Mcroalloyed medium carbon steels for forging and bar products

摘要

Microalloyed medium carbon steels have been developed for forging and bar applications at the aim of cost reduction since the early 1980's in China. Chemical compositions and mechanical properties of microalloyed medium carbon steels in National Standard established in 1995 are presented, showing a wide range of alloying eelmetn combination and ultimate element combination and ultimate tensile strength from 590MPa to 835MPa. The addition of microalloying elements and hot deformation parameters need to be controled carefully to attain microstructures and properties expected. Toughness, being of the drawback for the steels to make any further application, can be improved by several means, such as titanium microalloying or optimum sulfur addition, due to grain refinement and increase of ferrite volume fractin. Self tempered martensite steel with ultimate tensile strength from 900MPa to 1200MPa has been researched, presenting great potentials for the application requiring higher strength and toughness.