The Research of Controlled Rolling and Cooling Process in X70 Grade Pipeline Steel with Vanadium Microalloying

摘要

In Formastor-Ⅱ thermal expansion phase transition instrument,determine test steel's thermal expansion curves with different cooling rates during continuous cooling.Using thermal expansion combined with metallographic-hardness method to draw the continuous cooling transformation curve (CCT).According to the test results draft thermal simulation program,in Gleele-3500 thermal simulation test machine,conduct thermal simulation experiment for vanadium microalloying X70 grade pipeline steel at different deformation temperature,deformation extent and coiling temperature.Analysis that the microstmcture was influenced by different rolling process.The results showed that:in industrial production,the experiment steel's rough rolling temperature should be controlled more than 1020°C,finishing temperature controlled in 820±20°C and coiling temperature controlled in 500～530°C to obtain acicular ferrite.