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Development of New Weldable Al-Zn-Mg Alloy with High Resistance to Stress Corrosion Cracking.

开发具有高抗应力腐蚀开裂能力的新型可焊接铝锌镁合金。

基本信息

批准号：
59850125
负责人：
KURODA Toshio
金额：
$ 2.5万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research
财政年份：
1984
资助国家：
日本
起止时间：
1984 至 1985
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-59850125/
关键词：
Pitting potential Pitting Stress corrosion cracking Al-Zn-Mg alloy Minor alloying elements Corrosion Resistance 溶接部

项目摘要

The purpose of this investigation is to present the development of new weldable Al-Zn-Mg alloy with high resistance to stress corrosion cracking by means of additions of minor alloying elements.The stress corrosion cracking of Al-Zn-Mg alloy occurs by the pitting or corrosion. In this investigation, the measurement of pitting potential was carried out as the evaluation of corrosion resistance.As the new alloy, Al-4.5%Zn-1.2%Mg alloys separately added 0.2%Cr 0.5%Mn,0.05%Ti and 0.2%Fe-0.1%Si, and then Al-4.5%Zn-1.2%Mg alloy with various contents of Cr,Zr and Cu up to 1 % in order to improve the corrosion resistance were prepared.The effect of the minor alloying elements on aging characteristics and corrosion resistance was studied by means of metallurgy and electrochemistry by anodic polarization characteristics. The results were summarised as follows.1. The addition of Cu or Cr to the Al-4.5%Zn-1.2%Mg alloy causes the increase of the pitting potential. But the pitting occurs predominantly at the grain boundaries above 0.2%Cu or 0.2%Cr. Therefore,addition of 0.2%Cu or 0.2%Cr is effective ,concerning the stress corrosion cracking.2. The addition of 0.05%Ti,0.2%Fe-0.1%Si or 0.5%Mn is effective to inhibit the grain growth, but hardly affect the pitting potential.3. The Zr addition up to 0.2% to the Al-4.5%Zn-1.2%Mg alloy affects the refining of the grain size,but the Zr addition above 0.5% causes the reduction of corrosion potential and causes the stress corrosion cracking.4. On the basis of the results above mentioned, the additions of 0.05%Ti,0.2%Cr,0.5%Mn,0.2%Fe-0.1%Si,0.2%Zr and 0.2%Cu to the Al4.5%Zn -1.2%Mg alloy are effective to improve the stress corrosion cracking and corrosion resistance of the weld heat affected zone.

通过添加微量合金元素，研制了一种具有高抗应力腐蚀开裂性能的可焊Al-Zn-Mg合金。本研究采用点蚀电位法对Al-4.5%Zn-1.2%Mg合金的耐蚀性进行了评价，在Al-4.5%Zn-1.2%Mg合金中分别添加0.2%Cr、0.5%Mn、0.05%Ti和0.2%Fe-0.1%Si，然后再添加不同Cr含量的Al-4.5%Zn-1.2%Mg合金，为了提高合金的耐蚀性，制备了1%的Zr和Cu微量合金元素，并通过阳极极化曲线和电化学方法研究了微量合金元素对合金时效特性和耐蚀性的影响。研究结果如下：1. Cu或Cr的加入使Al-4.5%Zn-1.2%Mg合金的点蚀电位升高。但当Cu含量大于0.2%或Cr含量大于0.2%时，点蚀主要发生在晶界处。因此，添加0.2%Cu或0.2%Cr对应力腐蚀开裂是有效的. 0.05%Ti、0.2%Fe-0.1%Si或0.5%Mn的加入能有效抑制晶粒长大，但对点蚀电位影响不大.当Zr的添加量达到0.2%时，Al-4.5%Zn-1.2%Mg合金的晶粒得到细化，但当Zr的添加量超过0.5%时，合金的自腐蚀电位降低，导致应力腐蚀开裂.结果表明，在Al 4.5%Zn-1.2%Mg合金中添加0.05%Ti、0.2%Cr、0.5%Mn、0.2%Fe-0.1%Si、0.2%Zr和0.2%Cu，可有效地改善焊接热影响区的应力腐蚀开裂和耐蚀性。