【導讀】一個大型溫度場用有限元法研究和9號試驗鋼在實驗室中被設計。微觀結構和硬度調(diào)查時用在空氣中冷卻和控制冷卻速度的類似的模擬冷卻。硬度之間波動在兩種冷卻條件下。米×800毫米×3200毫米上均勻分布。耐磨，高硬度，耐腐蝕，韌性，拋光性，纖維化性質(zhì)，可焊性，可加工性。長久以來一直被廣泛應用著，因為它們的良好的綜合性能。P20系列通過調(diào)質(zhì)的形。式從鋼鐵廠的模具生產(chǎn)商生產(chǎn)出來，模具已加工后不需要進行進一步熱處理。常被稱為調(diào)質(zhì)預硬塑料模具鋼。鋼，同時減少生產(chǎn)周期和耗能。它的新優(yōu)勢被用于各項測試中。磨損測定中使用了精度為。這些估計的冷卻速率提供了參考依據(jù)為選擇合適的淬透性預硬鋼。由于潛熱是沒有考慮到有限元模擬，體淬透性密切相關[7]。稱為貝氏體淬透性。高溫多邊形鐵素體轉(zhuǎn)化效率而對貝氏體相變的影響不大。%到%之間應該考慮增加其他合金元素以延緩過冷奧氏體的轉(zhuǎn)變。構無論是在核心和表面上看，并沒有出現(xiàn)大規(guī)模的鐵氧體，如圖3所示。

　　

【正文】 have little influence on the bainite transformation. Especially , the“ ” design in the low carbon steel can obtain fully bainitic structures over a wide range cooling rate[8 ] . The molybdenum content is within % % considering the addition of other alloying elements having a similar action to retard the overcooling austenite and chromium are also added to increase the hardenability , as they can give maximum depression of Bs temperature and minimum depression of Ms temperature , which is good for the has been chosen to cont rol austenite grain growth , and its content is %. 3 Factory Trial Production of NQP Steel Based on the steel , the NQP steel was produced after fing. It s size was 460 mm 800 mm 3200 mm. The hardness was measured every 20 mm along the directions of 460 mm and 800 mm separately , and it fluctuated between HRC 37 and microstructures were bainite both in the core and surface , and no massive ferrite appeared() Fig 3 Microstructures of NOP steel 4 Conclusions The cooling rates at core and surface of a block are estimated by FEM simulation and physical simulation in the laboratory , which provides the data to select the suitable hardenability for the NQP steel. The steel with good bainitic hardenability is selected from the 9 test steels prepared in t he laboratory , whose chemical position is . It has better machineability pared with C45 steel [9]. The NQP steel is produced successfully in the factory based on the steel produced in the laboratory. It s microstructure is bainite and its hardness fluctuates between HRC 37 and 40 in the 460 mm 800 mm 3200 mm mould. References : [ 1 ] CHEN Zaizhi , MA Dangshen. Plastic Mould Steel Application Manual [M] . Beijing : The Chemistry Industry Press ,2021 (in Chinese) . [ 2 ] LUO Yi , WU Xiaochun. Research Progress of the Work on Prehardened Plastic Mould Steel [J ] . Heat Treatment of Metals , 2021 , 32 (12) : 22 (in Chinese) . [ 3 ] SONG Dongli , GU Jianfeng , ZHANG Weimin , et al . Numerical Simulation on Temperature and Microst ructure DuringQuenching Process for LargeSized AISI P20 Steel Blocks Used as Plastic Die [J ] . Transactions of Materials and Heat Treatment , 2021 , 25 (5) : 740. [ 4 ] WU Xiaochun , ZHANGJie , CUI Kun. The Microst ructure and Mechanical Properties of Unquenched and Untempered Die Steel for Plastic Mould [J ] . Journal of Huazhong University of Science and Technology , 1995 , 23 (12) : 1 (in Chinese) [ 5 ] J IANG Laizhu , WANGJianghui . Development of a NonQuenched NonTempered Bainitic Steel for Plastic Mould :Continuous Cooling Transformation Behavior [A] . J eglit sch F , Ebner R , Leitner H , eds. Proceedings of the 5 th International Conference on Tooling [C] . Leoben : 1999. 685. [ 6 ] SONG Dongli , GU Jianfeng , PAN Jiansheng , et al . Design of Quenching Process for LargeSized AISI P20 Steel Block Used as Plastic Die [J ] . Journal of Materials Science and Technology , 2021 , 22 (1) : 139. [ 7 ] LIU Zhuang , WU Zhaoji , WU Jingzhi , et al . Numerical Simulation of Heat Treatment [M] . Beijing : Science Press ,1996 (in Chinese) . [ 8 ] Pickering F B. Physical Metallurgy and t he Design of Steels[M] . London : Applied Science Publishers LTD , 1978. [ 9 ] Vetter P , Hippenstiel F. A New PreHardened Plastic Mould Steel as a Tailored Solution for Large Moulds [A] . Rosso M ,Actis Grande M , Ugues D , eds. Proceedings of t he 7t h International Conference on Tooling [ C] . Torino : 2021. 317.