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研究了控轧和正火的09MnNb钢低温下冲击断裂行为,通过不同温度下冲击试验的负荷-挠度曲线研究,证明两种状态的钢低温下均具有较高的抗撕裂能力。在脆性转变温度下的断裂是以解理-韧窝混合型断裂方式进行的。控轧钢具有混合的α晶粒——等轴的和冷加工拉长的α晶粒,并具有较高的位错密度;正火钢则是较细的等轴α晶粒,具有位错的胞状亚结构。正火钢的这种组织特征降低了有效α晶粒尺寸,并导致较高的低温冲击韧性。
The impact fracture behavior of 09MnNb steel during controlled rolling and normalizing at low temperature was studied. The load-deflection curves of the impact test at different temperatures were studied. It was proved that the steel of the two states possesses higher tear resistance at low temperature. Fracture at brittle transition temperature is based on cleavage-dimple fracture mode. Controlled-rolled steels have mixed α-grain-isometric and cold-drawn α grains with high dislocation density; normalized steels are thinner equiaxed α-grains with dislocation-like cells Sub-structure. This tissue characteristic of normalized steel reduces the effective alpha grain size and results in higher low temperature impact toughness.