichannel welding process was studied by themulti-layer welding test and multichannel joint organization performance analysis, for thesame material welding of FGS90WV. In this paper, the different level of intensity of weldingmaterial combination impacts on the match welded joint strong toughness and microstructurewas analyzed by the joint strong toughness match test, for the dissimilar steel welding ofFGS90WV-20CrMnTi.The experimental result shows that low-temperature preheating before welding wasneeded, because of the cold cracking sensitivity of FGS90WV-FGS90WV、FGS90WV-20CrMnTi In this paper experimental conditions. The equalmatching weld jointcan be obtained when T Union GM120wire was used in multi-lager and multi-pass weldingof FGS90WV steel pipe. The welding technology by multi-pass and small thermal input, caneffectively prevent the HAZ coarse crystal to grow up and effectively improve the jointstrength and toughness.When welding with dissimilar steel, such as FGS90WV-20CrMnTi, welding joints’strength decrease with the decreation of welding material’s strength level, while theelongation of welding joints and impact toughness of welding have an opposite performance.Based or filled with moderate low strength welding material can definitely improve thewelding ductility and toughness. It is showed in the welding obdurability matchness thatwelding material of moderate low strength can meet or exceed the required welding strength.Metallographic analysis showed that the root of weld ferrite content had increased and the ratio of pearlite gradually had reduced as the loss of the weld material strength leve.