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.

Agricultural Accounting and Information System for Farmers

Context: E-agriculture is modern form of agriculture that integrates information and communication technology (ICT) into agricultural practices. The objective of e-agriculture is to fulfill increasing food demand with least input resources. E-agriculture achieves this goal by using the automated systems to control the field operations and provides necessary information to agriculturists efficiently. In literature, various information systems have been proposed, however such systems are expensive for small land farmers. Moreover, such systems are not easy to use and information presented is hard to be interpreted by farmers. Pakistan is an agricultural country and agriculture contributes 21% to the GDP of Pakistan. Therefore, agricultural reforms are very important to provide timely information to farmers and provide them with tools that can help them in managing agricultural activities especially agricultural finance management. Objectives: The aim of this research was to propose a web based information system by systematically analyzing the existing literature on e-agriculture and identifying the information and accounting issues of local farmers. The system could provide accurate, necessary and timely information to small land farmers and could support them in managing agricultural finance. Method: To achieve research objectives a multi method research approach was adopted. In this approach, a combination of empirical research methods were used that complement each other. At first, a mapping study was conducted to investigate evidences available in the existing literature one-agriculture. Secondly, case study in District Pakpattan was conducted to identify the agricultural financial accounting and information issues of local farmers and to resolve these issues by developing a web based system. The system was evaluated by measuring users? satisfaction by customizing Delone and Mclean Information Success (IS) model. Hypotheses were developed and field survey was conducted in rural area of Punjab to collect data. The results were produced and hypotheses were tested by employing regression analysis. Results: From this research, we identified that the research on e-agriculture was introduced in 2003. Various systems were proposed to support farmers in agricultural activities. It was identified that agricultural farms using these systems are getting more profit. However, interfaces of these systems were complex, their cost was high and requires technical expertise therefore adoption rate of these systems was low and they were beyond the reach of small land farmers. The proposed application developed in this research was evaluated through field study. The results showed that famers were very satisfied with system and service quality provided in the proposed application, however information quality was not considered significant. Conclusion: In developed countries automated systems are used to gain high yield, however, in developing countries e-agriculture is still at its initial stage. Farmers are semi-literate and have low digital literacy to use technology. To get full benefits of e-agriculture, there is need to introduce reforms and trainings to local farming community about the use of computer and hand held devices such as mobiles. Also, there is need to provide easy to use information systems with local language support. From this study, we concluded that easy to understand information system especially designed for semi-literate farmers with the support of native language are more likely to be accepted by the farmers? community.