Effect of Microstructure on the Corrosion Resistance of TIG Welded 1579 Alloy

Abstract

The paper studies microstructure, chemical composition and corrosion activity of the tungsten inert gas welded joint of the Al-Mg-Sc alloy. An intensive corrosion attack of the heat affected zone (HAZ) was found due to precipitation of secondary phases at recrystallized grain boundaries. The ccorrosion process initiated along the boundary of α-Al grains, where a high concentration of anodic (Mg2Si and Mg2Al3) and cathodic phases ((MnFe)Al6) was observed. Increased temperatures during welding led to coalescence of the anodic phases in HAZ. Additionally, HAZ was found to be enriched with hard intermetallic compounds (Mg2Si and (MnFe)Al6). This area had a higher microhardness (930 MPa) compared to base metal (BM, 895 MPa) and fusion zone (FZ, 810 MPa). The volume fraction of secondary phases was 26% in BM, 28% in FZ and 38% in HAZ. The average grain size increased in the following order: (9 ± 3) µm (BM) < (16 ± 3) µm (HAZ) < (21 ± 5) µm (FZ). A plasma electrolytic oxidation (PEO) coating of aluminum-based material was applied to protect the weld from oxidation. The PEO-coating provided a high corrosion protection in the aggressive Cl−-containing environment.

New Polycaprolactone-Containing Self-Healing Coating Design for Enhance Corrosion Resistance of the Magnesium and Its Alloys

“…This results in pitting formation, and finally, the loss of mechanical integrity is realized. Therefore, the structure of the base PEO coating should be modified to prolong the period of material exploitation [ 6 , 11 , 12 , 13 ].…”

Effect of Cooling Rate at the Eutectoid Transformation Temperature on the Corrosion Resistance of Zn-4Al Alloy

“…The resultant electrochemical potential was closely related to the phase heterogeneity of the zinc alloy, i.e., to the corrosion potential of each phase. The phases with various electrode potentials became anodic and cathodic during contact between the alloy and the electrolyte [28]. Al has a nobler electrochemical behavior than Zn [17,29], and similar behavior should be attributed to Al-base and Zn-base solid solutions.…”

Влияние Структурной Гетерогенности На Коррозионное Поведение Алюминиевых Сплавов И Их Сварных Соединений

“…В разделе 5.2.1 было установлено, что покрытие, формируемое ПЭО, повышает стойкость сварного материала в агрессивной среде и ингибирует процесс коррозии. В данной части монографии и в наших работах [853,854] технологии SVET/SIET были использованы для прецизионного установления влияния микроструктуры сварного соединения на гетерогенность и защитные свойства формируемых покрытий.…”