热加工过程对Al-Mg-Si-Cu合金组织、织构演变及力学性能的影响（英文）

系统研究热加工过程对Al-Mg-Si-Cu合金组织、织构及力学性能的影响。通过工艺优化获得了力学性能各向异性很弱的合金板材。热轧和冷轧板材的显微组织均呈拉长态组织。热轧板表层的织构组分以H{001}<110>和E{111}<110>为主,而1/4层和中间层的织构以β取向线为主。与热轧板相比,一次冷轧板的β取向线密度增加而表层的H取向减弱。经中间退火后,形变织构基本消失,最终冷轧后的织构以β取向线为主。随着厚度的减小,织构梯度逐渐变弱。合金板材固溶处理后的再结晶织构组分仅含有cubeND{001}<310>织构。此外,分析了热加工过程、显微组织、织构以及力学性能之间的关系。

Sb变质Mg-6Al-1Zn-0.7Si镁合金的组织和性能

研究了Sb变质Mg-6Al-1Zn-0.7Si镁合金的凝固行为、铸态组织及力学性能。研究结果表明:Mg-6Al-1Zn-0.7Si合金的铸态组织主要由初生!-Mg、M17Al12和Mg2Si相组成,其中Mg2Si相的汉字状形态非常明显,且比较粗大。而添加0.4%Sb变质后,合金组织中的Mg2Si相变得相对细小,从而使合金的拉伸性能以及抗蠕变性能得到提高。此外,添加0.4%Sb对Mg-6Al-1Zn-0.7Si合金凝固过程中的相变类型没有影响,并且对合金的相变峰值温度、开始转变温度和凝固温度范围的影响也不大。

化学成分及热处理对Al-Mg-Si合金汽车板材力学性能的影响

研究了Al-Mg-Si合金中过剩硅和Mg2Si的含量以及热处理工艺对该合金汽车板材的显微组织和力学性能的影响。结果表明,增加过剩硅含量,模拟烘烤前板材的抗拉强度提高30%左右,伸长率提高15%左右;而模拟烘烤后板材强度的增加不超过15%,伸长率则没有明显变化。随着Mg2Si含量增加,模拟烘烤前后板材的强度均有所增加,但不会对板材伸长率产生显著影响。在T4P状态下,当Mg2Si含量由1.25%增加到1.97%时,模拟烘烤后板材的抗拉强度分别由316MPa增加到383MPa。预时效对合金模拟烘烤前的屈服强度和塑性影响不大,因此不会对板材的变形性能产生显著影响。但对模拟烘烤后的力学性能影响显著,板材的抗拉强度最高可以达到383MPa,接近T6状态的抗拉强度,同时塑性有所增加,有利于提高板材的服役性能。

Effects of Cr and Cr/Mn Combined Additions on Semi-Solid Microstructures of Al-Mg-Si Alloys Produced by D-SSF Process

The effects of Cr and Cr/Mn combined additions on the semi-solid microstructure of wrought Al-Mg-Si alloys are investigated.In the Cr-added alloy,the Al-7Cr compound is formed with homogeneously distributed in theα-Al matrix after homogenization.Both of the Al-7Cr andα-Al-（12）Mn3-Si-2 dispersiod particles are found in the homogenized microstructure of the Cr/Mn-added alloy.In the semi-solid microstructures,the smallestα-Al grains are obtained in the 60% cold-rolled alloys.After prolonged holding time,theα-Al grain size of the Cr/Mn-added alloy is smaller than that of the Cr-added alloy.Heavy deformation by cold-rolling accelerates spheroidization of theα-Al grains.The D-SSF process is found to be useful to modify the microstructures of both the Cr-added and Cr/Mn-added Al-Mg-Si alloys.

Al-Mg-Si合金滑移面结合及位错运动机制

运用固体经验电子理论(EET理论),对A l-Mg-S i合金GP区(L10型,下同)、β相(Mg2S i)相邻滑移面之间总的共价键结合能力进行了计算,结果表明:GP区与β相滑移面之间总的结合能力分别为基体A l的1.36与3.32倍,通过这种结合能力的比较,可以合理解释它们的硬度及其对合金的硬化强化作用与位错不同交互机理的内在原因.

Si含量对Mg-5Sn-1.5Al-1.2Zn合金组织性能的影响

在熔炼过程中以镁硅中间合金形式加入Si元素,研究了0～1.6%范围内不同Si含量对Mg-5Sn-1.5Al-1.2Zn镁合金铸态组织及力学性能的影响。结果表明:合金元素Si与Mg基体结合生成了强化相Mg2Si,并在该相周围有Mg2(Si,Sn)复合相产生,Mg2(Si,Sn)相的出现对Al、Zn元素形成τ-Mg32(Al,Zn)49相有促进作用;Si元素在0～1.6%变化时,试样合金的抗拉强度、伸长率呈现先升高后降低的趋势,当Si含量为1.0%时强度、塑性出现较佳配合,而合金的硬度则呈现持续增加,Si含量1.2%～1.6%范围内,硬度上升趋势变缓。

INFLUENCE OF COMPOSITION AND DISPERSOID ON FATIGUE FRACTURE BEHAVIOUR OF Al-Mg-Si ALLOYS

A study was made of the fatigue fracture behaviour under different aging conditions of two Al-Mg-Si alloys with different chemical compositions and dispersoid contents.The dispersoid phase can alter the mode of the deformation uniformity of alloys.The dispersoid it- self may decohere from the dispersoid/matrix interface under cyclic stress to form small dimples.

Characterizations of precipitation behavior of Al-Mg-Si alloys under different heat treatments

The solidification-precipitation behavior of Al-Mg-Si multicomponent alloys has long been an absorbing topic. Experiments were carried out to analyze the precipitation behaviors of Al-Mg-Si alloys under different heat treatments. All specimens were homogenized at 570 °C for 8 h, and then solution treated at 540 °C for 55 min. Subsequently, the specimens were age treated for different times at temperatures of 100 °C, 150 °C and 180 °C, respectively. The experimental results show that the occurrence of dispersed free zones(DFZ) is caused by the uneven distribution of dispersed phase. During the aging process, pre-β″ phases form at the initial stage and an aging temperature of 100 °C is too low to complete the transformation of pre-β″ to β″. At 150 °C, the precipitation sequence is concluded as SSSS-pre-β″-pre-β″+β″-β″-β′-β. Moreover, changes in sizes and densities of the pre-β″, β″and β′ phases during the aging process has an important influence on the evolution of microhardness and electrical resistivity. The microhardness peak value of 150 °C is similar to that of 180 °C, which is ~141 HV. While, at 100 °C, the microhardness increases slowly, and the attainable value is 127 HV up to 19 days. When the aging temperature is 100 °C, the electrical resistivity has the highest average value. When the aging temperature exceeds 100 °C, with the occurrence and growth of β″and β′, the resistivity has a distinct decrease with prolonged aging time.

铝合金挤压在线热处理技术

（上接2010年第四期） 2.3挤压前锭坯的预热条件 锭坯挤压前预热可采取两种方法,即锭坯预热到固溶度曲线温度以上（超溶解）保温,然后骤冷到较低的合适的挤压温度。或者控制炉子保持锭坯低于快速析出区温度（即临界温度范围）,

铝合金挤压在线淬火技术(续)

This article fully discusses the basic principle of on-line quenching for aluminum alloy extrusion and process conditions to realize on-line quenching,lists on-line quenching parameters for partly common aluminum alloy extrusion,indicates chemical composition of aluminum alloy;billet quality and homogenizing treatment;pre-heating condition of billet before extrusion;quenching sensitivity of alloy and cooling speed of extrusion on-line quenching;Advanced precision water-mist-gas quenching device is a necessary and sufficient condition to realize this process.It is an advanced and effective process which can simplify process flow,improve production efficiency,shorten production period,reduce production cost and has important economic value.

高强度铝合金线杆的冶金质量控制

铝合金的冶金质量通常是指铝合金铸坯的内在质量,主要包括内在合金元素的含量控制和分布均匀性、晶粒结构,以及熔体内部杂质控制,包括气体杂质和非金属夹杂,铝合金铸坯的冶金质量将直接影响后续加工产品的质量。针对铝镁硅系高强度铝合金线杆的铸轧特点,重点介绍铝镁硅系高强度铝合金线杆制造过程中的冶金质量缺陷原因分析及控制方法。

Gd含量对Mg-7Al-1Si合金组织及蠕变性能的影响

利用光学显微镜、扫描电镜、X射线衍射分析及高温压缩蠕变装置等,研究了稀土元素Gd对Mg-7Al-1Si合金显微组织及蠕变性能的影响。结果表明,适量Gd的加入能明显细化Mg-7Al-1Si合金的晶粒尺寸、改善Mg2Si相的形态,使β相分布更弥散,并提高了合金的抗高温蠕变性能,Gd的加入还使基体中出现新相Al2Gd。Gd含量为1.0%时,合金的组织和成分均匀,细化效果最好,抗高温蠕变性能也最佳。此时晶粒平均尺寸由79.08μm减小到39.12μm,β相含量由10.88%减少到6.98%,同时Mg2Si相形态明显改善,由粗大汉字状变为短杆状及颗粒状,从而提高了合金的抗高温蠕变性能。

Mechanical properties,microstructure and surface quality of Al-1.2Mg-0.6Si-0.2Cu alloy after solution heat treatment

The effect of solution heat treatment （SHT） on mechanical properties, microstructure and surface quality of Al-1.2Mg-0.6Si-0.2Cu-0.6Zn alloy was investigated by tensile test, Erichsen test, surface topography, scanning electron microscope （SEM） and electron back-scattered diffraction （EBSD）. The results indicate that with the increase in SHT temperature, yield strength and cupping test value （IE） of the sheets increase greatly and reach a peak value, then decrease. Meanwhile, intermetallic com- pounds dissolve into matrix gradually. The grains grow up as SHT temperature increases, and abnormal grain growth leads to the surface defects after solution-treated above 560 ~C. Considering mechanical properties, IE value, residual phases, grain size and surface quality of the sheets, SHT temperature for the alloy should not be higher than 550 ℃.

基于3DAP及第一性原理的Al-Si-Cu-Mg合金团簇及沉淀演变

基于Three Dimensional Atom Probe（3DAP）以及First-Principles对Al-Si-Cu-Mg合金中团簇及后续沉淀的演变过程进行了研究。3DAP试验表明,Al-1.0Si-1.5Cu-0.5Mg合金时效0.25h后基体中主要存在点状的Si-Si团簇、Si-Mg团簇、Si-Mg-Cu团簇,与第一性原理计算所表明的以上各结构中溶质原子间结合较强的结果相符,同时由于大量Si原子的扩散聚集,导致Si-Cu团簇结构出现;时效0.25-2h后基体中Si、Mg、Cu原子继续聚集,点状的Si-Si、Si-Cu、Si-Mg团簇长大并向针状的Si-Mg-Cu团簇演变;时效2-4h后,Si、Mg、Cu原子继续聚集,促进针状Si-Mg-Cu结构长大的同时,部分大尺寸的Si-Mg-Cu结构逐渐向板条状的Q′相转变,同时富Cu结构出现。

微合金化元素Sn对Al-Mg-Si合金高温时效强化相析出路径的改变

研究了Sn(0.2%,质量分数)的添加对一种富Mg的Al-Mg-Si合金经历不同时间的自然时效后在250℃下人工时效过程中的时效硬化行为的影响,并利用TEM观察揭示了其微观机理。结果表明,在Al-Mg-Si合金中添加微量Sn(0.2%)可以改变合金250℃人工时效的强化相析出路径:当直接进行人工时效时,析出相主要为b"相;当进行自然时效+人工时效处理时,随着自然时效时间的延长,b"相的比例不增反降,而b'相的比例不降反增,但最终b"相的比例仍高于b'相的比例。Sn对强化相析出路径的改变,可以明显提高合金高温人工时效的硬化能力。Sn的添加提高了基体中有效的Si浓度,从而改变了不含Sn合金的强化相析出路径。

P-Sb复合变质对Al-Si合金组织的影响

研究P变质、P-Sb复合变质、Mg含量对Al-Si合金组织及力学性能影响。结果表明,P变质后,初生Si尺寸由40μm减小至20μm,共晶Si长度由20μm减小至12μm,而且分布更均匀,抗拉强度、屈服强度均提高15%。P-Sb复合变质后,初生Si尺寸减小至5μm,共晶Si变为蠕虫状,α-Al枝晶得到细化,与P变质相比,抗拉强度、屈服强度均提高8%。Mg含量增多,激化Sb变质效果,共晶Si变为球体状,初生Si消失、α-Al枝晶更细小,与P-Sb复合变质相比,抗拉强度、屈服强度均提高3%。