薄带连铸因瓦合金的组织、织构及力学性能研究

Study on Microstructure,Texture and Mechanical Properties of Strip Casting Invar Alloy

将薄带连铸技术引入因瓦合金的制备流程,利用金相显微镜、XRD、EBSD、微观硬度计、拉伸实验机等设备,围绕薄带连铸因瓦合金的组织织构演化及力学性能开展研究.结果表明:在钢液过热度较高的条件下,因瓦合金凝固组织以粗大的柱状奥氏体晶粒为主,织构为强烈的λ纤维织构(<100>//ND).冷轧过程中形成大量的变形亚结构,使硬度(HV)由铸态的165提高至230~240,冷轧织构以典型的铜型织构({112}<111>)及S型织构({123}<634>)为主.0.7 mm厚冷轧板经900℃退火10 min,形成包含大量退火孪晶的再结晶组织,织构较漫散,其屈服强度、抗拉强度和断后延伸率分别达293 MPa,433 MPa和33.4%,与传统流程制备的0.7 mm厚因瓦合金的性能相当.

The twin-roll strip casting technology was introduced into the process of manufacturing invar alloy.Using optical microscope,XRD,EBSD,micro hardness(HV)and tensile testing instruments,the evolution of microstructure,texture and mechanical properties of the strip-casted invar alloy were investigated.The results show that the solidification microstructure of the strip-casted invar alloy is dominated by the coarse columnar grains of austenite and the associated texture is mainly the strongλ-fiber texture(<100>//ND).Thereafter,a large amount of deformation substructures are formed during a cold-rolling process,which increase the hardness(HV)from 165 to 230~240,and the cold-rolled texture is mainly composed by the typical copper texture({112}<111>)and S texture({123}<634>).A recrystallization microstructure containing numerous annealing twins together with a weak texture is observed in the 0.7mm-thick sheet after annealing at 700℃for 10 min.The yielding strength,tensile strength and final elongation are 293 MPa,433 MPa and 33.4%,respectively,which are similar to those of the 0.7mm-thick annealed sheet produced by the conventional process.