60Si2Mn半固态轧制有限元模拟

采用多孔材料的几何模型,利用MARC软件对弹簧钢60Si2Mn半固态轧制进行了有限元模拟,分析了在热力耦合条件下,将半固态材料视为可压缩的刚-粘塑性体时的应力场、速度场、温度场的状况,并研究了不同变形条件下,应力场、速度场的变化规律,由此所进行的模拟工作较好地反映了半固态轧制过程中金属的变形规律。

小热变形半固态A2017合金的二次加热组织与半固态轧制

对单辊搅拌技术制得的A2 0 17半固态材料小热变形后二次加热时的组织演化进行了研究。小热变形后的半固态材料加热到半固态区后可获得细小的球形组织 ;在加热过程中 ,由于位错能与界面能的存在以及溶质的扩散使合金发生块状化、再结晶、熔断球化 3阶段变化 ;小变形促进该过程的进行 ;由于细小球形组织成形性能好 ,半固态轧材的断裂强度提高了 75MPa ,延伸率提高了 16 %。

变形参数对半固态轧制影响规律的有限元模拟

建立了半固态材料刚 -粘塑性分析模型 ,以高温钢铁材料为研究对象 ,用MARC软件模拟分析了半固态轧制时 ,轧辊辊缝、轧辊转速等变形参数和浆料初始温度对应力场、速度场的影响 ;结合有限元模拟结果 ,进行了半固态实际轧制试验。实际轧制试验表明 ,轧辊辊缝、轧辊转速和浆料初始温度对半固态轧制试验的影响规律基本与有限元模拟一致 。

气雾化粉末在半固态轧制过程中的液相渗透现象(英文)

在氢气保护性气氛下,采用半固态轧制工艺将Al-5.8Zn-1.63Mg-2.22Cu-0.12Zr（wt%）粉末制备出生带材。研究了加热相同温度610℃（i.e.液相分数f s≈53%）时,不同的加热时间对生带材显微组织的影响,重点研究了液相渗透现象。结果表明：液相渗透程度越高,颗粒在接触界面的边界加速消失,颗粒边界发生了较大的变化。当在610℃下加热,保温时间由10 min延长至30 min时,η（Mg Zn2）相的数量减少,且在晶界处析出了更多的Al2Cu颗粒。Al-5.8Zn-1.63Mg-2.22Cu-0.12Zr（wt%）粉末在610℃下半固态轧制,其最优的保温时间为20~30 min。研究结果表明通过优化半固态轧制工艺可以制备出性能优异的带材。

半固态60Si2Mn直接轧制成形技术的研究

利用自行研制的高熔点半固态金属材料和轧制设备 ,对 60Si2Mn弹簧钢进行半固态直接轧制成形 ,并研究流变行为和规律 ,探索出适合于半固态钢铁材料直接轧制成形的生产工艺。研究结果表明 :固 -液两相的塑性变形行为是不同的 ,从而导致了轧制产品的心部和边部在组织及性能上的差异。在变形过程中 ,大多数的固相集中在试样的心部 ,而液相则流向轧件的边部。随着固相率的提高 ,固相颗粒发生塑性变形的程度亦提高。若半固态浆料中液相含量过少或变形速率过大、轧辊表面与轧件的温差过大 。

高碳工具钢半固态流变轧制

探讨了高碳工具钢常规的加工方法和半固态流变轧制技术,结果表明将在凝固过程中进行搅拌后制备的高碳工具钢半固态浆料直接进行流变轧制,可生产出成分均匀、没有偏析的产品,消除了在常规轧制中很难克服的网状碳化物等缺陷;半固态固相颗粒细小而且星球状可生产出高强、高韧性的工具钢。半固态轧制有可能成为未来高碳工具钢生产的一种新工艺。

工艺条件对AZ91镁合金半固态流变轧制组织的影响

利用自行设计的半固态流变轧制装置,成功制备了断面为5 mm×50 mm的AZ91镁合金板材,并研究了工艺条件对制品组织的影响。结果表明：在工作辊线速度一定的条件下,浇注温度在650~730℃变化时,随着浇注温度的降低,固相率增大,浆料受到倾斜板的剪切作用增强,合金组织逐渐细化。当浇注温度一定时,工作辊线速度在0.052~0.087 m.s-1变化时,随着工作辊线速度增大,轧制时间缩短,组织中固相率减小。当浇注温度和工作辊线速度不变时,在工作辊中通冷却水提高浆料的冷却强度,提高了合金的过冷度及形核率,有效抑制了晶粒的长大,工作辊通水冷却更容易获得组织细小的制品。在本试验条件下,半固态流变轧制AZ91镁合金的最佳工艺条件：工作辊通水冷却,浇注温度为650℃,工作辊线速度为0.052 m.s-1。

温度与保温时间对半固态粉末轧制AA2024带材性能与显微组织的影响

采用半固态粉末轧制法制备2024铝合金带材,研究粉末加热温度和保温时间对轧制力、带材的相对密度及显微组织的影响。结果表明:2024铝合金带材的相对密度随粉末温度升高而增大,随保温时间延长而提高。粉末在585℃保温40 min后轧制,可获得形貌规整、无表观缺陷且晶粒细小均匀的等轴晶带材,带材相对密度达到93.28%。半固态粉末轧制力仅为室温下固态粉末轧制力的33.5%。半固态粉末轧制带材组织内仍存在少量孔隙,进一步热轧后可达到近全致密,显微硬度提高77.8%。因此,半固态粉末轧制对于缩短工艺流程,减小轧制力,制备高致密度的2024铝合金带材具有明显的优势。

半固态粉末轧制法制备SiC_p/AA2024复合带材的显微组织与力学性能

以组合雾化法制备的2024铝合金粉末和SiC颗粒为原材料,采用半固态粉末轧制法,在575~635℃温度下制备10%SiC_p/AA2024复合带材,研究粉末加热温度对带材显微组织与力学性能的影响,并与相同条件下制备的AA2024铝合金带材进行对比。结果表明:升高粉末加热温度可促进AA2024粉末变形或破碎,所得10%SiC_p/AA2024复合带材具有半固态特征的球状或近球状显微组织。与AA2024合金带材相比,SiC_p/AA2024复合带材的基体晶粒更加细小。SiC颗粒与液相Al没有发生显著的界面反应,未生成对体系有害的Al4C3物质。SiC_p/AA2024复合带材和AA2024合金带材的屈服强度、抗拉强度及伸长率都随粉末加热温度适当升高而提高,SiC_p/AA2024带材的屈服强度和抗拉强度分别在366~412 MPa和425~514 MPa之间,均明显高于AA2024合金带材,伸长率为3.1%~4.9%,断裂方式主要为脆性断裂。AA2024带材的屈服强度在265~348 MPa范围内,抗拉强度为362~423 MPa,拉伸断裂方式随加热温度升高由脆性断裂向韧性断裂转变。

辊型对半固态变形影响的三维有限元分析

采用多孔材料的几何模型,利用MARC有限元软件对弹簧钢60Si2Mn半固态轧制过程进行了三维有限元模拟,分析了在平辊和孔型轧制条件下的应力、应变场.在孔型中轧制,轧件变形区横截面上应力、应变场分布均匀.模拟结果与实验结果相吻合,说明半固态材料适合在孔型中轧制.

半固态成形技术的研究概况与发展前景

半固态成形技术是 ７０年代才发展起来的新的金属成形技术，主要包括半固态轧制、半固态锻造、半固态挤压、流变铸造、触变铸造等工艺类型，和旧有工艺相比优点明显，应用日趋广泛，有着良好的发展前景，被称为２１世纪新兴的金属制造关键技术之一。

液芯铸轧制实验及生产研究进展

集中论述了近年来液芯铸轧制技术在国内外的实验研究和工业化生产中的探索。分析了目前工业化应用中应解决的问题和实验室应开展的进一步研究。

Effects of technical parameters of continuous semisolid rolling on microstructure and mechanical properties of Mg-3Sn-1Mn alloy

A sloping semisolid rheo-rolling process of Mg-3Sn-1Mn alloy was developed, and the effects of process parameters on the microstructure and mechanical properties of Mg-3Sn-lMn alloy strip were studied. The results show that the primary grain average diameter of the strip increases with the increase of the roll speed. The primary grain average diameter decreases firstly and then increases with the increase of the vibration frequency, and the tensile strength and elongation of the strip increase firstly and then decrease with the increase of the vibration frequency. The primary grain average diameter increases with the increase of casting temperature, and the tensile strength and elongation of the strip decrease correspondingly. When the casting temperature is 670℃, the roll speed is 52 mm/s, and the vibration frequency is 60 Hz, Mg-3Sn-1Mn alloy strip with good properties is produced. The mechanical properties of the present product are higher than those of Mg-3Sn-lMn alloy casting with the addition of 0.87% Ce （mass fraction）.

Microstructure evolution and solidification behaviors of A2017 alloy during cooling/stirring and rolling process

A novel semisolid rheo-rolling process of A2017 alloy was achieved by combining the shape rolling mill with the vibrating sloping plate device. The microstructure evolution and solidification behaviors during the process were investigated. The high cooling rate caused by the sloping plate and stirring action caused by the vibration and metal flow lead to a high nucleation rate as well as two primary grain growth patterns, direct globular growth as well as dendrite growth and subsequent breakage, which causes the formation of fine spherical or rosette primary grains. During the rolling process, the grains of the strip were elongated. The primary grain size of A2017 alloy strip increases with the increment of casting temperature. When the casting temperature was between 650 °C and 660 °C, A2017 alloy strip with good quality was produced by the proposed process. The microstructures of the strip are mainly composed of spherical or rosette grains.

Microstructural evolution of gas atomized Al-Zn-Mg-Cu-Zr powders during semi-solid rolling process

Under H2 atmosphere, the green strips were prepared from Al-5.8Zn-1.63Mg-2.22Cu-0.12Zr(mass fraction, %) powders by the semi-solid rolling process with a relative density from 76.1% to 88.0%. The role of temperature on microstructure and mechanical properties was investigated. With increasing rolling temperature from 580 to 610 °C, the disappearance of primary powder boundary and isolated pores, inter-diffusion of species and the change of grain boundary were accelerated. Moreover, the mechanism of microstructure evolution changes from the densification dominant regime to the coarsening dominant regime; the amount of η(MgZn2) phase decreased and more Al2 Cu particles precipitated at grain boundaries. The optimum temperature for semi-solid rolling of Al-5.8Zn-1.63Mg-2.22Cu-0.12 Zr powders was determined. The liquid fraction in the range of 53% to 67% corresponds with a high density level of green strips. The present experimental analysis suggests that semi-solid powder rolling can be optimized to manufacture strips with high mechanical properties.

Densification process of 10%B_4C-AA2024 matrix composite strips by semi-solid powder rolling

Semi-solid powder rolling（SSPR） is a novel strip manufacturing process,which includes the features of semi-solid rolling and powder rolling.In this work,densification process and deformation mechanisms of B4 C and AA2024 mixed powders in the presence of liquid phase were investigated.The relationships between relative densities and rolling forces were analyzed as well.The results show that liquid fraction plays an important role in the densification process which can be divided into three stages.Rolling deformation is the main densification mechanism in deformation area when the liquid fraction is lower than 20%.When the liquid fraction is equal to or higher than 20%,the flowing and filling of liquid phase are the densification mechanisms in deformation area.The relative densities increase with increasing rolling forces.The relative density–rolling force curves are similar at 550 °C and 585 °C.The characteristics of the curve shapes are apparently different at 605 °C and 625 °C.

粉末轧制成形技术研究进展

介绍了粉末轧制过程,论述了粉末轧制技术的工艺参数、技术改进和以其为基础开发的半固态粉末轧制技术,阐述了近些年来粉末轧制技术的应用情况,最后对这些技术进行了总结和展望。