Development Of "X100" High Grade Pipeline Steel

With the characteristics of highly active,economical and safty, pipeline is a effective tool to transport the oil and natural gas. In order to improve the transportation efficiency,reduce energy consumption,reduce investment and cut down pipeline operating costs, it has become a trend that long-distance pipeline would develop to the high-pressure and large diameter. Along with the X80 grade pipeline steel were gradually used in the oil and gas pipeline projects, in order to further reduce the cost of pipeline construction and operation, the development goals was focus on the research of X100 and the higher-grade pipeline steels. Using X100 or above grade pipeline steel can significantly reduce the pipeline construction and operation costs.In this paper, using the thermal simulation experiment, we have researched the effect of the alloy composition and process parameters on the properties of X100 high grade pipeline steel. And then we produced the X100 High Grade Pipeline Steel successfully. Get the following results:①Increasing the reduction of finish rolling deformation would reduce the austenite stability and raise the phase transformation starting temperature. At the same time, the micro-hardness reduced, and the microstructure by a smaller amount of deformation dominated by lath bainite (lower bainite), while in case of the larger deformation, the microstructure was mainly composed of granular bainite.②When the finishing deformation was 25%-40% and the end of the cold temperature was 600~350℃, the microstructure of the experimental steel was mainly composed of granular bainite, along with the end of the cold temperature decreases, the microstructure gradually refined, and the lath bainite (the lower bainite) appeared; when the final cooling temperature is below to 350℃, there would be appeared more lath bainite or martensite.③At the control cooling stage, along with the increase of cooling rate, there are more lower-bainite in the microstructure of experimental steels, and the microstructure become finer, as well as the micro-hardness increase correspondingly.④Raising the reduction of finish rolling deformation and the cooling rate, the content of M-A islands decreases, and the M-A islands become finer and more dispersed.⑤In order to obtain fine and dispersion M-A islands, the finally cold temperature should be chosen about 400℃.⑥Using the component design of C 0.048, Si 0.24, Mn 1.96, Ni 0.41, Cr 0.31, Cu 0.21, Nb 0.077, Ti 0.014, Mo 0.24 ,with the process parameter of 230 1100℃195-166-141-120-102-76-54 950℃43-35-30-25-21-17 820℃15 cooling rate> 25℃/ s 400℃furnace cooling (coiling) - room temperature, the steel plates can achieve the performance requirements X100 High Grade Pipeline Steel.