共查询到20条相似文献,搜索用时 109 毫秒
1.
通过工艺结构设计和生产过程中制定有效的控制措施来提高铸件质量,减少和消除夹渣缺陷,从而提高阀门及法兰类铸件的密封性。生产实践证明,工艺设计应尽量避免铸件密封面作为浮渣面,不可避免时,则必须在浮渣面上设置集渣结构,或者增加加工余量。在蜡回收过程中尽量减少蜡杂质,脱蜡后的型壳避免夹杂物掉入型腔,以及熔炼过程中合理采用脱氧工艺、控制钢水的二次氧化及浇注温度的合理设定等都将有效地避免或减少铸件夹渣缺陷。 相似文献
2.
介绍了国内铸造行业熔炼工艺的现状和发展,详细阐述了以Si C为基体的预处理剂在熔炼过程中的使用方法及作用机理,指出了在感应电炉熔炼条件下,合理选择和使用预处理剂能有效提高铸件的综合品质。生产应用数据表明:熔炼时添加炉内预处理剂及出炉前添加出炉预处理剂,可以改善原铁液的冶金质量,降低原铁液的白口倾向;改善铸件的石墨形态,提高铸件的力学性能;提高铸件组织的致密性,降低铸件的渗漏废品率;降低铸件不同部位的硬度散差,改善铸件的加工性能及延长中频感应电炉炉衬的使用寿命。 相似文献
3.
总结了双联熔炼工艺中灰铸铁熔炼材料的要求和特点,并针对使用过程中容易出现的问题进行了分析,同时分析了熔炼材料对铸件性能可能造成的影响,为合理选用熔炼材料提供了依据。 相似文献
4.
5.
时和林 《特种铸造及有色合金》2009,29(2)
同一般的不锈钢熔模铸件相比,高尔夫球头由于形状复杂,表面品质和内在品质要求高,易产生夹杂物、超重、变形等缺陷.从制模、制型、脱蜡及焙烧、熔炼与浇注以及清理整修等方面,进行了控制,很好地解决了上述缺陷. 相似文献
6.
压铸铝合金熔炼是压铸生产过程中的一个重要工序,熔炼工艺控制不严,会造成Al液含渣量及含气量增多,并且会使化学成分产生变化,导致铸件产生针孔、氧化夹渣、缩松和化学成分不合格,影响铸件品质。通过对熔炼过程中熔炼前的新旧料配比,熔炼温度,Al液除渣净化、精炼除气等关键工序进行试验研究,确定合理的工艺范围,从而提供优质Al液,最终获得合格铸件。 相似文献
7.
铝合金铸造工艺过程中,合金熔炼质量的好坏,是影响铸件质量的首要因素.因此,在解决铸件的技术质量关键中,必须特别注意合金的熔炼质量,不断总结经验,掌握规律,使铸件质量稳定下来.在熔炼工艺定型以后, 相似文献
8.
9.
10.
11.
12.
We have observed some kinds of defects in unseeded rapid zone-melting-recrystallized(RZMR)Si filmsformed with a RF-induced graphite strip heater system,using cross-section specimen electron microscope.Theobserved defects are subgrain boundaries(SGB),dislocations and microtwins.The most commonly observeddefects are SGB which formed as a result of some orientation differences between adjacent grains during theirrapid self-nucleation growth.Mixed type SGB were frequently observed,although some pure tilt or twist SGBexisted also in the Si films.The rotation angular component around the axis parallel to scanning direction ismuch larger than that around other axes.SGB consist primarily of arrays of dislocation and havecrystallographic angular deviations of one degree or less.During Si film cooling,dislocations and microtwinswere formed due to non-uniform thermal stress.The crystallographic characters of the dislocations in Si filmsare the same as those in common bulk Si single crystals.Their Burgers vectors are b=a/2<110>.Some dis-locations run across the Si film,and the amorphous SiO_2 layers on and underneath the Si film can effectivelyblock the dislocations and prevent them from entering the layers.Microtwins were observed in the Si filmssometimes,the twinning planes being{111}. 相似文献
13.
14.
缩孔、缩松是铸铁件的常见缺陷,对这类缺陷的控制标准取决于铸件的功能要求。以汽车铸件为例,介绍了防止缩孔、缩松缺陷的几种常用方法,包括:(1)冒口补缩;(2)熔炼浇注工艺调整控制;(3)冷铁激冷;(4)用冷却筋、散热片局部加速冷却;(5)采用导热率高的型砂、芯砂局部加速冷却;等。同时还介绍了这些方法的原理、使用范围和选择原则。 相似文献
15.
16.
《中国有色金属学会会刊》2020,30(10):2577-2589
The high-cycle fatigue and fracture behaviours of the selective laser melting (SLM) AlSi10Mg alloy were investigated. Flat specimens were designed directly in the shape required for the fatigue tests under pulsating loading in tension (R=0, R is the dynamic factor). The fatigue–life (S–N) curves were modelled with a conditional Weibull's probability density function, where the real-valued genetic algorithm (GA) and the differential ant-stigmergy algorithm (DASA) were applied to estimating the needed Weibull's parameters. The fractography of the fatigue specimens showed that the fatigue cracks initiated around the surface defects produced by SLM and then propagated in an unstable manner. However, the presence of large SLM defects mainly influenced the crack initiation period and did not have a strong influence on the crack propagation. The obtained experimental results present a basis for further investigation of the fatigue behaviour of advanced materials and structures (e.g. cellular metamaterials) fabricated by additive manufacturing (AM). Especially, in the case of two-dimensional cellular structures, the cross-section of cellular struts is usually rectangular which corresponds to the specimen shape considered in this work. 相似文献
17.
本研究分别利用水冷铜坩埚真空感应熔炼气雾化(VIGA-CC)和等离子旋转电极(PREP)两种技术制备出球形Ti-6Al-4V合金粉末,作者利用SEM、同步辐射CT扫描-三维重建和氩气含量测试等分析手段对不同粒径的Ti-6Al-4V合金粉末的孔洞缺陷和氩气含量、硬度值进行了表征。实验结果表明, VIGA-CC粉末粒度分布宽,细粉收得率较多,粉末粒度分布在40~180 μm之间, PREP粉末的粒度分布较窄,主要集中在110~180 μm之间;金属粉末内部的孔隙率、气体含量和孔尺寸随着粉末粒度的增大而增大,且同一粒径范围内VIGA-CC粉末的气孔概率多于PREP粉末;随着粉末粒径减小,粉末截面组织逐渐细化,其硬度值逐渐升高,整体上VIGA-CC粉末硬度值高于PREP粉末。 相似文献
18.
Conventional vacuum arc consumable electrode melting continues to play a large role in the production of titanium alloy ingots. Titanium melting will be performed by electron-beam and plasma cold-hearth melting in some applications, for the production of titanium rotor-grade ingots. The current reports indicate that hard-alpha defects and high-density inclusions can be eliminated through hearth melting. Automatic controls for electron-beam melting and plasma-arc melting will play an important part in their development for producing high quality titanium ingots. Processes such as cold-wall induction may be integrated into atomization, spray deposition and casting systems. Other combinations of melting techniques can be used for new titanium products in the future. 相似文献
19.