采用力学性能试验、化学成分分析、金相检验、能谱分析及冲击断口形貌观察等方法, 分析了X80M钢热轧板卷冲击性能不合格的原因。结果表明: 冲击性能不合格是因为板卷中存在严重的带状组织, 该组织是以板条马氏体为主的脆性组织, 存在明显的锰、硅元素偏析, 它是冲击时的起裂源; 带状组织中存在较多铌和钛的碳氮化物夹杂物, 夹杂物呈方形, 最大尺寸达到13 μm, 进一步降低了冲击韧性; 解决或减轻带状组织的最有效手段是在板卷生产时减少或消除铸坯中的枝晶偏析程度。

The reasons for unqualified impact property of X80M steel hot rolled coil were analyzed by mechanical property test, chemical composition analysis, metallographic examination, energy dispersive spectroscopy and impact fracture morphology observation. The results show that the impact property of the coil was unqualified because there was severe banded microstructure, a sort of brittle microstructure mainly composed of lath martensite, in the coil. The obvious segregation of manganese and silicon was founded in the banded microstructure which was the crack source of impact coil. There were many carbonitride inclusions of niobium and titanium in the banded microstructure. The inclusions were square with a maximum size of 13 μm, which reduced the impact toughness further. The most effective method to get rid of or reduce the banded microstructure is reducing or eliminating dendritic segregation in ingot during rolling process.