6082铝合金的微观组织演变规律和晶间腐蚀行为研究
发布时间：2018-07-31 07:34
【摘要】：6000系铝合金一般没有晶间腐蚀倾向性,但是合金中添加Cu、Mg与Si的质量比不适当或者不合适的热处理工艺都会降低6000系铝合金的抗晶间腐蚀性能。本文以6082挤压和锻造铝合金为研究材料,采用光学显微镜(OM)、扫描电镜(SEM)及其自带的能谱仪、背散射电子衍射仪(EBSD)、透射电镜(TEM)、维氏硬度计等分析手段,采用晶间腐蚀实验、维氏硬度测量等测试手段,分析研究了6082铝合金的微观组织演变规律和晶间腐蚀行为,研究结果表明:对于T6态6082铝合金,随着晶间腐蚀时间的延长,其最大腐蚀深度逐渐增加,当腐蚀时间超过5 h之后,纵向最大腐蚀深度增加幅度很小,但腐蚀在晶界处向晶内扩展却越来越严重,横向腐蚀范围和腐蚀程度逐渐增大。对于T6态6082铝合金,均匀化温度由510℃上升到530℃,均匀化时间由6 h延长到8 h,再结晶晶粒更加细小,成分组织更加均匀,其最大晶间腐蚀深度均减小,而且升高均匀化温度比延长均匀化时间使最大晶间腐蚀深度降低的更多,说明均匀化处理温度对合金抗晶间腐蚀性能的影响比处理时间更显著。T6态6082铝合金锻件在晶间腐蚀之后发生中间区域重腐蚀和周围区域轻腐蚀的现象,发生轻腐蚀的区域为单晶组织,是非常粗大的晶粒组织;发生重腐蚀的区域为多晶组织,该区域晶界上没有发生溶质原子的偏聚,也没有析出,说明发生重腐蚀的原因与晶界析出无关。挤压工艺、锻造工艺造成的不均匀变形是导致锻件固溶处理之后产生粗大晶粒组织的主要原因,不均匀变形会使合金晶界的界面能增大,晶核迅速长大,从而形成粗大的晶粒组织。本文实验用的6082铝合金晶界上没有发生原子偏聚现象,没有析出相,发生晶间腐蚀的原因与晶界析出无关,晶间腐蚀是由α-Al基体与Mg2Si相以及α-Al基体与单质Si之间的腐蚀电位差引起的点蚀导致其周围基体逐渐溶解,扩展至晶界造成的,点蚀的过程包括点蚀的萌生和点蚀的扩展,点蚀首先萌生于在晶内或晶界附近,结合电化学反应对6082铝合金点蚀的机理进行了分析研究。
[Abstract]:Generally, 6000 series aluminum alloys have no intergranular corrosion tendency, but the intergranular corrosion resistance of 6000 series aluminum alloys can be reduced when the mass ratio of CuPmg to Si is not suitable or the heat treatment process is not suitable. In this paper, 6082 extruded and forged aluminum alloy was used as the research material. The intergranular corrosion test was carried out by means of optical microscope, (OM), scanning electron microscope (SEM) and its own energy spectrometer, backscatter electron diffractometer, (EBSD), transmission electron microscope, (TEM), hardness tester, etc. The microstructure evolution and intergranular corrosion behavior of 6082 aluminum alloy were studied by Vickers hardness measurement. The results showed that for T6 6082 aluminum alloy, the intergranular corrosion time increased with the increase of intergranular corrosion time. The maximum corrosion depth increased gradually. When the corrosion time was more than 5 h, the longitudinal maximum corrosion depth increased very little, but the corrosion spread to the grain boundary more and more serious, and the transverse corrosion range and corrosion degree gradually increased. For T6 6082 aluminum alloy, the homogenization temperature is increased from 510 鈩，
本文编号：2154875
[Abstract]:Generally, 6000 series aluminum alloys have no intergranular corrosion tendency, but the intergranular corrosion resistance of 6000 series aluminum alloys can be reduced when the mass ratio of CuPmg to Si is not suitable or the heat treatment process is not suitable. In this paper, 6082 extruded and forged aluminum alloy was used as the research material. The intergranular corrosion test was carried out by means of optical microscope, (OM), scanning electron microscope (SEM) and its own energy spectrometer, backscatter electron diffractometer, (EBSD), transmission electron microscope, (TEM), hardness tester, etc. The microstructure evolution and intergranular corrosion behavior of 6082 aluminum alloy were studied by Vickers hardness measurement. The results showed that for T6 6082 aluminum alloy, the intergranular corrosion time increased with the increase of intergranular corrosion time. The maximum corrosion depth increased gradually. When the corrosion time was more than 5 h, the longitudinal maximum corrosion depth increased very little, but the corrosion spread to the grain boundary more and more serious, and the transverse corrosion range and corrosion degree gradually increased. For T6 6082 aluminum alloy, the homogenization temperature is increased from 510 鈩，
本文编号：2154875
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