未服役30CrMnSiNi2A钢轮轴在存放一段时间后，其表面镀硬铬区域出现裂纹，通过形貌观察、化学成分分析、显微组织观察、力学性能分析、氢含量及残余应力测试等方法研究了轮轴表面开裂原因，并提出了控制开裂的措施。结果表明：在电镀硬铬过程中渗入轮轴表面的氢和在磨削加工硬铬层时引入的拉应力的协同作用，导致轮轴发生氢致延迟开裂（氢脆）；通过采取改进电镀工艺、镀后及时除氢、改善镀层磨削加工工艺和增加去应力退火工序等措施，该类轮轴未再出现开裂现象。

When the unserviced 30CrMnSiNi2A steel axle was stored for a period of time, cracks appeared in the electroplated hard chrome area on surface of the axle. The surface cracking cause of the axle was studied by morphology observation, chemical composition analysis, microstructure observation, mechamical property analysis and hydrogen content and residual stress testing. The measures to control cracking were proposed. The results show that the hydrogen-induced delayed cracking (hydrogen embrittlement) of the axel occurred by the synergistic effect of the hydrogen diffused in surface of the axle during electroplating hard chrome and the tensile stresses introduced during grinding of the hard chrome layer. By the measures of the improvement of electroplating process, removing hydrogen in time after electroplating, modifying the grinding process of the electroplated layer and increasing stress relief annealing procedure, no cracking occurred in the axle.