Dong Mei Zhu

Deformation Control in Wear-Resistant Steel Quenching Process

Computation model for TNM360 wear-resistant steel quenching process is established by finite element method. Four work conditions are designed for studying the effect of different location of cooling zone on quenching plate shape. And the temperature field and stress-strain field under four work conditions are calculated through the established model. For 20mm thick steel plate, the effect of uneven cooling of the front of cooling zone on the plate shape is larger than that of the rear of cooling zone. Under different work conditions, the effect of thermal stress on plate shape is different with phase transition stress. The results of the study provide important theoretical basis to control wear-resistant steel plate shape and improve production efficiency and manufacturing yield.

Uniformity Analysis on Temperature Field of Big Diameter GCr15 Bearing Steel Bar in the Process of Immersion Quenching

Based on the immersion quenching cooling used at steel bar, numerical simulation about temperature field of big GCr15 bearing steel bar is carried out by the FLUENT. The influence on temperature field uniformity brought by different elements during the immersion quenching cooling is analyzed, such as the number and the diameter of the nozzle when the total cross-sectional area is constant and the distance between the nozzle and the surface of the steel bar. The results show that: a better uniformity of the temperature would be achieved when the number of the nozzle is 11and the diameter of the nozzle is 26mm.when the distance between the nozzle and the surface of the steel bar is 250mm, a better uniformity of the temperature would be gained.

On-Line Pre-Hardening Process of Large Plastic Die Steel

The thermal parameters of 3Cr2Mo plastic die steel were tested. The temperature fields of 3Cr2Mo plastic die steel with the thickness 120mm were calculated and analyzed under two quenching processes. The results showed that for interrupted process the cooling velocity was faster when the temperature was more than 500°C, which was not in the transformation zone of bainite and martensite. And the fast cooling rate effectively avoided the pearlite appearance. When the temperature was less than 500°C, the cooling velocity under interrupted cooing process was slower, which avoided the big microstructure stress. So for the 3Cr2Mo plastic die steel with the thickness 120mm, the interrupted process was better. In the paper, the hardness was tested after interrupted cooling process and tempering. The tempering hardness difference was less than or equal to 3HRC. The study provided references for large plastic die steel on-line pre-hardening process formulation and optimization.

Numerical Simulation Research of Aerosol Cooling

Through the establishment of the mixture model and the discrete phase model of aerosol cooling, the heat transfer characteristics between the aerosol and high temperature die steel plate are studied. When the discrete phase volume fraction is greater than 10%, mixed convection heat transfer model is used to study the effect of the gas-water volume fraction on heat transfer characteristics; when the discrete phase volume fraction is less than 10%, the discrete phase model is used to study the effect of the discrete phase mass flow rate and particle size on the heat transfer characteristics. The results can provide important references for the die steel quenching equipment design and production.

Research on On-Line Pre-Hardening Process of 718H Die Steel

New on-line pre-hardening (OPH) equipment for quenching die steel has been developed by University of Science and Technology Beijing and Dongbei Special Steel Group in Dalian Special Steel Co., LTD. OPH consists of strong cooling water jet, medium cooling water jet, weak cooling water jet, air-water spray and side water jet and has flexible cooling and control ability. Based on the equipment, online quenching process of 718H die steel was performed by numerical simulation and production experiment. The result of temperature field by numerical simulation agrees well with experiment result, which can prove that numerical simulation can be a very good guidance for production experiment. Experimental tempering metallographic structure of the whole 718H plate is tempered troostite and sorbite and the tempering hardness difference of 718H die steel can be controlled within 2 HRC in the whole plate under on-line pre-hardening process by numerical simulation. The prediction technology of numerical simulation can meet the different cooling rate control and make quenching process comply with preset quenching route to guarantee material microstructure and performance.

Numerical Simulation and Experiment on Quenching Process of P20 Die Steel with New Online Pre-Hardening Equipment

A new online pre-hardening (OPH) equipment for quenching die steel has been developed by University of Science and Technology Beijing (USTB) and Dongbei Special Steel Group in Dalian Special Steel Co., LTD. OPH equipment consists of strong cooling water jet, medium cooling water jet, weak cooling water jet, air-water spray, and side water jet and has flexible cooling and control ability. Based on the equipment, online quenching process of AISI P20 (3Cr2Mo) die steel was performed by numerical simulation and production experiment. The result of temperature field by numerical simulation agrees well with experiment result, which can prove that numerical simulation can be a very good guidance for production experiment. Experimental tempering metallographic structure of the whole P20 plate is tempered troostite and the tempering hardness difference of P20 die steel can be controlled within 3 HRC in the whole plate under quenching process by numerical simulation. The prediction technology of numerical simulation can meet the different cooling rate control and make quenching process comply with preset quenching route to guarantee material microstructure and performance.

Study on the Side Blowing Parameters of High-Density Pipe Cooling Equipment

The three-dimensional unsteady model of the side blowing of high-density pipe cooling equipment is calculated by the finite element method. The effects of different jet velocity, the nozzle height and spray angle on the side blowing are analyzed. And the temperatures of the plate under various conditions are studied. The results provide theoretical basis for the improvement of the cooling device.

Cooling Process of Die Steel during On-Line Pre-Hardening

Pre-hardening plastic die steel can be directly processed into the mold, and it doesnt need quenching and tempering again, which avoids quenching deformation and ensures the size precision of the mold. On-line quenching of die steel can shorten the production cycle, and it has the advantage of energy saving. In the paper, a new on-line quenching device was introduced, and the temperature field calculation model of 3Cr2NiMo die steel was established. The cooling technology of three typical thickness steel plates was studied. The results provided the theoretical basis for die steel production.

Numerical Simulation and Experiment on Quenching Process of 718 Mould Steel with New Online Hardening Equipment

A new type online hardening equipment for quenching has been developed by University of Science and Technology Beijing and Dongbei Special Steel Group in Dalian Special Steel Co., LTD., which consists of strong water jet, medium water jet, weak water jet, air-water spray and side water jet and has flexible cooling and control ability. Based on the equipment, the online quenching process of 718 mould steel is performed by numerical simulation and field experiment. The result of temperature field by numerical simulation agrees well with that of experiment, which can prove that numerical simulation can be very good guidance for field experiment. Experimental tempering hardness difference of 718 mould steel can be controlled within 2 HRC in the whole plate according to numerical simulation. Prediction technology can meet the different cooling rate control and make quenching process comply with preset quenching route to guarantee material microstructure and performance.

Influence about the Cooling Pipe´s Inlet of Bars Pattern on the Cooling Effect

In this paper, the cooling process of Large-diameter bars is simulated by the 3D numerical simulation calculation method of Finite Element Coupling Field. Then, the influence, which about the controlled cooling inlet pattern on the cooling effect, has been analyzed. The results show that the bar cooling effect of annular nozzle inlet cooling pipe is the best among the several inlet patterns in this paper; relatively the bar cooling effect of four circular nozzles inlet cooling pipe is the worst among the several nozzles patterns in this paper. This numerical simulation result provides reference for choosing inlet pattern of bar controlled cooling equipment.