金红石对1Cr-0.5Mo合金系焊条工艺性能和熔敷金属力学性能的影响

研究了金红石对1Cr-0.5Mo合金系焊条工艺性能和熔敷金属力学性能的影响。结果表明,金红石对该合金系焊条的工艺性能和熔敷金属力学性能均有较大的影响。随着药皮中金红石加入量的增加,焊条工艺性能得到改善,熔敷金属的强度增加,-20℃夏比冲击功降低。     

E5015（J507）焊条药皮中大理石的颗粒度对其熔敷金属化学成分及力学性能的影响

选取大理石作为研究对象,对大理石粉料进行了筛分并进行了焊条制备和测试。研究了药皮原料中大理石的颗粒度对E5015焊条熔敷金属化学成分及力学性能的影响。试验结果表明：随着大理石颗粒度的减小（由40—60目减小至100目以下）,E5015焊条的熔敷金属化学成分Si、Mn含量逐渐下降,其熔敷金属屈服及抗拉强度逐渐降低而冲击功则逐渐升高。     

MnO对碳钢药芯焊丝性能影响研究

以T492T1-1C1A型药芯焊丝为例,通过对熔渣组分、熔敷金相组织、熔敷金属化学成分、扩散氢含量、力学性能的试验对比与分析,研究了MnO在配方中不同加入量对焊缝组织及熔敷金属力学性能的影响。结果表明,随着MnO的加入量增多,熔敷金属中Mn与O含量未呈现明显变化;熔敷金属的拉伸试验伸长率和低温冲击吸收功先升高后降低,在MnO质量分数为0.5%时获得了较好的焊缝微观组织和力学性能;熔敷金属扩散氢含量有降低趋势。     

铁粉焊条熔化过程中基本参数研究

通过试验研究了焊条直径和铁粉加入量对焊条熔化参数的影响．试验结果表明，焊条直径增加，焊条药皮重量系数、熔敷效率增加，熔化速度和熔敷速度降低；熔敷金属中合金元素Mn、Si含量增加，但Mn、Si的过渡系数减小．当增加药皮中铁粉加入量，药皮重量系数、熔敷效率和熔敷速度增加。熔化速度降低，由于铁粉的稀释作用使熔敷金属中合金元素Mn、Si含量及过渡系数降低。     

两种焊接工艺对焊接接头冲击韧度的影响

针对对接焊缝金属的冲击吸收功低于熔敷焊接接头中的熔敷金属的冲击吸收功的现象,分别从材料的力学性能和显微组织方面进行探讨。结果表明:对接焊缝金属中的屈氏体含量高于熔敷金属中的含量,组织较粗大,从而使得对接焊缝金属容易形成裂纹,致使相同温度下对接焊缝金属与熔敷金属相比其冲击吸收功较低,韧性-脆性转变温度较高。     

脱氧剂对电焊条熔敷金属力学性能的影响

向焊条药皮中添加不同比例的脱氧剂金属锰和钛铁获得4种电焊条,通过焊条熔敷金属化学成分分析、力学性能试验及金相试验,研究了金属锰、钛铁作为脱氧剂对电焊条熔敷金属力学性能的影响。结果表明,随着药皮中金属锰含量的增加,焊条熔敷金属拉伸强度升高,冲击韧性出现峰值;随着钛铁含量增加,焊条熔敷金属拉伸强度升高,冲击韧性提高。     

焊条药皮碱度对熔敷金属中硫磷含量的影响

通过试验研究了焊条药皮碱度对熔敷金属脱硫脱磷行为的影响。结果表明,焊条药皮碱度与硫在渣 铁水中的分配比呈极大值的抛物线关系,熔敷金属中的硫含量与焊条药皮碱度的关系曲线呈极小值的抛物线;药皮碱度的提高可使磷的分配系数提高,熔敷金属中的含磷量降低;但依靠焊条药皮碱度的提高来增加脱硫、脱磷的效果是有限度的。     

氧含量及夹杂物对高强钢金属芯焊丝E120C-K4熔敷金属冲击韧性的影响

本工作通过改变保护气体配比和Zr-Ti、Ti-B微合金化研究了金属芯焊丝E120C-K4熔敷金属中的氧含量及夹杂物对其微观组织和冲击韧性的影响。研究表明:在金属芯焊丝E120C-K焊接熔敷金属中,随着氧含量的增加,熔敷金属组织晶粒尺寸增大,粒状贝氏体含量增加,夹杂物尺寸增大、含量增加,熔敷金属的冲击韧性明显降低;添加微量Zr-Ti微合金的熔敷金属中夹杂物面积在单位面积所占比例降低,夹杂物的平均粒径减小,尺寸集中于0.4～0.7μm之间,为针状铁素体(AF)形核提供了潜在质点,从而提高了熔敷金属的冲击吸收功。     

690镍基合金焊条熔敷金属的组织与性能研究

采用金相显微镜、扫描电镜、拉伸试验、弯曲试验和晶间腐蚀试验分析了690镍基合金ENiCrFe-7焊条中各元素对熔敷金属组织、缺陷和力学性能的影响,研制符合核电设备使用要求的焊条.研究表明:焊缝熔敷金属中的沿晶裂纹引起焊缝金属拉伸性能、冲击韧性和弯曲性能的降低;随着焊缝中Nb,Ti元素含量的增加,焊缝析出相(Nb,Ti)(C,N)和NbC的数量增加,焊缝中滑移晶界受到析出相的钉扎,裂纹扩展受到抑制,焊缝熔敷金属的强度、塑性和弯曲性能得到提高;Nb和Ti的加入减小了Cr_(23)C_6析出数量,抑制了晶间腐蚀裂纹的产生.新研制的镍基焊条满足核电设备对焊缝熔敷金属的性能要求.     

Mo元素对船用高强钢碱性焊条熔敷金属组织和性能的影响

测试5种不同Mo含量的船用高强钢焊条的熔敷金属力学性能,采用光学显微镜和透射电镜进行微观组织观察和分析,并采用Jamtpro软件模拟计算熔敷金属的焊接CCT图。结果表明,随着Mo含量增多,熔敷金属屈服强度和抗拉强度显著提升,但冲击韧性及塑性呈下降趋势;焊接CCT曲线逐渐向右下方移动,熔敷金属的组织由韧性较好的针状铁素体逐渐向硬脆的贝氏体和马氏体转变;当Mo含量高于0.482%时,熔敷金属中会产生对韧性不利的M-A组元,当Mo含量高于0.887%时,熔敷金属中会析出Mo的碳化物,造成严重脆化。     

EVA-g-MAH对CaSO_4晶须/尼龙6复合材料性能的影响

采用马来酸酐接枝乙烯-醋酸乙烯酯共聚物(EVA-g-MAH)对CaSO_4晶须/尼龙6(CaSO_(4W)/PA6)增韧改性。通过双螺杆挤出机制备了CaSO_(4W)/PA6二元、CaSO_(4W)-(EVA-g-MAH)/PA6三元复合材料,用SEM、DSC、XRD等观察和表征了形貌、结构和结晶参数,并测试了力学性能。研究表明:添加少量CaSO_(4W)可提高PA6的结晶速率,而高含量CaSO_(4W)导致PA6结晶速率降低,促进γ晶型形成。添加10%(质量分数)CaSO_(4W)可同时提高PA6的刚性和韧性;添加30%CaSO_(4W)可进一步提高PA6的刚性,但PA6的韧性明显降低。添加2.5%和5%(质量分数)EVA-g-MAH,能使30%CaSO_(4W)-(EVA-g-MAH)/PA6的抗冲击强度分别提高25.0%和76.7%,并使其具有较高韧性。冲击强度的提高主要源于EVA-g-MAH所产生的能量耗散、改善应力的有效传递、增强CaSO_(4W)与PA6的界面以及EVA-g-MAH/PA6共混体系较好的相容性。     

硝酸活化时间对煤基电极材料结构及性能的影响

研究了硝酸活化时间对煤基电极材料表面性质及吸附性能的影响,采用扫描电子显微镜(SEM)、傅里叶红外光谱(FTIR)对煤基电极材料表面性质及形貌进行表征。研究表明,随着硝酸活化时间的延长,煤基电极材料的活化产率和抗压强度逐渐减小,而碘吸附值则呈先增大后减小的趋势,材料表面羧基、内酯基及酚羟基含量逐渐增加。活化8h时煤基电极材料的收率为67.64%,抗压强度为0.234 MPa,碘吸附值达到了301.72mg·g~(-1),表面含氧官能团总量提高了1.44倍。电化学测试结果表明,煤基电极具有良好的电容特性并形成稳定的双电层结构,活化时间越长,扩散过程内阻越小。电吸附处理后氰化废水中各离子的去除率均随活化时间的延长而增大,活化8h时铜及总氰离子的去除率分别可达到90%与68%。     

磨碎玻璃纤维增强环氧树脂复合材料的制备及力学性能研究

用硅烷偶联剂对磨碎玻璃纤维表面进行改性,并制备玻璃纤维/环氧树脂复合材料,采用超声分散对复合材料分散处理,探讨不同磨碎玻璃纤维粉质量比对环氧树脂基复合材料压缩、拉伸性能的影响。研究表明,添加磨碎玻璃纤维后,环氧树脂的强度和硬度显著增强。当磨碎玻璃纤维掺量在15%~25%之间时,复合材料的综合力学性能最好,其压缩强度、压缩模量、拉伸强度最高达到67.1 MPa、1.68 GPa、57.6 MPa,与纯环氧树脂相比提高了24%、35%、34%;断裂伸长率随着掺量的增加逐渐降低,当含量达到30%时比纯环氧树脂的降低了48%,表明添加玻璃纤维粉后环氧树脂脆性增强。目数小粒径较大的玻璃纤维粉对环氧树脂力学性能增强效果更优,但影响程度不如含量对复合材料力学性能的影响大。     

Effects of heat treatment process and niobium addition on the microstructure and mechanical properties of low carbon steel weld metal

The mechanical properties and microstructure were evaluated and analyzed by optical microscopy (OM) and transmission electron microscopy (TEM) for micro-alloy carbon steel weld metal with and without Nb addition, respectively, under different heat treatment processes including stress relief annealing, normalizing, and no treatment after welding. The strength and elongation of the weld metal without treatment after welding were improved with the addition of Nb element, and the impact toughness was not affected obviously with the Nb addition. After stress relief annealing, the strength decreased for the Nb-free weld metal, while the elongation and impact toughness increased. However, for the Nb-bearing weld metal, stress relief annealing improved the strength of the weld metal significantly, and deteriorated the elongation and impact toughness. In the case of normalizing treatment to the weld metal, it was shown that with the increase of the holding time at the normalizing temperature of 920 °C, for both the weld metals with and without Nb addition, the microstructure of the columnar grain zone (CGZ) was transformed from one of columnar grain into one of equiaxed grain. The grain size of the equiaxed grain zone (EGZ) increased initially, then remained almost unchanged with the prolonging of the holding time. The mechanical properties of the weld metal with and without Nb addition showed no obvious change with the increasing holding time. With the increase of the normalizing temperature, the strength of the Nb-bearing weld metal increased, while the elongation and impact toughness decreased significantly. OM and TEM analysis found that the fine NbC particles were precipitated at the normalizing temperature of 920 °C, which refined the grains of the weld metal and increased the impact toughness. With the increase of the normalizing temperature, the content of widmanstatten ferrite (WF) in the Nb-bearing weld metal increased, whereas the quantity of the NbC particles decreased, which improved the strength and lowered the impact toughness.     

CSW/POE-g-MA/PA6三元复合材料的结构和性能

采用马来酸酐接枝乙烯一辛烯共聚物(POE-g-MA)对CaS04晶须/尼龙6(CSW/PA6)共混物增韧改性,研究了csw/PA6和CSW/POE-g-MA/PA6复合材料的力学性能、热性能、形貌和加工性能.适量添加CSW可同时提高PA6的刚性和韧性.与纯PA6性能比较,10％CSW/PA6的拉伸强度、弯曲强度、弯曲模量和冲击强度分别增大7.5％、9.1％、21.1％和11.6％;当CSW含量增至30％,CSW/PA6的韧性明显降低.POE-g_MA可促进PA6基体中csw的均匀分散,增强CSW与PA6的界面粘附,提高CSW/PA6 (30/70)的冲击韧性.源于CSW和POE-g-MA的协同作用,CSW/POE-g-MA/PA6 (30/5/65)的冲击强度和弯曲模量与纯PA6相比较,分别提高了36.8％和22.1％,拉伸和弯曲强度接近纯PA6.     

Effect of polyethylene glycol on the mechanical property, microstructure, thermal stability, and flame resistance of phenol–urea–formaldehyde foams

In this study, polyethylene glycol (PEG) was added to phenol–urea–formaldehyde foam to improve its toughness, and the effects of PEG, with different molecular weights and dosages, on the mechanical property, microstructure, thermal stability, and flame resistance of phenol–urea–formaldehyde foam were studied. The addition of PEG significantly increased the toughness and impact strength and decreased the pulverization rate of the foam. The compression strength of the foam first increased and then decreased with increasing amounts of PEG. When 2 wt% PEGs were added, the compression strength of foams was the highest. The addition of PEG significantly influenced the microstructure of phenol–urea–formaldehyde foams, in which the cell diameter decreased and wall thickness increased with increasing amount and molecular weight of PEG. The addition of PEG also slightly decreased the thermal stability of phenol–urea–formaldehyde foams, and increased the heat release rate, total heat release, and total smoke release of the foams.     

Improvement of impact toughness of AWS E6010 weld metal by adding TiO2 nanoparticles to the electrode coating

The effect of TiO₂ nanoparticles in the electrode coating on the impact toughness of three weld metals prepared by the shielded metal arc welding process was investigated and the main factors affecting the impact toughness were discussed. The microstructure, mechanical properties and fracture surface morphology of the weld metals have been evaluated and the results are compared. When the content of TiO₂ nanoparticles in the composition of electrode coating is increased, the morphology of ferrite in the microstructure of columnar zone will change from Widmanstätten ferrite to acicular ferrite. This finally changes to allotriomorphic ferrite when the amount of TiO₂ nanoparticles in the electrode coating goes relatively high. Furthermore, the addition of TiO₂ nanoparticles is effective in refining the ferrite grain size of the reheated microstructures of weld metals. This effect is attributed to the increased number of nucleation sites on the oxide nanoparticles. The impact toughness of the weld metal was improved by adding TiO₂ nanoparticles, especially when a medium TiO₂ nanoparticle content was used in the electrode coating. A significant increase in the impact toughness of weld metal was shown to be due to the increased percentage of acicular ferrite and refinement of microstructure.     

Variations of Microstructure and Mechanical Properties of Si—B—O—N Ceramics with Sintering Temperatures

Si-B-O-N powder without B-O bonds synthesized by polymeric precursor were hot-pressed into ceramics at different tempera-tures.The variations of microstructure and mechanical properties of Si-B-O-N ceramics have been investigated.Crystallization of Si-B-O-N ceramics occurred at about 1400℃.Density, elastic modulus,and flexural strength of the ceramics increased with the increasing sintering temperatures, and reached to their maximum values at 1600℃ .By contrast, hardness and frac-ture toughness of the ceramics monotonically changed with increasing sintering temperatures.Hardness decreased,while the fracture toughness increased.The principal toughening mechanisms including crack deflection, crack bridging and plate grain pulling-out effects are discussed.     

Effect of thickness on the fracture characteristics of fetal membranes

The mechanical characteristics of the chorioamniotic membrane were evaluated with a new burst test apparatus by rupturing 35 specimens that were taken from a sample of seven afterbirths. Strength, stiffness, toughness, and ductility were measured. Mechanical characteristics did not change significantly with variation in thickness. While ductility should not correlate with thickness, the lack of a significant increase in strength, stiffness and toughness with an increase in thickness is most unusual and requires an explanation. Subsequently, an additional experiment, which was designed to ascertain the mechanical stability of membrane specimens with prolonged exposure to air, showed a dramatic increase in stiffness as membranes were allowed to dry. The increase in stiffness indicates that strength and toughness also increase with drying, provided that ductility remains constant. Thus, the degree of hydration of the membrane, which is reflected in thickness, regulates mechanical characteristics. The increase in the water content of certain amniotic layers has a lubricating effect on the amnion-chorion interface. This lubrication increases as term approaches. Thus, hydration must increase as gestation progresses, and strength, stiffness, and toughness must decrease until the membrane is weak enough to rupture at the end of gestation. Thus, hydration must increase as gestation progresses, and strength, stiffness, and toughness must decrease until the membrane is weak enough to rupture at the end of gestation.     

道间温度对10CrNi5MoV钢气体保护焊接头力学性能的影响

通过屈服强度和冲击韧性测试、组织分析,研究了两种焊接热输入条件下道间温度对10CrNi5MoV钢气体保护焊接头力学性能的影响。结果表明,随着道间温度从40℃提高到300℃,焊接热输入为8 kJ/cm和18 kJ/cm的焊缝金属屈服强度分别从868 MPa和855 MPa单调下降至728 MPa和693 MPa,-50℃冲击韧性分别从70 J和69 J升高至117 J和72 J(道间温度分别为200℃和100℃),然后降低至67 J和43 J;焊缝金属的组织差异是不同道间温度下焊接接头力学性能不同的原因。随着道间温度从40℃提高到300℃,焊缝金属中马氏体组织逐渐消失,粒状贝氏体组织逐渐增多,针状铁素体组织比例先增加再减少,含量最高时的道间温度与冲击韧性峰值水平相一致。