某35MnBH钢链轨节在台架试验时发生开裂。采用宏观观察、化学成分分析、金相检验等方法对链轨节的开裂原因进行了分析。结果表明：该链轨节开裂的主要原因是链轨节在锻造过程中存在过烧现象，使得其力学性能降低。在台架试验过程中，链轨节受到冲击、扭转等各种复杂应力的作用，使链轨节表面过烧组织处形成裂纹源，裂纹迅速扩展，最终发生开裂。

A 35MnBH steel caterpillar track section cracked during the bench test. The causes of caterpillar track section cracking were analyzed by means of macroscopic observation, chemical composition analysis and metallographic examination. The results show that the main cause for the cracking of the caterpillar track section during bench test was that the overburnt phenomenon existed in the forging process, and the mechanical properties were reduced. In the process of bench test, the impact, torsion and other complex stresses on the caterpillar track section led to the formation of crack source at the overburnt structure on the surface of the caterpillar track section. The crack propagated rapidly and finally cracking occurred.