Study On The Rapid Spheroidizing Technology And Life Cycle Assessment Of GCr15 Steel

The eco-materials request the material to have the characteristics of good comprehensive properties, environment consciousness and comfortibility simultaneously. And metallic material also requests to have comprehensive performances after heat treatment. For the sake of solving the question to different dimensions and having no united normalization, comprehensive quantization of multi-index is put forward, and it can turn multi-index system into an Integrated Value of Performance. The Relative Index of Performance (RI), Equivalent Index of Performance (EI) and Integrated Value of Performance (IV) are clearly defined in this method. This evaluating method is applied to the choice of the temperature of A_clf, the fast isothermal annealing and fast hardening and tempering of GCr15 steel, and also applied to the comparison of quality of heat treatment between different spheroidizing processes and the solution to the green degree equation, etc.In order to realize the actual application of the method of the comprehensive quantization, the conventional spheroidizing processes of GCr15 steel that is characterized as long processing period, big energy consumption and low production, were studied expecting to work out an energy-saving spheroidizing process. The improvement was focused on the two elemental varieties of the soaking time and the holding-temperature. The improvement of the conventional isothermal annealing was also explored in this article. According to the theory of A_clf temperature of equalization spheroidizing annealing process, an orthogonal test was implemented. Then the diameter, volume percentage and the content of the residual carbide of different processes were calculated. Using the comprehensive quantization method, the three performance indexes of the dimension, the content of the residual carbide and the hardness were comprehensively assessed. The value of Aclf, 800℃, to the steel under the heating speeds of 800℃/h was obtained. Then the non-homogeneous spheroidizing microstructures in annealing were discussed, and finally a new fast isothermal spheroidizing process was put forward. The conventional hardening and tempering spheroidizing process was also checked in this article. The hardening scheme at Aclf temperature for equalization heating was brought forward. According to the P curve of the steel GCr15 for tempering and the curve of the effect of tempering temperature and time upon stress lowering of GCr15 steel, a tempering process with the higher holding temperature and shorter holding time was drawn up. And fast hardening and tempering spheroidizing was built in the end.Because of the specific characteristics of the Life Cycle Assessment for the spheroidizing process, the hierarchy of LCA in spheroidizing of GCr15 steel and the balance of input/output in spheroidizing process of GCr15 steel were established, and five hypothesises, such as equipments of spheroidizing and so on were set up. Thenthe conventional isothermal annealing, fast isothermal annealing, hardening and tempering and fast hardening and tempering of GCr15 steel were analyzed. The energy relation of work-pieces and furnace under ideal conditions was calculated. Finally the approaches to increase the spheroidizing efficiency and green degrees of spheroidizing were put forward, and green degree equation regarding quality of heat treatment was established using the method of the comprehensive quantization.The metallographic pictures were taken and mechanical properties of different processes were measured with the help of optical microscope, the scanning electron microscope, the X-ray diffraction, the hardness tester, the pendulum impact testing machine and the friction/wearing tester, etc.