Application Of Numerical Simulation Technology In Forging And Heat Treatment Process Of Gas Turbine Parts

With the development of modern science and technology, the requirement of productswith better property and reliability has increased. As important solid state material processingtechnologies, forging and heat treatment play an important role in increasing the properties ofproducts. However, due to the complexity of forging and heat treatment technology, theresearch on forging and heat treatment is mainly based on experiments and empiricalformulations previously. For the complicated technology and die design, the experiments maybe conducted again and again, and even the workpiece is scrapped sometimes. It will causethe rise of cost and prolong the production period. With the improvement of finite elementmethod and rapid development of computer's software and hardware, the precision andefficiency of numerical simulation are improved largely. Now, the finite element method hasbecome an important means to study forging and heat treatment process. Through numericalsimulation analysis, the distribution laws of stress, strain and temperature in the workpiecemay be obtained, and the probable defects can be predicted, which may provide scientificfoundation for designers to analyze process and optimize technology.In this paper, the forging and heat treatment processes of some components of heavy gasturbine and aero-engine are studied by finite element method. The distribution laws ofphysical fields are obtained and the defects occurring in the process are also predicted. On thebasis of simulated results, the process parameters are optimized. A brief introduction to thedoctoral dissertation and its main results are as follows:The multi-stage forging process of a gas turbine compressor blade is simulated using 3Dcoupled thermal-mechanical rigid-viscoplastic finite element method. As a result, the metalflow laws during forging process are analyzed and distributions of some thermomechanicalfield variables such as temperature, stress and strain and the load-time curves are obtained. Onthe basis of simulated results, an optimized process is put forward. The simulation resultsshow that the temperature, strain and forging load meet the technological requirements underthe optimized process. The feasibility of optimized process is verified through comparisonswith industrial trials. Now, the optimized process is applied to actual production successfully.A 3D FEM simulation mechanics model has been proposed for the cold roll forgingprocess of a comprosser blade. The temperature field, stress field and strain field of the bladeduring roll forging process are simulated. And the rolling forging force, roll forging torqueand axial force during roll forging process are also obtained. On the basis of simulated results,the forming mechanisms of advancing slip, lateral bending and critical deformation areanalyzed. At the same time, the effects of different billet design principles on forming process are simulated, which can provide theoretical foundations for optimization of blank and rollforging dies during cold roll forging process of compressor blades.The virtual forging process of TC4 titanium alloy mounting part is realized in thecomputer by using finite element method. Through analysis of metal flow and field variablessuch as stress and damage, the forming mechanisms of forging defects are studied. On thebasis of simulated results, the die dimensions are optimized and an optimum die cavity depthis obtained. The feasibility of optimized process is verified through comparisons withindustrial trials, and the acceptable products are forged in production.Considering the effects of hammer movement on deformation stress, the forging processof TC6 titanium alloy clasp is simulated by finite element method, and the die stressdistribution during forging process is also analyzed. The simulation results, such as metalflow, forging load and die stress distribution, are obtained. On the basis of simulated results,the die cavity is optimized and an optimized die design is proposed, which may decrease theforging load and die stress. This study can afford theoretical basis for die optimization ofhammer forging process of TC6 titanium alloy clasp. Now, the optimized dies are applied toactual production successfully.The quenching process of a gas turbine compressor disk is simulated by general FEMsoftware MSC.Marc combined with a series of subroutines. The effects of phasetransformation on temperature and stress are taken into account simultaneously. Andinterrelated experiments are conducted to determine thermal physical properties and interfaceheat transfer coefficient. The distributions of temperature, microstructure and stress underdifferent quenching processes are obtained. On the basis of simulated results, the air coolingprocess is proposed. The feasibility of air cooling process is verified through comparisonswith experiments, and this process is applied to production successfully. This study isdirective to control and improve the heat treatment process of gas turbine compressor disk.