Abstract The microstructure evolutions of hot work tool steel 5CrNiMoV throughout the heating, deformation and quenching procedures are investigated. Microstructures of the heated, compressed, and cooled specimens are observed by high-temperature confocal laser scanning microscope (HT-CLSM), optical microscope, and electron backscatter diffraction (EBSD). The measurement shows that the austenite transformation starts at 730 °C and ends at 765 °C. After the temperature exceeds 850 °C during the heating, the in-situ observed grains are first refined by static recrystallization (SRX) and then grow with the holding time, accompanied by the grain boundary gradually become straight. The microstructures of hot compressed specimens indicate that the dynamic recrystallization (DRX) fraction increases with growing temperature and strain, in which discontinuous dynamic recrystallization (DDRX) is the main mechanism of DRX. The grain boundaries formed by DDRX are serrated and have a larger curvature, which are different from those formed by SRX and subsequent grain growth. The lath martensite generated from the water quenching following the compression tends to align parallel to each other in the prior austenite grain (PAG). It comprises the packets containing the elongated blocks with the same habit planes.

中文翻译：

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热作工具钢5CrNiMoV在加热、变形和淬火过程中的组织演变

摘要 研究了热作工具钢 5CrNiMoV 在整个加热、变形和淬火过程中的组织演变。通过高温共聚焦激光扫描显微镜 (HT-CLSM)、光学显微镜和电子背散射衍射 (EBSD) 观察加热、压缩和冷却样品的微观结构。测量表明，奥氏体转变开始于 730 °C，结束于 765 °C。加热过程中温度超过850℃后，原位观察到的晶粒首先通过静态再结晶（SRX）细化，然后随着保温时间的延长而长大，伴随着晶界逐渐变直。热压缩试样的微观结构表明，动态再结晶 (DRX) 分数随着温度和应变的增长而增加，其中不连续动态再结晶（DDRX）是DRX的主要机制。DDRX 形成的晶界呈锯齿状，曲率较大，这与 SRX 和随后的晶粒长大形成的晶界不同。压缩后水淬产生的板条马氏体倾向于在原始奥氏体晶粒 (PAG) 中彼此平行排列。它包括包含具有相同习性平面的细长块的包。