Recovery of Mechanical Properties of a 6061-T6 Aluminum Weld by Heat Treatment After Welding
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- 作者：Javier Serrano Pérez ; Ricardo Rafael Ambriz…
- 刊名：Metallurgical and Materials Transactions A
- 出版年：2016
- 出版时间：July 2016
- 年：2016
- 卷：47
- 期：7
- 页码：3412-3422
- 全文大小：3,136 KB
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Chemistry
Materials Science
Metallic Materials
Structural Materials
Physical Chemistry
Ceramics,Glass,Composites,Natural Materials - 出版者：Springer Boston
- ISSN：1543-1940
- 卷排序：47
文摘
The dilution effects in welds of a 6061-T6 (Al-Si-Mg) alloy obtained by the modified indirect electric arc (MIEA), using an ER4043 filler metal (Al-Si), and postweld heat treatment (PWHT) were analyzed. The soft zone (55 to 70 HV0.1) formed by the microstructural transformation in the heat-affected zone (HAZ) was eliminated. The hardness measurements were presented on a traditional microhardness profile and mapping representation. A hardening effect of the fusion zone was observed; the hardness values were above 120 HV0.1 and tended to be uniform. This behavior could be attributed to the chemical composition of the filler metal, the Mg migration from the base to the weld metal, and the reversible process of the PWHT, which promotes precipitation hardening. Improvement for yield (260 MPa) and tensile strength (310 MPa) of the MIEA joints was observed; these values were similar to those obtained for the base metal. However, the presence of porosity in the fusion zone limits the ductility of the joints (4.3 pct). Even though the yield and tensile strengths of the base metal and welded joints were similar, the stress concentration due to porosity in the weld metal generated data dispersion in fatigue life. As a consequence, the high-cycle fatigue life decreases with respect to the base metal. In contrast, when the crack propagates under elastic conditions, the crack-tip singularity is affected by the porosity in the weld metal (stress liberator). This aspect, in conjunction with the hardening effect in joints subjected to PWHT, improves the fatigue crack growth rate when compared to the as-welded condition.Manuscript submitted July 13, 2015.