An Overview of Microalloyed Steels, Part II: Their Mechanical Behavior 960309
Microalloyed (MA) steels have been developed as economical alternatives to the traditional quenched and tempered (QT) steels. The physical metallurgy principles underlying their basic composition-processing-microstructure-property interrelationships have been reviewed in the first part of the review. In this second part of the review, mechanical properties as well as fabrication properties, such as mahinability, weldability, and formability, are discussed. Flat products (such as strips, sheets, and plates), long products (including bars, rods, sections/profiles), and forging articles made of MA steels are investigated. Since most engineering components made of these steels are subjected to cyclic loading, fatigue and fracture performance of MA steels and their comparison with the QT steels are also evaluated in this review. Mechanical property comparisons with the conventional QT steels indicate that MA steels are a promising class of materials to replace the QT grades because of the high potential for significant cost savings. Increased efforts are however needed in enhancing the fracture toughness of these steels.