热处理工艺对22MnB5钢铝硅镀层氧化层厚度和组织演变的影响  

Effect of Heat Treatment on the Thickness of Al2O3 Scale and Microstructure Evolution of Al-Si Coating on 22MnB5 Steel

作　　者：谢昀映 成毅 吴广新[1,2,3] XIE Yun-ying;CHENG Yi;WU Guang-xin(State Key Laboratory of Advanced Special Steel,Shanghai University,Shanghai 200444,China;.Shanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai University,Shanghai 200444,China;.School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China)

机构地区：[1]上海大学省部共建高品质特殊钢冶金与制备国家重点实验室,上海200444 [2]上海大学上海市现代冶金与材料制备重点实验室,上海200444 [3]上海大学材料科学与工程学院,上海200444

出　　处：《表面技术》2020年第4期245-253,共9页Surface Technology

基　　金：国家自然科学基金资助项目(51674163);上海市科委自然科学基金资助项目(16ZR1412000)。

摘　　要：目的探究奥氏体化工艺对铝硅镀层氧化层厚度和微观组织的影响规律及其演变机理。方法以热浸镀Al-10%Si的22MnB5为研究对象,采用扫描电子显微镜(SEM)、辉光放电光谱仪(GD-OES)和X射线衍射仪(XRD)等仪器,观察镀层在奥氏体化过程中氧化层厚度的变化和微观组织的演变规律。结果当试样以15℃/s的速率升温到900℃后立即水淬,镀层氧化层最薄,当试样升温到900℃保温5 min后水淬,镀层氧化层出现了不同程度的开裂,镀层表面出现孔洞和脱落的现象,氧化层厚度明显增加。结论奥氏体化保温时间比奥氏体化升温速率对镀层氧化层厚度的影响更大,保温时间越长,氧渗入镀层的深度越深,氧化层越厚,奥氏体化时间的延长不利于镀层氧化层保持完整性,影响镀层对钢基体的保护功能。镀层及其氧化层的微观组织演变规律为:镀层中首先形成Al2Fe3Si3(τ1)和Fe2Al5相,随后Fe2Al5相生长并伴随FeAl2相形成,而后FeAl2+Fe2Al5相生长且有FeAl析出,随后FeAl相生长,氧化层出现孔洞,最后氧化层破裂,镀层表面孔洞增加,最终组织为FeAl2+Fe2Al5+FeAl。The effect of austenitizing process on the thickness of Al2O3 scale and microstructure evolution of Al-10wt.%Si coating were investigated.The increase of Al2O3 scale thickness and microstructural evolution of hot-dipped Al-10wt.%Si coating on 22MnB5 steel during austenitizing process were studied by scanning electron microscopy(SEM), glow dischargeoptical emission spectrometer(GD-OES) and X-ray diffractometer (XRD). When the sample was heated to 900 ℃ at the rate of15 ℃/s, the Al2O3 scale was the thinnest. When the sample was heated to 900 ℃ before holding for 5 min, the Al2O3 scale ofcoating have cracked in varying degrees. There were some holes on the surface of coating, and the thickness of Al2O3 scaleincreased obviously. The depth of oxygen infiltrated into Al-10wt.%Si coating and the thickness of Al2O3 scale increasedgradually with the prolongation of holding time. The effect of austenitizing holding time on the Al2O3 scale thickness wasgreater than that of austenitizing heating rate. Reducing austenitizing holding time was beneficial to preserving a complete Al2O3scale and protecting the steel substrate. The microstructural evolution of Al-10wt.%Si coating was as follows: First,Al2Fe3Si3(τ1) and Fe2Al5 phases formed. Next, Fe2Al5 grew, FeAl2 phase formed, and FeAl2+Fe2Al5 phase grew, FeAlprecipitated. Then, FeAl phase grew, some holes appeared on the Al2O3 scale. Finally, the Al2O3 scale cracked, the number ofholes on the surface of coating increased. The final microstructure of coating was FeAl2+Fe2Al5+FeAl.

关 键 词：Al-Si镀层 奥氏体化 金属间化合物 氧化层 组织演变 

分 类 号：TQ153[化学工程—电化学工业]