共查询到19条相似文献,搜索用时 375 毫秒
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利用自主开发的填丝静止轴肩T形接头焊接工具开展了6061-T4铝合金填丝T形接头的焊接试验,获得了成形良好的无缺陷T形接头. 对接头内部成形、显微组织、硬度分布、静载强度及疲劳性能进行了测试与分析. 结果表明,接头轴肩影响区表面存在超细晶区,内部质量良好,焊核区不同位置填充材料与母材发生了不同程度的混合. 接头底板及筋板硬度较母材有不同程度的降低,拉伸测试中底板和筋板方向接头均断裂于热影响区,接头系数分别0.68和0.83. 过渡圆角明显提高了接头的疲劳性能,在2 × 106疲劳寿命下的具有90%置信度及97.5%存活率的特征疲劳强度可达101.4 MPa,远高于IIW建议的设计准则. 疲劳断口显示疲劳裂纹萌生于接头表面轴肩压入边缘,在交变载荷作用下向内部扩展,裂纹稳定扩展区可见明显的疲劳条带,断裂机制为穿晶断裂. 相似文献
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为了评价激光薄板填丝焊接接头的高周疲劳性能,利用升降试验法评价了指定2×10~6周次寿命的0.7 mm厚激光填丝焊接接头样件高周疲劳强度,借助扫描电子显微镜分析了断口及断裂位置。结果显示,激光填丝焊接接头的高周疲劳强度为396.6 MPa,断口形貌显示近无夹杂物,裂纹源区呈解理特征,裂纹主要为沿晶扩展,在裂纹扩展区呈现典型的疲劳条纹特征,且条纹间距随裂纹扩展长度的延长而加宽,瞬断区主要呈现与拉伸断口一致的韧窝形貌。观察断口截貌可知,裂纹主要在焊缝上表面焊趾附近萌生,并沿板厚方向扩展,在沿焊接方向扩展过程中会跨越熔合线,在焊缝区内和相邻母材区内扩展。 相似文献
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《中国有色金属学会会刊》2016,(3)
采用双光束双侧同步填丝焊接的方法制备Ti-6Al-4V合金T型接头,并对焊缝成形、组织、力学性能及其相互关系进行研究。结果表明,试验获得了质量良好的焊缝,未出现不连续、焊瘤、可见的裂纹及气孔等缺陷,同时发现其与焊接过程中稳定的熔池行为及良好的熔滴过渡有关。从接头截面可以发现,蒙皮及筋条侧热影响区的形状完全不同。热影响区和熔合区的组织包含针状马氏体α′相。热影响区及熔合区的显微硬度均高于母材,且在筋条侧靠近融合区的热影响区处显微硬度最大。沿蒙皮及筋条方向的拉伸试样均断裂于母材处,其断裂方式为延性断裂。 相似文献
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《材料热处理学报》2016,(1)
研究了钨极氩弧焊GH625高温合金焊接接头的室温疲劳裂纹扩展行为。采用金相显微镜及扫描电镜对其焊接接头的显微组织和疲劳裂纹扩展断口形貌进行观察。结果表明,GH625高温合金的钨极氩弧焊焊接接头主要是由枝晶状焊缝组织和γ奥氏体等轴晶母材组成,焊缝区析出大量的白色针状δ-Ni3Nb相和块状颗粒状Laves相;其焊接接头的显微硬度高于母材;室温下,在低ΔK区间,GH625高温合金钨极氩弧焊焊接接头的疲劳裂纹扩展速率比母材低,这是由于焊缝处硬质的析出相、二次裂纹以及扩展路径的曲折多样使得其裂纹扩展时需要消耗更多的能量;在高ΔK区间内,焊接接头疲劳裂纹扩展速率高于母材。 相似文献
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刘帅吴冬冬柴东升周思雨马广义周平吴东江 《中国有色金属学报》2016,(12):2555-2563
对0.5 mm厚Hastelloy C-276薄板激光焊接接头进行疲劳试验,结合应力-寿命(S-N)曲线和疲劳断口形貌,研究母材及焊接接头的疲劳性能,分析母材和焊接接头的疲劳断裂机理。结果表明:0.5 mm Hastelloy C-276薄板焊接接头和母材的S-N曲线斜率基本相同,焊接接头疲劳性能和母材的基本相当;母材疲劳断口疲劳裂纹起源于试样侧表面,主要沿宽度方向扩展,随着应力的减小,疲劳源数目减少,疲劳裂纹扩展速率减小;焊接接头在母材和焊缝处随机断裂,焊接接头母材区断口形貌和母材断口形貌基本一致,而焊接接头焊缝区断口的疲劳裂纹起源于侧表面棱角处和焊缝表面,焊缝表面是主要疲劳源,裂纹主要沿厚度方向进行扩展,疲劳裂纹扩展区呈现出准解理断裂特征。 相似文献
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针对2.5 mm和3 mm的碳钢材料的T形接头熔透焊接,采用ER50-G焊丝作为填充金属,对优化工艺参数焊接的T形接头的疲劳性能进行试验,对断口的宏观及微观断裂特征进行了分析。结果表明:指定寿命为1×10~7次循环下,激光填丝焊T形接头的中值疲劳极限σ_(0.1)为222.5 MPa;疲劳试件均断裂于焊趾部位,主要是由于该处存在较大的应力集中;断裂试件疲劳裂纹的启裂区和启裂扩展区具有典型的疲劳断裂特征,疲劳条带清晰,扩展区的大小随疲劳循环次数的增加而增大,瞬断区断口形貌均为大小不一的浅韧窝。研究结果可为激光填丝焊的车体结构工程化应用提供数据支持。 相似文献
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《中国有色金属学报》2016,(12)
对0.5 mm厚Hastelloy C-276薄板激光焊接接头进行疲劳试验,结合应力-寿命(S-N)曲线和疲劳断口形貌,研究母材及焊接接头的疲劳性能,分析母材和焊接接头的疲劳断裂机理。结果表明:0.5 mm Hastelloy C-276薄板焊接接头和母材的S-N曲线斜率基本相同,焊接接头疲劳性能和母材的基本相当;母材疲劳断口疲劳裂纹起源于试样侧表面,主要沿宽度方向扩展,随着应力的减小,疲劳源数目减少,疲劳裂纹扩展速率减小;焊接接头在母材和焊缝处随机断裂,焊接接头母材区断口形貌和母材断口形貌基本一致,而焊接接头焊缝区断口的疲劳裂纹起源于侧表面棱角处和焊缝表面,焊缝表面是主要疲劳源,裂纹主要沿厚度方向进行扩展,疲劳裂纹扩展区呈现出准解理断裂特征。 相似文献
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在T形接头横截面方向预置0.1 mm铜箔作为示踪材料,进行了角接静轴肩搅拌摩擦焊,焊后对T形接头角焊缝进行X-ray 2D透射和X-ray 3D扫描,得到了角焊缝示踪材料的2D流场和3D流场. 在前进侧热塑性材料主要以摩擦剪切为主,材料流动主要向焊接方向流动,并流向前进侧后方,后退侧材料主要以挤压为主,由于T接搅拌针螺纹的存在,使得材料整体向后退侧下方流动. 同时发现,在T接静轴肩后沿附近下方存在示踪材料"堆积区",表明T接静轴肩对附近的材料塑性流动存在一定的阻碍作用. 根据所获得的观察结果,建立了T形接头角焊缝的三维流动主要特征模型. 相似文献
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G. Zhou X. Q. Yang L. Cui Z. H. Zhang X. D. Xu 《Journal of Materials Engineering and Performance》2012,21(10):2131-2139
Friction stir welding (FSW) of T-joints with 3?mm thickness for AA6061-T4 sheets has been performed, and the influences of process parameters on the microstructures, defects, hardness profiles, and tensile strength were discussed specifically. It is found that the macrostructures and microstructures are similar in different process parameters, and the microstructure features in the skin welds have the same patterns as that of butt-joints. The unique microstructures of T-joints are the two fillet zones. Two lower hardness zones in the skin and one lower hardness zone in the stringer are found. Additionally, the tensile properties of T-welded joints are examined along the skin and the stringer plane directions. Results show that the tensile strength is in the range of 170-180?MPa for all the specimens along the skin direction, and the specimens fail in the heat affected zone (HAZ). In the stringer direction, the larger tunnel defects (DA) (the DA is greater than 0.1?mm2) would reduce the ultimate tensile strength of the T-joints and cause the joints to fracture at the bonding interface. The smaller tunnel defects (the DA is less than 0.015?mm2) and the zigzag lines have no pronounced effect on the failed location. In the stringer direction, tensile efficiencies of T-joints could be 83% of the base material (BM) when ??/v?=?1541/218 r/mm is applied. 相似文献
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采用静轴肩搅拌摩擦焊接法(SSFSW)在不同的焊接速度下制备了2A14-T4铝合金T形接头。在优化的焊接工艺参数下,可以得到光滑的T形接头焊缝表面。结果表明:焊接熔核区(WNZ)的显微组织为完全动态再结晶产生的细小等轴晶,第2次焊核区(WNZ2)的平均晶粒尺寸最大,焊接重合区(WNOZ)次之,第1次焊核区(WNZ1)的平均晶粒尺寸最小。WNZ的再结晶机制主要是几何动态再结晶,并伴有部分连续动态再结晶。WNZ1和WNZ2织构类型为弱{111}<110>,而WNOZ经过2次搅拌后织构类型为弱{100}<001>。热机械影响区(TMAZ)发生塑性变形,而热影响区(HAZ)只受到焊接热循环作用,不发生塑性变形和晶粒的动态再结晶。WNZ的硬度较高,硬度最低的区域位于靠近TMAZ的HAZ。随着焊接速度的增加,接头抗拉伸强度先增大后减小。底板和加强板的主要断裂形式是脆性/韧性混合断裂。 相似文献
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采用双光束同步激光填丝焊接的方法制备了Ti-6Al-4V合金T型接头,使用高速摄像机拍摄了焊接过程图像并研究了热输入对焊接过程稳定性、焊缝成形、组织及力学性能的影响。试验结果表明,热输入显著影响熔池行为和填丝焊接熔滴过渡,进而影响T型接头焊缝形貌及质量。随着热输入的增加,T型接头组织发生变化,晶粒尺寸变大。热影响区及焊缝处的马氏体使得这2个区域的显微硬度高于母材。另外,沿蒙皮方向及筋条方向的抗拉伸强度随着热输入的增加而增大。由于接头处马氏体增强作用,拉伸断裂均发生于母材处。 相似文献
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采用激光-TIG弧复合焊接工艺对钛合金T形结构单面焊背面双侧一次成形焊接新技术进行了研究,通过综合试验、对比分析等方法,研究了多种试验条件下T形结构焊缝成形特点及影响因素,给出了采用激光-TIG复合焊接工艺实现钛合金T形结构单面焊背面双侧一次成形焊接的最佳工艺方案.结果表明,采用激光-TIG复合焊接工艺焊接钛合金T形结构与钨极氩弧熔透焊工艺相比在焊缝组织、焊接效率、焊缝成形、间隙适应性等方面有明显的优势. 相似文献
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《Science & Technology of Welding & Joining》2013,18(3):199-207
AbstractOne of the most relevant aspects of friction stir welding is the possibility to weld different materials. In the present paper, the authors present an improved continuum finite element model for the simulation of friction stir welding processes aimed to obtain T joints, made of a stringer in AA7175-T73511 and of a skin in AA2024-T4. The model, taking into account the thermomechanical behaviours of the two different materials, is utilised to study the occurring material flow and residual stress state. Numerical results are compared with experimental observations: the model is able to predict the material flow, obtaining important information on the joint failure mode. 相似文献
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Comparison of single and double pass friction stir welding of skin–stringer aviation aluminium alloy
《Science & Technology of Welding & Joining》2013,18(7):610-615
AbstractTo enhance the strength of the skin–stringer structures used in aircraft, comparative tests between single and double pass friction stir welding (FSW) were performed. Aluminium alloy was used for the skin (2524-T3, 1·8 mm) and stringer (7150-T77511, 2·4 mm). An equilateral right angled structure was used, and perfect joints without internal defects were obtained. Tensile, peel and metallographic tests were also implemented. The results show that the average peel strength of a double pass FSW joint is at least twice that from single pass FSW. Therefore, double pass FSW is an effective way of improving the connection strength of an aircraft skin–stringer structure. 相似文献
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采用双侧同步激光焊接的方法获得Ti-6Al-4V合金T形接头,借助红外热成像的方法,研究激光焊接T形接头拉伸过程中典型缺陷如咬边、未熔合、气孔等的影响及特征. 结果表明,拉伸过程中温度的升高虽然出现在两侧蒙皮母材中,但随着变形量的增加,接头咬边处的应力集中效应凸显,温度也在该区域出现了大幅上升,塑性变形增大,并最终在此处发生断裂. 未熔合及气孔缺陷一般处于硬化区中部,不影响该区域的强化作用,温度的大幅增加仍位于蒙皮一侧母材处,最终在温度最高点处发生断裂. 相似文献
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The effects of welding on the tensile and fatigue properties of fully annealed and cold-worked Fe-12Cr-20Mn austenitic stainless
steel were evaluated. Room temperature and 500 °C tensile tests and room temperature cantilever beam fatigue tests were accomplished
on specimens that contained autogenous bead-on-plate welds. The tensile and fatigue properties of the fully annealed material
were not significantly influenced by welding. The tensile properties of the welded cold-worked material were also not significantly
affected by the presence of a weldment. However, welding caused a large reduction of the fatigue life of the cold-worked material.
Fatigue cracks preferentially initiated at large Mn-Si inclusions that formed in the fusion zones of the weldments. 相似文献