Study on Production Process, Microstructure, Properties of 15MnNbR Pressure Vessel Steel

The production process, microstructure, and mechanical properties of 15MnNbR pressure vessel steel were studied by optical microscopy, universal tensile testing, and low-temperature impact toughness testing. It was found that the microstructure obtained after controlled rolling and cooling (known as thermo-mechanical control processing) consisted of ferrite and pearlite with non-uniform grain size. The banded microstructure was prominent, the strength was high, and the toughness was poor. After normalizing, the grain size was refined, both the microstructural uniformity and the banded microstructure were improved, and the strength and toughness of the steel were enhanced. After normalizing and water cooling, the grain was further refined, the microstructure was homogenized, the banded microstructure disappeared, and the strength and toughness of the test steel were improved simultaneously, resulting in excellent comprehensive mechanical properties.

Enhancing the mechanical strength and toughness of epoxy resins with linear POSS nano modifiers

Glass transition temperature (Tg) is always deteriorated while improving the strength of epoxy resins which inherently suffered from brittleness. Herein, a novel linear polyhedral oligomeric silsesquioxane (POSS)-epoxy nano modifiers is...

Tensile and Liquid Absorption Properties of Polyester-based Composites as Alternative Marble Materials

Three polyester-based composite materials were prepared with different volume fractions of three types of fillers (i.e. cement, gypsum and limestone) with the aim of improving the tensile and liquid absorption properties of the former for the synthetic marble industry. The tensile strength, modulus of elasticity, toughness, ductility and liquid absorption percentage of the composites were characterized. Results revealed an increase in the modulus of elasticity, tensile strength and toughness of all prepared composites, as well as a decrease in their ductility, with increasing filler amount. The liquid absorption values of all composites increased with increasing filler content. The composites were able to absorb water extensively but absorbed benzene, kerosene and gasoil minimally.