美国海军新型飞机上用的6013铝合金板

近期研制成功的6013-T6铝合金板材已被美国海军选作P-7A飞机机身蒙皮板及一些其他应用件的材料,取代了以前惯用的2024-T3包铝板材。6013-T6合金具有很好的耐蚀性,这一点与老牌的同系合金6061相似,因此不用包铝。该合金的疲劳强度、疲劳裂纹扩展速率和断裂韧性均优于2024-T3的。用6013合金取代2024合金还能降低成形零部件的加工成本,因为6013合金易于在T4状态下成形,随后就可轻易地时效到T6状态,这样就避免了象2024合金那样昂贵的热处理及矫直工序。     

热处理工艺对2A97Al-Li合金拉伸性能的影响:实验和BP人工神经网络模拟(英文)

研究热处理工艺对2A97Al-Li合金拉伸性能的影响。结果表明:从传统T8工艺改进的、具有预时效和中间变形的热处理工艺可以有效地改进Al-Li合金的拉伸性能。合金经该热处理工艺处理后,在峰时效条件下,基体中析出大量的T1相,同时,晶界无第二相析出,并且晶界上无沉淀析出带不明显。峰时效合金的抗拉强度、屈服强度和伸长率分别为597MPa、549MPa和7.4%。此外,建立BP人工神经网络模型对经不同热处理工艺处理的合金的拉伸性能进行预测,所得预测结果与实验结果吻合较好,表明该人工神经网络模型可用于预测2A97Al-Li合金的拉伸性能。     

热处理对7085铝合金应力腐蚀开裂、断裂韧性和强度的影响

采用慢应变速率拉伸应力腐蚀测试、Kahn撕裂实验和室温拉伸实验结合透射电子显微镜和扫描电子显微镜,研究热处理对7085铝合金应力腐蚀开裂、断裂韧性和强度的影响。结果表明：与T6时效相比,经T74时效处理的合金的断裂韧性提高22．9％,但屈服强度降低13．6％;经回归再时效（RRA）处理的合金屈服强度与T6的相当,断裂韧性提高14．2％。经两次回归再时效（DRRA）处理的合金断裂韧性与T74处理的相当,但屈服强度提高14．6％。合金的应力腐蚀开裂抗力依次为：T6〈RRA〈DRRA≈T74。热处理对合金应力腐蚀开裂和断裂韧性的影响主要与基体析出相和晶界析出相有关。     

T6热处理对6061铝合金大型锥筒形件的力学性能及组织的影响

研究了T6热处理对成形后6061铝合金构件组织和力学性能的影响。在经过不同的T6热处理后,通过电子拉伸实验研究构件力学性能的变化规律,利用光学显微镜、扫描电子显微镜和X射线衍射仪对热处理温度和时间对组织结构的影响进行分析。结果表明,固溶处理的合金中存在β-Al₅FeSi和Mg₂Si相。固溶处理温度和时间对合金的拉伸性能及塑性有显著影响。随着固溶温度及时间的增加,在560℃固溶4 h时抗拉强度及塑性最好,分别为211.62 MPa和和38.3%;相对于人工时效保温时间,人工时效温度对合金的拉伸性能及塑性的影响更大,在170℃人工时效10 h时力学性能最好,屈服强度和抗拉强度分别为145.26和363.30 MPa,伸长率为18.32%。     

固溶工艺对6061铝合金组织和拉伸性能的影响

采用光学显微镜、扫描电镜和拉伸试验等方法,研究了固溶处理工艺对6061铝合金微观组织和力学性能的影响。结果表明,随固溶时间的延长和固溶温度的升高,合金中可溶第二相粒子逐渐溶解,再结晶增强,晶粒细化,合金拉伸性能升高;进一步延长固溶时间和提高固溶温度,合金晶粒粗化,合金强度下降。热处理后残留粗大第二相粒子的多少和合金晶粒大小是影响合金拉伸性能和断口形貌的主要因素。时效工艺为180 ℃×8 h条件下,6061铝合金的最佳固溶工艺为535 ℃×80 min。     

一种新型Al-Cu-Li合金性能研究

摘 要: 设计一种新型Al-Cu-Li-Mg-Ag合金，探索热处理制度对新合金拉伸性能及裂纹扩展性能的影响，利用光学显微镜、透射电镜和扫描电镜等手段研究合金微观组织及断口形貌。研究结果表明：该新型铝锂合金经过540℃固溶1小时，（12?AaRT（5d） 145℃（20h））双级时效热处理后获得良好的综合性能：抗拉强度σb =443Mpa，屈服强度σ0.2 =397Mpa，延伸率δ=16.5%，裂纹扩展速率da/dn≈1.34*10-3mm/cycle（△K=30 Mpa*m1/2）。双级时效态下析出大量细小均匀的T1相，在保证合金强度的同时，提高合金的抗疲劳裂纹扩展性能。T8态下析出相对粗大的T1相，θ′相和极少量的S′相，合金强度达到项目要求，抗疲劳裂纹扩展性能较差。T3态下析出相数量少，合金强度不满足项目指标。     

热处理工艺对7050铝合金的抗拉性能及碱性NaCl溶液中抗应力腐蚀性能的影响

通过进行恒定拉伸速率实验（CERT）,研究了热处理工艺（即T6、T73、RRA、OP1、OP2）对7050铝合金的抗拉强度及其在pH=12的3．5％NaCl溶液中抗应力腐蚀性能的影响。研究结果表明：T6态时合金抗拉性能提高,而抗应力腐蚀性能降低。相反,T73态（即T6＋160℃／30h）时合金的抗应力腐蚀性能提高,但其抗拉性能降低。回归再时效工艺（RRA,即T6＋200℃／10min＋水淬＋120℃／24h）下的合金抗拉性能和抗应力腐蚀性能均有提高,但此类现象仅限于薄且小的试样。分级淬火时效工艺（SQA,即470℃／1h＋分级淬火200℃／1min＋水淬或空冷＋室温自然时效／1周＋120℃／24h）则是一种应用性较强的热处理工艺,无论水淬（OP1）或空冷（OP2）均能同时提高抗拉性能和抗应力腐蚀性能。通过电化学测试和微观组织结构观察表明,7050铝合金的抗拉性能和抗应力腐蚀性能决定于合金本身的微观组织结构,而材料的微观组织结构又依赖于材料的热处理工艺。     

热处理对A356铝合金组织结构和力学性能的影响

用两种不同的热处理制度对稀土和锶综合细化变质的A356合金进行处理,一种是长时间标准处理制度T6（535℃固溶4h＋150℃时效15h）,另一种是短时间的热处理制度ST（550℃固溶2h＋170℃时效2h）。采用光学显微镜、扫描电镜及室温拉伸实验等手段分析热处理制度对A356合金微观组织和拉伸力学性能的影响。结果表明：在550℃下固溶2h可以获得Mg、Si过饱和且分布均匀的α（Al）固溶体,并使共晶硅相球化;再经170℃人工时效2h后,可以达到传统T6处理的时效析出效果。拉伸实验结果表明,A356铝合金经传统T6处理得到了最高的拉伸强度和断裂伸长率;通过ST短时热处理后,其拉伸强度、屈服强度及伸长率分别可以达到T6处理时的90%,95%和80%。     

冷加工和时效处理顺序对6061铝合金力学性能的影响(英文)

研究不同的析出硬化和冷加工组合对6061铝合金拉伸性能的影响。结果表明,在不同的热处理过程中,在180℃单时效4h能提高合金的强度和伸长率。然而,双时效处理不能改善其力学性能。另外,预时效对随后的析出硬化有负面影响。合金力学性能的变化归因于析出硬化、应变硬化和加工软化的竞争而引起的显微组织演变。     

T6I6时效对6061铝合金拉伸及晶间腐蚀性能的影响

对T6I6时效处理的6061铝合金的拉伸性能、晶间腐蚀性能和电导率进行了测试,并采用OM和TEM对其组织进行了观察.结果表明,6061铝合金经180℃×8 h T6峰值时效后,虽然强度较高,但有严重晶间腐蚀倾向;T6I6预时效时间对拉伸性能影响不大,但中断时效温度和时间对其影响显著.由于较高的中断时效温度和较长的中断时间能获得高密度的晶内析出相和呈球状不连续分布的晶界析出相,因此,T6I6时效处理后的6061铝合金不仅能保持较高强度,同时还能显著提高晶间腐蚀抗力.经180℃×2 h+150℃×2160 h+180℃×8 h T6I6时效,合金抗拉强度和屈服强度分别为348.5和326.9 MPa,相对于T6状态,仅分别下降了2.1%和1.4%,腐蚀类型由T6状态的晶间腐蚀转变为均匀腐蚀,腐蚀深度约为30μm.     

Microstructure and mechanical properties of laser beam welding 6061 aluminum alloy with different states

With the diversification of manufacture methods,joining the same materials with different states becomes indispensable in practical application.In present work,6061 aluminum alloys with different states were welded by laser beam welding (LBW).The microstructures of welded joint,before and after heat treating,were investigated.The mechanical properties,such as the tensile properties and microhardness,were tested.And the fracture characteristic was observed by means of scanning electron microscope (SEM).The results show that the 6061 aluminum alloys have superior weldability and the microstructures are different significantly in different states.Besides,the grain boundaries of the joint microstructures become unclear after the heat treating.The strength and the elongations of welded joints could reach to those of the base metal.The tensile fracture occurs in the fusion zone and near 6061-0 alloy.And the fracture presents ductile rupture.Therefore,the LBW is an effective method for 6061 aluminum alloy.     

Aluminum alloy 6013 sheet for new U.S. Navy aircraft

The recently developed aluminum alloy 6013-T6 has been selected for the fuselage skin and other applications on the U.S. Navy’s P-7A airplane, in place of the traditional 2024-T3 clad sheet. Alloy 6013-T6 is naturally corrosion resistant, like the well-established alloy 6061, and hence is used unclad. Its fatigue strength, fatigue crack growth and fracture toughness compare favorably with 2024-T3. Replacement of alloy 2024 with alloy 6013 also reduces manufacturing costs for formed parts, because 6013 is readily formed in the T4 temper, then simply aged to T6, thus avoiding the costly heat treatments and straightening required for alloy 2024.     

Mechanical properties of friction stir welded Al alloys with different hardening mechanisms

The mechanical properties of precipitation hardened Al 6061-T651 and Al 7075-T6 and strain hardened Al 5083-H32, friction stir welded with various welding parameters, were examined in the present study. 4 mm thick Al 6061-T651, Al 7075-T6, and Al 5083-H32 alloy plates were used for friction stir welding (FSW) with rotating speed varied from 1000 to 2500 rpm (rotation per minute) and welding speed ranging from 0.1 to 0.4 mpm (m/min). Each alloy displayed slightly different trends with respect to the effect of different welding parameters on the tensile properties of the FSWed Al alloys. The tensile elongation of FSWed Al 6061-T651 and Al 7075-T6 tended to increase greatly, while the tensile strength decreased marginally, with increasing welding speed and/or decreasing rotating speed. The tensile strength and the tensile elongation of Al 6061-T651 decreased from 135 to 154 MPa and 10.6 to 17.0%, respectively, with increasing welding speed from 0.1 to 0.4 mpm at a rotating speed of 1,600 rpm. Unlike the age-hardened Al 6061-T651 and Al 7075-T6, the strain-hardened Al 5083-H32 showed no notable change in tensile property with varying welding parameters. The change in the strength level with different welding parameters for each alloy was not as significant as the variation in tensile elongation. It was believed that the tensile elongation of FSWed Al alloys with varying welding parameters was mainly determined by the coarse particle clustering. With respect to the change in tensile strength during friction stir welding, it is hypothesized that two competing mechanisms, recovery by friction and heat and strain hardening by plastic flow in the weld zone offset the effects of different welding parameters on the tensile strength level of FSWed Al alloys.     

热处理对砂型铸造Mg-4Y-2Nd-1Gd-0.4Zr镁合金显微组织和力学性能的影响(英文)

研究热处理工艺对砂型铸造Mg-4Y-2Nd-1Gd-0.4Zr镁合金显微组织和力学性能的影响,分析不同热处理条件下合金的断裂机制,获得最佳热处理工艺。结果表明:Mg–4Y–2Nd–1Gd–0.4Zr合金的最佳T4和T6热处理工艺分别为525°C,8 h和(525°C,8 h)+(225°C,16 h)。在最佳T6热处理条件下,Mg-4Y-2Nd-1Gd-0.4Zr合金的硬度、屈服强度、抗拉强度和伸长率分别为HV91、180 MPa、297 MPa和7.4%。此外,不同状态的Mg-4Y-2Nd-1Gd-0.4Zr镁合金也显示出不同的拉伸断裂方式。     

Effects of heat treatments on AA6061 aluminum alloy deformed by cross-channel extrusion

In this study, the relationship between microstructures and mechanical properties of the cross-channel extrusion (CCE) processed AA6061 alloy caused by different heat treatments were investigated. The ultimate tensile strength of the homogenized AA6061 can be strengthening to 194 MPa after extruded at 448 K for 8 passes. After T6 treatment, the strength was increased from 194 to 323 MPa caused by the formation of fine precipitates; however, the grains were coarsened. The Post-CCE aging treatment was applied on AA6061 alloy that the alloy was processed in supersaturated state at 448 K for 8 passes, and then artificial aged. A higher tensile strength of 364 MPa which is 13% higher when compared with the T6 treated sample was obtained since it consisted of fine-grained matrix with grain structure size of 0.2–0.5 μm and precipitation hardening effect. It demonstrates that the Post-CCE aging treatment is a suitable method for producing a heat treatable Al alloy with improved strength when applied to CCE process.     

Evaluation of corrosion behavior of Al-Mg-Li alloys in seawater

Weldalite 050, a high-strength Al-Mg-Li alloy, was evaluated for its corrosion resistance in deaerated and air saturated Arabian Gulf water to determine its suitability for marine applications. Weight loss and electrochemical studies showed that the alloy had minimum corrosion rates of 1.82 and 4.82 mpy (mils per year), respectively, in deaerated and air saturated Arabian Gulf water with very high total dissolved solids (TDS) content. Weldalite 050 exhibited good resistance to corrosion at velocities up to 3.9 m/s. The formation of Al₂MgLi, Al-Li, Al₁₂Mg₁₇, and Al-Li precipitates has a pronounced effect on its corrosion resistance. The corrosion resistance of Weldalite 050 compares favorably with that of alloys 5052 and 5054, wrought alloys 6061 and 6013, and silicon carbide (SiC) reinforced alloys 6061 and 6013.     

Effect of thermal exposure on the microstructure,tensile properties and the corrosion behaviour of 6061 aluminium alloy sheet

Sheet material of the Al‐Mg‐Si alloy 6061 in the tempers T4 and T6 was thermally exposed at temperatures ranging from 85 to 120°C for 1000 h. The microstructure, tensile properties and the corrosion behaviour in the different heat treatment conditions were investigated using differential scanning calorimetry and transmission electron microscopy as well as performing tensile tests and various corrosion tests. The additional heat treatments, which should simulate aging during long‐term service usage, caused an increase in strength of 6061‐T4 sheet, associated with changes in the naturally aged microstructure. Thermal exposure at 120°C for 1000 h resulted in tensile and corrosion properties being similar to those obtained for peak‐aged sheet. Alloy 6061 in the T6 temper exhibited microstructural stability when additionally heat treated at 85 and 120°C for 1000 h. No significant alterations in the microstructure, tensile properties, and corrosion performance were observed after exposure to slightly elevated temperatures.     

喷射成形6061铝合金的热处理工艺

对喷射成形6061铝合金的热处理工艺进行研究,采用硬度测试、拉伸试验和透射电镜等研究固溶温度、时效温度和时效保温时间对合金显微组织和力学性能的影响规律。结果表明:随固溶温度的升高,合金硬度也随之升高,而其抗拉强度、屈服强度和断后伸长率则先增大后减小;合金硬度、抗拉强度和屈服强度随时效温度的升高先增大后减小,断后伸长率却一直减小;合金硬度、抗拉强度和屈服强度曲线随时效温保温时间的延长呈驼峰状变化,断后伸长率则变化不大,只在17 h时有所增大;喷射成形6061铝合金的最佳热处理工艺为530℃固溶1 h+175℃时效8 h。     

固溶热处理对AA7085铝合金组织与性能的影响

采用拉伸试验、电导率测试、剥落腐蚀试验、金相观察及透射电镜分析等方法,研究了不同固溶热处理工艺(包括常规固溶、高温预析出固溶与部分重固溶)对AA7085铝合金的强度、剥落腐蚀性能及显微组织的影响。结果表明,采用部分重固溶工艺并时效处理后,合金的抗拉强度降低,但电导率与抗剥落腐蚀性能明显得到提高。其原因是通过部分重固溶处理并时效处理后,合金中的晶界析出细小且非连续分布的η析出相,从而提高了AA7085铝合金的抗腐蚀性能。