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本文通过金相分析证明,镍基铸铁焊条焊缝组织并非如传统观点认为的那样,为奥氏体加点状石墨,而是奥氏体加点状石墨加晶间相。晶间相包含共晶形态的石墨及其它由Ni—S—P—Si等构成的低熔点共晶。晶间相的数量、分布形态是影响热裂纹生成的基本因素。镍基铸铁焊条焊缝热裂纹具有结晶裂纹的生成机理。因此,防治措施主要应从改善镍基焊条焊缝组织形态入手。作者研制的XZ308焊条焊缝组织中晶间相具有断续、团状分布特征,因而具有较强的抗热裂能力。
In this paper, metallographic analysis shows that the weld microstructure of Ni-based cast iron welding rod is not as austenite plus point-like graphite, but rather as austenite plus point-like graphite plus intergranular phase, as the traditional view holds. The intergranular phase includes eutectic graphite and other low-melting eutectic composed of Ni-S-P-Si and the like. The number and distribution of intergranular phases are the basic factors that affect the formation of hot cracks. Nickel-based cast iron electrode weld crack with a crystal crack formation mechanism. Therefore, prevention and control measures should be mainly from the improvement of nickel-based welding seam morphology. The XZ308 electrode developed by the author has intergranular interphase and slug distribution in the weld microstructure, which has strong resistance to thermal cracking.