低碳球墨铸铁断口的观察和分析

利用扫描电镜(SEM)对珠光体、铁素体和准铸态贝氏体金属基体的低碳球铁拉伸断口形貌进行了分析和研究.结果表明,珠光体低碳球铁的断口应属于脆性断裂的范畴;准铸态贝氏体低碳球铁断口中韧窝明显增多,解理花样大大减少,属于韧-脆性混合型断口;铁素体低碳球铁的断口则完全呈现出韧性断裂的特点.研究还表明,ADI在固态相变时,高温奥氏体快速冷却到贝氏体转变温度的过程中,不可能再形成发达的奥氏体枝晶,也不可能再形成枝晶间的缩松区域.因此,ADI可在获得较高强度的前提下,使材料的韧塑性得到大大提高.

Observation and Analysis About the Fracture of Low Carbon Ductile Iron

Using the scanning electronic microscope(SEM), orienting to the low carbon ductile iron with pearlite matrix, ferrite matrix and Quasi-as-cast bainite matrix, the analysis and research have been done about the tensile fracture's shape and appearance of low carbon ductile iron. The result indicates that the fracture of pearlite low carbon ductile iron belongs to brittle fracture; toughness puteus increasing and cleavage pattern decreasing obviously in the fracture of Quasi-as-cast bainite low carbon ductile iron, it belongs to the toughness-brittle hybrid fracture; that of ferrite low carbon ductile iron completely present the characteristic of brittle fracture. The research also indicates that in the process of pyro-austenite cooling rapidly to the bainite transforming temperature, it is impossible for ADI to forming austenite dendrite, as well as the shrinkage area among the dendrite. So, on the premiss of good intensity, ADI advances the toughness and plasticity of the materials.