某钢管厂热轧13Cr钢管时使用钼顶头并配套使用2Cr13马氏体不锈钢束节, 在使用过程中发现束节连接顶杆部分频繁出现断裂。通过宏观分析、化学成分分析、金相分析等方法对束节断裂原因进行了分析。结果表明: 引起束节断裂的主要原因是,温度过高导致束节材料晶粒粗大并产生大量沿晶分布的δ铁素体,不仅降低了材料韧、塑性, 而且破坏了基体连续性, 从而使束节发生沿晶脆性断裂。

Molybdenum piercing mandrel matched with 2Cr13 martensite stainless steel beam section was used by a steel pipe plant for hot-rolling 13Cr steel tubes, and it was found that the beam sections fractured frequently at the connecting top rod position during use. The fracture reasons were analyzed by means of macro observation, chemical composition analysis, metallographic examination and so on. The results show that the main reason for the facture was overheating which resulted in coarse grain and a great deal of δ-ferrite on the grain boundary. It was not only reduced the toughness and plasticity of the material, but also destroyed the continuity of the matrix, so intergranular birttle fracture occurred to the beam sections.