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焊接过程中的界面温度是研究接头组织形成变化机理的关键参量。根据线性摩擦焊接过程准稳定摩擦阶段焊件中(不包括飞边)准稳定温度场基本保持不变,所产生的热量主要被飞边带走的特点,通过理论分析,求解出了线性摩擦焊接过程准稳定摩擦阶段焊接界面的平均温度,利用半自然热电偶实际测量了TC17钛合金线性摩擦焊接时的焊接界面不同位置的温度变化。结果表明,典型参数下TC17准稳定摩擦阶段焊接界面的实测温度大约为1 228℃,焊后冷却至500℃的速度约52℃/s,准稳定摩擦阶段焊接界面中心点和边缘点的温度相差不超过10℃,界面中心点的升温速率以及降温速率均高于边缘点,测量值与理论计算值相差不超过10%。 相似文献
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基于ABAQUS/Standard模块,建立TC4线性摩擦焊接过程的二维有限元模型,采用网格重划分与映射技术来处理网格畸变问题,分析线性摩擦焊接接头温度场的演变和轴向缩短量的变化.结果表明:网格重划分与映射技术能较好地解决网格畸变带来的计算不收敛.焊接过程的前0.1 s内,焊接界面温度迅速升高至1 000 ℃以上,之后接头温度渐趋均匀,接头塑性金属开始被挤出形成飞边,轴向缩短量明显增加;摩擦停止时刻(3 s),单边轴向缩短量达到最大值,约为2.7 mm. 相似文献
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基于弹塑性有限元理论,采用三维塑性体/塑性体摩擦副模型,考虑实际焊接过程中两侧工件散热条件的差异,建立了FGH96高温合金管惯性摩擦焊过程有限元模型,计算了焊接过程中瞬态温度场和轴向应力场的分布,研究了初始转速、顶锻力和转动惯量对接头温度场和飞边形貌的影响。模拟的飞边形貌与试验所得焊件误差仅为5%,验证模型的可靠性。模拟结果表明,惯性摩擦焊过程中,摩擦界面升温迅速,峰值温度可达1 335 ℃,塑性变形主要发生在距界面4 mm的区域内,该区域轴向温度梯度较大。摩擦界面附近压应力值从中心到边缘逐渐降低,界面边缘应力状态由压应力转变为拉应力,飞边根部由于挤压变形,存在压应力集中。提高初始转速和转动惯量均能增加焊接热输入,延长摩擦时间,提升峰值温度,增加飞边挤出量;加大顶锻力可提高机械能转化成热能的效率,缩短摩擦时间,增加轴向缩短量和飞边卷曲度。
创新点: 塑性体/塑性体有限元模型能够综合考虑接触面力的相互作用,采用更符合实际的三维双塑性体模型,对FGH96高温合金环形工件惯性摩擦焊过程进行了数值模拟。 相似文献
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采用ABAQUS有限元软件,基于传热学及弹塑性力学有限元法,建立了径向摩擦焊接过程的二维轴对称、热力耦合及非耦合有限元计算模型.采用网格重划分技术模拟了径向摩擦焊接过程中焊接接头的温度场分布.结果表明,模拟出的接头飞边形貌与实际结果吻合良好.在二级摩擦阶段,摩擦界面由摩擦生成的热量与飞边形成带走的热量以及热传导散失的热量达到动态平衡,界面温度稳定在1320℃以下.在三级摩擦阶段,由于高温金属层被迅速挤出,界面温度迅速下降.通过分析金相组织,得出接头热循环过程.接头温度分布的模拟结果与实际结果吻合良好. 相似文献
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《热加工工艺》2016,(9)
基于Abacus大型有限元分析软件,对35Ni4Cr2MoA空心轴环形工件连续驱动摩擦焊温度场和变形进行了模拟,对摩擦和顶锻阶段的温度场及变形规律进行了分析,并采用热电偶分析法对连续驱动摩擦焊工件表面的热循环进行了实测。结果表明,在摩擦阶段,最高温度在圆环外侧,随焊接时间增加,接触面温度不断升高,高温区域逐渐扩大,1260℃左右时界面金属发生屈服而形成焊接飞边,界面温度处于动态平衡,稳定在1260℃附近;在顶锻阶段,随时间增加,界面温度逐渐降低,高温区域缩小,温度在径向呈均匀分布,焊接飞边和轴向缩量均较摩擦阶段增大;在整个焊接过程中,界面各点温度先快速升高,后保持稳定,最后逐渐下降。热循环模拟结果与实测结果吻合较好,所建立的摩擦焊数值模型是可靠的。 相似文献
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为了研究焊接参数对摩擦塞焊焊接区域温度场的影响,建立了摩擦塞焊焊接的产热模型,并进行摩擦塞焊焊接工艺试验。通过理论分析得出焊接过程中的产热量与焊接参数的关系,试验对理论分析结果进行验证,并深入探讨焊接参数对焊接区域温度场的影响。结果表明:焊接进给速度的改变影响焊接过程中的焊接压力大小,从而影响摩擦塞焊焊接初始阶段的产热,进而影响焊接区域温度场;较高的焊接转速提高摩擦界面材料的升温速率,提高材料塑化,避免焊接缺陷;应选择适当的焊接摩擦时间,尽量匹配较高的转速以缩短焊接摩擦时间。 相似文献
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介绍了半自然热电偶法测温原理,并对所选用的半自然热电偶进行了标定,线性度良好.采用自主研发的径向摩擦焊机进行径向摩擦焊接工艺试验.以摩擦焊接过程特点为依据,选择恰当的测温仪和热电偶.采用半自然热电偶对径向摩擦焊接过程中摩擦界面中心点温度进行了全过程测量;采用K型热电偶对管体侧距界面中线点纵向距离为1,2,3,6 mm的位置进行了温度测量.摩擦界面升温迅速,存在明显的温度恒定即稳定摩擦阶段.随着距摩擦界面纵向距离的增加,升温速率逐渐降低,升温时间逐渐增长.焊接过程结束后,温度逐渐趋于均匀化. 相似文献
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Deng-Kui Zhang Guo-Qing Wang Ai-Ping Wu Ji-Guo Shan Yue Zhao Tian-Yi Zhao Dan-Yang Meng Jian-Ling Song Zhong-Ping Zhang 《金属学报(英文版)》2019,32(6):684-694
In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone. 相似文献
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After nearly two years'tense construction the first phase of industrialized base of Shenyang Research Institute of Foundry 《中国铸造》2008,5(1):63-64
After nearly two years' tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry (SRIF), located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation. 相似文献
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目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。 相似文献
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Z. Sun S.L. Zheng Y. Zhang 《金属学报(英文版)》2007,20(3):187-192
Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process. 相似文献
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R. González-Martínez 《金属学报(英文版)》2007,20(4):235-240
The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke. 相似文献
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R.Z. Wu Z.K. Qu B.D. Sun D. Shu J. Wang 《金属学报(英文版)》2007,20(3):193-198
The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results. 相似文献
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B.W. Zhang B.W. Li 《金属学报(英文版)》2007,20(2):129-138
On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes' collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process. 相似文献
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Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems. 相似文献
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An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models. 相似文献
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Chen Wang Bei-Bei Wang Dong Wang Peng Xue Quan-Zhao Wang Bo-Lv Xiao Li-Qing Chen Zong-Yi Ma 《金属学报(英文版)》2019,32(6):677-683
A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency. 相似文献