Industrial continuous annealing process routes for dual-phase steels are mostly found to be non-isothermal in nature. The present study is an effort to understand the importance of non-isothermal annealing process parameters and their impact on the various metallurgical phenomena; such as recrystallisation and phase transformation behaviours of duel-phase steel. These, in turn, are expected to influence various structure parameters of martensite phase which are critical in determining the strength of duel-phase steel. A dual-phase steel sheet in 67% cold rolled full hard condition was subjected to non-isothermal annealing treatment with varying heating rate and inter-critical annealing temperatures. After processing the samples were investigated for structural parameters of martensite phase using a scanning electron microscope, X-ray diffraction, and nano-indentation technique. It was observed that due to non-isothermal nature of continuous annealing process, the hardness of the martensite phase did not follow the hardness trends as determined from conventional carbon concentration. Further, lattice tetragonality of martensite was also affected by increasing its volume fractions. The annealing process apparently influenced the evolution of texture because of the increasing fraction of martensite in dual-phase steel.

中文翻译：

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连续退火工艺对双相钢马氏体各种结构参数的影响

在本质上，大多数发现双相钢的工业连续退火工艺路线是非等温的。本研究旨在了解非等温退火工艺参数的重要性及其对各种冶金现象的影响。如双相钢的重结晶和相变行为。这些反过来又有望影响马氏体相的各种结构参数，这对于确定双相钢的强度至关重要。对67％冷轧全硬条件下的双相钢板进行非等温退火处理，并采用不同的加热速率和临界间退火温度。处理后，使用扫描电子显微镜，X射线衍射，和纳米压痕技术。观察到由于连续退火过程的非等温性质，马氏体相的硬度没有遵循由常规碳浓度确定的硬度趋势。此外，马氏体的晶格四方性也受其体积分数增加的影响。由于双相钢中马氏体含量的增加，退火过程显然影响了织构的发展。