铝合金微通道扁管EBSD晶粒度和织构分析

采用电子背散射衍射(EBSD)技术,研究经高温大挤压比成形的AA3003铝合金微通道扁管横纵截面的晶粒分布、晶粒度统计和择优取向。结果表明,铝合金扁管的横截面和纵截面晶粒均呈等轴状,椭圆的长短轴比均约1.7左右。横截面平均晶粒尺寸约34.4μm,纵截面的平均晶粒尺寸约41.2μm。扁管沿挤压方向未观察到挤压变形带和焊合线。此外,铝合金微通道扁管织构为弱立方织构(100)[001]混合沿着挤压方向强高斯织构(110)[001]。并且经过高温严重塑性变形铝合金的微通道扁管的组织为再结晶组织,晶粒呈椭球状,顺着挤压方向略有拉伸,并生成典型铝合金再结晶织构。     

Influence of Deformation Twins on Mechanical Properties and β Precipitation of Large-Cross-Section (290 mm × 230 mm) AZ80 Bar Fabricated by “Multi-direction Forging + Extrusion + Cold Compression ” Technique

采用“多向锻造+挤压+在线水冷”技术制备出截面尺寸为290 mm×230 mm的Mg-8Al-1Zn (AZ80,质量分数,%) 合金棒材,沿横截面的230 mm方向 (ND) 对棒材进行冷压缩,压下量约为20 mm,冷压缩导致横截面心部 (C) 产生大量变形孪晶,而表层 (O) 的孪晶较少。研究了形变孪生对力学性能和析出反应的影响。沿挤压方向 (ED)、截面的290 mm方向 (TD) 和 ND 3个方向从C 和 O 切取拉伸试样。测试结果表明：棒材的室温力学性能存在显著的各向异性和表里不一致性。挤压材的 O 沿 ED（ED-O）具有最高的强度,其性能为：RP0.2、Rm和 A分别为 295 MPa、401 MPa和10%, 而 C 沿 ND（ND-C）具有最低的强度,其性能为：RP0.2、Rm和 A 分别为164 MPa、273 MPa和 7%。织构是导致各向异性和表里不一致性的主要原因,而变形孪生对织构有重要影响。冷压缩之前,C存在2种取向,即： [0001]Mg∥TD 和 [0001]Mg∥ND;冷压缩后,O的织构几乎没有变化,而变形孪晶导致C的织构发生重大转变,[0001]Mg∥TD取向被大幅弱化,而[0001]Mg ~∥ND取向被大幅加强。合金155 ℃/7 h时效后,变形孪晶内析出了β连续析出相,这些孪晶内的β析出相比层片状β非连续析出相更加细小弥散     

6005A复杂截面铝合金车体型材挤压过程数值模拟与组织性能研究

以复杂截面的6005A铝合金车体挤压型材为研究对象,利用Hyperxtrude有限元软件对挤压过程进行模拟,分析了挤压变形过程中的温度场、速度场及形变场分布。在75 MN挤压机上对铝合金型材进行挤压成形,采用光学显微镜(OM)、扫描电镜(SEM)观察和硬度实验,研究了挤压过程中铝合金型材的组织及性能的变化,并与模拟结果进行了对比。结果表明:由于挤压型材尺寸比较复杂,同一截面上温度、速度和变形量的分布差别较大,对应温度高、速度快及形变量大的部位,其组织细小且第二相数量较多,硬度高;由于型材挤压过程中会产生明显的热效应,导致型材尾部的温度高于型材头部的温度,且型材尾部组织更加均匀,第二相分布更弥散,硬度值更高。     

服役后的A6N01S铝合金型材焊接接头组织与性能研究

对某型号高速列车铝合金车体经过较长时期服役后的侧墙与边梁A6N01S-T5铝合金挤压型材焊接接头进行了拉伸、弯曲、硬度和疲劳性能测试,并对接头组织形态及断口微观特征进行了分析。结果表明:经过较长时期服役后的A6N01S-T5铝合金焊型材接头,其焊缝及热影响区(HAZ)微观组织形态没有发生明显变化;所有接头拉伸试件仍是在距离焊缝10 mm~15 mm的HAZ软化区域破断,其抗拉强度以及弯曲性能符合标准规定的要求;其疲劳性能测试中接头在循环次数为107条件下的疲劳极限为91.5 MPa,符合标准规范规定的不低于89 MPa的要求。     

时效工艺对动车组6N01铝合金车体型材性能影响

采用力学性能测试和显微组织观察等方法,研究了动车组6N01铝合金车体型材时效工艺对其性能和组织的影响。结果表明,185℃3h时效制度对6N01铝合金车体型材很适宜,在此条件下,该合金型材的抗拉强度、屈服强度和伸长率分别为262.8N/mm2~231.1 N/mm2、224 N/mm2~214.3 N/mm2和13.1%~17.3%。这一结果说明,该时效制度比双级时效制度可节省保温时间7 h。     

轻量化汽车承载用铝合金挤压型材的研制

汽车承载用铝合金工字梁型材载面积大,宽度大,对力学性能、焊接性能、耐腐蚀性能和金相组织的要求都很严,生产难度大。通过优化调整7N01铝合金的化学成分,在熔炼工序采用炉底电磁搅拌、底部喷吹N2+Ar+熔剂精炼除气除渣,在铸造工序采用在线除气、双级陶瓷片过滤净化,添加Al-Ti-B丝细化晶粒,在挤压工序采用等温挤压技术、快速均匀水冷在线淬火,控制合适的停放时间,再经过双级人工时效处理。在整个生产工艺过程中实行精密控制,生产出了达到使用要求的合格的7N01-T6铝合金工字梁型材。     

含Sr的7085铝合金挤压材的各向断裂韧性

采用断裂韧性试验和显微观察研究了含Sr7085铝合金挤压材经固溶、预应变及时效处理后在平行(R-L)和垂直于(L-R)挤压方向上的断裂韧性与微观组织之间的联系。结果表明:7085铝合金挤压材的组织与断裂韧性存在着明显的方向性。在R-L方向其组织沿挤压方向呈带状分布,断裂韧性(Kq)值为25.76 MPa·m1/2;而在L-R方向其组织无明显带状特征,断裂韧性(Kq)为41.33 MPa·m1/2。R-L向裂纹沿着呈带状分布的细小晶粒的晶界启裂,晶界强度低;LR向裂纹穿过晶粒或沿着较大晶界启裂,强度高。细小晶粒带仅出现在挤压方向,其形成与合金中沿挤压方向呈条(带)状分布的粗大不(难)溶第二相粒子诱导的再结晶有关。     

AZ31镁合金挤压薄板织构及力学各向异性

研究AZ31镁合金挤压薄板的显微组织、织构及室温下板面内各不同方向的力学性能。织构分析表明,挤压薄板主要有{0002}<1-010>和{10-10}<11-20>2种织构组分。拉伸测试结果显示,沿挤压方向屈服强度最高,达到200.4MPa,这是由于这种取向基面滑移和{1-012}锥面孪生均不能开动,发生织构强化的结果;与挤压方向呈45°方向伸长率最高达19.0%,这是由于具有{10-10}<11-20>织构组分晶粒的基面滑移开动;与挤压方向呈90°方向屈服强度最低仅为挤压方向相应值的一半左右,这是由于具有{10-10}<11-20>织构组分晶粒发生了{10-12}锥面孪生。     

挤压温度对Mg-Al-Zn系镁合金宽幅型材性能的影响分析

对含Y的Mg-Al-Zn系镁合金宽幅型材进行了不同温度的挤压,并进行了显微组织、XRD、力学性能和耐腐蚀性能的测试与对比分析。结果表明,当挤压温度从300℃升高至450℃,该宽幅型材的晶粒尺寸减小,晶面织构强度先基本不变后明显下降,抗拉强度和冲击韧度下降,伸长率和耐腐蚀性能先提高后下降。与300℃的挤压型材相比,350℃挤压的型材能使平均晶粒尺寸增大6μm,晶面织构强度基本不变,抗拉强度减小3 MPa,冲击韧度下降3.43%,伸长率增加2.2%,腐蚀电位正移104 m V。     

直径为160mm AZ40镁合金棒材的混晶组织和力学性能各向异性(英文)

采用"多向锻造(MDF)+挤压+在线冷却"技术制备的AZ40(直径为160 mm)镁合金棒材具有混晶组织和力学性能各向异性,通过光学显微镜(OM)、扫描电镜(SEM)、X射线衍射织构测量和室温拉伸试验对上述特征进行表征和分析。结果表明:混晶组织来源于半连续铸锭中Al的微观偏析。均匀化处理((380°C,8 h)+(410°C,12 h))不能完全消除这种微观偏析。在后续MDF和挤压过程中,Al含量为3%~4%(质量分数)的枝晶心部转变成细晶区,而Al含量约为6%的枝晶边缘转变成粗晶区。表层、R/2和心部的XRD宏观织构都呈现典型的纤维织构特征,且表层的[0001]//Ra D取向强度(11.245)约为R/2处(6.026)和心部(6.979)的两倍。挤压态AZ40镁合金棒材沿挤压方向和半径方向具有优异的伸长率(A)和中等抗拉强度(Rm):A为19%~25%,Rm为256~264 MPa;然而,屈服强度(Rp0.2)呈现出各向异性和内外不均匀性,即Ra D为103 MPa,ED-C(心部)为137 MPa,ED-O(边部)为161 MPa,这主要是织构造成的。(155°C,7 h)+(170°C,24 h)时效处理对AZ40镁合金棒材的强度和伸长率几乎没有影响。     

A High-Ductility Mg–Zn–Ca Magnesium Alloy

A new kind of Mg–2 Zn–0.6 Ca(wt%) alloy was fabricated by casting and hot extrusion as a high-ductility structural material. The extruded alloy exhibits a superior elongation of ～30%, yield strength of 130 MPa and ultimate tensile strength of 280 MPa along the extrusion direction at room temperature. Microstructure, texture and tensile properties of the extruded alloy were investigated in details. The remarkable improvement of ductility is ascribed to the weakened basal texture, refined grains and a small number of second phase in the alloy.     

热挤压对7055铝合金力学性能及组织的影响

采用挤压铸造成形工艺制备7055高强铝合金,研究了热挤压参数对合金力学性能及微观组织的影响,并与铸态下的力学性能及微观组织进行了对比.结果表明,热挤压态下的7055铝合金的微观组织和力学性能均优于铸态,并且晶粒随着比压的增加趋于细化,抗拉强度随着比压的增加趋于提高.当比压为75 MPa时,在730 ℃温度下进行挤压浇注,经过双级固溶处理和时效后,合金的晶粒明显细化,抗拉强度达到681.4 MPa,伸长率达到7.14%.     

Microstructure and Mechanical Properties of AZ31 Mg Alloy Fabricated by Pre-compression and Frustum Shearing Extrusion

The AZ31 Mg alloys were processed by 6% pre-compression and frustum shearing extrusion at various temperatures, and the microstructure, texture and mechanical properties of the resulting alloys are systematically investigated. The results show that the grain size monotonically increases from 6.4 to 12.6 lm and the texture intensity increases from 6.7 to 9.6with the increase in the extrusion temperature. The combining effect of the pre-twinning and the frustum shearing deformation is found to contribute to the development of the weak basal texture in Mg alloys. The Mg alloy sheet produced at the extrusion temperature of 563 K exhibits excellent mechanical properties. The yield strength, ultimate tensile strength and elongation for the extruded alloys are 189.6 MPa, 288.4 MPa and 24.9%, respectively. Such improved mechanical properties are comparable or even superior to those of the alloys subjected to other deformation techniques, rendering the pre-compression and frustum shearing extrusion a promising way for further tailoring properties of Mg alloys.     

铸造冷却速度对Mg-4.4Zn-0.3Zr-0.4Y挤压态合金组织性能的影响

本文通过两种不同冷却速度制备成分相同、铸造组织特征不同的Mg-4.4Zn-0.3Zr-0.4Y铸态合金,研究不同铸造组织特征对挤压变形态合金组织和力学性能的影响。研究结果表明：与空冷铸造合金相比较,通过水冷冷却增大了熔体冷却速度,使铸态组织得到细化,抑制了W-相（Mg3Y2Zn3相）的形核,并促进了I-相（Mg3YZn6相）的生成,获得了更大体积分数的准晶相(I-相)。经过挤压变形后,水冷铸造合金中的再结晶晶粒细小均匀,经过挤压变形破碎的细小I-相颗粒弥散分布在基体上,{0002}基面织构得到弱化,而{101 ?2}织构强度增强,从而使挤压态Mg-4.4Zn-0.3Zr-0.4Y合金的强度和塑性都得到了大幅的提高。水冷铸造Mg-4.4Zn-0.3Zr-0.4Y合金经过挤压变形后,屈服强度和抗拉强度分别达到297.0MPa和327.3MPa,与空冷铸造挤压态合金相比分别提高了46.4MPa和21.4MPa。水冷铸造Mg-4.4Zn-0.3Zr-0.4Y挤压态合金的延伸率达到14.8%,与空冷铸造挤压态合金相比增大了4.7%。     

Evolution of microstructure and texture of AZ61 Mg alloy during net-shape pressing of extruded perform

The micro orientation theological behavior of AZ61 Mg alloy during net-shape forming of tensile specimens via close-die pressing of extruded preformed and the effect of the press deformation rate on the microstructure characteristics were characterized with electron back-scattering diffraction (EBSD) orientation imaging microscopy and metallography. The results indicate that the intensity distribution of basal {0001}<10(1)0 > texture on the cross-section of the extruded perform is uniform and parallel to the extrusion direction. Subjected to pressing in extrusion direction, deformation shear stress leads to grain rotation and basal texture {0001}<10(1)0> deviation from the extrusion direction, spreading in the direction perpendicular to pressing direction. The texture intensity increases with the press deformation rate and reaches its peak value at 50%, which is considerably lower than the value reached in extrusion deformation. Then, the texture intensity decreases with the press deformation rate reversely.     

Effects of rolling condition on the tensile properties of Mg-MM-Sn-Al-Zn alloy

The microstructures and mechanical properties of Mg-2MM-2Sn-1Al-1Zn (ETAZ2211) sheets fabricated under different conditions have been investigated. Two hot-rolling routes following extrusion have been carried out at 300 °C or 400 °C. One method is to roll the extruded strips parallel to the extrusion direction (ED); the other is to roll the extruded strips perpendicular to the extrusion direction (TD). The strength and the elongation-to-fracture of specimens prepared by a combination of extrusion and rolling processes are increased dramatically when compared those of the simply rolled specimens. Especially, the TD alloy sheet rolled at 300 °C exhibits the best combination of strength and ductility, i.e. yield strength of 178.5 MPa, ultimate tensile strength of 239.1 MPa, uniform elongation of 24.4 % and elongation-to-fracture of 37.9 %. Observation of texture reveals that the intensity of (0002) texture is lower for the TD alloy sheets than that for the ED alloy sheets, indicating that the texture intensity is reduced by change of the rolling direction.     

Effects of die angle on microstructures and mechanical properties of AZ31 magnesium alloy processed by equal channel angular pressing

1　INTRODUCTIONMagnesiumalloysarethelightestmetallicstruc turalmaterialsandhencetheyprovidegreatpotentialintheweightsavingofautomotiveandaerospacecomponents ,materialhandlingequipment ,portabletoolsandevensportinggoods[1,2 ] .Duetotheirhexago nalclose packed (HCP)crystalstructure ,magnesiumalloysperform poorformabilityandlimitedductilityatroomtemperature ,thustheirproductsaremainlyfabricatedbycasting ,inparticular ,die casting ,andtheapplicationsofwroughtmagnesiumalloysarelim ited .Nowit…     

非对称挤压腔循环膨胀挤出法制备AZ31合金的显微组织和力学性能

研究AZ31合金在非对称挤压腔循环膨胀挤出(CEE-AEC)过程中的显微组织、织构演化和力学性能.结果表明,在CEE-AEC过程中发生连续动态再结晶(CDRX)和不连续动态再结晶(DDRX).经过3道次变形后,变形试样的显微组织得到细化,非对称型腔区域合金的平均晶粒尺寸为6.9μm.随着道次的增加,基体织构的最大强度增...     

Fabrication and mechanical properties of high-performance aluminum alloy

High-performance Al–Cu–Mg alloy was fabricated by high-energy ball milling, sintering, and hot extrusion. The microstructure and mechanical properties of the material were preliminarily investigated. Results show that the formation of liquid phase during sintering promotes the densification of the aluminum powders. A97.1 % theoretical density is achieved in this alloy after sintering. The material shows excellent mechanical properties after extrusion and heat treatment. The ultimate tensile strength and yield strength of the extruded samples with heat treatment are 613 and 465 MPa, respectively.     

连铸AZ31镁合金的热挤压变形组织与性能(英文)

文章研究了电磁连铸AZ31镁合金经热挤压变形后的微观组织和力学性能。结果表明,挤压过程中的动态再结晶能够显著细化晶粒,局部细晶区的平均晶粒为2μm。与铸态合金相比,挤压后的AZ31镁合金具有更细小的晶粒和更均匀的微观组织。挤压变形后产生强烈的基面织构;挤压后材料的力学性能显著提高。屈服强度、抗拉强度和断面收缩率随着挤压比的增大而增大。挤压比为25时,屈服强度、抗拉强度和断面收缩率分别为259MPa,357MPa和30.5%,比铸态合金分别提高了86.33%,64.52%和67.40%。随着挤压比的增大,晶粒细化效果更为明显,微观组织更均匀。断口形貌分析表明,挤压变形后材料由韧脆混合型断裂,转变为韧性断裂。