共查询到20条相似文献,搜索用时 78 毫秒
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《材料热处理学报》2017,(3)
通过显微组织分析、断口分析、有限元模拟分析、疲劳裂纹扩展速率测试和应力腐蚀试验研究制造因素、结构因素和材料强塑性对抽油杆腐蚀疲劳抗力的影响。结果表明,制造环节易导致抽油杆钢表面氧化脱碳以及镦粗段偏斜从而对抽油杆腐蚀疲劳寿命产生不利影响;抽油杆结构导致抽油杆镦粗段及前沿存在应力集中,且最大应力总是出现在杆体表面。表面氧化脱碳与应力集中的耦合作用使得抽油杆在腐蚀环境中快速诱发疲劳裂纹;在腐蚀环境中,提高抽油杆强度会导致疲劳裂纹扩展速率的增加,并且高强度抽油杆的腐蚀疲劳裂纹扩展曲线上会出现应力腐蚀平台;降低抽油杆的强度,提高抽油杆的韧性可以有效降低抽油杆在H_2S环境里的应力腐蚀开裂敏感性。 相似文献
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对航空发动机涡轮盘服役后产生的榫槽裂纹进行失效分析,并通过喷丸强化改进。通过断口分析对故障涡轮盘进行失效原因确定;针对该种材料(GH2132)开展喷丸强化工艺试验,并在表面残余压应力、高温疲劳寿命及断口和显微组织等方面进行分析。结果表明故障涡轮盘属于疲劳断裂,疲劳裂纹并不是材料本身原因引起的,而是与应力集中和加工过程有关;实施表面喷丸强化工艺后,形成很高的表面残余压应力,高温疲劳寿命较喷丸前提高1~2个数量级,断口分析显示为单一疲劳源,显微组织显示晶粒明显细化。即涡轮盘榫槽裂纹为表面加工缺陷引起的疲劳断裂;喷丸强化则能够提高其高温疲劳强度极限,而喷丸强化层内的残余压应力和精细的亚晶粒是提高疲劳强度的主要因素。 相似文献
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张辉 《特种铸造及有色合金》2019,(9)
某活塞气动执行机构失效的原因为铝合金活塞板断裂。采用宏观观察、金相组织观察、化学成分分析及扫描电镜分析等方法,对出现断裂的活塞板进行了失效原因分析。结果表明,活塞板的开裂为疲劳破坏,密封槽底部存在严重的应力集中,且由于使用高强的7A19铝合金,在交变载荷作用下最终导致活塞板断裂。综合评定后,选用5083铝合金,通过适当工艺改进,使活塞板寿命明显提高。 相似文献
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分析了某种车型焊接7T驱动后桥总成垂直弯曲疲劳断裂的原因,详细介绍了如何降低车桥的应力集中,提高焊缝接头疲劳寿命,杜绝疲劳断裂的产生,提高其疲劳寿命.就某种车型焊接驱动7T后桥总成垂直弯曲疲劳断裂的实例进行了分析. 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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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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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
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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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X.B. Li Y.Q. Xie Y.Z. Nie H.J. Peng H.J. Tao F.X. Yu 《金属学报(英文版)》2007,20(1):27-34
On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K. 相似文献