The thermal effect of material radiated by laser is one of the most important physics phenomena after aim material radiated by laser. The laser radiating on material, makes the temperature ascension of the material surface different degree. In this process, the occurrence heat transmit, mass transfer, organization and structure variety are occurred, all of these are the important factors that influence the performance of material which radiated by laser. The research on thermal effect of material radiated by laser is the physical foundation of laser process, laser heat treatment and laser-induced thermal damage. The research has positive effect on organization structure analysis radiated by laser and material surface modification.Material radiated by high power density laser is finished in short time. The heat-affected zone changed with different influence factors, such as kinds of material, material surface appearance, power density of laser, the function time, and the laser incidence angle etc. With these different factors, its organization appearance, the distribution characteristics and the temperature field have complicated varieties. And these varieties are hard to be measured by experiment method. Numerical simulation on material radiated by laser has been used to simulate the temperature field at the present time.ANSYS, a finite element analysis software, was used to simulate the temperature field of pure aluminum, the copper-zinc alloy radiated by laser. The variety of temperature on surface and inner of material with heating time was concluded through the simulation. The accuracy of simulation was done by contrast the result of simulation with the molten pool of real sample. A series of simulations on material radiated by laser with different power density are carried out to conclude the critical value of laser power density which can make the pure aluminum and the copper-zinc alloy melt through analyzing the temperature field of numerical simulation.According to the result of simulation, the temperatures of samples rise linearly. A “platform” can be seen when the temperature arrived at the melting point because of the latent heat of melting. When the energy accumulated beyond the latent heat of melting, the temperatures rise linearly again. In one second, the threshold power density value of aluminum melting is 4200-4500 W/cm~2, and the threshold power density value of copper-zinc alloy melting is 6100-7300 W/cm~2.

0Cr13 steel, one type of stainless steel, is liable to generate crack. Heat stress is one of the major reasons for the cracks. This experiment simulated the temperature field and stress field based on the equipment parameters and process parameters of the 0Cr13 steel thick slab continuous caster from TISCO, providing technical guidance for the establishment of the 0Cr13 steel thick slab cooling process.This paper firstly summarized the slab defects,second cooling system,thermo-stress model and survey of stress studying.Then the model of thermo-stress for continuous casting of slab was developed with considering stress condition of slab.At the same time material thermo-properties relating to temperature were considered.Through some investigation in product spot ,the temperature field and stress field of 1020×200mm slab were discussed in production casting speed.The simulation shows that thermo-stress is very great because of surface reheating of slab when the slab goes out of mold.It is the main reason of crack defects.Exterior shell bears tensile stress and interior shell bears compressive stress during the early stage of solidification.As casting speed and superheat increases , stress decreases.It is possible to describe the formation of crack and to estimate danger areas.Thereby rational cooling system should be adopted to decrease the temperature gradients to avoid crack formation.The simulation results to determine a reasonable production of continuous casting system has some help.

0Cr13 steel, one type of stainless steel, is liable to generate crack. Heat stress is one of the major reasons for the cracks. This experiment simulated the temperature field and stress field based on the equipment parameters and process parameters of the 0Cr13 steel thick slab continuous caster from TISCO, providing technical guidance for the establishment of the 0Cr13 steel thick slab cooling process.This paper firstly summarized the slab defects,second cooling system,thermo-stress model and survey of stress studying.Then the model of thermo-stress for continuous casting of slab was developed with considering stress condition of slab.At the same time material thermo-properties relating to temperature were considered.Through some investigation in product spot ,the temperature field and stress field of 1020×200mm slab were discussed in production casting speed.The simulation shows that thermo-stress is very great because of surface reheating of slab when the slab goes out of mold.It is the main reason of crack defects.Exterior shell bears tensile stress and interior shell bears compressive stress during the early stage of solidification.As casting speed and superheat increases , stress decreases.It is possible to describe the formation of crack and to estimate danger areas.Thereby rational cooling system should be adopted to decrease the temperature gradients to avoid crack formation.The simulation results to determine a reasonable production of continuous casting system has some help.

In the high-power laser welding process,the laser beam acts on the baseplate.In few millseconds, melting, vaporization and ionization happened. Laser welding process is complex,and the time is short.So, the measurement of the laser welding process dynamic parameters is hard.Because of high cost of the experiment,traditional methods almost can’t use extensively because of wasting materials or craft complication,the author uses a new offline analysis method ,using image processing technology,analysicing the high speed camera picture of laser welding process,to measure the dynamic parameters and temperature field distribution feature,providing proof for deeper reseach of machnism and real-time detecting.Based on the reasch status of the laser welding process measurement,at first,the author analysised the hardness of the direct measurement ,the defect of the offline analysis method used and the reasons impacting the quality,then analysised the condition of the combination between image processing technology and laser welding process measurement.Based on the analysis,the photos of laser welding would be processed,the spray diameters and highest vilocity would be figured out.According to the relation between the spraying status and diameter and highest vilocity,constructing the model to forecast the spraying status by the Partial Least-Squres Regression method.In another way,the author analysised the laser welding pool photos.Through the analysis,the distribution of the temperature field, time parameters of the welding pool,and the time history of the welding pool center point would carry out.Experiment shows that the high speed camera picture of laser welding process can reappear laser welding process,offline analysis can be considerable as derect measurement.And the measurement method is more easier,reduce the cost of experiment.The reseach can provide the theoretical basis for practical production.

With the development of the national economy, the consumption of the cold rolling steel coil is increasing continuously, which asks higher requirement for the quality of the cold rolling steel coil simultaneity. The bonding defect of the cold rolling steel coil is universal in the bell type annealing technology. It is one of the long-term basis standing problems that puzzle the steel rolling researchers and engineers in all over the world.The origin of the cold strip coil cohesion was worked out systematically. The author thought that the pressure, temperature and time were the main causes. The most effective method is to reduce the pressure. The pressure is the thermal stress that arises from the uneven temperature field in the process of annealing. But the changes of the thermal stress effect the heat transfer and the distribution of the temperature field. There is a coupling relationship between the temperature field and the thermal stress.This paper analyzes the annealing process system and the heat transfer, and combined with the cause analysis of bonding defect and the production practice, on the basis of which the mathematical model of temperature field and thermal stress field are established. Heat transfer in different thermal processes, such as heating, heat preservation and cooling, is specified and analyzed in this thesis. According to the coil mechanical character which is anisotropy, the anisotropic axisymmetric two-dimensional non-stable thermal stress’s computation model is established accurately and the coil boundary condition in each working procedure is ascertained in this paper. Through finite difference method the stress equation, thermal elasticity displacement equation and boundary condition are discretized, then the thermal elasticity displacement’s finite difference equation and the stress finite difference equation are established. Coupling this thermal stress model and the two-dimensional conduction model by the coil radial conduction coefficient and the radial compress coefficient, the distributions of stress and temperature were obtained. Then the effects on the distribution of temperature and thermal stress caused by the two coefficients are analyzed.The research makes out that the steel coil distribution of temperature and thermal stress may be reflected by the mathematical models of thermal stress and temperature pretty well, which is helpful for the optimization of the coil annealing process in full-hydrogen annealing furnace.

Landfill is the main method of MSW disposal in China. MSW landfill generates high concentration of leachate, which can induce secondary pollutants to surrounding water body, when treated improperly. In order to control landfill leachate, it’s necessary to do some research on landfill leachate transport. Based on biochemical reaction mechanisms of landfill biodegradation and in view of convection, dispersion, diffusion, adsorption and organic biodegradation, the author established advection-dispersion transport model of landfill leachate, furthermore, the analytical solution of one-dimensional migration equation was solved.Based on the theory of solute transport in landfill, the author did the simulated experiment indoor. In this foundation, the effect of temperature change on leachate transport was analyzed, which caused the change of chemical index of landfill leachate.According to the theory of permeation fluid mechanics and thermodynamics of porous medium, thermal effect and seepage theory in landfill site were analyzed. From the non-isothermal angle, the interaction mechanism between, the moisture transfer and temperature change in landfill site was analyzed theoretically. Temperature change has an effect on seepage field, which manifests two aspects: one the one hand, temperature change influences seepage field by hydraulic conductivity tensor in the landfill body; one the other hand, temperature grads themselves also influence seepage field, moreover, the higher temperature gradient is, the stronger the effect it has on seepage field is, on this basis the author established the governing equation of seepage field which was affected by temperature change. By analyzing the effect that leachate transport had on temperature field, this thesis established the governing equation of temperature field, the results showed that: the distribution of temperature field and the distribution of seepage field are closely-related in the landfill body, the higher hydraulic gradient is, the stronger the effect it has on temperature field.Based on the analysis of coupling action between temperature and seepage field in the landfill site, the coupled double-field model for leachate transport was established. The finite element numerical solution method of the mathematical model was presented, also the analytical solution of one-dimensional simplify model was solved. By analyzing simplify model, it was shown that: the higher hydraulic gradient was, the more obvious the effect of seepage on temperature was, and the less obvious the effect of temperature on seepage was. When seepage flows from where the temperature is high to where the temperature is low, the temperature increases and the hydraulic head decreases; when seepage flows from where the temperature is low to where the temperature is high, the temperature decreases and the hydraulic head increases.

Quenching and tempering are regularly taken for alloy steel mechanical parts inorder to attain predefined mechanical properties and meet requirements in specificconditions. However, some premature failure of mechanical parts usually happenduring work because of quenching dimensional effect, improper material and heattreatment. So to select an alloy steel whose hardenability can well match requiredproperties of specific parts is an effective measure for the problem. But presentmain methods being widely used by international researchers to describehardenability of alloy steel are only suitable for cylindrical samples or parts, such asJC, critical quenching dimension, and equivalent depth of end quenching ,etc,which are limited in engineering greatly.In order to describe quenching dimensional effect for complex or heavy alloysteel parts in section, the concrete method was put forward combining temperaturefield calculation model with Continuous Cooling Transformation calculation modelin paper, and some application about selection and design for alloy steel parts werecarried out in accordance with the method and made successes. Following items aremajor content for the paper.(1) The best candidate alloy steel can guarantee 100mm hardening depth , 52～57HRC quality and correlated heat treatment for 8 rail straightening roller inPANZHIHUA IRON&STEEL CO. were determined based on temperature field andCCT diagrams.(2) 0.75C-2.9Cr-0.27Mo-1.8Mn-1.25Si-0.55Ni alloy steel was designed by usingThermo-Calc software for equilibrium phase calculation and CCT diagram calculation result based on temperature field calculations of 12 cold roller in orderto reduce stress and against early spallation&crack of roller body. The resultsindicated that air quenching critical diameter for cold roller is 140mm.In addition,optical microscope, TEM and X-Ray equipments also were used to analyzemicrostructure of the steel, the analyses can play strong theoretical role indevelopment and application for cold roller against spallation&crack.The economical air quenching cold-working die steel was designed followingprinciple above and applied to cold roller solved problems of inadequate hardeningdepth of 9Cr2MoV and spallation&crack of Cr12MoV, which indicated thatcombination of temperature field calculation, CCT diagram calculation andequilibrium phase calculation can be used to asses quenching dimensional effect forcomplex and heavy parts in section, the assesed results also are meaningful toselection and design for alloy steel.

In this paper, a lot of material properties has been consulted. For the part of melting the whole enthalpy and specific heat has been input in the range of melting point temperature, considered the influence of phase transfer in the simulation of melting. Then a tow-dimensional model has been developed and all the boundary conditions has been treated on ANSYS platform, such as temperature, heat flux and convection coefficient. The arc parameters of plasma has been calculated carefully and also make the foundations for the simulation of VAR.The simulation results show the changes of temperature and heat flux field in different parameters. The change trend of all the temperature and heat flux areas has been found. During the melting process the surface of molten pool has the highest temperature. The temperature distributes in the form of nonlinear gradients and high thermal gradient appears near the crucible wall where is close to the arc. Comparing the difference of heat flux between 4000A and 6000A, the heat received from arc with larger current is more. The changes of heat flux reflect the changes of heat distribution of arc. Comparing the different electric current of 4000A and 6000A it is apparent that the arc with larger current can achieve the steady melting period earlier and also has a better effect on refining and removing impurities for the molten pool. It can also be found that the arc can heat the electrode and molten pool effectively by researching the change of heat flux.In the paper, the change rates of width and depth of molten pool has been researched by calculating the temperature boundaries carefully. And on this basics the melting rates in different periods has been calculated. It is found that the rate rise at first and fall. Comparing the thermal effectivities and losses with different power, we can find that the thermal effectivity can rise remarkably by using the large power with reasonable melt rate.

Welding is a complicated physicochemical process which involves in electromagnetism, heat transferring, metal melting and freezing, phase-change welding stress and deformation and so on. However, the overwhelming majority welding process all can engender complex welding residual stress, crack, blowhole and so on in the work part, which reduce the welding structure performance, and affect the welding quality.Hammer peening is a kind of very effective method relieving welding residual stress, which was applied widely in engineering. However, the research of hammer peening can far meet its applications in practice. If welding process can be simulated with computer, obtained welding temperature field and stress field at different times, then can offer position and occasion of hammer peening for the weld with trailing peening.Based on summing up other’s research, employing numerical calculation method, discussed the finite element analytical system of the welding process, expound the numerical simulation method and basic theory of temperature field and stress field in welding process. When calculating, use ANSYS’ thermal-structure couple function, firstly calculate welding temperature field and save the result if it is right, then using the temperature result as load to calculate welding stress field. Although welding temperature filed and stress, strain field are bi-directional couple, but stress and strain field have little influence on temperature field, this paper only considers the single couple which temperature field effects on stress and strain field. Then provide the simulation method of welding temperature field and stress field of flat surface by FEM soft ANSYS. At the same time, the calculation result accord with traditional analysis result and theory result.The main contents of the paper are as following: choose the function of Gauss as heat source model, use APDL of ANSYS software to apply load of moving heat source. A mathematical model of transient thermal process in welding is established to simulate the move of heat source. The problem of the fusion and solidification of material has been solved by the method of changing the element attribute. Simulated single track bead weld of submerged arc welding, ignored metal deposition of weld bead, and solved the problem of the convergence difficulty or the un-convergence during the calculation of the thermal stress.A feasible dynamic simulation method on 3D welding temperature field, stress field has been established, which provides theory foundation and instruction on optimizing the welding technology and parameters, and provides theory foundation for the weld trailing peening technology at the same time.

Welding is a complicated physicochemical process which involves in electromagnetism, heat transferring, metal melting and freezing, phase-change welding stress and deformation and so on. However, the overwhelming majority welding process all can engender complex welding residual stress, crack, blowhole and so on in the work part, which reduce the welding structure performance, and affect the welding quality.Hammer peening is a kind of very effective method relieving welding residual stress, which was applied widely in engineering. However, the research of hammer peening can far meet its applications in practice. If welding process can be simulated with computer, obtained welding temperature field and stress field at different times, then can offer position and occasion of hammer peening for the weld with trailing peening.Based on summing up other’s research, employing numerical calculation method, discussed the finite element analytical system of the welding process, expound the numerical simulation method and basic theory of temperature field and stress field in welding process. When calculating, use ANSYS’ thermal-structure couple function, firstly calculate welding temperature field and save the result if it is right, then using the temperature result as load to calculate welding stress field. Although welding temperature filed and stress, strain field are bi-directional couple, but stress and strain field have little influence on temperature field, this paper only considers the single couple which temperature field effects on stress and strain field. Then provide the simulation method of welding temperature field and stress field of flat surface by FEM soft ANSYS. At the same time, the calculation result accord with traditional analysis result and theory result.The main contents of the paper are as following: choose the function of Gauss as heat source model, use APDL of ANSYS software to apply load of moving heat source. A mathematical model of transient thermal process in welding is established to simulate the move of heat source. The problem of the fusion and solidification of material has been solved by the method of changing the element attribute. Simulated single track bead weld of submerged arc welding, ignored metal deposition of weld bead, and solved the problem of the convergence difficulty or the un-convergence during the calculation of the thermal stress.A feasible dynamic simulation method on 3D welding temperature field, stress field has been established, which provides theory foundation and instruction on optimizing the welding technology and parameters, and provides theory foundation for the weld trailing peening technology at the same time.