【摘要】 通过冲击和拉伸试验，研究了γ＋δ双相低温铸钢力学性能与断口形貌之间的关系。试验结果表明，这种铸钢可在低温（至－１９６℃）条件下使用。同时发现，室温断口为穿晶韧性断裂，塑性和韧性较高；低温断口以沿晶韧性断裂为主，部分韧窝中存在数量较多的夹杂物，而且由于δ铁素体的存在，－１９６℃断口中产生局部解理断裂区域和二次裂纹，从而导致塑性和韧性不同程度地降低。更多还原

【Abstract】 In this paper,the relation between the low-temperature mechanical properties and fracture mode of the cryogenic cast steel with micro-duplex structure consisted of γ+δ was studied by impact and tension test.Experimental results have shown that the cast steel can used for castings low-temperature (down-196℃).It has also been found that the fracture of this cast steel at room temperature appeares as the transgranular tough fracture mode,and the impact toughness and plasticity values are higher;while it appeares essentially as the intergranular mode at low-temperature,and has more inclusions in sectional dimples,and the impact toughness and plasticity have differently reduce because δ-ferrite has become brittle and spot cleavage fracture and secondary crack appear in the break.Therefore, if fining process is adopted and brittle phase is avoided in the structure,this is undoubtedly important on higher low-temperature toughness and plasticity.更多还原