A Fundamental Study on Chemical Metallurgy in Welding Processes

对金属材料电弧焊过程中的气渣金属反应进行了热力学研究。结果表明：(1)采用气钨弧焊和GTA焊接的方法，研究了铁合金熔液在焊接过程中对氮气的吸收。铁合金在电弧熔炼和电弧焊接过程中的吸氮行为不服从西弗茨定律。弧熔金属的氮含量高于平衡溶解度。焊缝金属的氮含量低于平衡溶解度，只有在溶解度高的情况下，如高铬合金或加压氮气氛下。这说明高温电弧的存在和反应时间的缩短会影响焊缝金属的含氮量。然而，合金元素对电弧熔化或电弧焊接铁合金氮吸收的影响与平衡态的影响大致相等。(2)在包括氧气在内的各种气氛下，对铁合金进行气钨弧焊和GMA焊接。系统地研究了合金元素（硅、锰、铝、钛）对焊缝金属吸氧性能的影响。通过分析焊缝金属中氧化物夹杂物的组成、形态、数量和数量，探讨了氧吸收和脱氧的机理。(3)采用简化焊剂成分的埋弧焊方法，研究焊接过程中渣-金属的反应。系统地研究了焊剂成分对焊缝金属氧含量的影响。

Gas-and slag-metal reactions during arc-welding processes of metallic materials were studied thermodynamically. The results are as follows:(1) Iron alloys were gas-tungsten-arc-melted and GTA welded under various atmospheres including nitrogen gas to study the nitrogen absorption of molten iron alloys during welding processes. The nitrogen absorption behaviour of iron alloy during arc-melting or arc-welding did not obey sieverts' law. The nitrogen contents of arc-melted metals were higher than the equilibrium solubilities. The nitrogen content of weld metal was lower than the equilibrium solubility, only when the solubility is high, such as the cases of high chromium alloys or pressurized nitrogen atmospheres. These facts suggest that the presence of high temperature arc and the shortage of reaction time affect the nitrogen content of weld metal. However, the effects of alloying elements on the nitrogen absorption of arc-melted or arc-welded iron alloys were roughly equal to equilibrium ones.(2) Iron alloys were gas-tungsten-arc-melted and GMA welded under various atmospheres including oxygen. The effects of alloying elements ('silicon, manganese, aluminium, titanium) on the oxygen absorption of weld metal were systematically studied. The mechanisms of oxygen absorption and deoxidation were discussed by examining the composition, morphology, number and amount of oxide inclusions in the weld metals.(3) Steels were submerged-arc-welded with simplified flux compositions to study slag-metal reactions during welding processes. The effect of flux composition on the oxygen content of weld metal was examined systematically.