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关于金属断口中的结晶台阶(即几何花样),文献报道以在铝合金中发现的最多,在镍基合金、钼单晶和钢的白点中也曾观察到。结晶台阶一般为梯田状,只有一个取向而具有较完整晶体学特征的很少见。金属和合金在铸造或焊接凝固过程中,有时会产生一些疏松或缩孔。结晶台阶就是在这些疏松或缩孔的自由表面上形成的,是自由表面逐次长大的结果。在锻件中所发现的这种结晶台阶系属于未完全锻合而保留下来,特别是当有氧化膜存在时,出现这种情况的可能性更大。本文介绍我们在研究铸铁轧辊断口时观察到的发育非常完美的结晶台阶花样。通过对这些花样的分析,有益于加深了解金属的凝固结晶过程。
With regard to the crystallization step (ie, geometric pattern) in the metal fracture, it has been reported in the literature to find the most in aluminum alloys, also observed in white points of nickel-based alloys, molybdenum single crystals and steels. Crystallization steps generally terraced, only one orientation with more complete crystallographic features are rare. Metal and alloy in the casting or welding solidification process, sometimes produce some loose or shrinkage. Crystallization steps are formed on these loose or craters’ free surfaces as a result of the successive growth of free surfaces. This type of crystallization step found in forgings is retained by incomplete forging and is more likely to occur when an oxide film is present. This article presents the very well-developed crystalline step patterns we observed when studying the fracture of cast iron rolls. Through the analysis of these patterns, it is beneficial to deepen the understanding of metal solidification and crystallization process.