利用等温退火工艺显示齿轮钢连铸坯枝晶形貌

Dendrite Revelation of Continuous Casting Billet of Gear Steel by Isothermal Annealing Method

提出了一种齿轮钢连铸坯枝晶显示方法，其核心在于利用等温退火工艺将碳元素富集到合金元素较高的枝晶间，在缓冷后形成珠光体，之后用浓度为4％的硝酸酒精溶液将其侵蚀出来。采用本方法能将齿轮钢连铸坯的枝晶清晰地显示出来，并可以测量一次枝晶间距和二次枝晶间距，为优化齿轮钢连铸工艺提供依据。本方法和现有方法相比，枝晶显示得清晰、准确，省去了复杂的腐蚀试剂的配制，便于检测人员操作的规范和快捷，并适合推广到其他合金钢种枝晶显示。

A new method for dendrite revelation of continuous casting billet of gear steel was presented in this paper. By isothermal annealing, carbon was concentrated in the interdendritic regions in which alloy elements were enriched. Pearlite formed after slow cooling was etched out with 4 vol% Nital, thus represented the interdendritic regions. The morphology of dendrite was clearly observed by adopting the new method, and the primary dendrite spaces and the secondary dendrite spaces could be measured, which provided a basis for optimizing the parameters of the continuous casting. Compared with traditional methods, advantages of this method were that clear and accurate images of the dendrite morphology could be obtained by using 4 vol% Nital rather than some complex etchant and could be widely used in other alloy steels.