锅炉蛇形管摩擦焊接头残余寿命计算模型

以可靠性理论为基础,制定了电站锅炉蛇形管焊接接头的加速寿命试验规范。通过对大量新制的15CrMo摩擦焊接头的高温内压爆破持久试验。证明了试验规范的正确性和各组合应力水平的失效机理的一致性。在此规范的基础上,对已运行过132kh的12CrMoV摩擦焊接头,建立了带有可靠度指标的残余寿命数学模型,计算结果表明摩擦焊接头,在设计寿命期内是完全可靠的,摩擦焊这种焊接工艺是质量是稳定可靠的。文中提出的试验方法和数学模型对高温承压部件的残余寿命的预测和确定那些短期服役管道或接头的更换时间方面具有实际意义。     

搅拌摩擦焊搅拌头疲劳寿命的模拟研究

针对搅拌摩擦焊稳定焊接阶段,建立搅拌头受力模型与有限元分析模型,由计算结果可知,在稳定焊接阶段,前行处搅拌头根部为搅拌头薄弱部位,在垂直于搅拌头轴线方向,正侧面受拉应力,背面受压应力,分别为115.5, 127.5 MPa,若设计不当易从此处断裂。在此基础上结合Ramberg-Osgood模型,采用应变-寿命(E-N)法,对搅拌头进行疲劳寿命估算。结果表明,在当前焊接工艺参数下,搅拌头疲劳循环寿命为3.896×10~9次,可焊接6.487 25×10~4 m,不会出现疲劳断裂。结合实际生产中搅拌头并未出现断裂这一现象,今后在搅拌头设计中应更多考虑搅拌头焊接时的粘着磨损现象。     

焊接接头的强度

20061079 X80管线钢焊接粗晶区的组织和性能；20061080 基于应力-强度干涉模型的摩擦焊接头寿命预测。     

AA5083铝合金的搅拌摩擦焊接工艺参数对搅拌头受力和热输入的影响(英文)

采用系统实验设计方法研究AA5083铝合金搅拌摩擦焊接工艺参数对搅拌头受力和热量输入的影响,得到了用来设计搅拌摩擦焊搅拌头和焊机的经验模型。当采用计算机来控制搅拌摩擦焊接时,这些模型可用来确定AA5083这类铝合金的摩擦焊接工艺参数、编制焊接程序及工艺参数控制。结果表明:影响轴向力和热量输入的重要参数是搅拌头转速、焊接速度和搅拌头轴肩直径,而影响纵向应力的重要参数是焊接速度和探头直径。     

铝合金搅拌摩擦焊接头腐蚀性能研究进展

综述了铝合金搅拌摩擦焊接头腐蚀性能的研究进展,总结和评价了接头耐蚀性的常用研究方法。介绍了铝合金搅拌摩擦焊接头应力腐蚀开裂敏感性和常规试验方法,并提出要对搅拌摩擦焊接头腐蚀寿命进行预估,最后列举了改善接头耐蚀性的处理方法。     

GH4169高温合金惯性摩擦焊接接头的蠕变性能

研究了GH4169高温合金惯性摩擦焊接头的高温蠕变和持久性能,在595℃条件下,随着应力的增大,接头和母材在达到同一稳态蠕变速率ε时,接头承受的蠕变应力略小于母材;在断裂前,相对于母材,接头能承受更大的稳态蠕变速率.在650℃,承受较大应力水平时,GH4169惯性摩擦焊接头持久强度稍弱于母材,但差别很小;较低应力水平时,接头的持久强度则显著大于母材.     

CLAM钢搅拌摩擦焊接头高温蠕变行为

针对核聚变堆用CLAM钢,对焊后热处理的搅拌摩擦焊接头在823 K条件和180～300 MPa应力水平下的单轴拉伸蠕变性能、断口形貌、显微组织进行了研究.结果表明,当蠕变应力由300,260及220 MPa降低到180 MPa时,CLAM钢搅拌摩擦焊接头的蠕变寿命分别由1.5,19.2及883 h增加到6769 h以上...     

车体铝合金熔化极气体保护焊与搅拌摩擦焊残余应力研究

采用小孔法分别对6 mm厚度7020铝合金的熔化极气体保护焊及搅拌摩擦焊对接接头的残余应力进行了测试。结果表明,用两种焊接方法得到的焊接接头,其纵向应力均大于横向应力,对比7020铝合金搅拌摩擦焊接头和熔化极气体保护焊接头中的纵向残余应力,发现搅拌摩擦焊接头的纵向残余应力峰值要远远小于熔化极气体保护焊接头中纵向残余应力峰值。搅拌摩擦焊接头的最大纵向残余应力为50 MPa,而熔化极气体保护焊接头的纵向残余应力最大值已经达到了90MPa。     

阵列射流冲击热沉搅拌摩擦焊接新方法

基于动态低应力无变形技术的原理,设计开发了阵列射流冲击热沉搅拌摩擦焊接新方法.结果表明,采用该方法可以有效减小搅拌摩擦焊接头残余应力,焊后试件基本无变形.采用射流冲击热沉的动态低应力无变形搅拌摩擦焊接头残余应力分布规律与常规搅拌摩擦焊类似,但应力峰值明显降低,约为常规FSW接头应力峰值的45%,可以实现FSW薄壁结构的低应力无变形焊接.该项技术可以提高一些铝合金材料FSW接头性能,具有较好的技术经济价值.     

薄壁铝合金搅拌摩擦焊焊接应力变形与控制

搅拌摩擦焊(FSW)焊接残余应力变形表现出与传统熔焊不同的规律,文中研究了薄壁铝合金搅拌摩擦焊残余应力分布规律和焊接变形控制方法,结果表明,纵向残余应力峰值并非出现于焊缝中心,热影响区和热机影响区是残余应力相对较大的区域.基于动态低应力无变形焊接方法,设计开发了一套热沉系统,进行了动态低应力无变形FSW试验.研究表明,动态低应力无变形焊接技术可以有效减小搅拌摩擦焊接头残余应力和变形,接头残余应力分布规律与常规搅拌摩擦焊接头残余应力分布类似,但应力峰值降低50%以上.     

变幅载荷下摩擦焊接头疲劳寿命的分布及模拟

试验研究并分析了45钢摩擦焊接头切口件恒幅载荷下的疲劳性能,表明其疲劳寿命结果可很好地表示当量应力幅的函数,即Ni=C[△σ∧2/（1 n）eqv-(△σeqv)∧2/(1 n)th]∧-2,表达式中疲劳抗力系数C和疲劳门槛值（△σeqv)th服从对数正态分布。根据C和（△σeqv）th的物理意义及概率分布,可知疲劳试件个体间的差异可以由C、（△σeqv)th来区别,而疲劳试验结果的随机分散性产生于试件个体间的差异,据此提出了一种新的模拟45钢摩擦焊接头切口件变幅载荷下疲劳寿命试验及其分布的方法,给出了相应的模拟计算步骤,模拟结果与试验结果进行了比较,结果表明,45钢摩擦焊接头切口件在变幅载荷下的疲劳寿命分布的模拟结果服从对数正态分析,并与试验结果符合得很好。因此该模式方法可用于摩擦焊接结构的疲劳可靠性分析,从而节省大量的人力、物力。     

7A52铝合金搅拌摩擦焊工艺优化

接头强度是搅拌摩擦焊接头性能的一个重要指标,通过搅拌头旋转频率、焊接速度和轴肩下压量等焊接工艺参数的不同组合制备了35个7A52焊接试板,对试板进行拉伸试验检测了接头的抗拉强度,建立并分析了焊接接头抗拉强度与焊接工艺参数之间的回归模型,搅拌头旋转频率n,焊接速度v和轴肩下压量d<,ta>单独变化时,接头抗拉强度都有峰值...     

铝铜异种金属冷压焊及其焊缝接头显微组织和性能

研究了铝铜异种金属冷压焊的焊接工艺,对铝和铜的焊接性能及冷压焊的焊接特点进行了分析.用冷压焊进行了铝铜异种金属对接接头的焊接试验,并对冷压焊的焊接工艺参数的选择进行了试验和分析.对焊接接头的显微组织、抗拉强度、抗弯强度、电阻性能、耐温度变化性能及接头耐高温性能进行了试验和分析,其结果为铝铜异种金属焊接在电气产品中的使用提供了依据.     

基于RS_RBFNN的钛合金焊接接头疲劳寿命预测

建立了基于RS与RBF神经网络集成的钛合金焊接接头疲劳寿命预测模型(RS_RBFNN),该模型首先基于熵的连续属性离散化算法离散化疲劳数据并应用遗传算法约简疲劳寿命评价指标;基于最小约简指标提取焊接结构疲劳寿命分类判别规则以及对RBF神经网络进行训练;最后使用粗糙集理论判别与规则库匹配的检验样本疲劳寿命等级,使用RBF神经网络判别不与规则库任何规则匹配的检验样本疲劳寿命等级.基于钛合金疲劳试验数据的实证分析结果表明,RS_RBFNN模型容错性较好、精度较高,对钛合金焊接结构疲劳寿命预测具有一定的实际指导意义.     

搅拌摩擦焊AA7075-T651铝合金接头的疲劳裂纹扩展(英文)

研究12 mm厚AA7075-T651铝合金板搅拌摩擦焊接头的疲劳裂纹扩展行为。从搅拌摩擦焊接头以及母材中截取试样,对试样进行疲劳裂纹扩展实验。对搅拌摩擦焊接头以及母材的横向拉伸性能进行评估。用光学显微镜和透射电镜分析焊接接头的显微组织。用扫描电镜观察试样的断裂表面。与母材相比,焊接接头的ΔKcr降低了10×10-3 MPa·m1/2。搅拌摩擦焊AA7075-T651接头的疲劳寿命明显低于母材的,其原因可归结于焊缝区的析出相在搅拌摩擦焊接过程中的溶解。     

Subsection method of fatigue design for welded joints treated by ultrasonic peening

Concerning the notable difference between the S-N curve slope of welded joints treated by ultrasonic peening treatment （UPT） and that of as-welded joints, the subsection method is put forward for fatigue design of welded joints treated by UPT, using the design method of nominal S-N curves. Results show that, in medium life zone, strength grade of the fatigue design curves for UPT welded joints is two grades higher than that for as-welded joints. Furthermore, in medium life zone, strength grade of the fatigue design curves for UPT welded joints is three grades lower than that in long life zone. Conclusion of the comparison is that as for different joint types in different life zones, fatigue design should be processed according to different S-N curves respectively.     

GH4169合金与FGH96合金惯性摩擦焊接头组织和力学性能

在主轴转速为650 r/min、转动惯量为340 kg·m2、焊接压力为450 MPa焊接参数下，实现GH4169与FGH96异质材料惯性摩擦焊接，并对焊后热处理的接头进行显微组织与力学性能分析.在焊接热-力耦合作用下，焊接接头不同区域的金相组织发生变化，晶粒出现不同程度的细化、变形，基体强化相出现不同程度的溶解、变形.焊接接头显微硬度呈"山峰"状分布特征，焊接接头室温抗拉强度平均值为1 366 MPa，高温抗拉强度平均值为1 176.7 MPa，在650℃，641 MPa条件下的平均持久寿命为215 h，焊接接头具有良好的综合力学性能.     

Effect of friction welding conditions and aging treatment on mechanical properties of A7075-T6 aluminium alloy friction joints

Abstract

This article describes the effect of friction welding conditions and aging treatment on the mechanical properties of type 7075-T6 aluminium alloy (A7075) friction welded joints. A7075 was joined by using a continuous drive friction welding machine with an electromagnetic clutch in order to prevent braking deformation during as rotation speed decreases. That is, it was welded by using the 'Low Heat Input Friction Welding Method' (LHI method) developed by the authors, in which heat input is lower than in the conventional method. The maximum joint efficiency at a friction pressure of 30 MPa was approximately 25%, and that at 90 MPa was approximately 64%. These joints were made without forge pressure. The low joint efficiency was due to the existence of non-joined regions at the welded interfaces. However, the welded joint had approximately 82% joint efficiency when the friction time was 0·5 s at a friction pressure of 90 MPa with a forge pressure of 180 MPa. The welded joint softened at the welded interface and its adjacent region. It had approximately 90% joint efficiency after aging for 730 days at room temperature (natural aging). It also had approximately 95% joint efficiency after aging for 48 h at 393 K (120°C), and had no softened region at the welded interface. The heat input of the welded joint with the LHI method could be decreased to approximately 50% of that with the conventional method. The LHI method has several advantages for A7075 friction welding; less heat input than with the conventional method, and light post-weld processing (machining, etc.) because the flash can be minimised.     

Fatigue property of stationary shoulder friction stir welded additive and non-additive T joints

Abstract

Additive and non-additive T joints were successfully fabricated by stationary shoulder friction stir welding using various welding parameters. No interior defects were observed in all joints by microstructural examination. The fatigue property of both additive and non-additive joints was revealed by four-point bending fatigue test. The microstructure and the stress concentration were investigated at the fatigue crack initiation sites of various T joints. Stress concentration determines the fracture location, and the surface microstructure influences the fatigue property. The stress concentration at the internal corner was evidently lower for additive joint than non-additive joint. The surface of stationary shoulder friction welded joint was characterised by ultrafine grains, which evidently enhanced the fatigue property.