共查询到17条相似文献,搜索用时 109 毫秒
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为了优化22MnB5超高强度钢的热成形工艺并提高其综合性能,开展了淬火温度对22MnB5超高强度钢组织及性能的影响研究。分别对22MnB5超高强度钢加热至830、860、890、920、950℃温度后水淬,采用金相显微镜分析其组织状态,并通过拉伸试验、撕裂试验评价其强度及断裂韧性,采用扫描电子显微镜对断口形貌进行分析研究。结果表明,当淬火温度低于920℃时,随着温度升高,组织马氏体含量升高,材料强度不断上升,塑性较为优异。综合考量,在920℃下保温淬火,能够使22MnB5获得最佳的使用性能。 相似文献
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通过热膨胀试验、显微组织分析和硬度测试,分析了冷却速率和Ti元素对两种22MnB5热成形试验钢相变温度、显微组织、析出相以及硬度等的影响,并绘制了CCT曲线。结果表明,当冷却速率低于5 ℃/s时,试验钢的显微组织主要为铁素体和珠光体;冷却速率达到5 ℃/s后开始形成贝氏体;冷却速率达到30 ℃/s时,获得单一马氏体组织。Ti微合金化可降低Ms点,并通过析出Ti(C, N) 相细化奥氏体晶粒,从而获得细小的马氏体板条,产生的析出强化和细晶强化效应提高了试验钢的强度。 相似文献
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热冲压成形22MnB5钢板的组织和性能 总被引:6,自引:0,他引:6
采用扫描及透射电镜观察和力学性能实验研究了22MnB5钢板热冲压成形件的组织形貌和力学性能。结果表明,加热温度930℃,保温4.5 min,初始成形温度850℃,冲压速度75 mm/s条件下,22MnB5钢板热冲压成形完成完全马氏体转变,得到均匀板条马氏体组织,组织内产生高密度位错,强度大幅提升,抗拉强度达到1550 MPa。形变有助于动态再结晶并获得更为细小的马氏体组织,促进细晶强化。硼元素在晶界发生偏聚,延长奥氏体转变孕育期,提高了22MnB5钢的淬透性,同时引起点阵畸变,促进相变强化。 相似文献
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为改善热成形钢的强塑性,利用DIL805A热膨胀仪将22MnB5钢加热至830~920 ℃、保温2~20 min奥氏体化后淬火,在光学显微镜下观察了原奥氏体晶粒。根据晶粒长大特点,对22MnB5钢板进行淬火、回火处理后,通过单轴拉伸试验检测了其拉伸性能。结果表明,该22MnB5钢在830~890 ℃、有效保温10 min以内,可以获得均匀细小的奥氏体晶粒;有效保温时间延长至20 min时,860 ℃奥氏体化便开始出现混晶。与传统热成形相比,通过控制淬火晶粒显著改善了22MnB5钢的强塑性,强塑积由9.0~11.0 GPa·%提高至13.0~14.5 GPa·%。 相似文献
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热冲压成形钢22MnB5主要用于汽车防撞部件。热冲压成形钢显微组织的不同对产品的力学性能和产品的最终使用性能有着极其重要的影响。为了在控轧控冷后获得稳定的组织和性能,并为热轧生产工序制定工艺参数提供充分的理论依据,文章介绍了采用膨胀测量法并结合金相测定22MnB5钢的动态连续冷却转变曲线(CCT曲线)及显微组织的演变。实验结果表明:在较低冷却速度下显微组织由铁素体、珠光体和贝氏体组成;随着冷却速度的不断增加,铁素体和珠光体的含量逐渐减少直至为零,马氏体和贝氏体的含量则逐渐增多;当冷却速度≥10℃·s-1时,显微组织主要为马氏体和贝氏体。 相似文献
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以20Cr2Ni4A和钒微合金化的齿轮钢为对象,研究了其在不同淬火方式下的变形行为,并分析了渗碳热处理过程中渗碳深度与组织演变规律。结果表明,随着淬火方式从空冷到水冷再到油冷,齿轮用钢的平均变形率逐渐上升。油淬热处理后齿轮钢的有效硬化层深度大于空淬热处理。经过油淬处理后,齿轮钢组织中含有细小的马氏体组织,使得其显微硬度高于具有贝氏体+马氏体组织的空淬处理齿轮钢。 相似文献
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Third-generation advanced automotive medium-Mn steel, which can replace 22MnB5 steel, was newly developed to improve the lightweight and crashworthiness of automobile. Studies on the formability and simulation method of medium-Mn steel have just been initiated. In this study, finite element simulation models of square-cup deep drawing were established based on various material property experiments and validated by experiments. The effects of blank holder force (BHF), fillet radii of tools (die and punch) on the maximum drawing depth (MDD), thickness distribution of the formed products, and the microstructure before and after forming were investigated and compared with those on 22MnB5 steel. Results show that the MDD of the two steels decreased with increased BHF but increased with the fillet radius of punch; however, the fillet radius of die showed no significant effect on the MDD for both steels. Compared with hot-formed 22MnB5 steel, the martensitic transformation of the hot-formed medium-Mn steel is rarely influenced by the process parameters; thus, it holds the complete, fine-grained, and uniform martensitic microstructure. Moreover, the medium-Mn has better formability, lower initial blank temperature, and smaller impact of BHF and fillet radius of tools on the hot-formed product. Thus, a theoretical basis for the replacement of 22MnB5 steel by medium-Mn steel in hot forming process is provided. 相似文献
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Hongzhou Li Xin Wu Guangyao Li 《Journal of Materials Engineering and Performance》2013,22(8):2131-2140
Hot stamping of ultra-high strength steels possesses many superior characteristics over conventional room temperature forming process and is fairly attractive in improving strength and reducing weight of vehicle body product. However, the mechanical and failure behavior of hot stamping boron steel 22MnB5 are both strongly affected by strain hardening, temperature, strain rate, and microstructure. In this paper, the material yield and flow behavior of 22MnB5 within the temperature and strain rate range of hot stamping are described by an advanced anisotropic yield criterion combined with two different hardening laws. The elevated temperature forming limit diagram (ET-FLD) is constructed using the M-K theoretical analysis. The developed model was validated by comparing our predicted result with experimental data in the literature under isothermal conditions. Based on the verified model, the influence of temperature and strain rate on the forming limit curve for 22MnB5 steel under equilibrium isothermal condition are discussed. Furthermore, the transient forming limit diagram is developed by performing a transient forming process simulation under non-isothermal transient condition. 相似文献
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高强度钢热成形时,由于加热与淬火的交互作用形成多层复合微观结构。对22MnB5钢热成形进行实验研究表明,多层复合微观结构可使材料的硬度、强度由里到表依次降低,延展性依次增加,其平缓的冲击力水平及材料的逐层失效,能够使结构保持较高的吸能能力;具有变形抗力小、塑性好以及成形极限高的特点,而且成形零件的精度和强度较高。多层复合微观结构综合了各单相材料的优秀性能,适用于承受冲击吸能的构件。 相似文献
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利用Gleeble-3500热模拟试验机,在温度为700℃~950℃、应变速率为0.01/s~0.4/s的条件下,对高强度硼钢22MnB5的热变形行为进行研究。结果表明,随着变形温度的升高,硼钢的延伸率升高,变形抗力降低;随着应变速率的提高,硼钢22MnB5的变形抗力和延伸率增大。根据高温拉伸实验得出的数据,构建硼钢22MnB5的稳态流变应力模型和热变形方程,并将试验结果和构建的本构方程输入ABAQUS软件进行U型件热弯曲成形的回弹模拟,数值模拟结果与实验结果吻合较好,验证了模型的可靠性和正确性,为成形所需的最大载荷及设备选择提供依据。 相似文献
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Press hardened 22MnB5 steels are steady broadening their applications in vehicles since they allow to meet the increasing demands for weight reduction and safety standards. Press hardened parts have been typically applied as structural reinforcements where high rigidity and crash resistance are required. However, the need for further weight reductions in vehicles leads to potential applications in chassis areas, where parts must face up to cyclic loads. The fatigue behaviour of the press hardened 22MnB5 steel and the effect that post-forming processes (such as trimming or punching that usually follows press hardening) on the fatigue behaviour is scarcely known. Thus, the aim of this work is to analyse the fatigue behaviour of 22MnB5 press hardened steels cut using different strategies. The fatigue limit has been obtained in tensile samples of 22MnB5 with an Al–Si coating. Samples were cut by laser and shearing with two different clearance values. Results are compared to those obtained with a high drawing quality mild steel and a dual phase steel with a tensile strength of 1000 MPa, DP1000. It is shown that the fatigue behaviour of press hardened 22MnB5 steels and DP1000 is governed by the defects introduced in cut edges, while the behaviour of the mild steel is almost independent of the cut edge quality. This finding indicates that high strength steels are markedly sensitive to pre-existent defects, such as burr, cracks at the cut edge or surface cracks, and they can be considered as low damage tolerant steels. On the contrary, mild steels are highly damage tolerant, i.e. the fatigue life is mainly independent of the initial defect size. In press hardened 22MnB5, even when cut edges have a high surface quality, the fatigue limit is still limited by the presence of cracks in the brittle Al–Si coating. Crack propagation due to the low damage tolerance capacity of the press hardened steel has been successfully rationalized through a fracture mechanics approach. Thus, if coated press hardened 22MnB5 steels are to be applied in vehicle components subjected to cyclic loads, they must be designed following fracture mechanics concepts to state the safe loading conditions for adequate fatigue resistance. 相似文献
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针对22MnB5钢板在热冲压成形过程中易被氧化且氧化层易脱落,不仅影响工件的美观和表面质量,也会对模具造成一定磨损的问题,需研究热冲压成形钢的高温氧化行为。采用模拟试验对22MnB5和22MnMoB5钢板的高温氧化行为进行了分析。结果发现,除含Mo和不含Mo外,两种钢板在其他元素含量及工艺参数相同条件下,22MnMoB5钢板的氧化程度明显低于22MnB5钢板,这主要是因为Mo能够在基体表面富集,阻碍易被氧化元素向氧化层扩散;同时,促进Cr氧化物在基体和外氧化层间富集形成保护层,从而抑制基体被进一步氧化。 相似文献