Papers by Author: Jian Ping Li

Abstract: Fe-6.5wt%Si steel is an excellent soft magnetic material due to the near-zero magnetostriction and low core losses. In this study, a 0.3 mm-thick grain-oriented 6.5wt%Si steel sheet was produced by a novel strip casting and two-stage rolling. The microstructure and texture evolution were investigated with a special emphasis on the nucleation and growth of Goss grains. The thin normalized strip was composed of large columnar grains and small equiaxed grains. During intermediate annealing, Goss grains nucleated in the shear bands of the deformed <111>//ND grains, and the deformed {111}<112> grains provided most of the nucleation sites. After primary annealing, the Goss grains distributed across the entire thickness, which was different from the conventional rolling route. The fraction of high-angle boundaries (20°-45°) surrounding the Goss grains was apparently higher than those of the matrix grains, which promoted the abnormal growth of the Goss grains during secondary recrystallization.

Abstract: One industrially C-Mn steel was studied in the present work. The Mn pre-partitioning process during continuous annealing was used. The results showed that the stability of retained austenite is increased because of the Mn pre-partitioning. The amount of retained austenite was about 5%, when increase the partition time to 100s. With the increase of the partition time, the amount of retained austenite increases, the tensile strength decreases, the yield strength and elongation both increase. Compared with quenching and tempering (Q&T) process, the tested steel after pre-partitioning quenching and partitioning (PQ&P) process has higher uniform elongation and the product of strength and elongation (UTS×TEL).

Abstract: Pilot hot rolling mill is developed with perfect measuring devices and automation system. The hot rolling experimental studies of the plate and strip can be done on this mill. Automation system for this pilot mill is composed with Basic Automation System (BAS), Process Control System (PCS) and Human Machine Interface system (HMI). PC server is used as the PCS hardware, and Microsoft software is used as the operation system and developing software. With the coordination of the functions such as date communication, process tracking, data management, and model calculation, the PCS software function is realized. The effect on the model calculation accuracy with the pilot mill using condition was analyzed. This pilot hot rolling mill gets a lot of application. The practical application shows that the PCS’s setup has a high precision.

Abstract: The symmetric/asymmetric hot rolling experiments were carried out to investigate the effect of shear deformation on microstructure of vessel steel by using electron back-scattered diffraction (EBSD) and field emission transmission electron microscope. The study shows that gradient distribution grain size through the thickness is formed in asymmetric rolled specimen. The grain size in surface is smaller than the one in center. The grain distribution is homogeneous in symmetric rolled specimen. The grain in asymmetric rolled specimen is smaller than the one in symmetric rolled specimen in the same thickness position. The precipitate particles morphology are random precipitate and interphase precipitate in symmetric and asymmetric rolled specimen. The precipitate particles tend to nucleate and grow in the grain in symmetric rolled specimen. The precipitate particles located in grain boundary are observed in asymmetric rolled specimen.

Abstract: Through study on the regulation of tensile strength and reduction of area after artificial aging and natural aging for SWRH82B wire rod, indicate that the tensile strength of wire rod unchanged through artificial aging or natural aging treatment while the reduction of area changes significantly the reduction of area is effected by aging temperature and aging time. Reduce the residual stress in the wire rod and lattice distortion is the main reason for reduction of area improving the composite brittle inclusions in the wire rod are not good for the rod plastic recovery.

Abstract: Through the thermal simulation test of the Nb-Ti micro-alloyed steel austenite cooling process and microstructure observation & microhardness test, the tests indicate cooling rates have effect on the phase transition and microstructure of tested steel, the critical quenching speed of Nb-Ti micro-alloyed steel is about 23°C/s with very good hardenability. With the increasing of the cooling rate, the beginning and ending temperature of phase transformation decrease and the ferrite structure content was decreased at room temperature. It’s easy to happen Bainite transformation at the beginning, and make the M block or flake M fine, which is to increase the strength and toughness of the steel.

Abstract: Through the thermal mechanical simulation experiment，combined with the metallographic analysis and microhardness test on the Nb-Ti micro-alloyed steel for the austenitic continuous cooling process. The results shows that: with the increasing of the cooling rate, the phase transformation starting and ending temperature decrease and the ferrite content was decreased at room temperature. In less than 5°C/s low cooling speed region, with the increasing of the cooling rate, the grain size of tested steel obviously increases; In more than 17°C/s high cooling speed region, the grain size and vickers hardness of tested steel change and tends to be smoothly.

Abstract: The development of new products of seamless tubes require the development of corresponding grooves in order to manufacture tubes with high precision, high efficiency at low cost. In this work, a finite element model and dynamic simulation of continuous rolling pass for seamless tubes process has been implemented under the ANSYS/LS-DYNA environment to verify the validity of the pass design. The result show the deformation characteristic of cross-section, the variation regularity of rolling force, strain and stress conform to the reality. The work is effective for developing new grooves and products for seamless tube continuous rolling.

Abstract: Bending process is one of the important methods to form thick hull plate, whose accuracy is directly related to the quality of hull plate forming.In this paper, bending process of thick hull plate is simulated by using finite element software ANSYS, and some simulation results on bending deformation of thick hull plate such as the deformation of meshes in deformation zone, the distributions of the Von Mises stress and effective strain are obtained.

Abstract: The fatigue property of welded specimen of different form of Ti6Al4V Titanium Alloy plate was researched in the environmental condition of atmosphere and salt fog,The test results indicate the holes along weld seam in welding specimen have great influence on fatigue property, The fatigue life of Ti6Al4V Titanium Alloy doesn’t low under the salt fog condition in high stress range. The salt fog brings about the influence on fatigue life obviously at the same corrosion condition with fatigue stress lowering.