Investigation of Microstructure and Stress Corrosion Cracking in Al-6061-T6 Alloy at Different Loads

Stress corrosion cracking (SCC) refers to the damage of mechanical components which are under the combined action of static load and corrosive environment. This phenomenon occurs in various applications including naval and aerospace industry where aluminum and steel alloys experience mechanical loadings in the presence of corrosive environments. In this research work, microstructural and environmental influence on corrosion behavior of Al-6061-T6 at different static loads was investigated. A new test fixture was developed for stress corrosion cracking. Dog-bone shaped tensile specimens of Al-6061-T6 were manufactured using CNC milling machine. Tests were conducted at constant loads of 200 N, 500 N and 800 N, in three different environments: dry ambient conditions, distilled water and 3.5% NaCl solution. Testing continued for different intervals of time i.e. 96 hours, 68 hours and 4.5 hours respectively. After each set of experiments, specimens were observed for cracks using metallurgical microscope. Detailed fractographic investigation of all the tested specimens was carried out using Scanning Electron Microscope (SEM). Excessive corrosion and material degradation was observed in specimens tested in distilled water and 3.5% NaCl environments. Microstructural analysis depicted pitting corrosion and crack deformation.  Some regions clearly showed that grain boundaries were attacked due to oxidation and chemical attack causing weakening of grain boundaries and resulted into intergranular corrosion. Precipitates and grain boundaries in Al-6061-T6 served as a reason of crack initiation due to hydrogen diffusion. Fractographic investigation provided the evidence of trans granular fracture as well as intergranular fracture which was observed as dimples and extensive ductile tearing.

Importance of Verbal Text in The Interpretation of Political Cartoons

Importance of Verbal Text in The Interpretation of Political Cartoons The combination of verbal and visual text plays an important role in conveying message and leaving strong impact on the minds of the people. Teachers, Media, advertising agencies etc are using this strategy to influence people and to endorse their ideas or products. It is also observed that sometimes verbal language dominates and visuals are used just to support the idea or at other instances visuals dominate and language is used just to enhance the meaning or to make it obvious. Language (verbal text) and visuals are thus influenced by each other. Language or visuals when used alone have their effect but the combination of both in communication can make it more influential or impactful. The combination of strong verbal and eye- catching visuals can thus lead to everlasting impact on the minds of the people. This research work focuses on the combination of these forms of communication in newspaper political cartoons. The political cartoons is a form of art and the name suggests that it is form of communication in which visuals are of great importance thus captions are optional or are added just to support the idea. This research aims at highlighting the importance of verbal text in the interpretation of political cartoons. Moreover, it also takes into account the combined effect of verbal and visuals in political cartoons. The collected data and its analysis has proved that the captions or verbal text is an important part of newspaper political cartoons in order to convey particular meaning and in the absence of verbal text the readers can interpret the visual text of the cartoons in varied ways. The political cartoons are drawn with reference to particular issues or events thus the addition of verbal text becomes essential to convey the desired meaning.