Laser-arc hybrid welding has become a new trend to realize the efficient production of aerospace ultra-high strength steel (UHSS). However, the porosity problem has not been solved. In this study, oscillating pulse laser-TIG hybrid welding (OPL-THW) was used to achieve porosity-free D406A steel...

This paper surveys methodological issues in subnational credit ratings and highlights key challenges for developing countries. Subnational borrowing from capital markets has been on the rise owing to fiscal decentralization and demand for infrastructure investments. A prerequisite for accessing...