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利用维氏硬度计、OM(光学显微镜)、EBSD(电子背散射衍射)和TEM(透射电子显微镜)对在600℃回火不同时间后的Ti-V复合微合金化马氏体钢的维氏硬度、微观组织及析出相随回火时间的演变进行了研究。结果表明:随回火时间的增长,实验钢的硬度变化为先下降后上升再下降。前期由于位错密度降低,引起实验钢硬度下降。回火开始后,由于析出相的沉淀强化作用,硬度逐渐上升,并在回火1 h时达到峰值。回火1 h后,析出相开始粗化并引起位错密度降低,实验钢的硬度又开始下降,并在100 h时达到最低值。在回火过程中析出相的形状和尺寸都发生了明显变化。在回火1 h时实验钢的主要强化机制为沉淀强化,沉淀强化增量占总强度的34.9%,而在回火100 h时沉淀强化仍是钢中的主要强化方式。
The Vickers hardness of Ti-V composite microalloyed martensitic steels after tempering at 600 ℃ with Vickers hardness tester, OM (optical microscope), EBSD (electron backscatter diffraction) and TEM (transmission electron microscope) The evolution of hardness, microstructure and precipitation with tempering time were studied. The results show that with the increase of tempering time, the hardness of experimental steel decreases first and then increases and then decreases. Early due to the decrease of dislocation density, the experimental steel hardness decreased. After the beginning of tempering, the hardness increased gradually due to the precipitation strengthening effect of the precipitated phase and reached a peak at 1 h of tempering. After 1 h of tempering, the precipitated phase began to coarsen and caused the dislocation density to decrease. The hardness of the experimental steel began to decline again and reached the lowest value at 100 h. In the tempering process precipitated phase shape and size have undergone significant changes. The main strengthening mechanism of the experimental steel during the 1 h tempering was precipitation strengthening, precipitation enhancement increment accounted for 34.9% of the total strength, while precipitation hardening was still the main strengthening mode in the steel 100 h after tempering.