低温预时效对6016铝合金汽车板烘烤硬化性能的影响

采用单轴拉伸力学性能测试,结合差示扫描量热法(DSC),分析低温预时效对6016铝合金烘烤硬化性能的影响。结果表明,低温预时效能够有效抑制6016铝合金的自然时效,改善烘烤硬化性能;经预时效处理,合金的DSC曲线中原子团簇吸热峰减弱,β″相放热峰提前,说明预时效能抑制自然时效,并且加速烘烤过程中β″相析出,加强烘烤硬化效果。     

6016铝合金汽车板材预时效处理工艺研究

研究了预时效处理工艺对汽车用6016铝合金板烘烤硬化性能的影响,试验结果表明,经过预时效处理可明显改善人工时效过程中合金软化现象。160℃、7 min预时效处理后板材硬度值高于T4态且呈现增长趋势,有效的抵消了自然时效过程中的合金软化现象。DSC结果表明,预时效处理可加快Mg2Si相析出速度,提高人工时效效果。拉伸结果表明,预时效后烤漆试样屈服强度达到321 MPa,相比自然时效烤漆试样硬度提高了60 MPa,降低自然时效对板材烤漆硬化性能的影响。对6016铝板材采用固溶处理+预时效+烤漆硬化工艺流程,有利于获得良好的板材冲压成形性能以及烘烤硬化处理效果。     

预时效对Al-Zn-Mg-Cu系铝合金组织及硬度的影响

研究了Al-Zn-Mg-Cu系铝合金形变热处理过程中时效制度变化对其组织和性能的影响。结果表明,预时效过程中适当地提高时效温度和延长时效保温时间,可以得到预时效的优化工艺参数;金相观察发现,预时效后合金再结晶明显细化,可观察到明显的析出相;预时效后随着形变量的增加,合金硬度随之增加,当形变量达到40%左右时合金硬度最高,随形变量增加,合金硬度略有下降;变形后的试样再进行终时效处理后,硬度提升不明显。     

6×××系汽车车身板铝合金的合金化及组织性能的研究

采用力学性能试验和光学金相分析法,研究了Mg和Mn等元素对6×××系汽车板铝合金组织及性能的影响。结果表明:Mg和Mn是提高6×××系汽车板铝合金时效初期硬化值的元素,但对时效初期硬化速度影响不大。提高Mg和Mn含量,合金经170℃30min时效后的强度增大,伸长率降低。合金固溶处理淬火后的晶粒尺寸和形态不随Mg含量而改变,但随Mn含量增加而显著细化。     

6000系铝合金时效析出过程的原位电阻表征

采用原位电阻测试、显微硬度测试、准静态拉伸试验、TEM等手段,以6063挤压型材为研究对象研究了Al-Mg-Si铝合金时效过程中强化相的析出行为。结果表明:6063型材在175℃时效8 h后达到强度和硬度峰值,时效初期主要析出相为β″相,材料力学性能快速提高;随时间延长强化相总数增加,但β″相逐渐向β'相转变且尺寸逐渐增大,强化效果逐渐降低。电阻值变化规律与力学性能变化规律有准确的对应关系,随原子团簇或GP区的生成,电阻升高;随GP区向β″相及β″相向β'相转变,电阻下降;电阻的下降速率随析出速率降低而降低。原位电阻测试方法可以对6000系铝合金时效的强化相析出过程进行有效的实时监测。     

预时效工艺对汽车用6016铝合金板时效稳定性和烘烤响应的影响

对汽车覆盖件用6016铝合金板材进行了室温到100℃的预时效处理,并进行了自然时效150 d以内的T4P态和烘烤态(2％预拉伸+ 185℃20 min)性能测试.结果 表明:相比于室温和60℃预时效,80℃和100℃预时效温度的板材表现出良好的时效稳定性,放置150 d之内没有因自然时效使强度显著提高.然而,随着预时效...     

预时效对6111铝合金时效硬化的影响

采用正交试验方法研究了两段预时效处理工艺参数(温度和时间)对6111铝合金最终时效行为的影响。结果表明:该合金有比较明显的回归现象,而且随第二段预时效处理温度升高,回归现象更加明显。第二段预时效温度对烤漆硬化效果影响最大,其他因素的影响依次为:第二段时效时间>第一段时效温度>第一段时效时间。     

预时效时间对2324铝合金组织和性能的影响

通过性能测试和透射电镜观察，研究预时效时间对２３２４铝合金组织和性能的影响。结果表明，随着预时效时间增加，抗拉强度提高、疲劳寿命略有降低，Ｋ１Ｃ变化不明显。当预时效时间为４－１０ｈ时，合金具有良好的综合性能。     

铍元素对7475铝合金时效组织及性能的影响

通过采用不同的时效处理工艺研究了Ｂｅ元素对７４７５铝合金组织、时效硬化进程及性能的影响，结果表明：加入一定量的Ｂｅ能加快７４７５铝合金时效硬化进程，使其硬度提高近１倍，同时还可境加时效沉淀相数目，减小其尺寸。     

预时效时间对Al-Mg-Si铝合金性能的影响

研究了在70℃预时效不同时间对6000系Al-Mg-Si铝合金人工时效后性能的影响.结果表明,随预时效时间的延长,6000系铝合金在170℃人工时效后强度下降,韧性提高,合金晶界处无析出带宽度减小,析出物大部分仍为随机型的β”相,平行四边形的β”相无明显增加.     

Effect of Mg on microstructures and properties of Al-Mg-Si-Cu aluminium alloys for automotive body sheets

The effects of variation of Mg content on microstructures, the tensile properties and the formability of Al-Mg-Si-Cu alloys for automotive body sheets were investigated by means of scan electron microscopy, optical metallographic analysis, tensile and Ericsson tests. The results show that for Al-Mg-Si-Cu aluminium alloys with excessive Si, with an increment of Mg content, the strength enhances, the specific elongation and Erisson values of alloys decrease, and the number of Mg2 Si constituent increases and that of AI(MnFe)Si type constituents reduces. Al-Mg-Si-Cu aluminium alloys with excessive Si for automotive body sheets can present obviously the paint bake hardenability during the paint hake cycle (i. e. artificial aging at 170℃ for 30 min immediately after the solution treatment and quenching). Suitable Mg content should be controlled in the range of 0.8% and 1.2%(mass fraction).     

Effect of pre-aging on microstructure and properties of 2000 series aluminum alloy for automotive body sheets

The effect of pre-aging treatment on the tensile properties, formability and microstructures of 2036 aluminum alloy for automobile body sheets were investigated through the tensile tests, DSC analysis and TEM observation. The results show that the alloy was softened, which was pre-aged at 180℃ within 20 min and then natural aging, namely T4P. However, the yield strength decreases first and then rises. The yield strength of the alloy after T4P （10 min） reach the minimal 202.3 MPa, but the elongation and strain hardening exponent arrive at the maximum, 25.5% and 0.26 respectively, which can improve its formability effectively. In the early stage of T4P, GP zones dissolve, and generate some θ＂ nuclei, so that the strengthening effect is restrained during the natural aging following the pre-aging. With the increment of pre-aging time, the θ＂ phases are formed. The number of the θ＂ phases grows, and the strength increases sharply during the paint-bake treatment. In contrast with the 6000 series aluminum alloy for automobile body sheets, the paint-bake hardenability of the 2036 alloy is lower and its yield strength before the paint bake is accordingly higher, which will add the difficulty of forming for the sheet.     

Effects of different tempers on precipitation hardening of 6000 series aluminium alloys

By means of Vickers hardness,mechanical property and formability tests,the effects of different tempers on precipitation hardening of 6000 series aluminium alloys for automotive body sheets were investigated.The results indicate that the short-time pre-aging at 170℃makes for subsequent artificial aging precipitation hardening.With the increase of pre-aging time,the artificial aging hardenability increases.The aging hardening rate reaches the maximum when pre-aging time is up to 10 min,and then it decreases.The short-time pre-aging at 170℃benefits sheets to obtain lower strength under delivery condition and consequently to improve stamping formability of automotive body sheets.The effects of different tempers on precipitation hardening are much more obvious than those of the alloying elements.It is a good treatment schedule to perform pre-aging for 5 min at 170℃right after solution treatment.     

预时效对A357合金组织与力学性能的影响

研究了低温预时效对含钪A357合金组织与力学性能的影响。结果表明,较理想的合金预时效工艺为120 ℃×4~6 h;120 ℃×4 h+175 ℃×5 h双级时效工艺使合金抗拉强度增至362 MPa,伸长率增至6%,分别较单级时效提高4.6%和7.1%。低温预时效能促进细密、弥散GP区的形成,有利于二次时效获得高密度、弥散分布的细小强化相Mg₂Si,从而提高合金力学性能。     

高润滑皮膜钢板的成形特性及在汽车覆盖件中的应用

高润滑皮膜钢板通过固化手段在合金化熔融镀锌钢板(GA钢板)表面的GA层形成固态润滑皮膜,紧密附着在钢板表面,从而降低钢板的表面摩擦系数,改善润滑性能,达到提高钢板成形性、削减原材料成本的目的。本研究采取适当方法对高润滑皮膜钢板和普通GA钢板的滑动性能、拉伸性能以及胀形性能进行了对比试验,并提出以成形余裕度作为成形性的评价参数,结合在实际汽车覆盖件生产中的成形余裕度测试。结果表明:高润滑皮膜钢板的各项性能对比普通GA钢板均有较大地提高;在成形稳定性方面,对比普通GA钢板提升了60%以上。目前,高润滑皮膜钢板已经在丰田、本田等汽车制造厂中被广泛使用。     

Mg含量对不同热处理的6000系合金成形性及烤漆硬化性的影响

通过硬度、力学性能及成形性试验,研究了Mg含量对不同热处理的6000系铝合金成形性及烤漆硬化性能的影响.结果表明:T4态合金无论是否模拟酸碱洗加热,进行170℃人工时效后,其时效初期的硬度均呈下降趋势,而元素Mg含量的变化影响不大.固溶淬火态和T4P(5min)态合金在模拟烤漆过程中均未出现软化现象.合金的热处理方式对烤漆硬化性的提高比元素Mg的作用更有效.Mg元素的作用主要改变合金的固溶淬火、T4和T4P态的硬度.随Mg含量增加,固溶淬火态硬度单调升高,而T4和T4P态硬度在Mg含量达到1.7%时降低.Mg对T4和T4P(5min)态合金的力学性能和成形性的影响规律是:增加Mg含量,有利于提高合金的强度,但不利于合金的冲压成形.     

铝合金激光焊接的工艺特性及其发展现状

概述了铝合金激光焊接的工艺特性及难点,指出了铝合金激光焊接技术的研究现状及发展方向。     

Effect of Mg, Si and Cu content on the microstructure of dilute 6000 series aluminium alloys

The effect of Mg, Si and Cu content on the microstructural development during ageing treatment of dilute 6000 series alloys have been investigated using transmission electron microscopy (TEM). Four dilute alloys were used in this study. These alloys were subjected to quenching and artificial ageing at 100 °C, 185 °C and 300 °C. The microstructural developments of the precipitates formed were monitored by TEM. The ageing temperature of 100 °C was found to be too low to form precipitates. It was found that needle or rod-shaped precipitates were formed in the alloys after ageing at 185 and 300 °C. Prolong ageing up to 1000 h at 300 °C resulted in the formation of Mg₂Si precipitate that coexists with the type of AlFeSi and Si precipitates. The results show a correlation between the Mg₂Si, Si and Cu content on the microstructure of the four dilute alloys after ageing treatment.     

预时效对车身用6016铝合金烘烤硬化性能的影响

采用硬度测试、拉伸试验和透射电镜等手段研究了不同预时效处理对6016铝合金烘烤前后微观组织和力学性能的影响。结果表明:6016铝合金具有较强的自然时效硬化能力,自然时效24 h的6016铝硬度比固溶态合金硬度增加了45.6%。自然时效超过24 h以后,合金硬度值变化不大。通过预时效处理可以显著提高6016铝合金的烘烤硬化效果。经550 ℃×30 min固溶+160 ℃×10 min预时效处理后,6016铝合金规定塑性延伸强度为131.4 MPa,伸长率为24.7%。再经175 ℃×30 min烘烤后合金规定塑性延伸强度达到199.5 MPa,烘烤硬化值(BH)为68.1 MPa,此工艺为6016铝合金车身板最佳的热处理工艺。