Novel steel microalloyed with 0.73 (Cr + V + Nb) has been subjected to thermomechanical processing (TMP) with varying parameters to simultaneously maximise the steel strength and ductility. Optical and electron microscopy studies coupled with uniaxial tensile testing were carried out to analyse the processing-microstructure-properties relationship. For the suggested steel composition, the simultaneously highest yield stress (960 MPa), ultimate tensile strength (1100 MPa), and elongation to failure (25%) were achieved following simulated coiling at 650 °C and holding for 30 min. The variation in the finish rolling temperature affects the ferrite grain size and the ratio of precipitates formed in austenite and ferrite. If a significant amount of solute is consumed for precipitation in austenite and during subsequent growth of strain-induced precipitates, then a lower fraction of interphase and random precipitates forms in ferrite resulting in a lower strength. Extended time at a simulated coiling temperature resulted in the growth of interphase precipitates and precipitation of random ones in ferrite. Fine tuning of TMP parameters is required to maximise the contribution to strength arising from different microstructural features.

中文翻译：

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工艺参数对新型CrVNb微合金钢相间析出和力学性能的影响

用0.73（Cr + V + Nb）微合金化的新型钢已经过热机械加工（TMP），具有各种参数，以同时使钢的强度和延展性最大化。进行了光学和电子显微镜研究以及单轴拉伸试验，以分析加工-微观结构-性能之间的关系。对于建议的钢成分，在650°C进行模拟卷取并保持30分钟后，可获得同时最高的屈服应力（960 MPa），极限抗拉强度（1100 MPa）和破坏伸长率（25％）。终轧温度的变化会影响铁素体的晶粒尺寸以及奥氏体和铁素体中形成的析出物的比例。如果消耗大量的溶质用于在奥氏体中沉淀以及在随后的应变诱导沉淀物生长期间，则铁素体中会形成较少比例的相间和随机沉淀物，从而导致强度降低。在模拟卷取温度下延长时间会导致相间析出物的生长和铁素体中无规析出物的析出。需要对TMP参数进行微调，以最大程度地提高不同微结构特征对强度的贡献。