The significance of different deoxidation practises on the ductility and impact toughness of next generation of microalloyed heavy plates was elucidated to explore the best deoxidation practice in obtaining required mechanical properties, which was judged by the combined effects of composition, size and number density of inclusions on the ductility of the experimental high-strength low-alloy steel. The impurity contents, i.e., total O + N + S contents, of 82 × 10⁻⁶ (Al-killed) and 118 × 10⁻⁶ (Zr-killed) have been induced to characterize both the steels. Ductility was characterized using tensile and Charpy V-notch testing. The number, size and composition of the inclusions were characterized using a field emission scanning electron microscope with an energy dispersive spectrometer. In the Al-killed steel, the inclusion structure consisted of titanium nitrides, stringer calcium aluminates and elongated manganese sulfides, whereas in the Zr-killed steel, the inclusion structure consisted of mainly fine spherical oxide inclusions with sulphide shells. The impurity content did not have a significant effect on the number density of inclusions, as with higher and lower impurity content, the number of inclusions was 83.7 and 78.8 mm⁻², respectively. However, the size distribution of the inclusions, especially the coarse inclusions with their longest length greater than 8 µm, differs much from each other. The number density of coarse inclusions differs from 0.8 to 1.1 mm⁻² with processing, and in Al-killed steel, 55.5% of the coarse inclusions were titanium nitrides or manganese sulfides, whereas in Zr-killed steel, only 22.5% of the coarse inclusions were titanium nitrides and manganese sulfides. Coarse titanium nitrides were especially detrimental to the impact toughness. The number density of them should be below 0.33 mm⁻² in order to guarantee the best possible toughness in the steel in question. The average crystallographic grain size detected by electron backscattered diffraction of Zr-killed steel (4.28 ± 2.70 μm) was smaller than that of Al-killed steel (6.00 ± 4.80 μm). As a result from the grain refinement and sulphide shape control, Zr-killed steel exhibited superior impact toughness (223 ± 70 J) at − 80 °C as compared with Al-killed steel (153 ± 68 J). Thus, Zr-killed steel was observed to provide good performance in terms of mechanical properties as compared with Al-killed steel.

阐明了不同脱氧方法对下一代微合金化厚板的延展性和冲击韧性的重要性，以探索获得所需机械性能的最佳脱氧方法，这是根据成分，尺寸和夹杂物数量密度的综合影响来判断的。实验性高强度低合金钢的延展性。杂质含量，即O + N + S的总含量为82×10 ^-6（铝灭活）和118×10 ^-6（Zr-killed）已被诱导表征两种钢。使用拉伸和夏比V型缺口测试对延性进行了表征。使用具有能量色散光谱仪的场发射扫描电子显微镜表征夹杂物的数量，大小和组成。在Al镇静钢中，夹杂物结构由氮化钛，铝酸钙纵梁和细长的硫化锰组成，而在Zr镇静钢中，夹杂物结构主要由带有硫化物壳的细球形氧化物夹杂物组成。杂质含量对夹杂物的数量密度没有显着影响，因为杂质含量越来越高，夹杂物的数量分别为83.7和78.8 mm ^-2， 分别。但是，夹杂物，特别是最长长度大于8μm的粗大夹杂物的尺寸分布彼此有很大差异。粗大夹杂物的数量密度在加工时从0.8到1.1 mm ^-2不等，在Al镇静钢中，55.5％的粗大夹杂物是氮化钛或硫化锰，而在Zr镇静钢中，仅22.5％的粗大夹杂物是氮化钛或硫化锰。夹杂物是氮化钛和硫化锰。粗氮化钛特别不利于冲击韧性。它们的数量密度应低于0.33 mm ^-2为了保证所讨论的钢具有最佳的韧性。通过Zr镇静钢的电子背散射衍射检测到的平均晶体晶粒尺寸（4.28±2.70μm）小于Al镇静钢的平均晶体晶粒尺寸（6.00±4.80μm）。晶粒细化和硫化物形状控制的结果是，Zr镇静钢在− 80°C时显示出比Al镇静钢（153±68 J）更高的冲击韧性（223±70 J）。因此，观察到与铝镇静钢相比，Zr镇静钢在机械性能方面具有良好的性能。