CAJ | 학술논문

以1000 M Pa级车用马氏体超高强度钢为研究对象，将其板材折弯为帽形型材，对各部位试样和原始板料做静态拉伸实验以及金相实验，并进行试件断口的扫描电镜分析。拉伸实验表明，弯角部分试样的屈服强度和抗拉强度均高于母材，并具有一定的脆性断裂特征；金相照片显示，弯角处的晶粒被拉长，产生了明显的塑性变形；断口的扫描电镜实验观察到，平板试样断口属于韧性断裂，而弯角处断口属于准解理断裂；研究结果表明，塑性加工造成的形变强化，极大增加了型材脆性断裂的危险性。
이1000 M Pa급차용마씨체초고강도강위연구대상，장기판재절만위모형형재，대각부위시양화원시판료주정태랍신실험이급금상실험，병진행시건단구적소묘전경분석。랍신실험표명，만각부분시양적굴복강도화항랍강도균고우모재，병구유일정적취성단렬특정；금상조편현시，만각처적정립피랍장，산생료명현적소성변형；단구적소묘전경실험관찰도，평판시양단구속우인성단렬，이만각처단구속우준해리단렬；연구결과표명，소성가공조성적형변강화，겁대증가료형재취성단렬적위험성。
To study the effect of strain hardening on mechanical properties of ultra‐high strength steel component ,a hat‐shaped section made of marten site ultra‐high strength steel with 1000MPa strength is observed .Static uniaxial tensile test and metallo‐graphic analysis are carried out ,and the fracture performance is analyzed by using SEM .The tensile test shows that both yield strength and tensile strength of bending corner specimens are higher than that of original material ,showing considerable brittle fracture characteristics .Grain at bending corner areas is detected to be elongated ,indicating a serious plastic deformation .SEM a‐nalysis shows that the fracture behavior for flat specimens is ductile ,while that for bending corner specimens is quasi‐cleavage fracture .The results indicate that plastic deformation considerable increases the risk of brittle fracture for ultra‐high strength steel component .