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《铸造技术》2015,(10):2423-2426
针对国内某钢厂生产37Mn5钢圆坯采用的LD-LF-CC工艺流程,对钢中显微夹杂物的类型进行了分析,并研究了工艺环节以及非稳态浇铸两个因素对显微夹杂物含量的影响。结果表明,铸坯中显微夹杂物以球形钙铝酸盐夹杂为主,类型为Al2O3-Si O2-Ca O-Mg O复合夹杂,Al2O3-Mn S复合夹杂和Mn S夹杂。不同工序对显微夹杂物去除效果不同,其中吹氩工艺去除效果最为明显,夹杂物含量降低36.05%,LF处理后夹杂物含量降低18.89%。非稳态浇铸下显微夹杂物含量较高的问题需通过提高钢包的自开率、中间包和结晶器流场优化、强化保护浇铸和稳定浇铸工艺来解决。 相似文献
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合金含量、精铸工艺参数(出炉温度、浇铸温度、模壳预热温度、保温时间、冷却方式)对叶片脆性问题存在一定的影响。为了消除静叶片的脆性断裂,采用正交试验对脆性问题进行了研究。结果表明,合金含量及工艺参数的交互作用对叶片脆性影响显著。 相似文献
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张以钟 《特种铸造及有色合金》1992,(4):26-27,30
考虑到离心浇铸机的能力,正确选取大型铜套离心浇铸时工艺参数,成功地浇铸出重量大于5t,尺寸为Φ500mm×4000mm的铜套。介绍了该铜套离心浇铸工艺的改进,及工艺参数的选择和校核。 相似文献
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为控制镁合金中杂质元素Fe及合金元素Mn的含量,本文通过控制浇铸温度的变化,探究AZ31、AZ61镁合金中Fe、Mn元素含量及微观组织的变化情况。研究结果发现,降低浇铸温度可以有效控制Fe、Mn元素的含量,最佳浇铸温度在630~680℃之间,Fe含量可以降低到20×10-6以下;随着浇铸温度的降低,第二相体积分数及形态发生变化;AZ61合金中形成的难溶第二相(Al-Mn-Fe)比AZ31合金中要少。因此,适当降低浇铸温度可以有效控制镁合金中杂质元素Fe的含量,从而提升镁合金基体的耐腐蚀性。 相似文献
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本文对尾座端面浮动式抱轴瓦离心浇铸机的结构设计及抱轴瓦的浇铸工艺作了介绍,着重阐述了浇铸机端面密封的关键所在,其结构特点对其它离心浇铸机的设计具有一定的参考价值. 相似文献
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本文对尾座端面浮动式抱轴瓦离心浇铸机的结构设计及抱轴瓦的浇铸工艺作了介绍,着重阐述了浇铸机端面密封的关键所在,其结构特点对其它离心浇铸机的设计具有一定的参考价值。 相似文献
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The present work investigated the solidification microstructure of AISI M2 high speed steel manufactured by different casting technologies,namely iron mould casting and continuous casting.The results revealed that the as-cast structure of the steel was composed of the iron matrix and the M2C eutectic carbide networks,which were greatly refined in the ingot made by continuous casting process,compared with that by the iron mould casting process.M2C eutectic carbides presented variation in their morphologies and growth characteristics in the ingots by both casting methods.In the ingot by iron mould casting,they have a plate-like morphology and grow anisotropically.However,in the ingot made by continuous casting,the carbides evolved into the fiber-like shape that exhibited little characteristics of anisotropic growth.It was noticed that the fiber-like M2C was much easier to decompose and spheroidize after heated,as a result,the carbides refined remarkably,compared with the case of plate-like carbides in the iron mould casting ingot. 相似文献
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在高铬不锈钢的生产中,影响质量最严重的是钢锭中的轴心裂纹和钢材中的髪纹。本文的研究结果指出,这两种缺陷属于同一来源,没有轴心裂纹的钢锭在锻成钢材后也没有髪纹。 钢锭中轴心裂纹是在凝固过程中形成的,因而冷凝条件对它有影响。利用耐火材料做锭模可以得到内部坚实的钢锭,减小锭模模壁厚度,增大钢锭圆锥度或降低浇铸温度等只能减轻而不能完全消除裂纹。 熔炼过程中的脱氧方法对钢中夹杂物的性质和形状分布有影响。改善脱氧方法并采用薄模浇铸,可以大大地减少轴心裂纹和髪纹,从而提高钢的收得率。我们认为夹杂物的性质、多寡及其形状分布可能对钢液的流动性和表面张力有影响;改善钢液的流动性或减小其表面张力可以促进钢液的充填性能,从而弥补凝固过程中由于冷凝收缩而产生的缺陷。 在一定压力以下的真空中熔化和浇铸可以得到内部良好的钢锭。通过真空熔铸所得到的钢锭,其柱状晶区大小缩小,而柱状晶的缩小对避免钢锭中轴心裂纹有利。得到这种效果的原因可能是多方面的,真空有去气作用,在真空中钢锭的凝固散热与在一般情况下有所不同,真空作用使钢液的性质发生变化等等。虽然,上述几方面的理论基础还有待于进一步研究,但从目前实际效果来说,真空熔化和浇铸应该认为是提高不 相似文献
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Effect of mould material on aluminum alloy ingot quality under low frequency electromagnetic casting
F or a semi-continuous aluminum casting process, it is essential to supply high quality aluminum alloy ingot without internal and outside defects. The use of electromagnetic fields to control the size and shape of grains has become one of the most promising methods [1-5] in many engineering applications and tends to be widespread in industries. The application of electromagnetic casting (EMC) technique for improving products quality has attracted a great deal of attention in recent years, and… 相似文献
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Shen HoufaChen KangxinLiu Baicheng 《金属学报》2018,(2):151-160
Many key forging components of heavy equipment are manufactured by large steel ingots. Macrosegregation in steel ingots is a key defect formed during the solidification process. Over the past few decades, numerical modeling has played a more and more important role in the study of macrosegregation. Various models have been developed and applied to different ingot casting processes. This paper focused on the application of macrosegregation models to the steel ingot. Firstly, the formation mechanism and influencing factors of macrosegregation were introduced. Then, the existing macrosegregation models and their recent development were summarized. Macrosegregation models accounting for such mechanisms as solidification shrinkage- induced flow and mushy zone deformation were analyzed, respectfully. To model macrosegregation due to solidification shrinkage, the key was to solve the free surface. A simple derivation showed that the multi-phase (including gas phase) models were equivalent to the VOF-based segregation models in dealing with the shrinkage-induced flow. Finally, our recent research work on numerical modeling of macrosegregation in steel ingots was illustrated, including application of the developed multi-component and multi-phase macrosegregation model to a 36 t steel ingot, and numerical simulation of multiple pouring process. The carbon and sulphur concentrations at about 1800 sampling points, covering the full section of a 36 t ingot, were measured. By detailed temperature recording, accurate heat transfer conditions between the ingot and mould were obtained. Typical macrosegregation patterns, including the bottom-located negative segregation and the pushpin-like positive segregation zone in the top riser, have been reproduced both in the measurements and the predictions, The carbon and sulphur concentrations predicted by the three dimensional multi-component and multi-phase macrosegregation models agreed well with the measurements, thus proving that the model can well predict the macrosegregation formation in steel ingots. As for the multi-pouring process simulation, the results show a high concentration of carbon at the bottom and a low concentration of carbon at the top of the mould after the multi-pouring process with carbon content high in the first ladle and low in the last ladle. Therefore, the multiple pouring process could get the initial solute distribution with the opposite form of segregation. Such carbon concentration distribution would reduce the negative segregation at the bottom and the positive segregation at the top of the solidified ingot, thus proving the ability of the multiple pouring process for the control of macrosegregation. 相似文献
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采用低频电磁场半连续铸造工艺制备Al-Mg-Si-Cu铝合金铸锭,研究了低频电磁场对Al-Mg-Si-Cu铝合金铸锭组织的影响。结果表明,施加低频电磁场可以细化Al-Mg-Si-Cu铝合金铸锭的晶粒组织,减轻晶内元素的偏析程度。与常规半连续铸造相比,施加频率为20 Hz、电流为120 A的交变电磁场后,铸锭中的等轴晶组织增多,枝晶状组织减少,晶粒尺寸变得更加细小,铸锭边部和中心平均晶粒尺寸由常规半连续铸造的170和259μm分别降至133和187μm,同时有利于提高溶质元素在晶内的分布,很大程度上减轻了溶质元素的偏析。此外,低频电磁场的电磁振荡使得液穴内部温度场和流动场更趋均匀,溶质元素分配系数增大,结晶区间变小,抑制了树枝晶的生长,促进了Al-Mg-Si-Cu合金半连续铸锭中非枝晶组织的形成和溶质元素的强制固溶,并且抑制了溶质元素的偏析。 相似文献
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分析了6063铝合金圆铸锭同水平热顶铸造的填充、斜坡、稳定和结束等四个阶段的工艺特点,阐述了在每个阶段根据其工艺特点,合理控制铸造温度、铸造速度和冷却水压三要素,以及采取的一些技术措施,确保生产出高质量的铸锭。 相似文献