20mm和40mm钢板金相组织见图1和图2，可以看出，钢板金相组织主要为板条马氏体/贝氏体。组织中硬相组织偏多导致强度较高，塑性较差。需要进一步进行热处理来改善钢板的塑韧性。

680℃-740℃回火后钢板的金相组织见图3，回火后部分板条马氏体粗化，同时形成一部分粒状贝氏体，这种复相组织降低了钢板的强度，同时提高了钢板的塑性和韧性。

The metallographic structure of the 20mm and 40mm steel plates is shown in Figure 1 and Figure 2. It can be seen that the metallographic structure of the steel plate is mainly lath martensite/bainite. Too many hard phases in the structure lead to higher strength and poor plasticity. Further heat treatment is required to improve the ductility of the steel plate.

The metallographic structure of the steel plate after tempering at 680℃-740℃ is shown in Figure 3. After tempering, part of the lath martensite is coarsened and a part of granular bainite is formed. This complex structure reduces the strength of the steel plate while increasing The plasticity and toughness of the steel plate are improved.