Abstract：The microstructure and properties of acicular ferrite steel tempered from 540 ℃ to 630 ℃ were studied. Compared with the steel as rolled, the yield strength of steel tempered at 630 ℃ was increased by 75 MPa, the mean elongation was decreased by 1.9% and the mean impact toughness was almost unchanged. By comparison of the microstructure and precipitates before and after tempering, it can be concluded that in tempered steel the intragranular dislocation density is lower and part of platelike subgrains is disappeared, but the mean size of precipitates is smaller. The mean size of precipitates becomes bigger with the raise of tempering temperature. After tempering at 630 ℃, the distribution frequency (f(D)) of precipitates in the range of 1～10 nm is increased by two to three times, the amount of precipitated niobium and vanadium was increased by 166.9% and 584.6% respectively. It is considered that the enhancement of strength is mainly due to the increase in number of small precipitates and disappearance of part of platelike subgrains.
康军艳;余伟;陈银莉. 回火工艺对针状铁素体钢组织和性能的影响[J]. 钢铁, 2006, 41(9): 0-65.
KANG Junyan;YU Wei;CHEN Yinli. Effect of Temper on Microstructure and Mechanical Properties of Acicular Ferrite Steel. Iron and Steel, 2006, 41(9): 0-65.
2006, Vol. 41 