Numerical Study of Temperature Distributions and Solidification Pattern in the Weld Pool of Arc Welded Plate

The study on heat flow in welding is essential as the quality of the weld depends on mainly heat flow through the welded plate. The heat input from welding source flows in a limited zone, and it subsequently flows into the workpiece by conduction. In this study, an attempt is taken to predict the transient temperature distribution and solidification pattern through a numerical model and the associated mathematical technique considering the solidification and heat transfer, of molten weld pool when it is covered with flux and without flux in arc welding process. The numerical model developed in this study solves fluid flow and heat transfer considering solidification and melting phase change the along with natural convection in the meltpool. It was found that the flux is functioning as insulation on the welded pool, hence it restricts rapid solidification and increases the mushy zone width.

The Role of Compounds in Graphite Formation in Cast Iron - A Review

The paper reviews original data obtained by the authors, from recent separate publications, specifically concerning graphite formation in the solidification pattern of industrial cast irons, focussing on grey iron versus ductile iron. Additional unpublished data and selected data from literature are represented in the paper. Complex compounds act as nucleation sites in commercial cast irons, generally in a three-stage graphite formation, but with different sequences: (1) first micro-compound formation is oxide/silicate in grey iron and sulphide in ductile iron; (2) the second compound nucleates on the first one, as complex manganese sulphide in grey iron and complex silicates in ductile iron; (3) graphite nucleation on the sides of stage 2 compounds, which have low crystallographic misfit with graphite. Resulphurization (Mn/S control), preconditioning with strong oxide forming elements (Al, Zr), more potent inoculants and inoculation enhancement with S, O and oxy-sulphide forming elements were found to be beneficial treatments especially in critical solidification conditions

Analysis of the Solidification and Properties of Plaster Cast Al Based Composites

Analysis of the Solidification and Properties of Plaster Cast Al Based CompositesThe present work deals with aspects related to the solidification and properties of an Al-Si10Mg/SiC20palloy cast in plaster moulds. Several strategies were followed to shorten its solidification time such as embedding copper tubes into the mould to make circulate cooling fluids immediately after the casting step. The analysis of cooling curves provided valuable information on the effect of the particles on solidification events. The precipitation of different phases of the MMC takes place at higher temperatures and earlier than in the case of the non reinforced alloy. Particles affect the solidification pattern of the alloy and play a noticeable role in the precipitation of the phases. This fact should be taken into account to design the filling and feeding systems correctly and for modelling and processing parameters as well as in thermal treatments. Eventually samples were obtained under the highest solidification rate conditions to analyse the microstructure and tensile properties of the MMC material.