本文選題：BR1500HS鋼板 + 淬火��； 參考：《重慶理工大學》2017年碩士論文

【摘要】：在汽車制造業(yè)領(lǐng)域中,制件輕量化、高碰撞性能和安全性保障理念正不斷推進,一種可淬火硼鋼板熱沖壓成形新工藝已脫穎而出,該工藝實現(xiàn)了汽車輕量化,突破了超高強鋼板傳統(tǒng)冷沖壓成形難的問題。在熱沖壓成形過程中,制件的高強度、高硬度性能主要取決于成形制件的最終馬氏體含量。而熱成形過程中制件發(fā)生相變主要集中于板料高溫沖壓成形后的淬火熱處理工藝。在高強度鋼板熱成形生產(chǎn)中,溫度場不僅影響淬火后制件的最終馬氏體相變,同時由于溫差與組織轉(zhuǎn)變還會使應力場發(fā)生變化,制件最終性能是其熱-力-相三場綜合效果的反映。所以,對易變形、易產(chǎn)生沖壓缺陷的壁薄結(jié)構(gòu)復雜的大多汽車制件熱沖壓成形而言,研究超高強度剛淬火過程熱-力-相變耦合規(guī)律具有實際意義!本文以熱沖壓成形鋼板BR1500HS為研究對象,在熱成形理論以及有限元求解方法分析基礎(chǔ)上,建立了淬火熱-力-相耦合數(shù)學模型和有限元求解模型;結(jié)合研究目的,專門針對BR1500HS熱沖壓成形的淬火過程進行了平板模具結(jié)構(gòu)設(shè)計。對BR1500HS熱成形鋼板室溫組織成分及相關(guān)性能進行物理試驗探究與分析,同時對其進行不同加熱溫度下、不同冷卻時間內(nèi)的直接水淬實驗。對水淬后的板料金相分析,研究加熱溫度與冷卻速度對板料組織的影響規(guī)律。同時利用Deform對該板料在相同實驗參數(shù)下的直接水淬熱處理進行數(shù)值模擬探究,將馬氏體相變模擬結(jié)果與水淬實驗結(jié)果對比分析,論證了Deform對BR1500HS直接水淬相變模擬方法的正確性。其次,利用Deform對超高強度鋼板熱沖壓成形過程中的淬火熱-力-相耦合變化規(guī)律及淬火應力影響參數(shù)優(yōu)化展開數(shù)值模擬研究與實驗驗證。先從直接水淬中相對簡單的熱-力-相變出發(fā),對BR1500HS鋼板直接水淬模擬進行不同加熱溫度下直接水淬過程模擬分析,找出溫度場對相變場、相變場對應力場影響規(guī)律。再建立板料在平板模具中淬火的簡化有限元模型,進行不同板料初始溫度、不同模具初始溫度以及不同冷卻通道與模具之間傳熱系數(shù)下的數(shù)值模擬。得到了三種影響參數(shù)下的板料在模具中淬火的熱-力-相變耦合規(guī)律。最后對模具中的淬火應力影響參數(shù)進行了優(yōu)化分析,找出了既能保證成形制件最終高強度性能同時又具有低應力的最佳淬火工藝參數(shù)。最后通過平板模具淬火的實驗驗證了模擬得到的研究結(jié)果。
[Abstract]:In the field of automobile manufacturing, the concept of lightweight parts, high impact performance and safety guarantee is being promoted, and a new hot stamping process for quenched boron steel sheet has emerged, which has realized the lightweight of automobile. It breaks through the problem of traditional cold stamping forming of ultra high strength steel plate. In the process of hot stamping, the high strength and high hardness of the parts mainly depend on the final martensite content of the forming parts. In hot forming process, phase transformation mainly focuses on the quenching heat treatment process after high temperature stamping of sheet metal. In the hot forming production of high strength steel plate, temperature field not only affects the final martensite transformation of quenched parts, but also changes the stress field due to temperature difference and microstructure transformation. The final performance of the workpiece is the reflection of its hot-force-phase three-field comprehensive effect. Therefore, it is of practical significance to study the thermo-force-phase transformation coupling law of ultra-high strength rigid quenching process for the hot stamping forming of most automobile parts with complex wall and thin structure which is easy to deform and produce stamping defects. In this paper, based on the hot forming theory and finite element method analysis, a heat force-phase coupled mathematical model and a finite element solution model for hot stamping steel BR1500HS are established. The structure design of plate die is carried out specially for the quenching process of BR1500HS hot stamping forming. The microstructure and properties of BR1500HS hot-formed steel sheet at room temperature were investigated and analyzed by physical experiments. At the same time, the direct water quenching experiments were carried out at different heating temperature and different cooling time. The effect of heating temperature and cooling rate on the microstructure of sheet metal was studied by means of metallographic analysis. At the same time, the deform is used to simulate the direct water quenching heat treatment of the plate under the same experimental parameters. The results of martensite transformation simulation and water quenching experiment are compared and analyzed, and the correctness of the deform method for direct water quenching phase transformation simulation of BR1500HS is demonstrated. Secondly, the numerical simulation and experimental verification are carried out on the variation law of quenching heat-force-phase coupling and the optimization of quenching stress effect parameters during hot stamping process of ultra high strength steel plate by deform. Starting from the relatively simple thermo-force-phase transformation in direct water quenching, the direct water quenching process of BR1500HS steel plate was simulated and analyzed at different heating temperatures, and the effect of temperature field on phase transition field and the corresponding force field was found out. Then a simplified finite element model of sheet metal quenching in flat die was established. The numerical simulation was carried out under different initial temperature of sheet metal, initial temperature of die and heat transfer coefficient between different cooling channel and die. The thermo-force-phase transformation coupling law of three kinds of sheet metal quenched in die under three kinds of influence parameters has been obtained. Finally, the influence parameters of quenching stress in die are optimized, and the best quenching process parameters which can guarantee the final high strength and low stress of the forming parts are found out. Finally, the simulation results are verified by the plate die quenching experiment.
【學位授予單位】：重慶理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG306

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