NUMERICAL SIMULATION OF FORGING AND SUBSEQUENT HEAT TREATMENT OF A ROD BY A FINITE VOLUME METHOD

A method to simulate processes of forging and subsequent heat treatment of an axial symmetric rod is formulated in eulerian description and the feasibility is investigated. This method uses finite volume mushes for troching material deformation and an automatically refined facet surface to accurately trace the free surface of the deforming material.In the method,the deforming work piece flows through fixed finite volume meshes using eulerian formulation to describe the conservation laws,Fixed finite volume meshing is particularly suitable for large three-dimensional deformation such as forging because remeshing techniques are not required, which are commonly considered to be the main bottelencek in the ssimulations of large defromation by using the finite element method,By means of this finite volume method, an approach has been developed in the framework of 'metallo-thermo-mechanics' to simulate metallic structure, temperature and stress/strain coupled in the heat treatment process.In a first step of simulation, the heat treatment solver is limited in small deformation hypothesis,and un- coupled with forging. The material is considered as elastic-plastic and takes into account of strain, strain rate and temperature effects on the yield stress.Heat generation due to deformation,heat con- duction and thermal stress are considered.Temperature - dependent phase transformation,stress-in- duced phase transformation,latent heat,transformation stress and strain are included.These ap- proaches are implemented into the commerical commercial computer program MSC/SuperForge and a verification example with experimental date is given as comparison.

Effect of Quench Treatment on Fe/Mo Order and Magnetic Properties of Double Perovskite Sr_2FeMoO_6

A quench-treatment technique is used to prepare a high-quality polycrystalline sample of double perovskite Sr2FeMo06 （SFMO）. X-ray powder diffraction analysis reveals that the sample has a single phase and exhibits I4/m symmetry. The cation order η of the sample increases to 98.9（2）% from 94.2（3）%, which is prepared by the traditional sol-gel method. The initial magnetization isotherm of the sample is detected at 300 K. Unit-cell magnetization for the current sample is 1.332 #s at 300 K, and the one for the traditional sol-gel method sample is 0.946#9. Unit-cell magnetization is enhanced to 40.80% by the quench-treatment technique. Quench treatment is an effective method of enhancing the Fe/Mo order and magnetic properties of double perovskite SFMO.

Stability of Retained Austenite Through a Combined Intercritical Annealing and Quenching and Partitioning(IAQP) Treatment

Intercritical annealing（IA） at various temperatures followed by quenching and partitioning（IAQP） treatments was conducted on a cold-rolled Fe-0.2C-1.42Si-l.87Mn（wt%） sheet steel.Optimized microstructure and enhanced mechanical properties were achieved through appropriate adjustment of IA temperatures.The steel which was annealed at1,033 K for 600 s,then quenched to 573 K and partitioned at 693 K for 20 min,designated as 1033 QP steel,exhibits maximum 16.3 vol% retained austenite（RA） with good mechanical properties（ultimate tensile strength 886 MPa and total elongation 27%）.It was found that the thermal and mechanical stabilities of RA are mainly influenced by the combined effect of its average carbon content and amount of adjacent martensite.Furthermore,the transformation-induced plasticity effect increased the peak n-values observed at the second stage of the work hardening of IAQP steels.

Study on Quenching and Tempering Process of Q960 High Strength Steel for Construction Machinery

To develop the Q960 high-strength quenched and tempered steel plates for construction machinery,the effects of quenching and tempering treating regime on the microstructures and mechanical properties were investigated.The results show that the perfect austenization and fine grain size can be achieved by the optimum quenching process that is quenching temperature 900℃ and holding time 20min.Considering performance and production efficiency,the optimum tempering process parameters are found that tempering temperature 600℃ and holding time 40min.The excellent overall properties of specimens with tempered sorbite microstructure can be ultimately obtained.The yield strength is 1030MPa,tensile strength 1080MPa,percentage elongation 16.8% and the Charpy impact energy 144J at-40℃.All these indexes come up to the National Standard GB/T 16270-2009.

Enhanced ferroelectricity and magnetism of quenched(1−x)BiFeO3-xBaTiO3 ceramics

Bismuth ferrite(BiFeO3)-based materials are multiferroic materials widely studied.This study reports that strong ferroelectricity and enhanced magnetic performance are simultaneously obtained in the quenched(1−x)BiFeO3−xBaTiO3(BFBT100x,x=0.2 and 0.3)ceramics.Quenching treatment can reduce the amount of defects and Fe2+ions and make the defect dipole in a random state,which is conducive to improving the ferroelectricity and magnetism.Compared with the conventional sintered samples,the quenched ceramics have higher remnant and saturation polarization.As for magnetism,the coercive field(Hc)of the quenched ceramics is smaller and the quenching treatment can increase the maximum magnetization by up to 15%.