线性电磁搅拌对K417高温合金母合金锭质量的影响

为了提高高温合金母合金锭的质量,本文提出了在高温合金真空熔铸过程中,施加线性电磁搅拌的真空电磁铸造新技术。使用电子探针和光学显微镜,研究了在真空熔铸的凝固过程,施加工频线性电磁搅拌对K417高温合金母合金锭质量的影响。实验结果表明:在K417高温合金真空熔铸的凝固过程中施加140A的工频线性电磁搅拌,能够细化高温合金母合金锭的等轴晶组织、增加高温合金母合金锭的断面等轴晶比例、大幅减轻枝晶偏析的程度并能将高温合金母合金锭的中心缩松缩孔比率从54%降低到35%,从而使高温合金母合金锭的质量得到明显改善。     

K417高温合金母合金锭真空电磁净化技术研究

为了提高高温合金母合金锭的纯净度,本文提出了在高温合金真空熔铸的凝固过程施加旋转磁场的真空电磁净化技术。使用扫描电子显微镜和图像分析仪研究了K417高温合金母合金锭真空电磁净化技术的非金属夹杂物去除机理,结果表明:在K417高温合金母合金锭真空熔铸的凝固过程中施加旋转磁场能够促使非金属夹杂物向母合金锭中心部位快速聚集、变大并上浮到冒口处,最终在切除冒口的同时也将夹杂物从合金中除去。     

中小尺寸高温合金件的无接触电磁成形

介绍了一种新型金属熔体无接触电磁成形技术及其原理,该技术将电磁铸造技术与高梯度定向凝固技术融为一体,对于熔化和成形活泼金属、高温合金难熔金属和高纯金属等中小尺寸构件具有重要的研究与应用价值。另外,从电磁场和凝固过程角度讨论了中小尺寸高温合金样件的电磁成形过程,探讨了工艺参数对成形过程的影响规律,并获得了表面质量较好的高温合金样法。     

铝(镁)合金消失模铸造近净成形技术研究进展

阐述了铝(镁)合金消失模铸造技术的研究现状,着重介绍了铝(镁)合金消失模铸造在金属液充型、振动凝固、压力凝固以及消失模壳型铸造等技术方面的最新研究进展。研究表明,铝(镁)合金在消失模铸造过程中,需重点解决针孔、缩松等缺陷,提高液态合金的充型能力和铸件的力学性能;通过采用振动凝固和压力凝固的手段,可以提高金属液充型能力、细化组织、提高组织致密性,明显提高铸件力学性能。真空低压消失模壳型铸造技术,可以解决普通消失模铸造易于出现的孔洞和夹杂等缺陷以及浇不足和浇注温度高等问题,是一种生产复杂薄壁高质量铝、镁合金精密铸件的新方法。     

K417高温合金电磁搅拌法真空晶粒细化技术研究

使用X射线衍射分析仪、扫描电镜、电子拉伸试验机、高温金相显微镜研究了在模壳内壁表面的涂层中添加孕育剂铝酸钴和在真空熔铸过程中施加工频旋转电磁搅拌对K417高温合金真空精密铸件凝固组织和性能的影响。结果表明:采用将在真空熔铸过程中施加150 A的工频旋转电磁搅拌和在模壳内壁表面的涂层中添加孕育剂铝酸钴相复合的方法,可以得到晶粒细化至95μm、断面等轴晶比例达到99%的K417高温合金真空精密铸件。当在电磁搅拌和孕育剂作用下将K417高温合金真空精密铸件的晶粒尺寸从3.45 mm细化至95μm,可以使其粗大等轴晶向细小粒状晶转变,(γ+γ’)共晶的尺寸减小,室温和650℃中温的拉伸性能得到明显改善。     

高Cr铸造镍基高温合金K4648的母合金净度研究

对两炉冲击韧性存在明显差异的高Cr铸造镍基高温合金K4648进行了对比研究,通过分析两炉母合金的主量元素和气体含量,采用电子束纽扣锭(EB锭)实验观察合金内夹杂物和对母合金用原材料金属Cr的显微组织分析等方法研究了K4648母合金净度。结果表明:1#与2#炉批母合金主量元素无明显差别。1#母合金由于气体元素O含量高达(20.5±7.5)×10-6,远高于2#合金的6×10-6,造成其室温冲击韧性(aku)不及2#合金的一半,低于技术条件要求的19.6J/cm2。电子束纽扣锭(EB锭)实验可有效地将K4648中的夹杂物汇聚,经分析主要是富Y,Ce的氧化物和富Al氧化物。证明高Cr铸造镍基高温合金K4648中添加稀土元素Y,Ce可有效攫取合金中自由态的O和S,生成稳定的稀土氧化物或硫化物,起到净化合金的作用。K4648母合金原材料中金属Cr基体中固溶有15%(质量分数)的元素O,还分布有富Cr氧化物和Cr,Al,Si的复合氧化物。此外,还存在含N、贫O区域,该区域的维氏显微硬度可达8.2GPa,是Cr基体1.3GPa的6倍,证明N使金属Cr的硬度明显升高。     

锌合金液态模锻凝固特征探析

研究了ＺｎＡｌ４Ｃｕ３合金在常规铸造和液态模锻时的凝固过程，探讨了压力对液态金属凝固过程温度场的影响。给出了在压制过程中不同比压和冲头温度下模具与制件不同位置的温度变化情况，根据实验结果计算得出液态模锻下冷却速度较之自由凝固提高近１０倍，并由此分析了液态模锻的凝固特征。     

电磁约束成形的技术特点及其发展前景

回顾了电磁约束成形技术的发展过程,通过分析圆形、椭圆形等不同横截面形状的纯铝、不锈钢以及高温合金等金属试样的电磁约束成形过程,从感应器结构、屏蔽罩插入深度、材料性状及抽拉速率等方面出发,详细论述了电磁约束成形定向凝固过程的技术特点,并阐述了电磁约束成形定向凝固技术的优缺点,指明了其今后的发展方向。     

电磁铸造5182铝合金锭的组织与性能研究

采用电磁铸造技术铸造了易拉罐用5182变形铝合金，采用光学显微镜和扫描电镜分析了其显微组织，而且对其进行了均匀化处理和对比实验。结果表明，电磁铸造锭有更加良好的内部组织和优良的力学性能，电磁铸造试样的硬度大约是普通连续铸造试样的两倍，疲劳性能是普通连续铸造铸锭的3倍，电磁铸造铸锭还有良好的耐磨性，电磁铸造锭的优良性能得宜于电磁搅拌的作用使整个铸锭获得均匀细小的晶粒组织，电磁铸造技术是一种无模铸造技术，它依靠电磁力约束液体金属成型，液体金属不与铸模接触，铸锭表面光滑如镜；相反，普通连续铸造锭表面因存在振动痕和亚表面偏析等铸造缺陷，力学性能大大降低。     

交变电磁场下金属熔体的电磁约束连续成形与凝固

论述了连续铸造中模壳材料对铸件性能的影响。在介绍液态金属电磁成形原理的基础上,重点讨论了铝合金和钢铁材料的电磁成形以及存在的问题,并提出了液态金属电磁近终成形技术。利用开发的双频电磁近终成形技术,成功地实现了两种不同频率组合下的电磁成形过程,制备出了复杂弯月截面、复杂形状无模壳电磁成形的样件。     

Research on vacuum-electromagnetic casting of IN100 superalloy ingots

In order to improve the inner quality of superalloy master alloy ingots, the new technology of superalloy vacuum-electromagnetic casting, i.e. applying electromagnetic stirring (EMS) to the solidification process of superalloy vacuum casting was developed. The effect of EMS on the inner quality of IN100 superalloy ingots was studied with EPMA and optical microscope. The results show that while an EMS with 50 Hz frequency and 60 A current is imposed, the equiax crystals of IN100 superalloy ingots can be effectively refined and increased, and the central shrinkage porosity and the dendritic segregation of IN100 superalloy ingots are greatly reduced, so the inner quality of IN100 superalloy ingots is obviously improved.     

Numerical and Experimental Determination of the Feeding Distance of Aluminum Alloys in Gravity Die Casting Using an Optimized Riser Shape

A finite difference thermal model was utilized to analyze the solidification process and to predict the maximum feeding distance in gravity die casting of aluminum alloys with an optimal riser shape. Predictions are verified experimentally for both pure aluminum and A1-12% Si alloy. The experimental maximum feeding distance for castings made from A1-12% Si alloy in gravity diecastings was found to be 10 times the casting thickness, compared to 9.1 times the casting thickness from numerical predictions. For pure aluminum, the experimental maximum feeding distance was 7 times the casting thickness, compared to 6.2 times the casting thickness from numerical analysis.     

动态布流平面凝固铸造AA1070/AA7050合金

提出了一种新的用于大尺寸复层铸锭平面凝固铸造的布流系统,并使用软件FLUENT对铸造过程中分流方式对温度场的影响进行了模拟分析,模拟结果表明,使用动态布流时熔体温度的均匀性显著优于定口布流,因而可实现凝固时固/液界面在上升过程中保持平坦。使用动态布流平面凝固铸造方法实现了1070/7050大尺寸双层铝合金的铸造复合,铸造结果表明,复合铸锭中两种铝合金的界面清晰平直,无气孔夹杂等缺陷,实现了冶金结合并存在元素扩散层;7050侧金相组织均匀,厚度方向上无明显宏观偏析。     

Influence of mould design on the solidification of heavy forging ingots of low alloy steels by numerical simulation

Ingot casting of a 6-ton, heat-treatable Cr–Mo low alloy steel was simulated using finite element method in three dimensions. Effects of casting parameters including bottom pouring rate, mould slenderness ratio, mould slope, and height and shape of the hot top isolate on solidification behaviour and crack susceptibility during subsequent hot forging of the ingot were investigated. The simulation model was validated against experimental data of two different ingot mould designs. Influences of the casting parameters on the riser efficiency and possible crack formation in the intersection of hot top and ingot body during subsequent open-die forging of the cast steel ingots were discussed. Results showed that pouring the melt under a constant rate, reducing the mould slenderness ratio, and using a proper design for the hot top isolate would all improve the riser efficiency and thereby possibly reduce crack susceptibility during subsequent hot forging.     

Al-Mg-Li-Zr系合金熔铸工艺研究

对Ａｌ－ Ｍｇ－ Ｌｉ－ Ｚｒ 系合金在工业条件下的熔炼与铸造工艺进行了详细和研究,控制氧化是稳定成分、减少夹杂的关键;采用氩气与真空精炼相结合并辅以合理的铸造保护措施可有效地降低合金中的氢含量,控制Ｎ 详细的研究,文章认为控制Ｎａ 含量;选用适当的铸造参数和保证方式可减少铸锭开裂,提高铸锭质量．     

Preparation of Cu-Nb alloys for multifilamentaryin situ superconducting wire

A study has been made of two techniques, chill casting and consumable arc melting, for preparing ingots of Cu-Nb alloy for production of multifilamentary Nb₃Sn superconducting wire. It was found that Y₂O₃, ThO₂ and graphite all make excellent crucible materials for melting Cu-Nb alloys at 1850° C. Some difficulty was found with Nb segregation in chill-cast 5 cm diameter ingots. The consumable arc casting technique was shown to produce a uniform Nb dendrite distribution with little macrosegregation in 5 cm diameter castings and is regarded as having excellent potential for scale-up production of uniform Cu-Nb ingots of 25 to 30 cm diameter.     

Study on casting composite ingot of 4045/3004/4045 aluminum alloys

Two kinds of equipments were designed for casting composite ingots, and three‐layer ingots of 4045/3004/4045 aluminum alloys were prepared by direct‐chill (DC) semi‐continuous casting process, macro‐morphology, microstructure, temperature distribution near the interface, elements distributions and tensile strength of the interface were investigated. The equipment suitable for casting composite ingots was determined, and results show that solid supporting layer with uniform temperature distribution forms near the interface, which ensures the stable casting process. The two different aluminum alloys are well bonded. The criterion for temperature control of solid supporting layer is founded based on the relationship between the interface bonding strength and the temperature of solid supporting layer when contacted by 4045 alloy melt.     

精密铝铸件电磁泵负压充型测试技术

电磁泵负压充型工艺是在电磁充型低压铸造工艺的基础上发展而来的一种铸造技术, 其充型能力强, 补缩能力高. 相比较传统的反重力铸造技术, 该技术配合合适的浇注系统对铸件性能有明显的改善作用. 通过分析介绍其技术原理及特性, 该技术尤其适合复杂精密铝合金铸件的生产, 具有广阔的发展前景.