共查询到20条相似文献,搜索用时 206 毫秒
1.
在Gleeble-1500热模拟试验机上对Ti-Al-Zr-Sn—Mo—Si—Y合金进行了热压缩试验,采用动态材料模型建立的加工图研究了在变形温度800~1100℃,变形速率在0.002~10s^-1范围内的热变形行为。结果表明:该合金的功率耗散效率的峰值区为875~925℃,应变速率为0.001-0.002s^-1,峰值效率为85%。在温度为900~1000℃,应变速率为0.1~3s^-1的区域和850~950℃,应变速率为0.001-0.01s^-1的环形区域内进行等温压缩,Ti-Al-Zr-Sn-Mo-Si—Y合金发生了动态再结晶,其功率耗散效率为40%~55%。在800~925℃,应变速率为0.03~10s^-1和温度为860~930℃,应变速率为0.003~0.03s^-1区域内易产生流变失稳现象。 相似文献
2.
在热模拟试验机上进行了高温压缩试验,研究了GH4698高温合金在不同变形温度(950~1200℃)和应变速率(0. 01~10 s^-1)条件下的流变行为,建立了基于流变曲线的本构方程及以动态材料模型为基础的热加工图。借助扫描电镜和背散射电子衍射技术(EBSD)对变形后试样进行组织分析。结果表明:GH4698高温合金流变应力随着变形温度的降低和应变速率的加快而逐渐增加。在变形温度为1000~1200℃、应变速率为0. 01~0. 05 s^-1的热变形条件下,GH4698高温合金具有较佳的热加工行为。在高、低功率耗散率区域中,随着功率耗散率值的增加,动态再结晶百分数均会增加,再结晶平均晶粒尺寸增大,大角度晶界分数增加。 相似文献
3.
应用加工图理论研究Ti2AlNb基合金的高温变形特性 总被引:3,自引:1,他引:2
基于动态材料模型(DMM),建立了Ti2AlNb基合金(Ti-22Al-25Nb)在温度94012-1060℃,应变速率0.001s^-1-10s^-1范围内的加工图,并利用该图分析了合金的高温变形特性。结果发现:在温度94012~97012,应变速率0.4s^-1~10s^-1和温度970℃—1060℃,应变速率1s^-1~10s^-1范围为流动失稳区,前者范围内主要发生绝热剪切变形和45°角剪切开裂,功率耗散率达到最小值;后者区域内以局部塑性流动和纵向开裂为主,功率耗散率小于33%。热加工图的其余部分为塑性加工的“安全区”,主要发生再结晶。在温度94012~970℃,应变速率0.001s^-1-0.4s^-1范围,以α2/O相板条球化为主;在温度970℃~1030℃,应变速率0.001s^-1~1S^-1范围,功率耗散率为35%-45%,呈现连续再结晶特征。在温度1030℃~1060℃。麻蛮谏率0.001s^-1-0.1s^-1范围。功率耗散率为45%~66%。达最大值,发生连续再结晶晶粒长大。 相似文献
4.
GH742合金热变形行为与微观组织演化 总被引:5,自引:0,他引:5
在MTS热模拟实验机上采用等温压缩实验的方法研究了GH742合金热塑性变形行为,获得了合金在温度为950—1150℃、应变速率为0.001—1s^-1的热加工变形条件范围内的流变应力数据,并对合金变形过程中的组织演变过程进行了分析.结果表明,当合金在1075℃以上的单相区内变形时具有低的流变应力,合金的表观激活能接近晶界扩散激活能,变形行为受再结晶晶界迁移过程的控制,易于获得充分动态再结晶组织.在两相区内,GH742合金具有高的表观激活能,随着变形温度的下降和应变速率的增大,流变应力大幅度升高,同时动态再结晶过程受到抑制.在单相区与两相区交界温度范围内,流变应力出现台阶式突变,同时表观激活能大幅度升高,由于应变诱导析出γ’相抑制了再结晶晶界的迁移,再结晶晶粒直径随变形量的增加而大幅度减小,从而使微观组织得到有效的细化. 相似文献
5.
GH4169合金热加工过程中的显微组织演化数学模型 总被引:6,自引:0,他引:6
采用Thermecmastor—Z型热加工模拟试验机对GH4169合金热态变形过程中(温度范围为960~1020℃,应变速率范围为10^-2~50s^-1,等效应变范围为0.357~0.916和变形后高温滞留阶段内(滞留时间为0~15s)的显徽组织演化过程进行了实验研究,定量地测定了试样内的动态再结晶晶粒尺寸和再结晶体积分数。根据实验结果,指出了GH41.69合金热加工过程中的主要显微组织演化过程是动态和亚动态再结晶,确定了峰值应力和峰值应变与锻造热力参数间的关系,建立了动态再结晶和亚动态再结晶过程的运动学方程和晶粒尺寸演化模型,从而为预测和控制GH4169合金锻件的组织性能提供了依据。 相似文献
6.
我国钛废料回收利用现状 总被引:8,自引:2,他引:6
黄永光 《稀有金属材料与工程》2007,24(1):1-3
采用热模拟压缩试验研究了Ti-40阻燃钛合金在温度900℃~1100℃、应变速率0.01s^-1~10s^-1范围内的高温变形特性,发现合金的流动应力-应变曲线具订应力峰和流变软化特征,在高温、高应变速率下,出现小连续屈服现象。根据动态材料模型(DMM)建立的Ti-40合金加工图大致可以分为5个区域:(1)在温度900℃-950℃,应变速率大于1s。时,易发生45°角剪切开裂,出现明显的剪切变形带,功率耗散率达最小值。(2)在温度1000℃~1100℃、应变速率人于1s^-1时,易出现“豆腐渣”式和纵向开裂,大变形时出现局部塑性流动。这2个区域为流动失稳区,在制定热加工工艺时应尽量避免。(3)在高温(≥1050℃)、低应变速率区(≤0.1s^-1),功率耗散率为46%-76%,达到盛大值,呈现连续冉结晶的特征。(4)在900℃-950℃、应变速率0.01s^-1~0.1s^-1区域内主要发生动态回复,功率耗散率为22%-32%。(5)在温度950℃~1050℃、应变速率0.1s^-1~1s^-1范用为再结晶区域,功率耗散率为36%~50%。结果表明,加工图是控制材料组织演变和优化工艺的一种有效手段。 相似文献
7.
在Gleeble热模拟机上对GH625合金进行了等温热压缩实验,获得了不同变形条件下该合金的真应力真应变曲线。利用DMM模型构建了GH625合金在不同应变量下的加工图,通过对加工图的分析,可以得到:GH625合金加工图中存在一个功率耗散效率较高的区域,其对应的变形温度为1100~1200℃,应变速率为0.01~1.0s-1,在该变形区域内,合金发生了完全动态再结晶。当功率耗散效率为0.4~0.45时,动态再结晶晶粒细小均匀;在峰值效率0.47时,动态再结晶晶粒出现明显的长大趋势;在低温高应变速率下存在一个较小的流变失稳区,该区域内的动态再结晶晶粒沿绝热剪切带分布。实际生产中工艺参数的制定应尽量选择在完全动态再结晶区内加工,避免在失稳区加工成型。基于GH625合金加工图及微观显微组织分析可得该合金的适宜加工区域为:ε=0.01~1.0s-1,T=1100~1200℃。 相似文献
8.
通过热模拟压缩实验研究了GH2907合金在变形温度为950~1100℃、应变速率为0.01~10s-1、变形量为60%条件下的热变形行为,流变应力随着变形温度的升高或应变速率的降低而显著降低;根据Arrhenius方程和Zener-Hollomon参数,计算了热变形激活能Q,建立了GH2907合金的热变形本构方程;根据动态材料模型,确定了GH2907合金在不同应变下的功率耗散图,功率耗散效率η较高的区域位于温度为1050~1100℃,应变速率为0.01~0.03s-1范围,在该变形区域内组织发生了明显的动态再结晶现象;基于Preased失稳判据,绘制了GH2907合金在不同应变下的热加工图,流变失稳区位于高温高应变速率区域,即温度为970~1100℃,应变速率为0.6~10s-1范围,在该变形区域内动态再结晶晶粒沿着绝热剪切带和局部流动分布。根据GH2907合金热加工图及微观组织分析得到适宜的加工区域是温度为1050~1100℃,应变速率为0.01~0.03s-1范围。 相似文献
9.
研究了镍基高温合金GH4700变形温度和应变速率对热变形行为的影响,建立了该合金的热变形本构方程和热加工图。结果表明:在变形温度1120~1210℃、应变速率0.01~20 s-1条件下,该合金的热变形流变曲线呈现出典型的动态再结晶型特征,存在稳态的流变应力,且随着变形温度的升高和应变速率降低,动态再结晶过程更充分;GH4700合金的热变形激活能为326.3165 kJ/mol;该合金在温度为1180~1210℃,应变速率为10~20 s-1的热压缩变形条件下,能量耗散率η值较高,大于0.30,显微组织发生完全动态再结晶,获得的组织晶粒细小且分布均匀。 相似文献
10.
热加工工艺对GH4586合金微观组织的影响 总被引:17,自引:1,他引:16
在MTS热模拟实验机上采用热压缩实验的方法研究了在温度为950—1150℃、应变速率为0.001—1s^-1。的实验条件范围内,GH4586合金高温塑性变形过程中变形温度、应变速率及变形量等工艺参数对流变应力和微观组织的影响.结果表明,流变应力随着变形温度的降低和应变速率的提高而迅速增大.提高变形温度能够有效的促进动态再结晶过程,在1100℃以上变形时,在30%的工程应变量下即能够获得完全再结晶的锻态组织;当变形温度低于1050℃时,工程应变超过60%仍未观察到动态再结晶.在变形量与热处理制度一定的条件下,材料热处理后的晶粒度随变形温度的升高而增大.有效控制材料的变形温度是获得良好热加工塑性、降低变形抗力和获得均匀微观组织的关键措施. 相似文献
11.
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
12.
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
13.
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
14.
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
15.
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
16.
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
17.
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
18.
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
19.
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
20.
A CUMULATIVE FATIGUE DAMAGE RULE UNDER THE ALTERNATIVE OF CORROSION OR CYCLIC LOADING 总被引:2,自引:0,他引:2
W.X. Yao 《金属学报(英文版)》2007,20(1):65-71
Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted. 相似文献