Surface modification technique to enhance metallurgical and mechanical properties of alloy C-276 weldment by laser shock peening without coating

Microsegregation of alloying elements is prone to hot cracking in the weldment of alloy C-276. The formation of topologically close packed phases P and µ is largely responsible for the hot cracking. The present study articulates the effect of laser shock peening (LSP) to improve the metallurgical and mechanical properties of the weld joint. The weld joint was fabricated by pulsed current gas tungsten arc welding (PCGTAW) using an ERNiCrMo-3 filler wire. LSP without coating was carried out on the cap surface of the weldment. Microstructural studies were carried out to compare the as-welded and laser-peened microstructure on the fusion zone. The results show that a fine equiaxed dendritic structure was observed in both conditions. EDS analysis was carried out to evaluate the microsegregation of alloying elements. EDS analysis indicates that there are no secondary intermetallic phases. X-ray diffraction analysis was carried out to evaluate the phase change and crystallite size in the as-welded and laser shock peened fusion zone. The result shows 48.99% reduction in crystallite size after LSP. Hardness and tensile strength results indicate there is a consequential increase in laser shock peened specimen compared with as-welded specimen.     

Physicochemical Modeling and Modification of the Composition of Magmatic and Metamorphic Rocks: Basic Picrobasalts

Using picrobasalt from the Bulatovskoe occurrence (Arkhangelsk oblast) as an example, we analyze the feasibility of using methods developed at the Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, for modifying the composition of magmatic and metamorphic rocks for mineral fiber fabrication and stone casting.     

Forest governance and REDD+ in Central Africa: towards a participatory model to increase stakeholder involvement in carbon markets

Forests play a significant role in the global carbon budget, and can help to mitigate climate change impacts. Tropical forests which experience high rates of deforestation and forest degradation are particularly important, as they are the most active in winter. Based on academic research into global environmental policies in Central Africa, this study finds that REDD+ policies can succeed when there is a carbon market mechanism that increases participation by developing countries, with better integration of forest management and community forestry. Incentives should be based on an appropriate baseline, accurate carbon stocks and fluxes estimation, a suitable silvicultural system and regular monitoring.     

Characterization of Waste and Reclaimed Green Sand Used in Foundry Processing

Silicon - The aim of this study is to discuss the importance of characterization of green, waste green and reclaimed sand. The transformations and changes which take place in the green sand, are...     

Thermal Analysis of Oxidation of TiB2 Powders for Wettable Composite Protective Coatings for Aluminum Electrolyzer Cathodes

Protection of Metals and Physical Chemistry of Surfaces - The resistance of different TiB2 powders to oxidative degradation is studied by synchronous thermal analysis. The temperature dependence of...