热处理对TC21合金力学性能及应变率敏感性的影响

采用万能材料试验机和分离式Hopkinson压杆,分别对不同热处理制度下的TC21合金试样进行测试,研究热处理对TC21合金静态、动态力学性能及其应变率敏感性的影响.结果表明,在准静态下,1#双态组织塑性最好,强度较低;2#三态组织的塑性相对较好,强度也有所增强;3#网篮组织的强度较高,但塑性较差;4#固溶时效组织的强度与3#相当,且具有更好的塑性.在高应变率下,1#表现出最大的应变,但流变应力最低;2#流变应力相对较高,但断裂应变更小;3#流变应力最高,断裂应变最小;4#流变应力与3#相当,但应变稍大.4种组织在高应变率下都表现出应变率敏感性,高低依次为4#3#2#1#.     

不同加工方式对TC4钛合金组织与力学性能的影响

分别采用激光快速成型(3D打印)技术、锻造和铸造方法制备了TC4钛合金试样.通过光学显微镜、扫描电镜和X射线衍射仪以及力学性能测试设备分别分析了不同制备方式成型样品的微观组织和力学性能变化规律.结果表明,3D打印成型的钛合金组织和性能有明显的取向性.3D打印横向样品抗拉强度和延伸率分别为1 013 MPa和8%,纵向抗拉强度和延伸率分别为972 MPa和15%;锻造样品抗拉强度和断后延伸率分别为877 MPa和18%;铸造样品的抗拉强度和延伸率分别为836 MPa和4%.不同成型方式样品力学性能的差异来自于其形成的不同微观组织和晶粒大小.3D打印TC4钛合金样品会在其成型快速冷却过程中形成网篮组织,且晶粒非常细小,约为2～3μm.锻造样品成型时形成等轴组织,晶粒尺寸约为10μm,且微观组织比3D打印和铸态合金更加均匀,因而具有更高的延伸率.铸造样品中形成魏氏组织,晶粒尺寸达到20～25μm,组织分布亦不均匀,因而,其具有更低的力学性能指标.     

退火温度对TC4ELI钛合金大规格环材组织和力学性能的影响

采用光学显微镜、万能材料试验机和金属摆锤式冲击试验机研究了退火温度对TC4ELI钛合金大规格环材（Φ3 384 mm/Φ3 300 mm×1 950 mm）的显微组织和力学性能的影响。显微组织分析结果表明：退火温度在850 ℃以下时,TC4ELI钛合金大规格环材退火后的显微组织与热加工态的显微组织基本相同;900 ℃退火后,TC4ELI钛合金大规格环材中部分片层状或针状α相的尺寸增大,同时出现了尺寸微小的等轴α相。力学性能测试结果表明：随着退火温度的升高,TC4ELI钛合金大规格环材的强度和伸长率有所提高;850 ℃以下退火,TC4ELI钛合金大规格环材断面收缩率变化不大,850 ℃以上退火,其断面收缩率显著升高。冲击试验结果表明：随着退火温度的升高,TC4ELI钛合金大规格环材的冲击功逐渐增加。经800～900 ℃保温2 h空冷后,TC4ELI钛合金大规格环材抗拉强度、屈服强度、塑性与冲击功达到较好匹配。     

循环热处理及形变对TC17钛合金片层组织球化和取向的影响

将循环热处理与形变相结合,利用电子背散射衍射等手段探究该工艺对TC17钛合金片层组织球化和取向的影响.结果表明:TC17钛合金在两相区进行单纯的循环热处理其片层组织球化程度有限,而经过循环热处理+压缩变形后,其魏氏组织消失,片层α相得到明显球化,但是其取向均匀性仍没发生较大变化.此外,变形中两相的再结晶速度及其强韧性导致了两相取向的差异性.α相的再结晶速度快于β相,在变形过程中,α相的各向异性首先降低;另一方面,由于α相比β相硬度高,热变形过程中,α相的变形程度小于β相,应变主要集中在与α相邻近的较软的β相,从而导致α相的取向均匀性高于β相.     

腐蚀环境对TC21钛合金疲劳行为的影响

基于飞机零部件在服役过程中因腐蚀导致疲劳断裂的问题,采用疲劳试验机、扫描电子显微镜对TC21钛合金在两种腐蚀环境以及室温空气环境下的疲劳进行了研究。结果表明,相同环境下随着应力降低,合金晶体内部位错累计能量速率减缓,合金疲劳寿命增加。同等应力条件下,3.5%NaCl水溶液环境下合金疲劳寿命最低,油箱积水环境下次之,室温空气环境下合金疲劳寿命最高。当应力较低时,差异更为显著。腐蚀环境下试样疲劳寿命较低,主要原因在于合金与溶液中离子发生反应形成大量腐蚀产物,促进裂纹萌生、加速裂纹扩展。     

显微组织对TC11钛合金机械性能的影响

对TC11钛合金进行预处理,然后在两相区用不同温度进行不同程度变形,获得等轴组织、双态组织和网篮组织,分别测试了3种显微组织的机械性能。结果表明,双态组织具有良好的室温及高温综合机械性能和较高的低周疲劳寿命。     

热处理工艺对某低合金钢组织和力学性能的影响

利用拉伸试验,研究了某低合金钢在不同温度退火和固溶处理后的力学性能行为,并通过金相组织分析探讨了其原因.结果表明,随着退火温度的升高,该钢的强度几乎不变,塑性和韧性略有降低.与退火态相比,固溶处理后,屈服平台宽度明显减少;碳化物沿晶界析出,起到明显强化作用,该钢强度显著增加,塑性、韧性和形变强化指数降低.     

多级断续时效对Mg-Zn-Mn合金显微组织和力学性能的影响

为探索镁合金的多级时效工艺,利用Ｘ射线衍射、光学金相、扫描电镜以及能谱分析、透射电镜、显微硬度、力学性能测试等实验手段,研究了多级断续时效（T6I6）对ZM61新型镁合金显微组织和力学性能的影响。结果表明,与T6态相比,T6I6工艺更能显著提高合金强度,显微硬度为90HV,屈服强度为340Mpa,抗拉强度达到356Mpa,强度增幅分别为13%和8%;T6I6处理使合金晶间干净,第一级和第二级过程中只有Mn以α-Mn的形式继续析出,形成更多的Mn单质颗粒,终级时效的硬化幅度增加,且峰时效时析出了弥散分布的β'相,使强化效应得到充分发挥。     

α相与β相比例对TC6钛合金力学性能的影响

 通过热处理方法获得TC6钛合金3种典型组织,利用电液伺服材料试验机测定3种组织的静态力学性能,通过专用图形分析软件测定3种组织中α相与β相比例,对比分析了α相与β相比例对TC6钛合金静态力学性能的影响.结果表明:组织中α相比例增大(即β相比例减少)时,相应组织塑性也增大,而强度随着α相比例增大(即β相比例减少)而减小.     

Influence of multi-stage heat treatment on the microstructure and mechanical properties of TC21 titanium alloy

Duplex-structured TC21 alloy samples were first solution-treated at a higher temperature in the α + β region(940°C) with furnace cooling(FC), air cooling(AC), and water cooling(WC), followed by a second-stage solution treatment at a lower temperature in the α + β region(900°C), and then finally aged at 590°C. The effects of the morphology and quantity of α phases on the structure and properties of the TC21 alloy after the different heat treatments were analyzed. The in-situ tensile deformation process and crack propagation behavior were observed using scanning electron microscopy(SEM). The quantity of equiaxed α phases as well as the thickness of lamellar α phases reduced, the tensile strength increased firstly and then decreased, the elongation decreased with the increasing cooling rate after the first-stage solution treatment. The amount and size of lamellar α phases increased after the second-stage solution treatment because of sufficient diffusion of the alloying elements, thereby leading to increased tensile strength. The amount of dispersed α phases increased after the third-stage aging treatment owing to the increase in the nucleation rate, resulting in a noteworthy strengthening effect. After the third-stage aging treatment, the first-stage FC sample exhibited better mechanical properties because it contained more equiaxed α and βtrans phases than the first-stage AC and WC samples.     

TC4钛合金薄板储能焊接头组织与性能

采用微型储能焊机对厚度为0．2mm的TC4钛合金薄板进行了快速连接,并研究了接头组织形貌及焊接参数对接头力学性能的影响。结果表明：储能焊能够实现TC4钛合金薄板的快速凝固焊接,焊接接头由熔核和熔核向母材过渡的熔合区（线）组成。极短的焊接时间和高的冷却速率,使得熔核凝固过程具有快速凝固特征,熔核中凝固组织得到显著细化。当焊接工艺参数为电压250V、电容6600妒、电极力20N时,接头剪切强度可达601MPa。     

室温下TC11钛合金准静态拉伸力学性能实验研究

针对典型航空材料TC11钛合金的拉伸性能,采用准静态拉伸实验对不同应变率条件下的TC11钛合金的应力-应变关系进行了研究,利用扫描电镜分析了其拉伸断口形貌。实验结果表明:TC11钛合金具有一定的应变率敏感性,抗拉强度和屈服强度均会受到应变率的影响;准静态拉伸时TC11钛合金试样出现了颈缩现象,试样截面形状为杯锥状,试样断口存在光滑的剪切唇区和灰色的纤维区,其断裂属于韧性断裂,但是其韧性较差;TC11钛合金拉伸断口形貌主要为大小不一的韧窝,随着应变率的增大,试样拉伸断口韧窝的大小和深度均变小,同时出现了少量的撕裂棱和准解理面,试样的断裂机制为以韧性断裂为主和伴有准解理断裂。因此,在准静态拉伸条件下,TC11钛合金的力学行为与应变率有关。     

Effects of heat treatment on the microstructure and mechanical properties of Ni3Al-based superalloys: A review

Ni₃Al-based alloys have drawn much attention as candidates for high-temperature structural materials due to their excellent comprehensive properties.The microstructure and corresponding mechanical properties of Ni₃Al-based alloys are known to be susceptible to heat treatment.Thus,a significant step is to employ various heat treatments to derive the desirable mechanical properties of the alloys.This paper briefly summarizes the recent advances in the microstructure evolution that occurs during the heat treatment of Ni₃Al-based alloys.Aside fromγ′phase andγphase,the precipitations ofβphase,α-Cr precipitates,and carbides are also found in Ni₃Al-based alloys with the addition of various alloying elements.The evolution in morphology,size,and volume fraction of various types of secondary phases during heat treatment are reviewed,involvingγ′phase,βphase,α-Cr precipitate,and carbides.The kinetics of the growth of precipitates are also analyzed.Furthermore,the influences of heat treatment on the mechanical properties of Ni₃Al-based alloys are discussed.     

热处理工艺对Mg-RE-Zn-Zr系合金显微组织及力学性能的影响

通过气体保护制备了Mg-RE-Zn-Zr[RE-Ce-40La（wt％）的富铈稀土]合金,并对合金进行了热处理,测试了不同状态下合金的硬度、抗拉强度及伸长率等力学性能,采用光学显微镜、X射线衍射仪及扫描电镜对合金显微组织、拉伸断口进行了分析。结果发现,采用T6热处理工艺后,合金的晶粒尺寸明显细化,硬度、抗拉强度、屈服强度和伸长率显著提高,分别提高了11％,24％,7．3％和102％。     

固溶处理对TC16钛合金显微组织和拉伸性能的影响

通过金相显微镜和室温拉伸性能测试,研究固溶处理对TC16钛合金棒材显微组织和拉伸性能的影响.结果表明:TC16钛合金低于800℃进行固溶处理,初始组织为初生α相和亚稳态β相,随着固溶温度的升高,亚稳态β相会发生α"马氏体转变,温度达到900℃时,α"马氏体析出晶界完整的β相,出现过烧组织,抗拉强度和屈服强度先降后升,温度对塑性影响不大.该合金固溶处理后,冷镦性能差,不同的冷却速度使钛合金有不同的α和β相比率,冷却速度决定β→α转变反应中间相的形成条件,水淬、空冷、炉冷后的TC16钛合金显微组织和拉伸性能差异较大.     

Effects of heat treatment on microstructure and mechanical properties of SLMed Sc-modified AlSi10Mg alloy

The influence of heat treatments on the microstructures and mechanical properties of the selective laser melting manufactured AlSi10Mg alloy modified with Sc was systematically investigated. The results showed that the addition of Sc element introduced primary Al₃ Sc, which increased the heterogeneous nucleation during the solidification of AlSi10Mg alloy, and then the ultrafine network eutectic structure was obtained, and hence the tensile strength was improved significantly(nearly 2...     

氧含量对Ti-35Nb-3.7Zr-1.3Mo-xO合金组织与力学性能的影响

根据d电子设计理论设计了新型亚稳β合金Ti-35Nb-3.7Zr-1.3Mo-x O,研究了氧含量对该合金组织与力学性能的影响.实验结果表明,合金经固溶后主要为β相,其晶粒尺寸随氧含量提高而细化.低氧合金中存在少量α″相,氧元素对水淬α″相的形成具有抑制作用.冷轧后组织仍主要为β相,但因大变形后缺陷增多而结晶度降低.不同氧含量的合金冷轧后分别出现细针α″相、板条状ω相、锯齿孪晶以及应力诱发α″相等特殊组织.冷轧态Ti-35Nb-3.7Zr-1.3Mo-x O合金的抗拉强度、弹性模量和硬度均随氧含量的提高而升高,但塑性变差.氧含量升高0.1%,则抗拉强度增加约100 MPa;氧含量升高0.3%,则维氏硬度升高约为50;弹性模量处于45~75 GPa之间.在氧含量超过0.6%以后,合金塑性明显变差.     

Effect of pre-annealing treatment on the microstructure and mechanical properties of extruded Al-Zn-Mg-Cu alloy bars

Taking extruded Al-Zn-Mg-Cu alloy (7A04 alloy) bars as the research object, the effect and mechanism of pre-annealing treatments on the microstructure and mechanical properties of the aged alloy bars were investigated. The results show that a pre-annealing treatment at 350℃ for 15 h before a T6 treatment substantially reduced the sensitivity of the microstructure and mechanical properties of the extruded 7A04 aluminum alloy specimens toward the extrusion temperature. The average grain sizes of the specimens extruded at 390 and 430℃ after T6 treatment were 3.4 and 8.1 μm, respectively, and their elongations to failure were 7.0% and 9.2%, respectively. However, after pre-annealing + T6 treatment, the differences in both the grain sizes and the elongations of the specimens became small, i.e., their average grain sizes were 3.2 and 3.8 μm and their elongations were 12.0% and 13.3%, respectively. For the specimens extruded at the same temperature, pre-annealing treatment obviously improved the plasticity of the alloy, which is attributed to an increase in soft texture or to grain refinement in the specimens as a result of the pre-annealing + T6 treatment.