以Q245R钢板为对象，进行不同尺寸试样在系列温度下的夏比V型冲击试验，论证试验的尺寸效应。结果表明：不同尺寸试样获得的冲击吸收能量一般不可换算，且与试样截面积没有对应关系。不同尺寸试样获得的韧脆转变温度数据也不可直接比较，随着试样尺寸减小，韧脆转变温度向低温方向移动。低温条件下，小尺寸试样可能导致材料韧性被高估，建议对小尺寸试样的试验温度进行调整。

The Charpy V-notch impact tests were performed under a series of temperature for samples with different size cut from Q245R steel plate to demonstrate the effect of size. The results show that the impact absorption energy of samples with different size was neither convertible nor corresponding to the cross-sectional area of samples. Furthermore, the data of ductile brittle transition temperature for samples with different size also could not be compared directly. With the decrease of sample size, the ductile brittle transition temperature would move to lower temperature. Samples with small size may lead to material toughness overestimating at low temperature. Therefore, it is suggested to adjust the test temperature for samples with small size.