CAJ | 학술논문

根据部分轮辐用热轧双相钢在模拟服役过程中多处发生开裂的问题，利用金相显微镜、扫描电镜等相关实验手段，对失效部位及原材料进行了深入研究。结果表明，造成轮辐用热轧双相钢疲劳失效的主要原因是：①样品心部马氏体粒子尺寸较大，数目较少，呈块状，宽度介于2～10μm，长度介于5～15μm，5μm以内的马氏体第二相粒子较少，不能为位错移动提供足够的有效障碍，导致开裂。②样品中存在一定量大尺寸夹杂物，复合Al2 O3类夹杂物沿轧制方向排成一排，单个夹杂物尺寸介于3～30μm之间。③板材中存在轻微的混晶现象，最大的晶粒尺寸为20μm，最小的晶粒尺寸只有2μm，由于服役过程中变形不协调而引起晶间应力集中加剧，使得粗晶粒提早产生裂纹。
근거부분륜복용열알쌍상강재모의복역과정중다처발생개렬적문제，이용금상현미경、소묘전경등상관실험수단，대실효부위급원재료진행료심입연구。결과표명，조성륜복용열알쌍상강피로실효적주요원인시：①양품심부마씨체입자척촌교대，수목교소，정괴상，관도개우2～10μm，장도개우5～15μm，5μm이내적마씨체제이상입자교소，불능위위착이동제공족구적유효장애，도치개렬。②양품중존재일정량대척촌협잡물，복합Al2 O3류협잡물연알제방향배성일배，단개협잡물척촌개우3～30μm지간。③판재중존재경미적혼정현상，최대적정립척촌위20μm，최소적정립척촌지유2μm，유우복역과정중변형불협조이인기정간응력집중가극，사득조정립제조산생렬문。
In view of problems of several cracks formed in the hot rolled dual phase steel for spokes during the simulated service, deep investigations on cracking parts and materials were made by means of OM, SEM and so on. The results showed that reasons are as follows:①The martensite particles in the core of the specimen with larger size is in a smaller number, forming lumps with width between 2~10 μm and length between 5~15 μm. There are few second-phase martensite particles of less than 5 μm so that they can′t provide enough and effective barriers against dislocation movement, resulting in cracking. ② There are a certain amount of large inclusions in the specimen. Compound Al2 O3 inclusions are in a row along the rolling direction, with size between 3~30 μm for single inclusion. ③ Minor mischcrystal phenomenon exists in the plates. The grain size is between 20 μm and 2 μm. Because the deformation and incoordination intensify the intergranular stress concentration during the service, cracks occur early in the coarse grains.