某重型汽车51CrMnVA钢板弹簧（板簧）预压后在冬天放置时发生断裂，通过断口分析、显微组织观察、力学性能测试、与正常服役后失效板簧进行对比等方法对其早期断裂原因进行了分析。结果表明：由于回火温度偏低，该板簧强度和硬度偏高，韧性偏低，加之钢中可扩散氢含量和预压变形应变速率过高，板簧在低温下发生脆性断裂；降低钢中可扩散氢含量，提高回火温度，延长回火时间，增加氢陷阱数量，得到适当的强韧性匹配，可有效避免板簧的早期失效和氢致延迟断裂。

A 51CrMnVA leaf spring of heavy duty truck broke when placed in winter after being preloaded. The early fracture reasons were analyzed by fracture analysis, microstructure observation, mechanical performance testing, and comparison with the fractured leaf spring after normal service. The results show that the high strength and hardness and low toughness of the leat spring due to a relatively low tempering temperature, and high diffusible hydrogen content in steel and high tension rates during presetting caused the brittle fracture of the leaf spring at low temperatures. Reducing the diffusible hydrogen content in steel, increasing the tempering temperature, extending the tempering time, increasing the number of hydrogen traps, and achieving appropriate matching of strength and toughness could effectively avoid early failure and hydrogen-induced delayed fracture of the leaf spring.