2012•The Heat TreatmentRequires access
Effect of Tempering Temperature on Microstructure and Properties of Q890 Grade High-strength Steel
HE Wen-wen
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Abstract
The effect of tempering temperature was investigated on microstructure and mechanical properties of Q890 grade high-strength steel quenched from a fixed temperature.The results show that with respect to Q890 grade steel quenched from 920℃,(a) the as-quenched martensite will gradually transform into tempered martensite,tempered troosite and tempered sorbite,and the hardness will tend to decrease,with the raise of tempering temperature in the range of 200 to 700℃;(b) after tempering at 600℃the microstructure is mainly tempered troostite and the hardness is about 35 HRC。In addition,the yield strength and impact toughness at - 40℃of 5 to 25 mm-thick Q890 grade plate all reach above 900 MPa and above 45 J respectively after quenching from 920℃and tempering at 600℃.