挤压工艺参数优化

挤压速度及温度极限与挤压机能力，合金的高温屈服强度，变形程度，表面质量和组织性能有关，本文主要阐述利用计算机确定挤压极限图，优化挤压工艺参数的方法。     

铝合金挤压时的热力学条件与出口温度的控制

温度-速度条件是铝合金热挤压过程中最重要的工艺参数,它们是决定产品组织、性能及表面质量等的关键因素,也是提高生产效率和经济效益的重要措施。本文分析了影响铝挤压材离开模子工作带出口温度的主要因素,并用传统的数值法和现代的计算机控制挤压法对出口温度进行了估算和分析,讨论了等温挤压、梯度加热和提高挤压速度等工艺技术问题,并举例说明了控制挤压的具体应用。     

粉末高温合金热挤压工艺研究进展

概述了欧美国家粉末高温合金热挤压工艺的发展历程与应用情况,阐述了我国粉末高温合金热挤压工艺的研究进展,介绍了René95、René88DT和FGH4096合金的挤压工艺参数选取原则,重点分析了挤压工艺参数（挤压比、挤压速度、挤压温度等）对粉末高温合金挤压成形及组织性能的影响规律,阐明了热挤压过程中粉末高温合金非金属夹杂物的演变行为。     

挤压工艺和模具对成品率的影响及措施

从挤压型材成品率低的原因入手，分析了挤压工艺及模具因素对成品率的影响，从铸锭长度、挤压系数、挤压温度－速度控制、模具方面提出了提高成品率的措施。     

Ti55合金挤压工艺参数研究

研究了新型耐热钛合金 Ti55的挤压工艺,提出最佳挤压温度范围,分析了坯料形状对挤压成形性的影响。同时对 FR6 防护润滑剂的合理配比等重要工艺参数进行了研究。对挤压变形前后合金的组织性能也进行了对比。     

挤压温度和挤压比对6063铝合金导热性能的影响

研究了挤压温度和挤压比对6063铝合金组织及导热性能的影响。结果表明：通过挤压能有效地改善该合金的组织,使得强化相Mg2 Si均匀弥散分布在α-Al基体上。随着挤压温度的增大,材料的热导率下降。当挤压比小于50时,材料的热导率随着挤压比的增大而增大;当挤压比大于50时,材料热导率下降。当挤压比为50,挤压温度为380℃时,材料有最大热导率221.2 W/（m.K）。     

金属挤压成形理论与技术发展的现状与趋势（3）

６ 等温挤压及ＣＡＤＥＸ技术６．１等温挤压的特点 在常规的正向热挤压过程中，金属的温度和变形是极不均匀的，导致产品的尺寸、形状组织和性能也极不均匀。当挤压开始时，由于铸锭头部与低温的模具接触，使温度降低，变形抗力增大，塑性下降，可挤压性变差。当继续挤压时，铸锭的中部和尾部由于受挤压筒高温加热及变形热的作用使温度逐渐升高。从而使铸锭的头、中、尾部的温差增大，产品质量极不均匀。为了解决这些问题，研制开发出了一种新的变形方法──等温挤压。等温挤压的特点就是要确保在整个挤压过程中，锭坯的变形温度始终保持恒…     

热挤压对FGH96镍基粉末高温合金微观组织的影响

研究了热挤压温度、挤压比、挤压速度、挤压前预处理对FGH96镍基粉末高温合金微观组织的影响规律,确定了获得晶粒尺寸小于10 μm的超塑性细晶组织的热挤压方法。研究结果表明,热等静压后FGH96合金发生了再结晶,实现了粉末的完全致密化成形,但晶粒大小极不均匀,且存在明显的原始颗粒边界(PPB)缺陷。采用热挤压前预处理工艺在确保合金晶粒不长大的同时,又可使γ'相粗化,显著降低热挤压变形抗力。随着挤压温度的升高,合金晶粒尺寸呈长大趋势。挤压温度为1 080 ℃时,获得平均晶粒小于10 μm的完全再结晶超塑性组织,挤压温度继续升高,晶粒尺寸将明显长大。随着挤压比的增大,挤压载荷明显增大,采用大于6∶1的挤压比,有利于获得平均晶粒小于10 μm的完全再结晶超塑性组织。载荷随热挤压速度的升高而增大,在保证合金组织为细晶的条件下,应尽量选择较低的挤压速度。由于在热挤压过程中合金已发生了完全的动态再结晶,未观察到明显的取向,力学性能测试结果也表明沿着挤压方向和垂直于挤压方向的性能相当,说明不同挤压方向的微织构对性能没有明显影响。     

挤压工艺对6×××系铝合金组织与性能的影响

研究了挤压工艺对6×××系铝合金挤压型材组织和力学性能的影响。结果表明:挤压温度和挤压速度对6×××系铝合金组织性能均有显著影响。挤压温度越高、挤压速度越快,容易促进型材再结晶以及晶粒的长大,不利于获得均匀、细密的显微组织。在考虑挤压机挤压能力的前提下,挤压温度控制在450℃、挤压速度3m/min可以获得较高强度的型材。     

TC2钛合金管材挤压工艺

TC2是一种a＋β型钛合金，化学成分为Ti-4Al-1.5Mn，属于中强钛合金，具有良好的可焊性，主要用作连接管路。该合金变形能力较差，压力加工成形较困难。在我国，该牌号钛合金的熔炼、锻造、棒材和板材加工技术已趋成熟，但管材加工仍属空白。针对该合金的特点，采用挤压后机加工的方法生产热加工管材。重点对化学成分、挤压温度、挤压比、退火温度对管材挤压成形、组织性能等的影响进行了研究，确定了合理的工艺参数，研制的管材表面质量、组织性能及尺寸精度完全满足相关标准要求。     

挤压工艺对TA15型材组织和性能的影响

研究了挤压变形条件与TA15挤压型材组织和性能的关系。结果表明,挤压温度在相变点以上70～120℃,挤压比为76.1～84.6时,可以获得具有细长条状α和晶界α的β转变组织及室温力学性能较稳定的型材。     

高密度钨合金静液挤压形变及其形变时效强化的研究

采用新近发展的静液挤压加工技术,对传统的W-Ni-Fe合金进行加工形变,并研究了形变时效强化作用。静液挤压加工具有良好的润滑条件和变形均匀等特点,可以提高高密度钨合金的工艺塑性,明显改善合金的力学性能。在对变形合金进行退火时发现,W-Ni-Fe合金在加热到500~600℃时有一形变时效强化区,经过时效处理的合金,其抗拉强度为1530MPa。系统研究了变形量和形变时效温度对合金力学性能的影响,讨论了合金强化的主要原因。作者认为,静液挤压加工技术是高密度钨合金形变加工的最佳工艺;随后的形变时效处理有利于进一步提高合金强度,其强化主要是钨颗粒和界面强化所致。     

温度对AZ31镁合金固相回收的性能影响

要提高镁合金的综合性能,需要进行热挤压变形.通过改变挤压温度提高镁合金的性能,并对挤压试样进行拉伸和金相观察.结果表明,挤压温度对合金的性能影响很大.通过试验,确定了合理的挤压温度.     

不同方法制备的钛及钛合金管坯组织与性能研究

分别用压力机热挤压法和两辊斜轧穿孔法获得钛及钛合金管坯,对比分析了两种不同方法制备的TA2,TA18,TC4管坯的显微组织和室温力学性能的差异。结果表明:管坯的力学性能受加热温度、变形量等因素影响,挤压管坯的组织均匀细小而斜轧穿孔的组织粗大,挤压工艺优于斜轧穿孔工艺。     

工艺流程对船用5083合金挤压型材性能的影响

为优化5083铝合金挤压型材的生产工艺,对拉伸变形及退火处理后的5083铝合金型材的力学性能及腐蚀性能进行了研究。结果表明,拉伸强化可以有效提升试样强度;完全退火降低了试样强度,提高了试样韧性;低温退火降低试样强度的同时还大幅降低了试样的抗腐蚀性能。考虑到成本因素优先考虑挤压+拉伸强化工艺流程,对于某些需要特定成型的船舶构件,也可考虑采用挤压+完全退火+拉伸强化的工艺流程。     

挤压温度和挤压比对AZ31镁合金组织性能的影响

本文研究了挤压比和挤压温度对AZ31镁合金热挤压材显微组织和力学性能的影响.结果表明,挤压可以显著细化AZ31合金的显微组织,挤压比越大,晶粒尺寸越细小,力学性能得到较大提高;随着挤压温度的升高,晶粒有所长大,抗拉强度基本呈减小趋势,而延伸率则先升后降;挤压比为35、挤压温度为350℃时,可得到细化均匀的合金组织和良好的力学性能.     

Evolution of microstructure and tensile properties of extruded Mg-4Zn-1Y alloy

In order to investigate the effect of extrusion on Mg-4Zn-1Y alloy, microstructure and mechanical properties were analyzed by optical microscopy（OM）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, X-ray diffraction（XRD）, energy dispersive spectrum（EDS） and tensile testing.The results indicated that the microstructure was obviously refined by extrusion and dynamic recrystallization.The second phases were dynamic precipitated and distributed more dispersively through extrusion.W-Phases（Mg3Zn3Y2） were twisted and broken, while I-Phases（Mg3Zn6Y） were spheroidized by deformation.Twin bands were formed to achieve the large deformation and hinder the slip of dislocations effectively to improve tensile properties.The tensile strength and elongation of extruded Mg-4Zn-1Y alloy were 254.94 MPa and 17.9% respectively which were improved greatly compared with those of as-cast alloy.The strengthening mechanisms of the extruded alloy were mainly fine-grain strengthening and distortion strengthening.     

Influence of extrusion ratio and temperature on microstructure and mechanical properties of 2024 aluminium alloy consolidated from nanocrystalline alloy powders via hot hydrostatic extrusion

Abstract

Nanocrystalline 2024 aluminium alloy powders with an average grain size less than 50 nm, prepared by a unique technique which combines rapid solidification and mechanical milling, were consolidated into bulk material under various technical conditions via hot hydrostatic extrusion and the microstructure and mechanical properties of the consolidated alloy were experimentally investigated. The influence of the two main technical parameters, extrusion ratio and temperature, on the microstructure and mechanical properties of the as extruded alloy is made clear and the reasons why these two parameters had such an influence on the microstructure and mechanical properties of the alloy are also discussed. Furthermore, suggestions are given for rationalising the extrusion ratio and temperature for the consolidation of the nanocry stalline 2024 aluminium alloy powders via hot hydro static extrusion.     

Mechanical behavior of Al-Li-SiC composites: Part I. Microstructure and tensile deformation

The microstructure and tensile properties of an 8090 Al-Li alloy reinforced with 15 vol pct SiC particles were investigated, together with those of the unreinforced alloy processed following the same route. Two different heat treatments (naturally aged at ambient temperature and artificially aged at elevated temperature to the peak strength) were chosen because they lead to very different behaviors. Special emphasis was given to the analysis of the differences and similarities in the microstructure and in the deformation and failure mechanisms between the composite and the unreinforced alloy. It was found that the dispersion of the SiC particles restrained the formation of elongated grains during extrusion and inhibited the precipitation of Al₃Li at ambient temperature. The deformation processes in the peak-aged materials were controlled by the S′ precipitates, which acted as barriers for dislocation motion and homogenized the slip. Homogeneous slip was also observed in the naturally aged composite, but not in the unreinforced alloy, where plastic deformation was concentrated in slip bands. The most notorious differences between the alloy and the composite were found in the fracture mechanisms. The naturally aged unreinforced alloy failed by transgranular shear, while the failure of the peak-aged alloy was induced by grain-boundary fracture. The fracture of the composite in both tempers was, however, precipitated by the progressive fracture of the SiC reinforcements during deformation, which led to the early failure at the onset of plastic instability.