【高强度低合金二氧化碳气体保护硷性药芯焊丝冶金过程研究】余圣甫.pdf

DissertationSubmitted to AcademicDegreesEvaluation Committeeof Huazhong University of Science andTechnology fortheDegreeof DoctorofPhilosophyinEngineering Studyon theMetallurgical Process ofBasic FluxCoredWiresinCOGasShieldedArc Welding of High Strength Low Alloy Steel Ph.D.

华中理工大学博士学位论文由于Si、Mn、Al-Mg合金为脱氧剂,能降低熔滴中氧的含量,增大熔滴的表面张力。因此,随着药芯粉中Si、Mn、A1-Mg合金的增加,熔滴直径增大,熔滴过渡频率降低.YJ657碱性药芯焊丝焊缝金属的显微组织由大量的针状铁素体、少量的先共析铁素体、贝氏体和M-A组元组成,这使得YJ657碱性药芯焊丝焊缝金属有良好的强韧性.图,适宜的Ni、Mn、Mo含量和焊接工艺参能促进焊缝金属中形成大量的针状铁素体.药芯焊丝焊缝金属中促进针状铁素体形核与长大的非金属夹杂物质点为 Ti、Al、Si、Mn的氧化物和Mn、Cu的硫化物。

华中理工大学博士学位论文 closely relatedto the size,mass andtransfer modeof droplet.With increased percentage ofNaSiF6in fluxpowders,the average diameter and mass of the droplet will decrease.When the percentage of Na2SiF6in flux powders reaches 16 ,the diameter andmass of droplet will get into a stable region.