Effect of Aging Processes on Properties of Microalloyed Steel for Bolt

The effect of various aging processes on the mechanical properties of microalloyed steel for fastener wire with 28% in draft were investigated through optical microscope and transmission electron microscope observation and tensile and impact test. The results showed that the microalloyed fastener wire sample aged at 300 ℃ for 2 hours demonstrated the best elongation and impact toughness, which increased by 37.4% and 8.7% respectively, which is attributed to the formation of stable or unstable sub-microstructure.