激光焊接ZK60变形镁合金的组织和力学性能（英文）

采用激光焊接技术成功焊接了2.0 mm厚ZK60变形镁合金板材并研究了焊接参数(激光功率和焊接速度)对接头组织和力学性能的影响。在优化工艺参数下,可以获得良好的焊接接头,其抗拉强度为300 MPa,伸长率为12.0%,分别高达母材的92.5%和65%。轧制板材晶粒细小且存在很多微细的析出相,对液化开裂具有抑制作用,从而没有观察到半熔化区(PMZ)的液化开裂现象。熔化区(FZ)具有等轴晶特征,平均晶粒粒径为8μm,与热影响区(HAZ)组织特征相似。这种组织特征有助于获得较高的焊接效率。     

ZK60镁合金CO2激光焊接接头的组织与性能

采用CO2激光对轧制态细晶粒ZK60镁合金板材进行了焊接.研究了焊接工艺参数对接头显微组织和力学性能的影响规律,并分析了细晶粒镁合金板材的焊接特点.结果表明,在合适的工艺条件下,可以获得成形性能良好,无半熔化区(PMZ)液化裂纹的焊接接头;其抗拉强度和伸长率达到了295 MPa,11.7％,分别为母材的91％和62％;熔池(FZ)边界处的胞状晶和柱状晶区范围较窄,约为20 μm,熔池区由细小的等轴晶构成;从熔池区(FZ)到热影响区(HAZ)再到母材(BM)晶粒尺寸差别在3 μm以下,焊接接头呈韧性断裂模式.     

ZK40高强镁合金CO2激光焊接接头的组织与力学性能

采用C2激光对轧制态ZK40镁合金板材进行焊接,并研究焊接工艺参数对接头显微组织及力学性能的影响规律.结果表明:在合理的工艺条件下,可以获得成型良好的焊接接头,其抗拉强度可达到315MPa,为母材的91.3%;熔池边界无外延生长的柱状晶,整个熔池完全由细小均匀的等轴树枝晶组成:分布于晶界及枝晶臂间的第二相粒子主要是Mg<,51>Zn<,20>;随着焊接热输入的增大,枝晶臂生长更为发达,晶粒粗化.     

ZK21镁合金激光焊接缺陷分析及防治措施

采用高功率激光对ZK21镁合金板材进行焊接,表征接头中存在的缺陷,分析其产生原因和防治措施。结果表明:结晶裂纹和表面凹坑是恶化接头质量的主要原因。结晶裂纹易产生于焊缝的末端及焊接速度较高的工艺条件下,焊接时,应使用同材质引弧板且不推荐采用导致熔池冷却速率过高的焊接工艺;表面凹坑是由高能量密度激光束加热下熔体的蒸发和烧损所致;半熔化区易发生的晶界液化并存在开裂风险,其主要原因与该合金凝固温度区间过宽有关;熔合线附近和焊缝上表面是气孔的高发区域,适当降低焊接速度或增大激光功率有利于抑制焊缝气孔的产生。     

AM60变形镁合金薄板激光焊接接头的组织与性能

以AM60变形镁合金薄板为研究对象，分析C02激光焊后接头的组织和性能，探讨镁合金激光焊接的工艺特点。结果表明：在合适的工艺参数下，能获得表面成型良好、变形小的焊接接头。金相观察分析发现接头中热影响区不明显，焊缝区组织致密，晶粒细小，晶界上均匀分布着脆性相（Mg17A112），但内部易产生气孔、裂纹等微观缺陷。硬度测试结果显示，焊缝硬度略高，母材和热影响区硬度相当。在本实验条件下采用C02激光焊能实现AM60镁合金的焊接，抗拉强度可达母材的94％，断口表现为混合断裂。     

ZK60镁合金微弧氧化改性研究

在NaOH电解液中,对ZK60镁合金进行微弧氧化处理。研究了微弧氧化过程的电压-时间曲线、微弧氧化电流、氧化时间对微弧氧化膜层的显微形貌和厚度的影响,测试了氧化膜的耐蚀性能。研究结果表明:随着微弧氧化电流和时间的增加,表面膜层厚度增加,但膜层中的微孔直径增加,表面粗糙度增加,氧化膜质量降低。在NaOH电解液中,微弧氧化电流为3A、氧化3min后,ZK60镁合金表面形成的氧化膜质量最好,厚度约为19.8μm。XRD分析表明微弧氧化处理后试样表面膜层由MgO相组成。耐腐蚀测试表明微弧氧化后样品的质量出现先增加而后降低的现象,其失重和析氢量均比未微弧氧化样品少,同时溶液pH值变化较慢,这说明微弧氧化后样品的耐腐蚀性提高。     

异种镁合金激光焊接接头分析

采用CO2激光对三种镁合金AZ31、NZ30K、ZK60进行焊接,并通过光学显微镜、扫描电镜、能谱仪及拉伸试验机对其焊接接头的微观组织和力学性能进行了分析和测试。结果表明,异种镁合金采用激光焊接均能得到良好的焊缝,其焊接接头的抗拉强度均小于母材的抗拉强度。元素分析表明,接头熔合区均存在明显的元素浓度梯度分布。     

多向锻造制备ZK60镁合金部分重熔组织演变和力学性能(英文)

为了提高ZK60镁合金的力学性能,采用多向锻造和部分重熔工艺;研究重熔温度和保温时间对ZK60镁合金半固态组织的影响;研究多向锻造和部分重熔工艺制备的ZK60镁合金构件在不同触变成形温度下的力学性能。结果表明:多向锻造加部分重熔工艺是一种制备半固态触变成形ZK60镁合金的有效方法。在部分重熔过程中,随着保温时间的延长和重熔温度的升高,晶粒长大。升高重熔温度,晶粒球化效果明显得到改善。当触变成形温度从560°C升高至574°C时,ZK60镁合金的力学性能明显提高。     

基于BP神经网络的ZK60镁合金力学性能研究

利用热模拟机对ZK60镁合金进行等温压缩变形实验,建立人工神经网络模型,并通过相关性系数和相对误差评估和验证模型的预测能力。结果表明,所建立的反向传播神经网络模型能够追踪实验值,可以描述ZK60合金在高温变形时各热力学参数之间高度非线性的复杂关系。     

Ca、Y对ZK60镁合金阻燃性能的影响

研究了ZK60镁合金在单独和复合加入Ca、Y时的阻燃性能.结果表明,在Ca、Y单独加入时,合金阻燃性能随Ca、Y含量增加而提高.添加1.62%Ca,燃点提高171℃,添加2.95%Y,燃点提高253℃.复合加入时,添加1.96%Y1.05%Ca合金燃点达到了峰值,在845℃保温30min而不燃烧.XRD和SEM分析表明,含Ca镁合金氧化膜分三层,氧化膜主要由MgO和ZnO组成,含Y镁合金氧化膜主要由MgO、Y2O3和ZnO组成,Ca、Y复合加入时,由于Ca的第三元素效应使合金燃点大幅度提高,其氧化膜主要由MgO和Y2O3组成.     

Influence of aging on microstructure and properties of ZK60 magnesium alloy

The different aging process was investigated for ZK60 magnesium alloy to get the ideal synthetic properties. The results show that the values of strength, hardness and plasticity of ZK60 magnesium alloy increase at first and then decrease with increasing aging temperature, the suitable aging temperature of ZK60 alloy is from 160 to 180 ℃, At the meantime, the microstructures of appear mesh texture under high ageing temperature, this is the main reason why the mechanical properties decrease.     

Influence of impurities on damping properties of ZK60 magnesium alloy

The influence of impurities on damping capacities of ZK60 magnesium alloys in the as-cast, as-extruded and T4-treated states was investigated by dynamically mechanical analyzer at room temperature. Granato and Lucke dislocation pinning model was employed to explain damping properties of the alloys. It is found that reducing impurity content can decrease the amount of second-phase particles, increase grain size and improve damping capacity of the as-cast alloy slightly. The as-extruded alloy with lower impurity content is found to possess obviously higher damping capacity in the relatively high strain region than that with higher impurity concentration, which appears to originate mainly from different dislocation characteristics. The variation tendency of damping property with change of impurity content after solution-treatment is also similar to that in the as-extruded and as-cast states. Meanwhile, the purification of the alloy results in an evident improvement in tensile yield strength in the as-extruded state.     

Superplasticity and diffusion bonding of magnesium alloy ZK60

1 INTRODUCTIONRecently , the use of magnesium alloys asstructural materials has significantlyincreased,forits good damping capacity , di mension stability ,machinability and lowcasting costs . But magnesi-umalloys normally exhibit lowductility near roomtemperature because of their HCP structure .Therefore ,it is necessary to i mprove the ductilityof these alloys for their use as structural compo-nents[1 3].In manufacturing,superplastic forming is of-ten combined with diffusion bonding, w…     

ZK60镁合金管材热挤压成形组织演变规律

采用数值模拟和试验方法研究了变形镁合金ZK60管材挤压成形组织演变规律。根据材料热模拟试验结果,得到了ZK60镁合金动态再结晶组织演变的Yada模型中的相关系数。结果表明,当挤压速度增大时,挤压管材晶粒尺寸减小,变化规律接近线性。当挤压温度增大时,挤压管材晶粒尺寸增大。挤压比增大时,晶粒尺寸减小。晶粒尺寸数值模拟结果与试验结果吻合,最大相对误差小于16%。当温度在300～360℃时,ZK60镁合金发生了完全动态再结晶,晶粒较小且组织均匀,平均晶粒尺寸是原始晶粒尺寸的38%。     

镁合金电阻点焊凝固裂纹机理

为了获得高性能的镁合金电阻点焊接头,利用光学显微镜、扫描电镜、能谱仪研究了点焊接头裂纹的形成机理.结果表明,结晶裂纹的形成,主要与Al和Mn元素偏析造成的晶间低熔点液态薄膜,以及冷却过程中产生的拉伸应力有关.点焊参数(热输入)对熔核结晶裂纹敏感性有很大的影响.热输入增加将增大由熔核收缩引起的拉伸应力,增加原子偏析浓度进而降低液态薄膜熔点,以致于延长拉伸应力的作用时间.因此,应该选择相对低的热输入来降低点焊接头的凝固裂纹敏感性.     

喷丸强化对ZK60镁合金高周疲劳性能的影响

研究高强度变形镁合金ZK60经喷丸处理后的表面变形层微观组织结构的变化及其对高周疲劳性能的影响.结果表明:ZK60镁合金的最佳喷丸强度(N试片)为0.05 mm,经喷丸强化后,ZK60镁合金表面变形层的微观组织和织构发生变化,疲劳强度由140MPa提高到180MPa,提高约29%,疲劳寿命得到显著提高;ZK60镁合金也表现出明显的过喷效应.     

Effects of heat-treatment on microstructure of wrought magnesium alloy ZK60

The microstructure of the as-cast, as-solution-treated and as-aged wrought magnesium alloy ZK60 was studied. The results indicate that the microstructure of the as-cast ZK60 alloy is mainly composed of network eutectic （a-Mg＋MgZn） and divorced euteetic MgZn, which semi-continuously distribute along the grain boundaries or in the interdendritic area and almost dissolve into the matrix after solid solution treatment. The Laves phase MgZn2 is not sensitive to the heat treatment and seems to form at the early stage of solidification and keeps its size and shape till the aging stage. It is believed that the occurrence of the Laves phase in the ZK60 alloy would possibly contribute to the defects. Many new phases, including MgZn phase which is different from that forms during eutectic reaction, precipitate after aging treatment.