对U75V失效钢轨的化学成分、力学性能、显微组织和断口形貌进行了分析。结果表明,钢中溶解过量的氢聚集后造成局部应力集中,形成内部微裂纹,形成白点;基体中硫化物夹杂的存在降低了钢的塑性和韧性,并加剧裂纹扩展;钢轨表面局部形成马氏体组织,其氢致裂纹敏感性高,产生极高的相变应力和热应力引起氢致开裂。 The chemical composition, mechanical properties, microstructure and fracture morphology of U75V failure rail were analyzed. The results show that the excessive concentration of hydrogen dissolved in the steel causes local stress concentration and forms internal microcracks and white spots. The presence of sulfide inclusions in the matrix reduces the ductility and toughness of the steel and aggravates the crack propagation. The local formation of horses It is highly sensitive to hydrogen-induced cracking and produces extremely high phase transformation stresses and thermal stresses that cause hydrogen-induced cracking.