590 MPa高强船板钢的高温氧化行为

Oxidation behavior of 590 MPa high strength ship plate steel at high temperature

借助热重分析仪(TGA)模拟了实际热轧钢坯的加热过程,研究了590 MPa高强船板钢在加热炉气氛中在1 100~1 250℃下保温120 min和1 250℃保温10~120 min的氧化规律,利用扫描电镜(SEM)、能谱仪(EDS)、场发射电子探针(EPMA)和X射线衍射(XRD)观察了氧化层表面和截面形貌及元素分布,检测了氧化层的物相组成,分析了590 MPa高强船板钢的氧化行为。结果表明:不同温度保温120 min后,氧化增重曲线符合抛物线规律,氧化速率逐渐变大,在1 250℃时氧化速率略微降低。1 250℃氧化后,实验钢氧化层截面由外向内依次是:外氧化表层、外氧化内层、过渡层。Fe氧化物与复合氧化物FeSiO3和FeCr2O4组成外氧化表层。Ni元素富集在氧化铁皮与基体界面处,阻碍氧化继续进行,Fe氧化物与富Ni金属颗粒成为外氧化内层。少量O离子扩散到合金内部,Si和Cr元素发生选择性氧化形核长大形成过渡层。随氧化时间延长,外氧化内层和过渡层逐渐变厚。

The actual hot rolling heating process was simulated by means of thermogravimetric analyzer(TGA),and the oxidation law of 590 MPa high strength ship plate steel was studied in a heating furnace atmosphere at 1100-1250℃ for 120 min and 1250℃ for 10-120 min in the heating furnace atmosphere.By the use of scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),electron probe micro-analyzer(EPMA)and X-ray diffraction(XRD),the morphology and element distribution on the surface and the cross-sections of the oxide layer were investigated,the phase composition of the oxide layer was detected and the oxidation behavior of 590 MPa high strength ship plate steel was analyzed.The results show that after holding at different temperatures for 120 min,the oxidation weight gain curve conforms to the parabolic law,the oxidation rate gradually increases,and the oxidation rate decreased slightly at 1250℃.After oxidation at 1250℃,the cross-sections of the test steel oxide layers are in the following order from outside to inside:outer oxide surface layer,outer oxide inner layer,and transition layer.With the increasing oxidation time,the outer oxide inner layer and the transition layer gradually grow thicker.The outer oxide surface layer consists of the Fe oxides and the composite oxides FeSiO_(3) and FeCr_(2)O_(4).The Ni elements are enriched at the interface between the oxide scale and the matrix,preventing the continuing oxidation while the Fe oxides and the Ni-rich metal particles form the outer oxidized inner layer.A small number of O ions diffuse into the interior of the alloy.The Si and Cr elements undergo selective oxidation and nucleated and grew to form the transition layer.With the prolongation of oxidation time,the outer oxide inner layer and the transition layer gradually thicken.