SiCp/2009Al复合材料搅拌摩擦焊T形接头组织与力学性能

在工具转速800 ~ 1200 r/min、焊接速度100 ~ 150 mm/min的工艺参数下，对6 mm厚的硬态(自然时效态)体积分数为15% SiCp/2009Al复合材料轧制板材进行T形搅拌摩擦焊(friction stir welding, FSW)，均获得了致密无缺陷的接头. 结果表明，FSW过程中，剧烈塑性变形使焊核区部分SiC颗粒发生一定程度的破碎，破碎程度随转速的增加而增加，随焊接速度的增加而减弱；焊核区中的微米级强化相发生破碎、溶解，并沿焊核区细晶界面析出. T形接头横板两侧各存在2个低硬度区，靠近焊核区的低硬度区的硬度比远离焊核区的低硬度区的硬度低；固定焊接速度为100 mm/min时，转速从800 r/min增加到1200 r/min时，接头的抗拉强度不变；固定转速为800 r/min时，将焊接速度从100 mm/min增加到150 mm/min时，接头的抗拉强度轻微降低. 接头拉伸过程中在横板与竖板交界处受应力最大，所有接头均在此区域断裂.     

焊接速度对5754铝合金FSW接头微观组织和力学性能的影响

对3 mm厚的5754铝合金板材进行搅拌摩擦焊接，研究了搅拌头在转速800 r/min条件下，不同焊接速度(100 ~ 400 mm/min)对搅拌摩擦焊接头微观组织和力学性能的影响. 结果表明，5754铝合金FSW接头横截面形貌呈“盆”形. 随着焊接速度增加，5754铝合金FSW接头的焊核区和轴肩区的面积逐渐减小，而搅拌针区面积先增加后减小. 当焊接速度为300 mm/min时，搅拌针区面积达到最大值6.66 mm2，轴肩区和搅拌针区面积比例为0.97，5754铝合金FSW接头的强度系数达到97.5%，这主要是因为轴肩区和搅拌针区面积相近，增大了焊核区和热影响区界面面积，从而提高了FSW接头强度，拉伸断裂在焊核区以外(热影响区或基材区)，断口为韧性断口. 当焊接速度为400 mm/min时，5754铝合金FSW接头的强度系数为58.8%，拉伸试样均断裂在焊核区，断口为脆性断口.     

焊接速度对AA6082搅拌摩擦焊接头根部 缺陷及性能的影响

研究了不同焊接速度对5.1 mm厚6082-T6铝合金搅拌摩擦焊接头根部缺陷及性能的影响.采用光学显微镜观察了不同参数下接头根部缺陷形貌并对不同焊接速度下的接头进行了拉伸和弯曲试验.结果表明,随着焊接速度的不断增加,接头根部未焊透缺陷倾向变大,接头软化区部位最低硬度值逐渐增高.焊接速度由50 mm/min增大到400 mm/min时,接头抗拉强度逐渐增加.进一步增大焊接速度到600 mm/min时,由于根部未焊透缺陷的严重性变大,造成接头强度下降.在软化区是接头薄弱区的条件下,其尺寸较小的根部缺陷不影响接头抗拉强度.但是对接头的抗弯强度有显著的不利影响.     

Microstructure and Mechanical Properties of Friction Stir Welded 1.5 GPa Martensitic High-Strength Steel Plates

In this study, 2.4 mm thick high-strength martensitic steel plates with a tensile strength of 1500 MPa were friction stir welded at various welding speeds of 40, 60, 80, 100, 120 mm/min and a constant rotation speed of 300 rpm. Sound joints could be obtained when the welding speed was 40, 60 and 80 mm/min, while a kissing bond was found in the joint welded at 100 and 120 mm/min. It was revealed that the peak temperature exceeded A_C3 (the end temperature at which all ferrite transformed to austenite when the steel was heated) for all the welding conditions and martensitic structures were finally formed in the stir zone of the joints. A significant decrease in hardness was located in the heat-affected zone, which had a transitional microstructure from tempered martensite near base metal to a mixed structure containing hard martensite, soft ferrite and bainite near stir zone. For the sound joints, the specimen was fractured in the heat-affected zone during tensile tests and the highest tensile strength could reach about 1058 MPa.     

1561铝合金搅拌摩擦焊接过程压力特征及接头组织性能分析

采用恒压力控制方式对4 mm厚1561新型高镁铝合金板材进行了搅拌摩擦焊接试验，并对焊接过程中搅拌头压力特征、接头微观组织以及力学性能进行了研究. 结果表明，焊接下扎阶段下压力呈先上升后下降再上升的趋势. 稳定焊接阶段，由于材料力学性能的周期性变化导致下压力呈近似正弦周期性变化. 固定焊接速度为200 mm/min，当转速低于800 r/min或高于1 800 r/min时，焊缝产生孔洞缺陷. 当转速超过1 000 r/min时，搅拌区产生"S"线. 接头抗拉强度在低转速时主要受接头金属强度影响，高转速时主要受"S"线分布特征影响. 随搅拌头转速的增加，接头抗拉强度先上升后下降.     

ZL114A铸铝搅拌摩擦焊接头性能

研究了采用不同焊接参数时ZL114A铸铝搅拌摩擦焊接头的金相组织、硬度分布及力学性能。结果表明，ZL114A铸铝的搅拌摩擦焊焊接性良好。焊核区的微观组织是无方向性的、细小的等轴晶粒。细化的硅粒子均匀布满整个焊核区。与粗大的树枝状母材相比，焊核晶粒细小、均匀而致密，没有观察到气孔等缺陷。焊缝区硬度分布较母材稳定，变化范围小。随着焊速增加，硅粒子所占体积比逐渐下降。热一机械影响区晶粒被拉长。接头的力学性能与焊接参数的匹配有关系。采用高焊速及转速与焊速比在3左右，获得的接头抗拉强度可达到母材的91％。焊后经T6热处理，可与同炉热处理母材等强。     

Microstructure evolution and fracture behaviour of friction stir welded 6061-T6 thin plate joints under high rotational speed

6061-T6 sheets with 0.8?mm thickness were successfully welded using high-speed friction stir welding (FSW) technology. The microstructural evolution and fracture behaviour of the joints were studied. The results show that sound joints could be obtained at the investigated high rotational speed of 8000?rev?min^?1 and welding speeds of 300–1200?mm?min^?1. Compared with conventional rotational speed, the grain size in the nugget zone (NZ) is obviously refined under high rotational speed. The Mg₂Si, Al₈Fe₂Si and Al₂CuMg precipitates reprecipitated adequately in the NZ during high-speed FSW, resulting in the number of the precipitates increased significantly, and further alleviating the weld softening. The difference in weld softening leads to different fracture characteristics during the tensile process. After artificial aging, the maximum welding softening in all joints is located in the heat affected zone, and the fracture is characterised by brittle fracture.     

5mm厚铝合金双面搅拌摩擦焊接

对5mm厚的1050-H24铝合金板材进行了双面搅拌摩擦焊接(FSW)，重点研究了接头的拉伸性能和断裂部位及其影响因素。研究结果表明，一次焊接参数、二次焊接参数和焊接方向对双面FSW接头的拉伸性能和断裂部位有不同程度的影响。一次焊接参数的影响较小，而二次焊接参数的影响显著并且存在最佳取值。同向焊接的接头强度较高且断在前进侧(AS)或后退侧(RS)，而异向焊接的接头强度较低且只断在AS。在文中的试验条件下，1500r／min的旋转速度、400mm／min的二次焊速和同向焊接方式是最佳的工艺组合，接头最高强度达到母材强度的78％。     

Friction Stir Welding of Low-Carbon AISI 1006 Steel: Room and High-Temperature Mechanical Properties

Friction stir welding (FSW) is an ecologically benign solid-state joining process. In this work, FSW of low-carbon AISI 1006 steel was carried out to study the microstructure and mechanical properties of the resulting joints at both room temperature (RT) and 200 °C. In the parameter space investigated here, a rotational tool speed and translation feed combination of 1200 rpm and 60 mm/min produced a defect-free weld with balanced mechanical properties and a superior Vickers microhardness profile compared to all other conditions and to base metal (BM). At faster translation feeds (100 and 150 mm/min), wormhole defects were observed in the weld microstructure and were attributed to higher strain rate experienced by the weld zone. Under tensile loading, welded material exhibited yield strength that was up to 86 and 91% of the BM at RT and 200 °C, respectively. On the other hand, tensile strength of welded material was nearly similar to that of the base metal at both RT and 200 °C. However, at both temperatures the tensile ductility of the welded joints was observed to be significantly lower than the BM. Annealing of the 1200 rpm and 60 mm/min FSW specimen resulted in tensile strength of 102% compared to base material and 47% increase in the strain at failure compared to the as-welded specimen. The Charpy impact values revealed up to 62 and 53% increase in the specific impact energy for the 1200 rpm and 60 mm/min welded joints as compared with the BM.     

Multi-objective optimization of friction stir welding parameters using desirability approach to join Al/SiCp metal matrix composites

Silicon carbide particulate (SiC_p) reinforced cast aluminium (Al) based metal matrix composites (MMCs) have gained wide acceptance in the fabrication of light weight structures requiring high specific strength, high temperature capability and good wear resistance. Friction stir welding (FSW) process parameters play major role in deciding the performance of welded joints. The ultimate tensile strength, notch tensile strength and weld nugget hardness of friction stir butt welded joints of cast Al/SiC_p MMCs (AA6061 with 20% (volume fraction) of SiC_p) were investigated. The relationships between the FSW process parameters (rotational speed, welding speed and axial force) and the responses (ultimate tensile strength, notch tensile strength and weld nugget hardness) were established. The optimal welding parameters to maximize the mechanical properties were identified by using desirability approach. From this investigation, it is found that the joints fabricated with the tool rotational speed of 1370 r/min, welding speed of 88.9 mm/min, and axial force of 9.6 kN yield the maximum ultimate tensile strength, notch tensile strength and hardness of 265 MPa, 201 MPa and HV114, respectively.     

Effects of Welding and rotational speeds on the Microstructure and Hardness of Friction Stir Welded Single-Phase Brass

This study focuses on the effects of rotational and welding speeds on the microstructure and hardness of joints in friction stir welded single-phase brass. Welds were achieved under low heat input conditions at rotational and welding speeds of 400-800 r/min and 100-300 mm/min, respectively. In order to characterize the obtained welds, optical microscopy and Vickers hardness measurements were taken on the weld cross sections. According to the obtained results, increasing the welding speed and/or decreasing the rotational speed caused the grain size of the stir zone to decrease and, hence, improved the average hardness of this region. These results are discussed with respect to the interplay between the welding parameters and the peak temperature in the weld thermal cycle.     

Influences of process parameters on tensile strength of friction stir welded cast A319 aluminium alloy joints

Fusion welding of cast A319 (Al-Si-Cu) alloy will lead to many problems including porosity, micro-fissuring, and hot cracking. Friction Stir Welding (FSW) can be used to weld A319 alloy without these defects. In this investigation, an attempt has been made to study the effect of FSW process parameters on the tensile strength of A319 alloy welded joints. Joints were made using different combinations of tool rotation speed, welding speed, and axial force, each at four levels. The quality of weld zone was analyzed using macrostructure and microstructure analysis. Tensile strength of the joints were evaluated and correlated with the weld zone microstructure. The joint fabricated with a 1200 rpm tool rotation speed, 40 mm/min welding speed, and 4 kN axial force showed superior tensile strength compared with the other joints.     

搅拌摩擦对接焊6061铝合金的高周疲劳行为

对6061铝合金进行搅拌摩擦对接焊,其焊接工艺参数为：旋转速度600、800、1000、1200 r/min,前进速度80、100 mm/min,探针插入深度1.85 mm。基于搅拌摩擦焊参数计算得到的能量输入结果表明,在输入能量为196～405 kJ的情况下,接头在297～354 kJ的输入能量范围内有最大的抗拉强度。在不同的应力比（R=0.5,0.3,0.1,-0.3,-0.5）下,将高强度、低强度2种焊接头进行疲劳测试。结果表明,对于这2种焊接头,显微组织特征明显影响其疲劳性能,比如搅拌区、热力影响区（TMAZ）和热影响区。从接头的显微组织、裂纹扩展路径和断裂表面观察等方面对其疲劳强度进行讨论。     

搅拌摩擦焊工艺参数对铸态A356铝合金抗拉强度的影响(英文)

A356是一种高强度铝硅铸造态合金,广泛用于食品、化工、船舶、电器和汽车行业。熔焊这种铸造合金时存在许多问题,如孔隙、微裂隙、热裂等。然而,用搅拌摩擦焊(FSW)来焊接这种铸造态合金可以避免上述缺陷发生。研究了搅拌摩擦焊工艺参数对铸造态A356铝合金抗拉强度的影响;对旋转速度、焊接速度和轴向力等工艺参数进行优化;从宏观和微观组织分析角度对焊接区的质量进行分析;对焊接接头的抗拉强度进行了测定,并对抗拉强度与焊缝区硬度和显微组织的相关性进行了研究。在旋转速度1000r/min、焊接速度75mm/min和轴向力5kN的条件下得到的焊接接头具有最高的抗拉强度。     

6063-T6铝合金双轴肩搅拌摩擦焊接头组织及力学性能分析

对4 mm厚6063-T6铝合金进行了双轴肩搅拌摩擦焊接试验. 结果表明,双轴肩搅拌摩擦焊可以实现6063-T6铝合金的焊接,得到表面成形良好且内部无缺陷的接头. 接头宏观形貌为哑铃状,其微观形貌分为焊核区、热力影响区、热影响区及母材区. 在搅拌头转速为1 200 r/min,焊接速度为400~700 mm/min的工艺区间内,接头强度呈先升高后降低的趋势,最高可达181.64 MPa,为母材的68.5%,硬度分布呈W状分布,接头断裂位置位于前进侧热影响区,断裂方式为韧性断裂.     

Cu-Cr-Zr合金搅拌摩擦焊接接头的组织和力学性能

采用旋转速度为750和1500 r/min,焊接速度为23.5 mm/min的焊接参数分别对时效态和固溶态的3 mm厚的Cu-Cr-Zr合金板进行搅拌摩擦焊接,研究转速及母材区(BM)初始状态对搅拌摩擦焊(FSW)接头的微观组织与力学性能的影响,并对接头的力学性能进行模型化定量分析。结果表明:FSW后,接头晶粒显著细化,沉淀相在搅拌头的高温热作用下固溶在基体中。当BM的初始状态为时效态时,与1500 r/min样品相比,750 r/min样品晶粒尺寸较小且存在沉淀相,750 r/min样品力学性能较高,主要是晶界强化和沉淀强化的作用。当BM的初始状态为固溶态时,与1500 r/min样品相比,750 r/min样品晶粒尺寸较小,力学性能较高,主要是晶界强化的作用。当FSW转速相同时,时效态接头的晶粒尺寸小于固溶态接头,而力学性能高于固溶态接头,主要是由于BM的初始组织状态不同导致的。综合分析表明:FSW过程中选用低转速焊接,可以获得性能较优的接头。     

2A12铝合金FSW板材时效成形性研究

为评价2A12铝合金搅拌摩擦焊构件时效成形工艺,设计了以时间参数为变量的焊后时效成形工艺模拟试验,进行了FSW(FSW-搅拌摩擦焊)焊件蠕变时效力学性能及成形性研究。结果表明,在搅拌头转速750 r/min、焊速60 mm/s的焊接工艺参数下,当时效成形时间为8 h时,FSW焊接件抗拉强度达到354.1 MPa,为母材强度的79.2%,其断裂位置基本位于热影响区前进侧。在该工艺下最佳回弹时间为8 h,此时回弹率为33.49%。硬度最低点在热影响区,该区域内硬度随时效时间的增加呈递减趋势。     

6061-T6铝合金的静止轴肩搅拌摩擦焊工艺及组织性能

采用自主研制的静止轴肩搅拌摩擦焊工具系统成功获得了6061-T6铝合金的对接接头. 对该接头的焊缝成形、显微组织、硬度分布以及拉伸性能分别进行了试验研究. 结果表明,SSFSW工艺所得6061-T6铝合金接头具有非常美观的焊缝成形,与常规的FSW工艺相比,几乎没有出现焊缝减薄的现象;焊缝组织分区也有明显的不同,TMAZ非常窄,只有几百微米;接头的硬度呈"W"形分布;在转速1 000 r/min,焊速为200 mm/min时,接头的抗拉强度和断后伸长率达到最大,分别为母材的71.5%和44.6%;拉伸试样均断裂在热影响区,它是接头发生断裂的最薄弱区域.     

Influence of Processing Parameters on Induced Energy, Mechanical and Corrosion Properties of FSW Butt Joint of 7475 AA

Friction stir welding (FSW), a promising solid state joining process invented at TWI in 1991, was used to join 9?mm thick 7475 aluminum alloy which is considered essentially unweldable by fusion processes. In the present work, the process parameters such as tool rotational speed were varied from 300 to 1000?rpm for a travel speed of 50?mm/min and the influence of process parameters in terms of energy input on microstructure, hardness, tensile strength, and the corrosion property of 7475 aluminum joints was evaluated and analyzed. The maximum tensile strength of FSW joints was obtained at rotational speed of 400?rpm and traverse speed of 50?mm/min (59.2?kJ) which attributed maximum stirred zone area and maximum hardness. The maximum corrosion resistance properties of weld in 3.5% NaCl solution, however, were obtained at rotational speed of 1000?rpm and traverse speed of 50?mm/min. Furthermore, for a given weld, stirred zone showed improved corrosion properties than TMAZ.     

7050-T7451铝合金的搅拌摩擦焊接试验分析

在不同焊接参数下进行了7050-T7451铝合金的搅拌摩擦焊接试验,对接头显微组织进行了光学和TEM分析,并测试了接头的抗拉强度和硬度分布.焊接工艺参数通过影响接头微观组织和焊接缺陷来影响接头的力学性能,在转速800r/min和焊速200mm/min的情况下,接头的抗拉强度最高达到母材强度的88%.焊接热输入较高时,接头的拉伸断裂出现在热影响区,而热输入较低时,焊缝底部出现未焊合,接头从此处首先发生开裂.结果表明,焊核区发生了动态再结晶和沉淀相溶解;热影响区发生了沉淀相粗化,晶间出现无沉淀带.