When heavy machines and large scaled receiver system of communication equipment are manufactured, it always needs to produce large-sized steel castings, aluminum castings and etc. Some defects of hot cracking by therm...When heavy machines and large scaled receiver system of communication equipment are manufactured, it always needs to produce large-sized steel castings, aluminum castings and etc. Some defects of hot cracking by thermal stress often appear during solidification process as these castings are produced, which results in failure of castings. Therefore predicting the effects of technological parameters for production of castings on the thermal stress during solidification process becomes an important means. In this paper, the mathematical models have been established and numerical calculation of temperature fields by using finite difference method (FDM) and then thermal stress fields by using finite element method (FEM) during solidification process of castings have been carried out. The technological parameters of production have been optimized by the results of calculation and the defects of hot cracking have been eliminated. Modeling and simulation of 3D thermal stress during solidification processes of large-sized castings provided a scientific basis, which promoted further development of advanced manufacturing technique.展开更多
A micro-modeling method (MM) for the quantitative prediction of the shrinkage cavity formation in SGiron castings is proposed. The mathematical models describing the volume changes during the solidification ofspheroid...A micro-modeling method (MM) for the quantitative prediction of the shrinkage cavity formation in SGiron castings is proposed. The mathematical models describing the volume changes during the solidification ofspheroidal graphite cast iron are established based on the models of solidification kinetics. The shrinkage cavityformation of T-shaped SG iron castings is calculated with MM method. The calculated results are compared with theexperimental results. It is shown that the predicted size, shape and distribution of shrinkage cavity by MM methodare in good agreement with the measured results.展开更多
Power ultrasonic treatment is an efficient way to improve the solidification structure and mechanical properties of metals. The effect of 600 W power ultrasonic treatment on the solidification process and structure of...Power ultrasonic treatment is an efficient way to improve the solidification structure and mechanical properties of metals. The effect of 600 W power ultrasonic treatment on the solidification process and structure of HT150 gray cast iron has been studied, and the fining mechanism of power ultrasonic has been analyzed.展开更多
Microstructure strongly influences the mechanical properties of cast iron. By inoculating the melt with proper inoculants, foreign substrates are brought into the melt and eventually the graphite can crystallize on th...Microstructure strongly influences the mechanical properties of cast iron. By inoculating the melt with proper inoculants, foreign substrates are brought into the melt and eventually the graphite can crystallize on them. The elements and substrates that really play a role for nucleation are yet unknown. Until now there is very little knowledge about the fundamentals of nucleation, such as composition and morphology of nuclei. In this work we utilized EN-GJL-200 as a base material and examined several produced specimens. The specimens were cast with and without inoculants and quenched at different solidification states. Specimens were also examined with a high and low oxygen concentration, but the results showed that different oxygen contents have no influence on the nucleation in cast iron melts. Our research was focused on the microscopic examination and phase-field simulations. For studying the samples we applied different analytical methods, where SEM-EDS, -WDS were proved to be most effective. The simulations were conducted by using the software MICRESS, which is based on a multiphase-field model and has been coupled directly to the TCFE3 thermodynamic database from TCAB. On the basis of the experimental investigations a nucleation mechanism is proposed, which claims MnS precipitates as the preferred site for graphite nucleation. This theory is supported by the results of the phase-field simulations.展开更多
Most lost-foam casting processes involve non-equilibrium solidification dominated by kinetic factors, while construction of a common dynamic solidification curve is based on pure thermodynamics, not applicable for ana...Most lost-foam casting processes involve non-equilibrium solidification dominated by kinetic factors, while construction of a common dynamic solidification curve is based on pure thermodynamics, not applicable for analyses and research of non-equilibrium macro-solidification processes, and the construction mode can not be applied to nonequilibrium solidification process. In this study, the construction of the dynamic solidification curve(DSC) for the nonequilibrium macro-solidification process included: a modified method to determine the start temperature of primary austenite precipitation(T_(AL)) and the start temperature of eutectic solidification(T_(ES)); double curves method to determine the temperature of the dendrite coherency point of primary austenite(T-(AC)) and the temperature of eutectic cells collision point(T_(EC)); the "technical solidus" method to determine the end temperature of eutectic reaction(T_(EN)). For this purpose, a comparative testing of the non-equilibrium solidification temperature fields in lost-foam casting and green sand mold casting hypoeutectic gray iron was carried out. The thermal analysis results were used to construct the DSCs of both these casting methods under non-equilibrium solidification conditions. The results show that the transformation rate of non-equilibrium solidification in hypoeutectic gray cast iron is greater than that of equilibrium solidification. The eutectic solidification region presents a typical mushy solidification mode. The results also indicate that the primary austenite precipitation zone of lost-foam casting is slightly larger than that of green sand casting. At the same time, the solid fraction(f_s) of the dendrite coherency points in lost-foam casting is greater than that in the green sand casting. Therefore, from these two points, lost-foam casting is more preferable for reduction of shrinkage and mechanical burntin sand tendency of the hypoeutectic gray cast iron. Due to the fact that the solidification process(from the surface to center) at primary austenite growth area in the lost-foam cylinder sample lags behind that in the green sand casting, the mushy solidification tendency of lost-foam casting is greater and the solidification time is longer.展开更多
The effects of metallurgical and processing parameters on the formation of shrinkage cavities and porosities in spheroidal graphite cast iron have been studied, considering the parameters of carbon equivalent, inocula...The effects of metallurgical and processing parameters on the formation of shrinkage cavities and porosities in spheroidal graphite cast iron have been studied, considering the parameters of carbon equivalent, inoculation, casting modulus, mold type (green or dry) and pouring temperature within specific ranges of these variables. Based on the orthogonal experiments, the metallurgical and processing parameters of the minimum casting shrinkage and the maximum casting shrinkage were obtained, and the effects of metallurgical and processing parameters on the formation of shrinkage cavities and porosities in spheroids graphite cast iron castings were discussed. Finally, two regression equations relating these variables to the formation of shrinkage porosity were derived based upon the orthogonal experiments conducted.展开更多
Based on a method using numerical simulation equations and their solution schemes for liquid metal flows andheat transfer during mold filling and the solidification process of casting, 3-D numerical simulation softwar...Based on a method using numerical simulation equations and their solution schemes for liquid metal flows andheat transfer during mold filling and the solidification process of casting, 3-D numerical simulation software SRIFCAST wascreated. This includes enmeshment of casting; velocity and temperature fields calculation; displaying iso-temperature lines;velocity vectors and 3-D temperature fields on a Windows 9x operating system. SRIFCAST was applied to produce soundcastings of automobile and diesel engines, and also to connect with microstructure simulation for ductile iron castings.展开更多
The solidification process of a horizontally continuously cast gray iron bar of 4.6cm in diame- ter was modelled.The function describing the distribution of heat flux at the internal surface of graphite sleeve,which w...The solidification process of a horizontally continuously cast gray iron bar of 4.6cm in diame- ter was modelled.The function describing the distribution of heat flux at the internal surface of graphite sleeve,which was equal to that on the surface of the iron bar,was inversely derived using numerical calculation from the temperature distribution in the sleeve measured in real production.By using the distribution of heat flux as a boundary condition on the surface of the iron bar,the numerical simulation on solidification of the iron bar taking longitudinal heat conduction into account was made.The profile of solidification front obtained from the numer- ical simulation was approximately coincident with that in real production.In addition,the quantitative relationships of the thickness of solidified shell at the exit of the mold to the main technological parameters,including the temperature of liquid iron at the entrance of the mold, the moving speed of the bar and the intensity of water cooling,were obtained from the numeri- cal simulation.展开更多
3-Dvelocity and temperature fields of mold filling and solidification processes of large-sized castingswere calculated,and the efficiency and accuracy of numerical calculation were studied.The mold filling andsolidifi...3-Dvelocity and temperature fields of mold filling and solidification processes of large-sized castingswere calculated,and the efficiency and accuracy of numerical calculation were studied.The mold filling andsolidification processes of large-sized stainless steel,iron and aluminum alloy castings were simulated by using ofnew scheme;their casting processes were optimized,and then applied to produce castings.展开更多
By self-made pulse electrical source and strong magnetic field solidification tester, the effect of strong pulse magnetic field on graphite morphology and solidification structure of gray cast iron was studied. The re...By self-made pulse electrical source and strong magnetic field solidification tester, the effect of strong pulse magnetic field on graphite morphology and solidification structure of gray cast iron was studied. The results show that the structure is remarkably refined after treated by pulse magnetic field, and the width of graphite flakes is decreased while the length is increased after a slight decrease. The solidification temperature and eutectic temperature are increased and the undercooling degree of eutectic transformation is decreased by magnetic field.展开更多
The microstructure of the laser hardened layer on the HT20-40 gray cast iron after laser melting processing'was examined by optical microscopy,transmission electron microscopy (TEM)and scanning electron microscopy...The microstructure of the laser hardened layer on the HT20-40 gray cast iron after laser melting processing'was examined by optical microscopy,transmission electron microscopy (TEM)and scanning electron microscopy(SEM).Experimental results showed that a struc- ture with dendritic(M+A')and interdendriticly laminal transformed ledeburite (M+A'+Fe_3C)was produced after laser melting processing.The martensite is a mixture of dis- location martensite and twin martensite.Dislocation pile-ups and twins were found in the residual austenite.Microsegregation of composition and heterogeneity of microstructure were also apparent after laser melting processing.展开更多
Rolling process based on the plastic deformation as a surface strengthening treatment was employed,aiming to improve the wear resistance ability and functional performance of the high carbon equivalent gray cast iron(...Rolling process based on the plastic deformation as a surface strengthening treatment was employed,aiming to improve the wear resistance ability and functional performance of the high carbon equivalent gray cast iron(HCEGCI).The microstructures and tribological performance of the untreated and rolled samples were characterized.In addition,the wear mechanism of HCEGCI samples was also studied via pin-on-disc tests.The experimental results show that the as-rolled samples possess the structure-refined layer of 15μm and work-hardened layer of 0.13 mm.In comparison with the surface hardness of untreated samples,the surface hardness of as-rolled samples increases by 84.6%(from 240HV0.1 to 443HV0.1)and the residual compressive stresses existed within the range of 0.2 mm.The wear rates of as-rolled samples were decreased by 38.4%,37.5%,and 44.4%under different loads of 5 N,10 N,and 15 N,respectively.The wear characteristics of the untreated samples mainly exhibit the peeling wear coupled with partial adhesive and abrasive wear.However,as for the as-rolled samples,the adhesive wear was limited by the structure-refined layer and the micro-crack propagation was controlled by the work-hardened layer.Therefore,the wear resistance of as-rolled samples can be improved significantly due to the low wearing degree of the friction contact zone.展开更多
A 3-D finite-element numerical simulation model of temperature field for CIESC casting solidification process was developed with the aid of ANSYS software and a series of corresponding experiments were made. The resul...A 3-D finite-element numerical simulation model of temperature field for CIESC casting solidification process was developed with the aid of ANSYS software and a series of corresponding experiments were made. The results showed that the good agreement was obtained between the numerical simulation and the experiments. Based on the numerical simulation results, the characteristics of temperature distribution in the castings during CIESC solidification process were analyzed and summarized. According to the G/R-1/2 method and numerical simulation results, there is no any shrinkage defect in the CIESC casting and structure or casting is fine and compact.展开更多
High strength compacted graphite iron (CGI) or alloyed cast iron components are substituting previously used non-ferrous castings in automotive power train applications.The mechanical engineering industry has recogniz...High strength compacted graphite iron (CGI) or alloyed cast iron components are substituting previously used non-ferrous castings in automotive power train applications.The mechanical engineering industry has recognized the value in substituting forged or welded structures with stiff and light-weight cast iron castings.New products such as wind turbines have opened new markets for an entire suite of highly reliable ductile iron cast components.During the last 20 years,casting process simulation has developed from predicting hot spots and solidification to an integral assessment tool for foundries for the entire manufacturing route of castings.The support of the feeding related layout of the casting is still one of the most important duties for casting process simulation.Depending on the alloy poured,different feeding behaviors and self-feeding capabilities need to be considered to provide a defect free casting.Therefore,it is not enough to base the prediction of shrinkage defects solely on hot spots derived from temperature fields.To be able to quantitatively predict these defects,solidification simulation had to be combined with density and mass transport calculations,in order to evaluate the impact of the solidification morphology on the feeding behavior as well as to consider alloy dependent feeding ranges.For cast iron foundries,the use of casting process simulation has become an important instrument to predict the robustness and reliability of their processes,especially since the influence of alloying elements,melting practice and metallurgy need to be considered to quantify the special shrinkage and solidification behavior of cast iron.This allows the prediction of local structures,phases and ultimately the local mechanical properties of cast irons,to asses casting quality in the foundry but also to make use of this quantitative information during design of the casting.Casting quality issues related to thermally driven stresses in castings are also gaining increasing attention.State-of-the-art tools allow the prediction of residual stresses and iron casting distortion quantitatively.Cracks in castings can be assessed,as well as the reduction of casting stresses during heat treatment.As the property requirements for cast iron as a material in design strongly increase,new alloys and materials such as ADI might become more attractive,where latest software developments allow the modeling of the required heat treatment.Phases can be predicted and parametric studies can be performed to optimize the alloy dependent heat treatment conditions during austenitization,quenching and ausferritization.All this quantitative information about the material's performance is most valuable if it can be used during casting design.The transfer of local properties into the designer's world,to predict fatigue and durability as a function of the entire manufacturing route,will increase the trust in this old but highly innovative material and will open new opportunities for cast iron in the future.The paper will give an overview on current capabilities to quantitatively predict cast iron specific defects and casting performance and will highlight latest developments in modeling the manufacture of cast iron and ADI as well as the prediction of iron casting stresses.展开更多
A high-energy pulse power source applied for studying solidifieation of metals and a Rogowski coil for measuring strong pulse current were developed according to the requirement of the present experiment. The variatio...A high-energy pulse power source applied for studying solidifieation of metals and a Rogowski coil for measuring strong pulse current were developed according to the requirement of the present experiment. The variation of electrical current during the discharge of pulse power source was analyzed. Furthermore, the quantitative relation between peak current, pulse width and pulse frequency etc. versus voltage, capacitance and transmission line of discharging circuit was examined.展开更多
文摘When heavy machines and large scaled receiver system of communication equipment are manufactured, it always needs to produce large-sized steel castings, aluminum castings and etc. Some defects of hot cracking by thermal stress often appear during solidification process as these castings are produced, which results in failure of castings. Therefore predicting the effects of technological parameters for production of castings on the thermal stress during solidification process becomes an important means. In this paper, the mathematical models have been established and numerical calculation of temperature fields by using finite difference method (FDM) and then thermal stress fields by using finite element method (FEM) during solidification process of castings have been carried out. The technological parameters of production have been optimized by the results of calculation and the defects of hot cracking have been eliminated. Modeling and simulation of 3D thermal stress during solidification processes of large-sized castings provided a scientific basis, which promoted further development of advanced manufacturing technique.
文摘A micro-modeling method (MM) for the quantitative prediction of the shrinkage cavity formation in SGiron castings is proposed. The mathematical models describing the volume changes during the solidification ofspheroidal graphite cast iron are established based on the models of solidification kinetics. The shrinkage cavityformation of T-shaped SG iron castings is calculated with MM method. The calculated results are compared with theexperimental results. It is shown that the predicted size, shape and distribution of shrinkage cavity by MM methodare in good agreement with the measured results.
文摘Power ultrasonic treatment is an efficient way to improve the solidification structure and mechanical properties of metals. The effect of 600 W power ultrasonic treatment on the solidification process and structure of HT150 gray cast iron has been studied, and the fining mechanism of power ultrasonic has been analyzed.
文摘Microstructure strongly influences the mechanical properties of cast iron. By inoculating the melt with proper inoculants, foreign substrates are brought into the melt and eventually the graphite can crystallize on them. The elements and substrates that really play a role for nucleation are yet unknown. Until now there is very little knowledge about the fundamentals of nucleation, such as composition and morphology of nuclei. In this work we utilized EN-GJL-200 as a base material and examined several produced specimens. The specimens were cast with and without inoculants and quenched at different solidification states. Specimens were also examined with a high and low oxygen concentration, but the results showed that different oxygen contents have no influence on the nucleation in cast iron melts. Our research was focused on the microscopic examination and phase-field simulations. For studying the samples we applied different analytical methods, where SEM-EDS, -WDS were proved to be most effective. The simulations were conducted by using the software MICRESS, which is based on a multiphase-field model and has been coupled directly to the TCFE3 thermodynamic database from TCAB. On the basis of the experimental investigations a nucleation mechanism is proposed, which claims MnS precipitates as the preferred site for graphite nucleation. This theory is supported by the results of the phase-field simulations.
基金financially supported by the National Development and Reform Commission(2010-324)
文摘Most lost-foam casting processes involve non-equilibrium solidification dominated by kinetic factors, while construction of a common dynamic solidification curve is based on pure thermodynamics, not applicable for analyses and research of non-equilibrium macro-solidification processes, and the construction mode can not be applied to nonequilibrium solidification process. In this study, the construction of the dynamic solidification curve(DSC) for the nonequilibrium macro-solidification process included: a modified method to determine the start temperature of primary austenite precipitation(T_(AL)) and the start temperature of eutectic solidification(T_(ES)); double curves method to determine the temperature of the dendrite coherency point of primary austenite(T-(AC)) and the temperature of eutectic cells collision point(T_(EC)); the "technical solidus" method to determine the end temperature of eutectic reaction(T_(EN)). For this purpose, a comparative testing of the non-equilibrium solidification temperature fields in lost-foam casting and green sand mold casting hypoeutectic gray iron was carried out. The thermal analysis results were used to construct the DSCs of both these casting methods under non-equilibrium solidification conditions. The results show that the transformation rate of non-equilibrium solidification in hypoeutectic gray cast iron is greater than that of equilibrium solidification. The eutectic solidification region presents a typical mushy solidification mode. The results also indicate that the primary austenite precipitation zone of lost-foam casting is slightly larger than that of green sand casting. At the same time, the solid fraction(f_s) of the dendrite coherency points in lost-foam casting is greater than that in the green sand casting. Therefore, from these two points, lost-foam casting is more preferable for reduction of shrinkage and mechanical burntin sand tendency of the hypoeutectic gray cast iron. Due to the fact that the solidification process(from the surface to center) at primary austenite growth area in the lost-foam cylinder sample lags behind that in the green sand casting, the mushy solidification tendency of lost-foam casting is greater and the solidification time is longer.
基金The paper was financially supported by the National Natural Science Foundation of China(Grant No.59235102).
文摘The effects of metallurgical and processing parameters on the formation of shrinkage cavities and porosities in spheroidal graphite cast iron have been studied, considering the parameters of carbon equivalent, inoculation, casting modulus, mold type (green or dry) and pouring temperature within specific ranges of these variables. Based on the orthogonal experiments, the metallurgical and processing parameters of the minimum casting shrinkage and the maximum casting shrinkage were obtained, and the effects of metallurgical and processing parameters on the formation of shrinkage cavities and porosities in spheroids graphite cast iron castings were discussed. Finally, two regression equations relating these variables to the formation of shrinkage porosity were derived based upon the orthogonal experiments conducted.
基金The reseach is supported by the TG 2000067208 project
文摘Based on a method using numerical simulation equations and their solution schemes for liquid metal flows andheat transfer during mold filling and the solidification process of casting, 3-D numerical simulation software SRIFCAST wascreated. This includes enmeshment of casting; velocity and temperature fields calculation; displaying iso-temperature lines;velocity vectors and 3-D temperature fields on a Windows 9x operating system. SRIFCAST was applied to produce soundcastings of automobile and diesel engines, and also to connect with microstructure simulation for ductile iron castings.
文摘The solidification process of a horizontally continuously cast gray iron bar of 4.6cm in diame- ter was modelled.The function describing the distribution of heat flux at the internal surface of graphite sleeve,which was equal to that on the surface of the iron bar,was inversely derived using numerical calculation from the temperature distribution in the sleeve measured in real production.By using the distribution of heat flux as a boundary condition on the surface of the iron bar,the numerical simulation on solidification of the iron bar taking longitudinal heat conduction into account was made.The profile of solidification front obtained from the numer- ical simulation was approximately coincident with that in real production.In addition,the quantitative relationships of the thickness of solidified shell at the exit of the mold to the main technological parameters,including the temperature of liquid iron at the entrance of the mold, the moving speed of the bar and the intensity of water cooling,were obtained from the numeri- cal simulation.
文摘3-Dvelocity and temperature fields of mold filling and solidification processes of large-sized castingswere calculated,and the efficiency and accuracy of numerical calculation were studied.The mold filling andsolidification processes of large-sized stainless steel,iron and aluminum alloy castings were simulated by using ofnew scheme;their casting processes were optimized,and then applied to produce castings.
文摘By self-made pulse electrical source and strong magnetic field solidification tester, the effect of strong pulse magnetic field on graphite morphology and solidification structure of gray cast iron was studied. The results show that the structure is remarkably refined after treated by pulse magnetic field, and the width of graphite flakes is decreased while the length is increased after a slight decrease. The solidification temperature and eutectic temperature are increased and the undercooling degree of eutectic transformation is decreased by magnetic field.
文摘The microstructure of the laser hardened layer on the HT20-40 gray cast iron after laser melting processing'was examined by optical microscopy,transmission electron microscopy (TEM)and scanning electron microscopy(SEM).Experimental results showed that a struc- ture with dendritic(M+A')and interdendriticly laminal transformed ledeburite (M+A'+Fe_3C)was produced after laser melting processing.The martensite is a mixture of dis- location martensite and twin martensite.Dislocation pile-ups and twins were found in the residual austenite.Microsegregation of composition and heterogeneity of microstructure were also apparent after laser melting processing.
基金Funded by the National Natural Science Foundation of China(No.51872254)the Yangzhou Hanjiang District Science and Technology Plan Project of China(No.HJM2019006)。
文摘Rolling process based on the plastic deformation as a surface strengthening treatment was employed,aiming to improve the wear resistance ability and functional performance of the high carbon equivalent gray cast iron(HCEGCI).The microstructures and tribological performance of the untreated and rolled samples were characterized.In addition,the wear mechanism of HCEGCI samples was also studied via pin-on-disc tests.The experimental results show that the as-rolled samples possess the structure-refined layer of 15μm and work-hardened layer of 0.13 mm.In comparison with the surface hardness of untreated samples,the surface hardness of as-rolled samples increases by 84.6%(from 240HV0.1 to 443HV0.1)and the residual compressive stresses existed within the range of 0.2 mm.The wear rates of as-rolled samples were decreased by 38.4%,37.5%,and 44.4%under different loads of 5 N,10 N,and 15 N,respectively.The wear characteristics of the untreated samples mainly exhibit the peeling wear coupled with partial adhesive and abrasive wear.However,as for the as-rolled samples,the adhesive wear was limited by the structure-refined layer and the micro-crack propagation was controlled by the work-hardened layer.Therefore,the wear resistance of as-rolled samples can be improved significantly due to the low wearing degree of the friction contact zone.
文摘A 3-D finite-element numerical simulation model of temperature field for CIESC casting solidification process was developed with the aid of ANSYS software and a series of corresponding experiments were made. The results showed that the good agreement was obtained between the numerical simulation and the experiments. Based on the numerical simulation results, the characteristics of temperature distribution in the castings during CIESC solidification process were analyzed and summarized. According to the G/R-1/2 method and numerical simulation results, there is no any shrinkage defect in the CIESC casting and structure or casting is fine and compact.
文摘High strength compacted graphite iron (CGI) or alloyed cast iron components are substituting previously used non-ferrous castings in automotive power train applications.The mechanical engineering industry has recognized the value in substituting forged or welded structures with stiff and light-weight cast iron castings.New products such as wind turbines have opened new markets for an entire suite of highly reliable ductile iron cast components.During the last 20 years,casting process simulation has developed from predicting hot spots and solidification to an integral assessment tool for foundries for the entire manufacturing route of castings.The support of the feeding related layout of the casting is still one of the most important duties for casting process simulation.Depending on the alloy poured,different feeding behaviors and self-feeding capabilities need to be considered to provide a defect free casting.Therefore,it is not enough to base the prediction of shrinkage defects solely on hot spots derived from temperature fields.To be able to quantitatively predict these defects,solidification simulation had to be combined with density and mass transport calculations,in order to evaluate the impact of the solidification morphology on the feeding behavior as well as to consider alloy dependent feeding ranges.For cast iron foundries,the use of casting process simulation has become an important instrument to predict the robustness and reliability of their processes,especially since the influence of alloying elements,melting practice and metallurgy need to be considered to quantify the special shrinkage and solidification behavior of cast iron.This allows the prediction of local structures,phases and ultimately the local mechanical properties of cast irons,to asses casting quality in the foundry but also to make use of this quantitative information during design of the casting.Casting quality issues related to thermally driven stresses in castings are also gaining increasing attention.State-of-the-art tools allow the prediction of residual stresses and iron casting distortion quantitatively.Cracks in castings can be assessed,as well as the reduction of casting stresses during heat treatment.As the property requirements for cast iron as a material in design strongly increase,new alloys and materials such as ADI might become more attractive,where latest software developments allow the modeling of the required heat treatment.Phases can be predicted and parametric studies can be performed to optimize the alloy dependent heat treatment conditions during austenitization,quenching and ausferritization.All this quantitative information about the material's performance is most valuable if it can be used during casting design.The transfer of local properties into the designer's world,to predict fatigue and durability as a function of the entire manufacturing route,will increase the trust in this old but highly innovative material and will open new opportunities for cast iron in the future.The paper will give an overview on current capabilities to quantitatively predict cast iron specific defects and casting performance and will highlight latest developments in modeling the manufacture of cast iron and ADI as well as the prediction of iron casting stresses.
文摘A high-energy pulse power source applied for studying solidifieation of metals and a Rogowski coil for measuring strong pulse current were developed according to the requirement of the present experiment. The variation of electrical current during the discharge of pulse power source was analyzed. Furthermore, the quantitative relation between peak current, pulse width and pulse frequency etc. versus voltage, capacitance and transmission line of discharging circuit was examined.
