倾斜式冷却剪切技术制备Al-3%Mg半固态合金坯料

应用自行设计倾斜式冷却剪切实验装置,对制备Al-3%Mg半固态合金坯料进行研究,分析工艺条件对半固态合金组织的影响,以及半固态合金坯料的二次加热组织及最优二次加热工艺。结果表明,采用倾斜式冷却剪切技术可以制备具有良好组织的Al-3%Mg合金半固态坯料。获得了制备半固态Al-3%Mg合金坯料的最优工艺条件:浇注温度660~680℃;倾角40°~60°。在合理的二次加热工艺条件下,可获得优良的适于进行触变成形的半固态合金组织。二次加热的最优工艺条件为:加热温度620~630℃;保温时间90~120 min。     

半固态ZL101合金触变成形的本构关系

对半固态ZL101合金坯料进行等温压缩实验,研究变形温度、应变速率对半固态ZL101合金流动应力的影响。结果表明,半固态ZL101合金的流动应力随着变形温度的升高而降低,随着应变速率的增大而增大。DOE实验表明,应变速率对材料的流动应力影响较大。采用遗传算法对半固态等温压缩实验数据进行拟合,得到ZL101合金的本构关系,并将其导入到有限元程序中进行计算,模拟结果与实验结果基本吻合。     

ZL112Y压铸铝合金摩托车零件的半固态高压铸造成形

采用高频感应加热装置和温度测定装置，研究了ZL112Y压铸铝合金坯料高频感应加热二次重熔合适的半固态重熔温度、加热功率和速度，以及这些工艺参数对坯料的触变性能和微观组织的影响。结果表明：该合金合理的半固态二次重熔温度为570～571℃；在优化的感应加热工艺条件下，半固态重熔坯料内部的温差在0～1℃；半固态重熔过程使原始料坯中的α枝晶组织变成球团状和节杆状组织，满足了半固态触变成型的要求。采用实验室所获得的二次重熔工艺成功地压铸成形了JH70型摩托车发电机支架零件。     

铸造速度对ZL116合金半固态坯料组织的影响

采用近液相线半连续铸造技术制备ZL116合金半固态坯料,研究了铸造速度对半固态坯料微观组织形成的影响,研究表明,ZL116合金采用近液相线半连续铸造工艺,当铸造速度为150~200mm/min时,可获得分布均匀、细小的蔷薇状半固态坯料组织。     

半固态ZL101合金重熔加热时初生相的组织演变

利用低过热度浇注技术制备了半固态ZL101铝合金坯料,研究了半固态温度区间重熔加热时半固态ZL101铝合金坯料的初生相形貌的转变过程。研究结果表明,在半固态两相区保温,半固态ZL101合金的初生相逐渐团球化,该过程随保温温度的升高而加快。半固态ZL101铝合金晶粒的圆度与保温温度和保温时间的关系不大,但晶粒的尺寸随着保温温度和保温时间的增加而增大。半固态ZL101合金试样重熔加热最佳工艺制度为583℃下保温30m in,其晶粒平均等积圆直径为80μm,晶粒平均圆度为0.83。     

再熔融加热对亚共晶铝硅合金半固态组织演变的影响

提出一种新的亚共晶铝硅合金半固态坯料制备方法，即再熔融加热制备法，其特点是不对熔融金属施加任何机械的或电磁的搅拌力，而是通过在金属凝固过程中进行再熔融加热，获得具有近球状初晶相的亚共晶铝硅合金半固态组织。研究了Al-7％Si—0．2％Ti半固态合金再熔融加热制备过程中再熔融温度及保温时间等关键工艺参数对半固态组织的影响，并讨论了再熔融加热对半固态组织演变的影响。     

微成形热挤压试验及模具设计

介绍了采用半固态ZL101铝合金进行挤压成形微型齿轮的试验研究,设计了挤压模具和加热及温控系统.试验结果表明,挤压过程中的坯料温度对零件质量产生重要影响,它决定了半固态合金的触变特性,合适的半固态加工技术可以成形微型零件.     

ZL201合金半固态触变压铸的组织与性能

研究了ZL201合金半固态触变压铸组织与性能,包括半固态坯料的制备、二次加热、压铸成形和成形件的热处理.结果表明:采用低频电磁搅拌半连续铸造制备的ZL201合金半固态坯料的微观组织为均匀、细小的非枝晶,在630℃下保温20 min可获得均匀的近球形二次加热组织.半固态压铸件的组织为较大的棒状、近球状的初生固相和由细小枝晶、等轴晶组成的二次固相,而且组织致密、内部无气孔.半固态压铸件经过535℃固溶9h和175℃时效6h处理后,硬度最大为HV 116.6.     

双层金属管用半固态坯料制备及二次加热

采用机械搅拌的方法制备半固态浆料,利用专门的制坯模按照预定尺寸制得能够使用于挤压成形双层金属管的半固态AZ91镁合金棒料和A356铝合金坯料,研究制备工艺以及二次加热温度及保温时间对半固态坯料微观组织的影响.通过组织分析,对双层金属管用AZ91镁合金坯料和A356铝合金坯料的触变性进行了研究.结果表明,双层金属管用AZ91镁合金坯料最佳尺寸为24 mm,二次加热温度为560 ℃,保温时间为21 min;A356铝合金环状坯料最佳尺寸壁厚为8 mm,二次加热温度为600 ℃,保温时间为20 min时,此时能得到适合于进行半固态触变成形的球化组织.     

新型倾斜板技术制备半固态铝合金坯料和浆料

采用自行设计的波浪型倾斜板,在斜板冷却条件下制备了组织和触变性能优良的半固态合金坯料。而在斜板加热条件下制备出了组织优良的半固态合金浆料。在采用波浪型的倾斜板制备半固态合金过程中,在熔体爆发形核与枝晶破碎的共同作用下,形成了细小球形的半固态合金组织,浇注温度、冷却强度、斜板倾角和斜板表面材质是影响半固态合金组织的主要因素。得出了本试验条件下制备AlMg3合金半固态坯料的浇注温度范围为660~690℃;制备AlSi6Mg2合金半固态坯料的浇注温度范围为660~680℃;制备AlSi6Mg2半固态合金浆料的合理工艺条件为:斜板预热温度为300℃时,合金浇注温度为680℃。     

镁合金半固态坯料重熔过程数值模拟

选取了有限元软件ANSYS对镁合金半固态坯料重熔过程进行了数值模拟,并采用电磁感应加热方法。该方法不仅可以提高加热速度,还能使温度均匀化。通过改变电流密度、加热时间、初始温度及频率等参数,找出加热参数与坯料重熔参数之间的关系,以取得通过控制加热工艺参数来获取理想的镁合金半固态坯料组织的理论依据,从而指导生产过程。将所模拟的几组数据比较,选择电流密度为15e6Mm^2,对生产比较有利。考虑到实际的条件。提出了较低电流密度与多极加热结合的想法指导生产。     

The effect of globular microstructure size on the mechanical properties in reheating process of aluminum alloys

One of the important steps in semi-solid forming is the process of reheating raw materials to the semi-solid state. This process is not only necessary to achieve the required semi-solid state of the billet, but also to control the microstructure of the billet. In the reheating process, the globule size is determined by the holding time of the final reheating step. Therefore, some experiments to investigate the relationship between the mechanical properties and the holding time in the last heating step were performed. The alloys used in this experiment were 357, 319, and A390 alloys. The experiments of reheating were performed using an induction heating system with a capacity of 50 kW. This article shows the evolution of the microstructure according to the holding time of the last reheating stage. Furthermore, to evaluate the effect of globule size as determined by holding time of the final reheating step, uniaxial tension tests were performed. The stress-strain curves were plotted according to the holding time, and a relationship between the microstructure and the flow stress of semi-solid material was formulated.     

ZL112Y半固态连续触变成形料坯的温度场数值模拟

根据半固态连续触变成形的原理,自行设计了一套水平式二次重熔连续感应加热装置。采用商业软件ANSYS对该装置的3台感应加热设备不同加热功率匹配下料坯的温度场进行了计算机模拟,可得到与ZL112Y铝合金所需半固态触变温度为570-572℃相吻合的结果。而且通过模拟,获得了坯料连续式二次重熔时合理的加热参数,即大、中、小3种加热功率设备的电流分别为1350、800、600A,依次加热3min,得到的坯料温度接近于理想的半固态温度。     

A356铝合金半固态成形坯料二次加热工艺的优化

使用多工位电磁感应旋转加热装置对A356圆棒料进行重熔加热。选用不同的加热功率和工位,得到不同的非树枝晶组织,借助晶粒参数(如晶粒平均大小、形状系数、固相率等)对得到的显微组织进行研究,选出综合指标最优的加热工艺,再对该工艺加热的坯料压铸成阶梯试样。通过对阶梯试样性能分析,验证了该工艺的合理性和优越性。结合凝固理论,分析了坯料二次加热的演变规律。     

Microstructure evolution of semi-solid 2024 alloy during two-step reheating process

A two-step reheating process was proposed and applied to perform reheating experiments on the semi-solid 2024 alloy billet. In this process, the semi-solid billet was firstly heated over liquidus temperature and then isothermally held at solid-liquid zone temperature. Microstructure evolution of the semi-solid billet during two-step reheating was studied by optical microscope and compared with that during isothermal reheating. The results show that the remelting rate of the semi-solid billet during two-step reheating is faster than that during isothermal reheating. Under the same reheating time, the grains of the semi-solid billet reheated by two-step reheating process are finer and rounder than those by isothermal reheating process. The present experimental results indicate that accelerating the formation of liquid phase during the two-step reheating process can restrain the coalescence of grains to a certain extent, and thus refine the grain size and promote the grain spheroidization.     

Effects of slope plate variable and reheating on semi-solid structure of ductile cast iron

Semi-solid metal casting and forming are known as a promising process for a wide range of metal alloys production. In spite of growing application of semi-solid processed light alloys, a few works have been reported about semi-solid processing of iron and steel. In this research inclined plate was used to change dendritic structure of iron to globular one. The effects of length and slope of plate on the casting structure were examined. The results show that the process can effectively change the dendritic structure to globular. In the slope plate angle of 7.5° and length of 560 mm with cooling rate of 67K·s^-1 the optimum nodular graphite and solid globular particle were achieved. The results also show that by using slope plate inoculant fading can be prevented more easily since the total time of process is rather short.
In addition, the semi-solid ductile cast iron prepared by inclined plate method, was reheated to examine the effect of reheating conditions on the microstructure and coarsening kinetics of the alloy. Solid fraction at different reheating temperatures and holding time was obtained and based on these results the optimum reheating temperature range was determined.     

7A04合金半固态触变模锻的组织演化

研究了SIMA法制备的7A04合金在半固态触变模锻工艺中的组织演化规律.结果表明:在半固态重熔加热过程中,随着加热温度的升高和保温时间的延长,晶粒逐渐球化和长大,且加热温度对重熔加热组织的影响比保温时间大;当将具有此特征的坯料进行半固态触变模锻后,其获得的触变模锻件的显微组织与半固态重熔组织密切相关.当模锻温度达到600℃以上时,模锻件的显微组织变化不大,仍是均匀的近球形的显微组织,而且模锻件各区域的合金成分基本一致.揭示了采用半固态触变模锻工艺可获得形状复杂的高质量制件.     

AZ61合金半固态二次加热工艺及组织演变

研究了应力诱发熔体激活法(SIMA)制备的AZ61镁合金半固态坯料在二次加热时加热温度和保温时间对其组织的影响,研究表明,二次加热初期半固态组织首先熔合合并,随着保温时间延长,晶粒逐渐长大和球化,液相份数增加;保温温度越高,晶粒长大和球化速度加快。在592℃加热、保温20min~40min,可以获得均匀、圆整的半固态组织,晶粒大小为80μm~90μm,液相率为40%~42%。高于597℃时,试样重熔过程中易发生严重变形。     

6061铝合金半固态坯料二次加热工艺及组织演变

针对近液相线半连续铸造技术制备的6061铝合金半固态坯料,在不同加热温度及保温时间下进行二次加热,采用光学显微镜及图像分析仪考察试样的微观形貌及尺寸特征,结合差热分析的方法研究加热过程中的液相形成、组织演变及晶粒长大过程。结果表明,二次加热温度及保温时间共同影响着微观组织演变过程,随着加热温度升高及保温时间延长,晶粒逐渐球化并长大。加热温度越高,组织演变速度越快;保温时间越长,晶粒球化并长大越明显。有效地控制二次加热温度及保温时间,能够获得均匀、圆整且相对细小的半固态组织。     

半固态触变成形二次加热数值模拟及参数优化

半固态触变成形技术以其节省能源、成形力小和近终成形等优点受到广泛关注。通过对ZL101铝合金试样在各种不同工艺参数下的感应加热温度及温度均匀性进行的研究，运用CAE技术模拟加热频率、加热时间、线圈电流强度、线圈尺寸、加热后停留时间等参数对坯料温度场的影响，提出二次加热中获得均匀温度场的工艺条件、参数与措施。模拟结果与感应加热的实测数据具有很好的吻合性。