用旋转挤压方法控制薄板的焊接变形

提出了旋转挤压控制薄板焊接变形的新方法,它足利用特定形状的挤压头对焊缝及近缝区金属进行旋转挤压,产生拉伸塑性应变,减小甚至抵消残余压缩塑性应变,以此来消除焊接残余变形.该方法处理后的焊道表面平整光滑,减小了应力集中.结果表明,旋转挤压法能将薄壁构件焊接变形降到非常低的水平,选择适当的工艺参数,该方法能将焊接残余变形控制在常规焊接状态的3%以下.旋转挤压控制薄板焊接变形的效果与多个工艺参数有关,只有当各个工艺参数取值适当且匹配良好时,才能取得良好的焊接变形控制效果.     

随焊旋转挤压对铝合金焊接接头组织和性能的影响

随焊旋转挤压是一种能够控制薄壁结构焊接应力和变形的新方法,这种方法同时能改善焊接接头的微观组织和力学性能.对2A12T4铝合金焊接接头的金相观察表明,随焊旋转挤压焊缝区晶粒明显细化,组织更加致密,气孔等缺陷大大减少.拉伸和三点弯曲试验结果表明,随焊旋转挤压之后焊接接头的抗拉强度、抗弯强度等力学性能得到不同程度的提高.由于薄弱的焊趾部位得到强化,部分试件的裂纹萌生部位由焊趾转移到焊缝.     

铝合金随焊控制焊接应力与交形的几种新方法

采用力学手段,对铝合金焊接熔池后方的脆性温度区间施加横向挤压应力,同时使焊缝纵向保持塑性延展,从而达到随焊控制焊接应力与变形并防止焊接热裂纹的目的.介绍了随焊冲击碾压、随焊旋转挤压、双向预置应力和随焊电磁冲击等几种控制焊接应力与变形的新方法.在合适的工艺参数条件下,可以将铝合金平板对接焊件的残余变形量降低到很低的程度,同时町以防止焊接热裂纹的产生.     

铝及铝合金反向挤压(2)

介绍了金属反向挤压法的基本原理、特点、主要分类、反向挤压生产中应注意的技术、质量问题和主要经济指标。介绍了国内50MN反向挤压机挤压生产工艺,反向挤压时金属流动特性,制品的组织、性能及尺寸精度,现代反向挤压设备的主要特点（如铸锭表面切屑加工、铸锭梯度加热与排气、穿孔针拉力显示与保护、过程信息与控制系统、挤压机中心精度控制技术等）,铝及铝合金管、棒、型材的反向挤压生产工艺。     

铝及铝合金反向挤压(1)

介绍了金属反向挤压法的基本原理、特点、主要分类、生产中应注意的技术、质量问题和主要经济指标。介绍了国内50MN反向挤压机挤压生产工艺,反向挤压时金属流动特性,制品的组织、性能及尺寸精度,现代反向挤压设备的主要特点（如铸锭表面切屑加工、铸锭梯度加热与排气、穿孔针拉力显示与保护、过程信息与控制系统、挤压机中心精度控制技术等）,铝及铝合金管、棒、型材的反向挤压生产工艺。     

热挤压工艺对6061铝合金组织及性能的影响

研究了不同热挤压工艺参数对6061铝合金微观组织和力学性能的影响。结果表明,当挤压温度为450℃时,随着挤压比的增大,晶粒明显细化,抗拉强度和伸长率也随之提高。当挤压比为10时,随着挤压温度的升高,再结晶晶粒数量增加。当挤压温度升高到500℃时,再结晶晶粒快速长大粗化,晶粒细化作用减弱,此时,合金的抗拉强度随挤压温度的升高整体呈下降趋势。在本试验范围内,6061铝合金经过挤压温度为450℃,挤压比为10的挤压变形后得到的组织均匀细小,力学性能较好。     

常规FSW与双轴肩FSW对铝合金接头组织和性能的影响

对采用常规FSW和双轴肩FSW所得到焊接接头性能进行试验研究,测试了两种焊接得到的焊接接头的抗拉强度、屈服强度和断后伸长率,并对接头的微观组织和断口形貌进行了观察和分析.结果表明,双轴肩FSW接头横截面形成了一组由内向外扩张“洋葱环”状的椭圆环;常规FSW焊核区与热力影响区之间组织发生明显变化;硬度的最低处为双轴肩FSW前进侧热力影响区,最高处为双轴肩FSW接头上表面焊核区;常规搅拌摩擦焊接头的综合力学性能最好,双轴肩次之;断口形貌分析表明,接头断裂模式均为韧性断裂,且常规FSW断口韧窝尺寸比双轴肩FSW接头韧窝小而深,表现出更好的塑性.     

铝合金薄壁圆锥体结构的焊接变形

利用实物模型试驻，自动脉冲TIG焊接工艺分别研究了铝台金薄壁圆锥体结构的焊接变形及其变化规律研究结果表明，焊接后结构的变形主要表现为沿母线的纵向挠曲变形和圆周方向椭圆度变化，采用纯氨气保护，两层两道焊接时，结构的最大挠度和椭圆度变化均小于采用氩气加氦气混台保护、一道焊接时的最大挠度值和椭圆度变化。同时采用解析方法对挠曲变形进行了计算，分析了造成两种焊接工艺挠度不同的原因，从而为下一步圆锥体薄壁结构的焊接数值模拟提供验证数据，进而为最终减小和控制结构的焊接变形提供了理论和试验依据。     

轨道车辆用6N01铝合金型材挤压焊合线形态的研究

轨道车辆用6N01铝合金经分流组合模挤压成空心型材,对其出现的挤压焊合线形态进行研究,利用先进的金相显微镜和扫描电子显微镜等设备进行系统分析,得出挤压型材因焊合不良形成的焊合线宏观及微观组织、力学性能、断口形态,为挤压产品焊合不良的检验、模具设计和挤压工艺制定提供参考。     

挤压速度对双通道等径角挤压7003铝合金力学性能的影响

采用扫描电镜、显微硬度计及万能试验机研究了挤压速度对双通道等径角挤压对7003铝合金力学性能的影响。结果表明：在任一挤压速度下,随着挤压道次的增加,材料的力学性能明显改善;挤压一道次后试样的抗拉强度由338.3 MPa提高到384.5 MPa,二道次后提高到431.5 MPa;屈服强度经一道次挤压后由260 MPa提高到325 MPa,二道次后提高到426 MPa,二道次涨幅更明显;随着挤压速度的增大,试样断后伸长率的变化总体上均呈现下降的趋势,当挤压速度为25 mm/min 时,一道次挤压后伸长率最小;经二道次挤压后的显微硬度,在挤压速度为25 mm/min时由原样退火态的73.5 HV提高到136.4 HV,且强度以及显微硬度均在挤压速度为25～35 mm/min时达到了最大值。     

Process of friction-stir welding high-strength aluminum alloy and mechanical properties of joint

The process of friction-stir welding 2A12CZ alloy has been studied. And strength and elongation tests have been performed, which demonstrated that the opportunity existed to manipulate friction-stir welding parameters in order to improve a range of material properties. The results showed that the joint strength and elongation arrived at their maximums ( 331 MPa and 4% ) at 37. 5 mm/min and 300 rpm. As welding parameters changing, joint tensile strength and elongation had similar development. Hardness measurement indicated that the weld was softened. However, there was considerable difference in softening degree for different joint zone. The weld top had lower hardness and wider softening zone than other zone of the weld. And softening zone at advancing side was wider than that at retreating side.     

Mechanical properties of underwater friction stir welded 2219 aluminum alloy

Underwater friction stir welding of 2219 aluminum alloy was carried out in order to further improve the joint performances by varying welding temperature history. The results indicated that the tensile strength of the joint can be improved from 324 MPa by external water cooling action in normal to 341 MPa. However, the plasticity of the joint is deteriorated. The underwater joint tends to fracture at the interface between the weld nugget zone and the thermal mechanically affected zone on the advancing side during tensile test, which is significantly different from the normal joint.     

铝合金拉杆的热挤压工艺及模具设计

分析了高压开关零件LW8-35SF6铝合金拉杆的热挤压成形工艺及模具设计.与传统的加工工艺相比,新工艺采用杆部反挤头部正挤的复合热挤压工艺进行生产,使材料利用率和生产效率大大提高.对铝合金拉杆零件进行了实际生产试验,结果表明,对直径为90 mm、高度为85 mm的棒料进行热挤压成形是可行的,设计制造的挤压模具结构简单、通用性强.采用新工艺增加了坯料尺寸精度,坯料重量减轻72%以上,提高了经济效益;同时,为在小设备上成形变形程度较大的长杆件提供了一种新方法.     

Microstructure and mechanical properties of 7005 aluminum alloy processed by one-pass equal channel reciprocating extrusion

An equal channel reciprocating extrusion (ECRE) was proposed first to obtain a severe plastic deformation (SPD) of 7005 alloy. The microstructure and mechanical properties of one-pass ECREed (ECRE processed) 7005 alloy were investigated. The results show that SPD occurring in ECRE leads to a mixed microstructure. ECREed 7005 alloy exhibits a significant improvement of ultimate tensile strength (UTS) and elongation. Mechanical properties in the region undergoing a complete ECRE process are higher than those in the region undergoing an incomplete ECRE process due to larger dislocation strengthening effect. Yield strength (YS) and UTS first decrease and then increase with an increase of extrusion temperature. The YS of 359.2 MPa, UTS of 490 MPa and elongation of 17.7% are obtained after T6 treatment. Fine-grain strengthening, dislocation strengthening and precipitation strengthening in the T6-treated ECREed sample all play important roles in improving the mechanical properties.     

铝合金薄板焊件纵向塑性应变场的数值模拟

利用弹塑性有限元分析软件对普通焊件的纵向塑性应变场进行了模拟.结果表明,对于尺寸为200 mm×100 mm ×2 mm的2A12T4铝合金薄板填丝对接焊件,其焊缝部位只存在纵向拉伸塑性应变;在靠近焊缝的区域,既存在纵向压缩塑性应变,也存在纵向拉伸塑性应变;在焊缝长度方向纵向残余塑性应变的分布不均匀,在靠近起弧端和收弧端的区域呈现复杂的分布特征.焊接过程中温度场的变化和热源旁侧金属受力状况的不同是近缝区金属纵向塑性应变不均匀分布的原因.     

粉末热挤压Al-Zn-Mg-Cu系合金的热处理工艺

通过XRD衍射分析、光学和透射电镜观察以及力学性能测试,研究了固溶和时效处理对粉末热挤压法制备的Al-Zn-Mg-Cu高强铝合金组织性能的影响.结果表明:挤压态合金中析出大量MgZn_2相;合金适宜的T6热处理制度为460℃×2.5h水冷+120℃×24h空冷;在此条件下合金的抗拉强度、屈服强度和伸长率分别为731MPa、670MPa和6.2%;晶粒细化是合金T6组织与铸锭挤压Al-Zn-Mg-Cu合金回归再时效(RRA)组织类似的主要原因.     

关于铝及铝合金的焊接工艺浅析

随着铝及其合金越来越多的被用于化工、航空航天、汽车制造等工业生产中,焊接结构不可避免,为了更好的解决铝、尤其铝合金的焊接工艺问题,我们通过实践,总结出一些系统的、比较成熟的工艺路线。并从理论上作了具体的论证,从而较好的解决了焊接铝合金的难点。     

随焊旋转挤压控制焊接热裂纹试验分析

介绍了随焊旋转挤压法的基本工作原理及其对焊接残余变形的控制效果.以高强铝合金2A12T4为研究材料,对随焊旋转挤压控制焊接热裂纹进行了试验研究和机理分析.结果表明,在合适的工艺参数下,该方法能够有效抑制铝合金焊接热裂纹的产生和扩展.挤压头与焊枪的距离和其对工件的垂直压力是决定焊接热裂纹控制效果的两个重要参数.随焊旋转挤压控制焊接热裂纹的机理是基于对起弧端热裂纹的压合和对焊件回转变形的拘束作用.     

Joint performance of laser-TIG double-side welded 5A06 aluminum alloy

The influence of welding parameters on mechanical properties and microstructure of the welds of laser-TIG double-side welded 5A06 aluminum alloy was investigated. The results show that the weld cross-sectional shape has an intimate relation with the mechanical properties and microstructure of the welds. The symmetrical "X" cross-section possesses a relatively higher tensile strength and elongation than the others, about 91% and 58% of those of base metal, respectively. The good weld profiles and free defects are responsible for the improvement of tensile properties. Due to low hardness of the fusion zone, this region is the weakest area in the tensile test and much easier to fracture. The loss of Mg element is responsible for the decrease of mechanical properties of the joints. The microstructure of "X" cross-section has an obvious difference along the direction of weld depth, and that of the "H" cross-section is consistent and coarse.