图为DZ2（连铸）钢不同温度下的紧凑拉伸断口形貌，由图可知，其断口形貌与DZ2（模铸）钢断口形貌类似，主要是由纤维区与解理或准解理断面组成，随着温度的降低其纤维区面积减小，对应的K_q或K_IC也逐渐减小。在20℃时，与1-1#钢不同，1-2#钢断口均为纤维区，并未出现解理或准解理断面，这是由于1-2#钢合金渗碳体尺寸小于1-1#钢，低温韧性优于DZ2（模铸）钢。

The figure shows the fracture morphology of compact tensile fracture of DZ2 (continuous casting) steel at different temperatures. It can be seen from the figure that the fracture morphology is similar to that of DZ2 (die casting) steel, mainly composed of fiber zone and cleavage or quasi cleavage section. With the decrease of temperature, the fiber zone area decreases, and the corresponding Kq or KIC also gradually decreases. At 20℃, 1-2# steel is different from 1-1# steel, the fracture is fiber area, no cleavage or quasi cleavage section, this is because 1-2# steel alloy cementite size is less than 1-1# steel, low temperature toughness is better than DZ2 (die cast) steel.