The quantitative evaluation of multi-process collaborative operation is of great significance for the improvement of production planning and scheduling in steelmaking–continuous casting sections(SCCSs). However, this...The quantitative evaluation of multi-process collaborative operation is of great significance for the improvement of production planning and scheduling in steelmaking–continuous casting sections(SCCSs). However, this evaluation is difficult since it relies on an in-depth understanding of the operating mechanism of SCCSs, and few existing methods can be used to conduct the evaluation, due to the lack of full-scale consideration of the multiple factors related to the production operation. In this study, three quantitative models were developed, and the multiprocess collaborative operation level was evaluated through the laminar-flow operation degree, the process matching degree, and the scheduling strategy availability degree. Based on the evaluation models for the laminar-flow operation and process matching levels, this study investigated the production status of two steelmaking plants, plants A and B, based on actual production data. The average laminar-flow operation(process matching) degrees of SCCSs were obtained as 0.638(0.610) and 1.000(0.759) for plants A and B, respectively, for the period of April to July 2019. Then, a scheduling strategy based on the optimization of the furnace-caster coordinating mode was suggested for plant A. Simulation experiments showed higher availability than the greedy-based and manual strategies. After the proposed scheduling strategy was applied,the average process matching degree of the SCCS of plant A increased by 4.6% for the period of September to November 2019. The multi-process collaborative operation level was improved with fewer adjustments and interruptions in casting.展开更多
The QP980-DP980 dissimilar steel joints were fabricated by fiber laser welding.The weld zone(WZ)was fully martensitic structure,and heat-affected zone(HAZ)contained newly-formed martensite and partially tempered marte...The QP980-DP980 dissimilar steel joints were fabricated by fiber laser welding.The weld zone(WZ)was fully martensitic structure,and heat-affected zone(HAZ)contained newly-formed martensite and partially tempered martensite(TM)in both steels.The supercritical HAZ of the QP980 side had higher microhardness(~549.5 Hv)than that of the WZ due to the finer martensite.A softened zone was present in HAZ of QP980 and DP980,the dropped microhardness of softened zone of the QP980 and DP980 wasΔ21.8 Hv andΔ40.9 Hv,respectively.Dislocation walls and slip bands were likely formed at the grain boundaries with the increase of strain,leading to the formation of low angle grain boundaries(LAGBs).Dislocation accumulation more easily occurred in the LAGBs than that of the HAGBs,which led to significant dislocation interaction and formation of cracks.The electron back-scattered diffraction(EBSD)results showed the fraction of LAGBs in sub-critical HAZ of DP980 side was the highest under different deformation conditions during tensile testing,resulting in the failure of joints located at the sub-critical HAZ of DP980 side.The QP980-DP980 dissimilar steel joints presented higher elongation(~11.21%)and ultimate tensile strength(~1011.53 MPa)than that of DP980-DP980 similar steel joints,because during the tensile process of the QP980-DP980 dissimilar steel joint(~8.2%and 991.38 MPa),the strain concentration firstly occurred on the excellent QP980 BM.Moreover,Erichsen cupping tests showed that the dissimilar welded joints had the lowest Erichsen value(~5.92 mm)and the peak punch force(~28.4 kN)due to the presence of large amount of brittle martensite in WZ and inhomogeneous deformation.展开更多
Mathematical(data-driven)models based on state-of-the-art(SOTA)machine learning and deep learning models and data collected from 12,786 heats were established to predict the values of temperature,sample,and carbon(TSC...Mathematical(data-driven)models based on state-of-the-art(SOTA)machine learning and deep learning models and data collected from 12,786 heats were established to predict the values of temperature,sample,and carbon(TSC)test,including temperature of molten steel(TSC-Temp),carbon content(TSC-C)and phosphorus content(TSC-P),which made prepa-ration for eliminating the TSC test.To maximize the prediction accuracy of the proposed approach,various models with different inputs were implemented and compared,and the best models were applied to the production process of a Hesteel Group steelmaking plant in China in the field.The number of tabular features(hot metal information,scrap,additives,blowing practices,and preset values)was expanded,and time series(off-gas profiles and blowing practice curves)that could reflect the entire steelmaking process were introduced as inputs.First,the latest machine learning models(LightGBM,CatBoost,TabNet,and NODE)were used to make predictions with tabular features,and the best coefficient of determination R^(2)values obtained for TSC-P,TSC-C and TSC-Temp predictions were 0.435(LightGBM),0.857(Cat-Boost)and 0.678(LightGBM),respectively,which were higher than those of classic models(backpropagation and support vector machine).Then,making predictions was performed by using SOTA time series regression models(SCINet,DLinear,Informer,and MLSTM-FCN)with original time series,SOTA image regression models(NesT,CaiT,ResNeXt,and GoogLeNet)with resized time series,and the proposed Concatenate-Model and Parallel-Model with both tabular features and time series.Through optimization and comparisons,it was finally determined that the Concatenate-Model with MLSTM-FCN,SCINet and Informer as feature extractors performed the best,and its R^(2)values for predicting TSC-P,TSC-C and TSC-Temp reached 0.470,0.858 and 0.710,respectively.Its field test accuracies for TSC-P,TSC-C and TSC-Temp were 0.459,0.850 and 0.685,respectively.A related importance analysis was carried out,and dynamic control methods based on prediction values were proposed.展开更多
In-situ SEM can intuitively observe the changes in microstructure and microcrack initiation during the deformation process of the specimen.In this paper,the microstructural evolution,mechanical properties,and damage n...In-situ SEM can intuitively observe the changes in microstructure and microcrack initiation during the deformation process of the specimen.In this paper,the microstructural evolution,mechanical properties,and damage nucleation modes of DP1180 laser welded joints were systematically discussed by the trans-mission electron microscope(TEM),focused ion beam(FIB),and in-situ tensile test.The precipitation of carbides and disappearance of dislocations tangles deteriorated the mechanical properties of tempered martensite in the sub-critical heat affected zone(SCHAZ),which caused its microhardness slightly de-creased(∼27 HV)and also called the softened zone.The joints fractured in the SCHAZ during the tensile and Erichsen cupping tests and microcracks initiated from the tempered martensite,while the microc-rack initiation of base material(BM)occurred at the ferrite/martensite interface.The dominant damage nucleation mode of the joint was tempered martensite cracking,and that of BM was ferrite/martensite interface decohesion during tests.展开更多
Mechanical properties and creep behavior of Q460E continuous casting slab were studied by means of uniaxial tensile tests on a Gleeble-3800 thermomechanical simulator from 1000 to 1100 ℃.The high-temperature creep co...Mechanical properties and creep behavior of Q460E continuous casting slab were studied by means of uniaxial tensile tests on a Gleeble-3800 thermomechanical simulator from 1000 to 1100 ℃.The high-temperature creep constitutional equation was derived based on experimental data.The parameters in the equation were calculated by using the regression analysis inverse-estimation method.The experimental curves in the primary and secondary creep stages are fitted well.A three-dimensional elastic-plastic and creep finite element model was proposed in order to investigate the bulging deformation of slab and the bulging deformation at the beginning position of bending segment on the slab continuous casting machine was computed accurately.The results indicate that the maximum bulging deformation appears at the geometric center of the slab.The maximum value of the bulging deformation obtained by the elastic-plastic analysis is 1.301 ram.Consideririg the creep effect,the deformation increases to 1.827 mm which is about 1.4 times the value obtained by the elastic-plastic analysis.The calculation of buleing deformation usin2 the elastic-plastic creed model is more reliable and/iccurate.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.50874014 and 51974023)the Fundamental Research Funds for Central Universities (No.FRF-BR-17-029A)。
文摘The quantitative evaluation of multi-process collaborative operation is of great significance for the improvement of production planning and scheduling in steelmaking–continuous casting sections(SCCSs). However, this evaluation is difficult since it relies on an in-depth understanding of the operating mechanism of SCCSs, and few existing methods can be used to conduct the evaluation, due to the lack of full-scale consideration of the multiple factors related to the production operation. In this study, three quantitative models were developed, and the multiprocess collaborative operation level was evaluated through the laminar-flow operation degree, the process matching degree, and the scheduling strategy availability degree. Based on the evaluation models for the laminar-flow operation and process matching levels, this study investigated the production status of two steelmaking plants, plants A and B, based on actual production data. The average laminar-flow operation(process matching) degrees of SCCSs were obtained as 0.638(0.610) and 1.000(0.759) for plants A and B, respectively, for the period of April to July 2019. Then, a scheduling strategy based on the optimization of the furnace-caster coordinating mode was suggested for plant A. Simulation experiments showed higher availability than the greedy-based and manual strategies. After the proposed scheduling strategy was applied,the average process matching degree of the SCCS of plant A increased by 4.6% for the period of September to November 2019. The multi-process collaborative operation level was improved with fewer adjustments and interruptions in casting.
基金Supported by National Natural Science Foundation of China(Grant Nos.51871010,51875129)Beijing Municipal Natural Science Foundation of China(Grant No.32020163212008).
文摘The QP980-DP980 dissimilar steel joints were fabricated by fiber laser welding.The weld zone(WZ)was fully martensitic structure,and heat-affected zone(HAZ)contained newly-formed martensite and partially tempered martensite(TM)in both steels.The supercritical HAZ of the QP980 side had higher microhardness(~549.5 Hv)than that of the WZ due to the finer martensite.A softened zone was present in HAZ of QP980 and DP980,the dropped microhardness of softened zone of the QP980 and DP980 wasΔ21.8 Hv andΔ40.9 Hv,respectively.Dislocation walls and slip bands were likely formed at the grain boundaries with the increase of strain,leading to the formation of low angle grain boundaries(LAGBs).Dislocation accumulation more easily occurred in the LAGBs than that of the HAGBs,which led to significant dislocation interaction and formation of cracks.The electron back-scattered diffraction(EBSD)results showed the fraction of LAGBs in sub-critical HAZ of DP980 side was the highest under different deformation conditions during tensile testing,resulting in the failure of joints located at the sub-critical HAZ of DP980 side.The QP980-DP980 dissimilar steel joints presented higher elongation(~11.21%)and ultimate tensile strength(~1011.53 MPa)than that of DP980-DP980 similar steel joints,because during the tensile process of the QP980-DP980 dissimilar steel joint(~8.2%and 991.38 MPa),the strain concentration firstly occurred on the excellent QP980 BM.Moreover,Erichsen cupping tests showed that the dissimilar welded joints had the lowest Erichsen value(~5.92 mm)and the peak punch force(~28.4 kN)due to the presence of large amount of brittle martensite in WZ and inhomogeneous deformation.
基金This research has been supported by the Natural Science Foundation of Hebei Province,China(E2022318002).Thanks are given to Tangsteel Co.,Ltd.of Hesteel Group and Digital Co.,Ltd.of Hesteel Group for providing detailed data,hardware and software support for model development and field production test.
文摘Mathematical(data-driven)models based on state-of-the-art(SOTA)machine learning and deep learning models and data collected from 12,786 heats were established to predict the values of temperature,sample,and carbon(TSC)test,including temperature of molten steel(TSC-Temp),carbon content(TSC-C)and phosphorus content(TSC-P),which made prepa-ration for eliminating the TSC test.To maximize the prediction accuracy of the proposed approach,various models with different inputs were implemented and compared,and the best models were applied to the production process of a Hesteel Group steelmaking plant in China in the field.The number of tabular features(hot metal information,scrap,additives,blowing practices,and preset values)was expanded,and time series(off-gas profiles and blowing practice curves)that could reflect the entire steelmaking process were introduced as inputs.First,the latest machine learning models(LightGBM,CatBoost,TabNet,and NODE)were used to make predictions with tabular features,and the best coefficient of determination R^(2)values obtained for TSC-P,TSC-C and TSC-Temp predictions were 0.435(LightGBM),0.857(Cat-Boost)and 0.678(LightGBM),respectively,which were higher than those of classic models(backpropagation and support vector machine).Then,making predictions was performed by using SOTA time series regression models(SCINet,DLinear,Informer,and MLSTM-FCN)with original time series,SOTA image regression models(NesT,CaiT,ResNeXt,and GoogLeNet)with resized time series,and the proposed Concatenate-Model and Parallel-Model with both tabular features and time series.Through optimization and comparisons,it was finally determined that the Concatenate-Model with MLSTM-FCN,SCINet and Informer as feature extractors performed the best,and its R^(2)values for predicting TSC-P,TSC-C and TSC-Temp reached 0.470,0.858 and 0.710,respectively.Its field test accuracies for TSC-P,TSC-C and TSC-Temp were 0.459,0.850 and 0.685,respectively.A related importance analysis was carried out,and dynamic control methods based on prediction values were proposed.
基金financially supported by the National Natural Science Foundation of China(Nos.51871010 and52005022).
文摘In-situ SEM can intuitively observe the changes in microstructure and microcrack initiation during the deformation process of the specimen.In this paper,the microstructural evolution,mechanical properties,and damage nucleation modes of DP1180 laser welded joints were systematically discussed by the trans-mission electron microscope(TEM),focused ion beam(FIB),and in-situ tensile test.The precipitation of carbides and disappearance of dislocations tangles deteriorated the mechanical properties of tempered martensite in the sub-critical heat affected zone(SCHAZ),which caused its microhardness slightly de-creased(∼27 HV)and also called the softened zone.The joints fractured in the SCHAZ during the tensile and Erichsen cupping tests and microcracks initiated from the tempered martensite,while the microc-rack initiation of base material(BM)occurred at the ferrite/martensite interface.The dominant damage nucleation mode of the joint was tempered martensite cracking,and that of BM was ferrite/martensite interface decohesion during tests.
基金National Natural Science Foundation of China (51275446)Hebei Provincial Natural Science Foundation of China (E2016203492).
文摘Mechanical properties and creep behavior of Q460E continuous casting slab were studied by means of uniaxial tensile tests on a Gleeble-3800 thermomechanical simulator from 1000 to 1100 ℃.The high-temperature creep constitutional equation was derived based on experimental data.The parameters in the equation were calculated by using the regression analysis inverse-estimation method.The experimental curves in the primary and secondary creep stages are fitted well.A three-dimensional elastic-plastic and creep finite element model was proposed in order to investigate the bulging deformation of slab and the bulging deformation at the beginning position of bending segment on the slab continuous casting machine was computed accurately.The results indicate that the maximum bulging deformation appears at the geometric center of the slab.The maximum value of the bulging deformation obtained by the elastic-plastic analysis is 1.301 ram.Consideririg the creep effect,the deformation increases to 1.827 mm which is about 1.4 times the value obtained by the elastic-plastic analysis.The calculation of buleing deformation usin2 the elastic-plastic creed model is more reliable and/iccurate.
