Analysis Of The Second Phase Precipitation Behavior In High Grade Pipeline Steel

Due to the increasing demand for energy in the worldwide, the exploitation scope of oil and gas resources is expanding continuously. the exploitation of petroleum and natural gas is gradually moving to the mountains, deserts and oceans. At this time the pipeline construction in the climate, the environment is extremely complex areas. At this time, the mechanical properties of pipeline steel requirements: high strength, high toughness, corrosion resistance and excellent deformation capacity, etc. With the development of technology, from the view of energy saving and cost, steel plate for pipeline steel is becoming more and more thicker. At present, the thick plate has become the main product of the new generation pipeline steel. For thick plate, due to the lack of strain accumulation in the rolling process, the precipitation of the second phase precipitates in the thick plate is suppressed, it is difficult to play a very good role in grain refinement. If you want to get high strength and toughness properties of the products, it must be controlled from the component design and roughing and finishing mill process. The main contents and results of this paper are as follows:(1) This paper from the point of view of the precipitation thermodynamics, the composition of low niobium and high niobium are calculated and discussed, and use software to simulate the niobium components of composite effect precipitates particle size and interparticle spacing, the composition of niobium choice has certain guiding significance, and the Nb is not the more the better. Software simulation effects of low nitrogen and high nitrogen content of composite precipitates particle size and spacing, the nitrogen component selection has certain guiding significance and low nitrogen components will be better, composite precipitate particle size and spacing is smaller.(2) In continuous casting billets, titanium nitride precipitation behavior analysis, under the condition of low nitrogen content, it can make the titanium nitride particles participate in solid area and then precipitated particle size is smaller, particle spacing is smaller. Through the analysis of the precipitation kinetics of titanium nitride, titanium nitride precipitation at high temperature, and mainly in the high temperature zone of 1100.(3) Through simple calculation in rough rolling process, it know that roughing austenite grain is not small and not get the required performance, it must be control austenite variable recrystallization behavior in finishing process. Low rolling temperature is used in the finishing process, which induced dynamic recrystallization of austenite and get fine austenite grains, and ferrite grain size smaller, finally get the ideal microstructure and performance. Only the roughing and finishing rolling compression ratio is good, can we achieve the fine grain size of the desired product.