316-paper-钢管在线加速冷却技术开发-english version.docVIP

Development of Online Accelerated-Cooling Process for Seamless Tube Guanghong Yin Abstract：The effect of chemical composition, and as well as of production process parameters, on the microstructure and mechanical properties is investigated under accelerated cooling conditions. The results show that accelerated cooling after mandrel milling using the spray cooling method can produce ideal N80 oil casing, and the quenching-tempering treatment is no longer necessary. 1 Background The purpose of thermal deformation applied to steels is not only to obtain the expected grain size, but also to improve the mechanical properties of steels. Thermal mechanical treatments (TMT) are just such a process by using both the thermal and the deformation effect produced during manufacturing. Among them, thermal mechanical controlled process（TMCP）falls into this category. TMCP is a complex technique that includes controlled rolling（CR） and accelerated cooling（ACC）[1].Nowadays, TMCP has been successfully applied to the production of structural steels, for example, steel plates, strips, etc., however, as to seamless steel tube, TMCP has always been far away from industrial production owing to its complexity and particularity of shape, of thermo mechanical process and of manufacturing equipment [2]. Ever since 1980, researchers have endeavored to the investigation on the TMCP of seamless steel tube. It is clear now that on-line normalization （OLN）and on-line accelerated cooling （OALC）are the two main methods to realize TMCP. On-line normalization （OLN）is described as follows, firstly, the tube is cooled to below the transformation temperature Ac1, through the phase transformation of austenite to ferrite after mandrel milling and before reheating, then phase transforms again after austenitization at the reheating furnace, thus the austenite grain size is refined through the paths of phase transformation. [2,4-6]。 On-line accelerated cooling （OALC） [2,3,5-7] is a process that the deform