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本文对双相钢的微观组织特征及其观察方法进行了研究。结果指出:用图象分析仪测定马氏体的体积分数时,采用苦味酸偏重亚硫酸钠比硝酸酒精腐蚀为好:用扫描电镜观察起裂相、裂纹扩展途径时,采用反复腐蚀抛光法(2%硝酸酒精腐蚀),可显示显微组织细节;用透射电镜观察双相钢的精细结构时,采用电解双喷射和离子清洗减薄相结合制膜,使膜厚度均匀、组织清晰。根据对起裂相、微裂纹的形态及显微组织和断口形貌的关系分析,得出了含钒双相钢的裂纹扩展途径和断裂模式。透射电镜观察发现:马氏体岛的精细结构与临界间退火温度有关,较低的临界间退火温度,以孪晶马氏体为主,临界间退火温度升高,则板条马氏体量增多;在铁素体中有马氏体相变诱发的密度较高的位错,有时还形成脆状结构。
In this paper, the microstructural characteristics of dual-phase steel and its observation methods were studied. The results show that: when using the image analyzer to measure the volume fraction of martensite, it is better to use picric acid than sodium nitric alcohol to corrode the nitric acid. Scanning electron microscopy is used to observe the cracking phase and crack propagation path. Nitric acid alcohol corrosion), can show the details of the microstructure; using transmission electron microscopy dual phase steel fine structure, the use of electrolytic double jet and ion cleaning thinning combined membrane, the film thickness uniform, clear organization. Based on the analysis of the relationship between the morphology of as-cracked phase and micro-cracks and the microstructure and fracture morphology, the crack propagation path and fracture mode of vanadium-containing dual-phase steel were obtained. The results of TEM showed that the fine structure of martensite island was related to the critical annealing temperature. The lower critical annealing temperature was dominated by twinned martensite, and the intercritical annealing temperature increased. The lath martensite content Increase; ferrites have martensitic transformation induced higher density of dislocations, and sometimes also form a brittle structure.