搅拌摩擦加工方向对AZ61镁合金组织和力学性能的影响

Effect of friction stir processing direction on the microstructure and mechanical properties of AZ61 magnesium alloy

摘要:

采用搅拌摩擦加工技术（Friction stir processing，FSP）对轧制态AZ61镁合金进行单道次加工，利用EBSD和SEM/EDS及室温拉伸、显微硬度测试等表征手段，研究了加工方向对加工区域微观组织演变及其对力学性能的影响规律．结果表明：沿轧制方向（Rolling direction, RD）和横向（Transverse direction, TD）FSP制备的镁合金晶粒尺寸分别为3.5 μm和4.3 μm，基面施密特因子平均值分别为0.42和0.34；沿RD方向制备的镁合金中第二相呈细小弥散分布，而TD方向的第二相颗粒较为粗大；两个方向制备的镁合金抗拉强度相当，沿RD和TD方向制备的镁合金的屈服强度分别为90 MPa和104 MPa、伸长率分别为34.8%和28.6%，而RD方向制备的镁合金硬度高于TD方向．屈服强度与霍尔佩奇关系不符，受织构影响，而硬度分布符合霍尔佩奇关系．

Abstract:

Friction stir processing (FSP) is utilized to process the rolled AZ61 magnesium alloy in a single pass. EBSD, SEM or EDS, tensile testing at room temperature and microhardness testing were conducted to investigate the effect of processing direction on the microstructural evolution and mechanical properties of the stirring zone. The results indicate that the grain sizes of AZ61 magnesium alloy prepared by friction stir processed (FSPed) along the rolling direction (RD) and transverse direction (TD) is 3.5μm and 4.3μm, respectively. For the RD and TD processing directions, the average basal Schmidt factor value is 0.42 and 0.34, respectively. The second phase of FSPed AZ61 magnesium alloy in the RD is refined and dispersed distribution, while of the second phase particles in the TD direction are relatively coarse. The tensile strength of the magnesium alloy prepared in the RD and TD directions is equivalent, the yield strength of RD and RD is 90MPa and 104MPa, respectively. The elongations are 34.8% and 28.6% in the RD and TD, respectively. The microhardness in the RD is higher than that of in the TD. The yield strength is inconsistent with the Hall-Patch relationship, and is affected by the texture, while the microhardness distribution conforms to the Hall-Patch relationship.