Owing to its graded function and agglomeration of contradictory properties over its structure, functionally graded materials (FGMs) are popular as second-generation composites. FGMs are intended to optimize performance capability and survive in a harsh working environment without failure or losing their properties. This article presents a comprehensive review of FGM literature, detailing the evolution and development history, classification, and manufacturing methods for different types of FGMs, citing the merits and limitations of each. Moreover, the current status of the industry-specific applications of each category of FGMs is also summarized and discussed. Furthermore, the key challenges and future scopes of FGM to provide insight into future research directions are also discussed.

Load-carrying capacity of weld joints could be identified by its shape and size where weld bead geometry and shape relationship parameters are of utmost importance. Heat input and preheating temperature together can control the cooling time of weld, which in turn determines the weld microstructure and its mechanical properties. To control the shape and geometry of weld bead, it is necessary to understand its relationship with cooling time. In present work, preheating temperature is used as process variable along with heat input varying parameters for understanding their effects on weld bead geometry and shape relationship parameters using submerged arc welding process on high-strength low alloy pipeline steel. The experimental investigation was then analyzed by using the mathematical modeling in context with response surface methodology. The mathematical model predicts the influential dependency of cooling time on the preheating temperature than the other weld process parameters. The associated effects in relation to the process parameters have been discussed and analyzed in the present study.