Effect of quenching temperature on microstructure of low alloyed corrosion resistant 27CrMo48VNb steel OCTG

Abstract

A series of quenching treatment at different temperatures were performed on low alloyed corrosion resistant 27CrMo48VNb steel OCTG. The microstructure, prior austenite grain and precipitates of the tested steel quenched at different temperatures were characterized by optical microscope and transmission electron microscope. The effect of quenching temperature on microstructure, grain size and precipitate was analyzed. The results show that the martensite can be observed in the tested steel after quenching. The size of microstructure and prior austenite grain gradually increases with the increase of quenching temperature. When the quenching temperature is 890-1000 ℃, the grain size increases slightly with the increase of quenching temperature; when the quenching temperature exceeds 1000 ℃, as the quenching temperature increases, the prior austenite grains are significantly coarsened. The change trend of microstructure and prior austenite grain size versus quenching temperature is related to the dissolution and precipitation behavior of precipitates at high temperature. Therefore, the quenching temperature from 890 ℃ to 1000 ℃ of the tested steel is recommended.