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1.
以常用轴承材料42CrMo钢为研究对象,采用Gleeble-3500热力试验模拟机,通过高温拉伸试验,分析了铸造42CrMo钢的高温拉伸力学性能。建立了抗拉强度模型,并验证了模型的准确性;计算了硬化系数和应变速率敏感系数。结果表明,铸造42CrMo钢的硬化系数随加热温度升高而减小,随应变速率增大而增大。应变速率敏感系数则随温度升高而增大,随应变速率增加而减小。  相似文献   

2.
用改进的WOL型试样研究了Cr-Mo-V系高强度钢在3.5%NaCl水溶液中的应力腐蚀断裂行为,并与常用的42CrMo钢进行了对比。结果表明,回火温度对实验钢的应力腐蚀开裂行为有显著影响。当回火温度较低时,Cr-Mo-V钢的KISCC较低,且随回火温度的升高缓慢提高,断裂方式主要为沿晶断裂;当回火温度超过约873K后,KISCC显著提高,断口中穿晶断裂所占的比例明显增加,断裂方式逐渐转变为穿晶型断裂为主。在相同的强度水平下,Cr-Mo-V钢的KISCC高于42CrMo钢,且在低强度水平下二者差别较大。对42CrMo钢,KISCC随屈服强度升高呈指数下降。但对Cr-Mo—v钢,则并非如此,即在强度保持不变(Rp0.2=1410—1440MPa)的条件下,KISCC随回火温度升高而明显提高。Cr-Mo—V钢和42CrMo钢的KISCC均随回火温度的升高呈指数关系增加。  相似文献   

3.
采用高温高压动态循环腐蚀试验,研究了35CrMo钢、42CrMo钢、3Cr13不锈钢、45号钢、304L不锈钢、316L不锈钢等6种材料在温度为30~65℃,压力为2 MPa,液相介质流速为1.2m/s的CO_2驱采出井环境中的腐蚀规律。采用扫描电子显微镜(SEM)和附带能谱仪(EDS)对腐蚀产物的形貌和成分进行了表征。结果表明:在本试验环境中,304L和316L不锈钢均未发生腐蚀;3Cr13不锈钢受到轻微CO_2腐蚀,腐蚀速率低于行业标准要求的0.076mm/a,其他材料的腐蚀速率均偏大,其在CO_2驱油田采出井环境中的腐蚀速率由大到小为:45号钢42CrMo钢35CrMo钢。合金中的Cr含量较低时(0~9%),随着Cr含量的升高,含Cr合金的耐CO_2腐蚀性增强;环境温度为30~65℃时,随着温度的升高,合金的腐蚀速率增大,这与腐蚀产物膜的生长情况有关。  相似文献   

4.
42CrMo钢在氯离子溶液中的腐蚀行为研究   总被引:3,自引:2,他引:1  
周文  兰伟  赵帅  曹献龙  邓洪达 《表面技术》2017,46(8):216-220
目的通过研究42CrMo钻具用钢在常温下不同Cl~-浓度溶液中的腐蚀行为,为其腐蚀速率的预测奠定一定基础。方法采用浸泡实验、电化学测试技术研究42CrMo在不同浓度NaCl溶液中的平均腐蚀速率和电化学特性,并结合SEM扫描电镜对浸泡58 h后的挂片试样进行分析。结果浸泡实验分析表明,当Cl~-达到60 g/L时,42CrMo钢的腐蚀速率达到最大值,为0.124 g/(m~2·h);当Cl~-浓度继续增大时,腐蚀速率随Cl~-浓度的增加而逐渐减小。开路电位Eocp分析表明,随着Cl~-浓度的增加,Eocp总体呈现下降趋势,显示出较大的腐蚀倾向性。极化曲线分析表明,阴极极化曲线的斜率明显比阳极大,并且自腐蚀电流密度在60 g/L Cl~-溶液中达到最大值,为5.952 35μA/cm~2。腐蚀形貌研究表明,42CrMo浸泡58 h后,表面的腐蚀产物分布并不均匀,均发生了局部点蚀现象。结论随着Cl~-浓度的不断增大,42CrMo钢的平均腐蚀速率呈现先增大后减小的趋势,且在Cl~-为60 g/L时,平均腐蚀速率最大。42CrMo钢在静态常温下高Cl~-浓度溶液中以局部点蚀为主,其电化学腐蚀过程主要受阴极去氧极化的控制。  相似文献   

5.
采用旋转弯曲疲劳和疲劳裂纹扩展实验研究一种新型Cr-Mo-V系高强度钢在不同回火温度下的疲劳破坏行为.结果表明,Cr-Mo-V系高强度钢的旋转弯曲疲劳极限σ-1与抗拉强度Rm的比值σ-1/Rm随回火温度的升高而增加.在相同的强度水平下,实验钢的疲劳极限高于商业42CrMo钢.对疲劳断口裂纹源的分析表明,实验钢的疲劳裂纹主要起源于钢中的非金属夹杂物.采用C-T试样测定疲劳裂纹扩展速率的实验结果表明,Cr-Mo-V系高强度钢疲劳裂纹扩展第二阶段的扩展速率随回火温度升高而有所降低.在1500 MPa强度水平下,实验钢的疲劳裂纹扩展速率低于42CrMo钢.  相似文献   

6.
采用慢应变速率拉伸、电子显微镜等现代分析方法,研究了35CrMo钢动态应变时效现象对力学性能的影响.结果表明:在应变量为5%、应变速率为5×10-4s-1的不同温度(293、323、373和473 K)下动态应变时效后的35CrMo钢的伸长率变化不大,但动态应变时效后的抗拉强度均明显增加;35 CrMo钢动态应变时效的最佳温度为373K.35CrMo钢试样在室温下经过动态应变时效处理之后的室温屈服强度明显增加.  相似文献   

7.
介质温度对35CrMo钢在CO2环境下腐蚀的影响及其机理   总被引:1,自引:0,他引:1  
为了研究35CrMo钢钻采工具的井下腐蚀行为,模拟了油田地层水环境,通过腐蚀质量损失、交流阻抗等试验方法,测试了该钢材在30、60、80和100 ℃等不同温度下的耐腐蚀性,用SEM、EDS、XRD手段对腐蚀产物膜的形貌、成分、结构进行了分析,对钢材在不同温度下的腐蚀机理进行探讨。结果表明,温度可以改变35CrMo钢的腐蚀产物膜结构,在30~60 ℃温度范围内,随温度升高,腐蚀速率变大,35CrMo钢表面的腐蚀产物膜为片层状、较薄且结构松散,主要成分为FeCO3和Cr(OH)3;在60~100 ℃温度范围内,随温度升高,腐蚀产物膜致密性变好,晶粒变细,腐蚀速率变小,腐蚀产物膜上层为晶体,主要成分为FeCO3,下层为片状生成物,成分为Cr(OH)3。  相似文献   

8.
常用集输管线钢在CO_2多相流中的腐蚀行为   总被引:2,自引:0,他引:2  
用高温高压釜考察了动态条件下温度、CO2分压和油水比等因素对X65、Q235B、16Mn三种钢的CO2腐蚀行为的影响;用扫描电镜对腐蚀试样进行了表面形貌观察,对腐蚀产物进行了能谱分析与X射线衍射分析。结果表明,钢在CO2多相流腐蚀介质中的耐蚀顺序为:16Mn,Q235B,X65。随着含水量、压力的增加,三种钢的腐蚀速率增加;随着温度的升高,钢的腐蚀速率先升高,60℃时最大,90℃时腐蚀速率最小。  相似文献   

9.
由于变形温度和应变速率是影响42CrMo4钢高温变形损伤断裂行为的重要因素,因此综合考虑了变形温度和应变速率对材料断裂的影响。基于Cockroft-Latham断裂准则,引入温度补偿应变速率因子Zener-Hollomon参数作为修正系数对Cockroft-Latham断裂准则进行改进。通过Gleeble-3800D热模拟试验机对42CrMo4钢进行了温度为950~1100℃、应变速率为0.01~10 s~(-1)条件下的高温拉伸试验。利用试验结果采用线性拟合确定修正系数,得到改进后的断裂准则,将准则预测结果与试验结构对比验证,二则能很好吻合。利用扫描电镜观察试样拉伸断裂断口的组织形貌。结果表明:42CrMo4钢高温拉伸断裂是典型韧窝型韧性断裂,随着温度的提升,材料塑韧性明显提高;随应变速率的提高,材料塑韧性随之不显著降低。  相似文献   

10.
基于理论分析和采用挂片实验,SEM以及电化学测量技术,研究了S135钻杆钢在不同温度下3.5%KCl溶液中的腐蚀行为.结果表明:钻杆钢试样开路电位随着温度升高负移;不同温度下的腐蚀控制因素是造成腐蚀速率变化的主要原因;电化学腐蚀主要受阳极反应控制;系统"弥散效应"随温度升高而增强,平均腐蚀速率呈现先增加后降低的趋势.  相似文献   

11.
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.
吴玉梅  熊晓云  靳蓉  孙敬民  杨林  罗晓星 《金属学报》2005,10(10):1100-1103
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   

13.
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   

14.
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   

15.
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   

16.
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   

17.
The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).  相似文献   

18.
This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.  相似文献   

19.
Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.  相似文献   

20.
A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.  相似文献   

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