2205双相不锈钢搅拌摩擦焊接头组织和性能

采用不同搅拌头转速,研究了搅拌头转速对4 mm厚2205双相不锈钢板材搅拌摩擦焊接头组织及性能的影响. 结果表明,当焊接速度为50 mm/min时,搅拌头转速在600 ~ 800 r/min的范围内,均可获得表面成形良好且内部无缺陷的接头.接头搅拌区在动态再结晶的作用下组织得到细化,硬度值较高,热影响区在焊接热作用下组织粗化,硬度值较低.整个接头的铁素体含量在50% ~ 60%范围内,且随着转速的升高搅拌区的铁素体含量有所增加. 当转速为600 r/min时,接头的抗拉强度达到最大824 MPa,为母材的97.3%,断裂位置为接头的热影响区.     

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.     

Effect of Intermetallic Compound Phases on the Mechanical Properties of the Dissimilar Al/Cu Friction Stir Welded Joints

Types and distribution of intermetallic compound phases and their effects on the mechanical properties of dissimilar Al/Cu friction stir welded joints were investigated. Three different rotation speeds of 1000, 1200 and 1400 rpm were used with two welding speeds of 20 and 50 mm/min. The results show that the microstructures inside the stir zone were greatly affected by the rotation speed. Complex layered structures that containing intermetallic compound phases such as CuAl₂, Al₄Cu₉ were formed in the stir zone. Their amount found to be increased with increasing rotation speed. However, the increasing of the rotation speed slightly lowered the hardness of the stir zone. Many sharp hardness peaks in the stir zones were found as a result of the intermetallic compounds formed, and the highest peaks of 420 Hv were observed at a rotation speed of 1400 rpm. The joints ultimate tensile strength reached a maximum value of 105 MPa at the rotation speed of 1200 rpm and travel speed of 20 mm/min with the joint efficiency ranged between 88 and 96% of the aluminum base metal. At the travel speed of 50 mm/min, the maximum value of the ultimate tensile strength was 96 MPa at rotation speed of 1400 rpm with the joint efficiency ranged between 79 and 90%. The fracture surfaces of tensile test specimens showed no evidence for the effect of the brittle intermetallic compounds in the stir zones on the tensile strength of the joints.     

High-Speed Friction Stir Welding of T6-Treated B_4Cp/6061Al Composite

T6-treated 20 wt% B_4 Cp/6061 Al sheets were joined under welding speeds of 400–1200 mm/min by friction stir welding(FSW) with a threaded cermet pin. The macro-defect-free FSW joints could be achieved at high welding speeds up to 1200 mm/min, but larger plunge depth was required at the welding speeds of 800 and 1200 mm/min to eliminate the tunnel defect. In the nugget zone(NZ) of the joints, the B_4 C particles were broken up and uniformly redistributed. The NZ exhibited lower hardness than the base metal(BM), and the hardness value almost did not change with increasing welding speed, attributable to the dissolution of precipitates. Compared with the BM, the joints showed lower tensile strength. As the welding speed increased from 400 to 800 mm/min, the joint efficiencies were nearly the same and up to ～ 73%. When the welding speed increased up to 1200 mm/min, the tensile strength significantly decreased, due to the occurrence of kissing bond defect at the bottom of the NZ. With increasing welding speed, the fracture location of the joints transferred gradually from the heat-affected zone to the NZ due to the kissing bond defects.     

Effect of welding speed on microstructures,mechanical properties and corrosion behavior of GTA-welded AISI 201 stainless steel sheets

Three welding speeds designated as low (1.5 mm/s), medium (2.5 mm/s) and high (3.5 mm/s) were operated during the gas tungsten arc welding (GTAW) process and joints made were subjected to analysis of the microstructures, mechanical and corrosion properties of the joints. It was found that the joints made using the high welding speed exhibited smaller weld bead size, higher tensile strength and elongation, higher hardness and higher pitting corrosion potentials than those welded with medium and low welding speeds. The dendrite length and inter-dendritic spacing in the weld zone reduced when increasing the welding speed which was the main reason for the observable changes in the tensile, hardness and corrosion properties of the weld joints.     

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.     

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.     

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.     

焊接参数对7A04铝合金搅拌摩擦焊接头组织与力学性能的影响

采用不同的焊接参数对3 mm厚7A04铝合金板进行焊接,并对接头的组织、沉淀相、力学性能及断口形貌进行了分析. 结果表明,焊核区组织发生动态再结晶,形成细小的等轴晶粒,热影响区晶粒发生明显粗化. TEM分析结果显示,经搅拌摩擦焊后,焊核区部分沉淀相溶解. 焊核区晶粒尺寸随焊接速度增大而减小. 当焊接速度为120 mm/min,旋转速度为800 r/min时,接头强度达到最大值 454.2 MPa,为母材的95%,断后伸长率为3.97%,为母材的70%. 硬度测试显示搅拌摩擦焊接头发生软化,焊缝区域硬度低于母材,硬度值最低点出现在热影响区;拉伸断口形貌SEM图像表明接头断裂方式为韧性和脆性混合型断裂.     

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6005A-T6铝合金双轴肩搅拌摩擦焊接头力学性能的影响

文中研究了转速和热输入特征值WP一定两种条件下焊接速度对6005A-T6铝合金双轴肩搅拌摩擦焊接头力学性能的影响. 结果表明,转速一定时,接头抗拉强度随焊接速度的增加呈先增大后减小的趋势;热输入特征值WP一定时,随着焊接速度的增加,接头的抗拉强度持续减小;接头呈现出三种断裂方式,分别为发生于热影响区的Ⅰ型断裂、发生于焊核区的Ⅱ型断裂和发生于热力影响区的Ⅲ型断裂;Ⅰ型断裂和Ⅱ型断裂为韧性断裂;Ⅲ型断裂为包含韧性断裂和脆性断裂的混合型断裂;接头拉伸断裂位置并非总出现在硬度最低处;焊接速度小于1 000 mm/min时,WP ≤ 1有利于提高接头力学性能,而焊接速度大于1 000 mm/min时,WP > 1更有利于提高接头力学性能.     

铝合金无减薄搅拌摩擦焊工艺优化及特征分析

为提高无减薄搅拌摩擦焊接头力学性能,基于响应面法对参数进行优化,建立了响应面模型,并对模型进行回归分析. 结果表明,无减薄搅拌摩擦焊是成形优良的焊接工艺,而且焊接参数对接头拉伸性能影响明显,其中主轴转速及焊接速度对其影响更为显著. 在无缺陷条件下,提高主轴转速的同时选取适中的焊接速度,以得到性能更优的焊接接头. 焊接参数为主轴转速1 000 r/min,焊接速度200 mm/min、轴肩下压量0.25 mm时,接头的抗拉强度最大为363 MPa,为母材的94.3%,断后伸长率11.2%. 而且相比于常规搅拌摩擦焊,无减薄搅拌摩擦焊在厚度方向上的性能更加均匀.     

6061-T6/7075-T6异种铝合金搅拌摩擦焊接头组织与性能

利用搅拌摩擦焊实现了2 mm厚7075-T6/6061-T6异种铝合金连接,并对材料放置位置和转速对接头成形与组织性能的影响进行了分析. 结果表明,7075-T6铝合金置于前进侧时更有利于焊接过程中材料的迁移行为,焊缝成形及接头性能更优.当焊接速度为150 mm/min、转速为1 000 r/min时,可获得内部无明显缺陷、外观良好的异种铝合金接头;相较于母材,热力影响区的小角度晶界含量增加,焊核区发生动态再结晶,小角度晶界转化为大角度晶界;接头拉伸性能随转速的增加,呈现先增加后减小的趋势.接头的平均抗拉强度和断后伸长率分别达到231 MPa和4.0%. 接头的断裂位置位于6061侧焊核区,与接头硬度最小位置相吻合.     

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.     

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。     

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.     

钛钢复合板搅拌摩擦焊接接头组织与力学性能

采用搅拌摩擦焊对接工艺焊接厚度为2 mm的TA2-Q235B钛钢复合板。采用光学显微镜和扫描电子显微镜观察焊接接头显微组织及断口形貌,并采用拉伸试验机和显微硬度计测试焊接接头力学性能及不同区域的显微硬度。结果表明,钛钢复合板焊接接头从上到下分为上部钢焊接区,中部钛钢混合区及下部钛焊接区3个区域,其中钛钢混合区呈交替层叠状结构。当轴肩旋转速度为300 r/min,焊接速度为40 mm/min时,焊接接头的抗拉强度为386 MPa,达到母材强度的80%以上,焊接区域的硬度平均值为243.5 HV,焊接接头断裂源于结合较弱的前进侧热机影响区域。     

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。     

搅拌摩擦焊工艺参数对纯铜接头组织和力学性能的影响

研究了搅拌摩擦焊工艺参数对3 mm的纯铜板材焊接接头组织和力学性能的影响.结果表明,在搅拌头旋转频率固定为800 r/m in,焊接速度在60~300 mm/m in范围内均得到了外表面美观、内部无缺陷的接头.焊接接头由两边向中间依次由母材区、热影响区、热力影响区和搅拌区组成.搅拌区组织由于动态再结晶作用使得该部分区域...     

新型9Cr-1Mo钢搅拌摩擦焊接头组织及性能

采用钨铼合金搅拌工具对新型9Cr-1Mo钢进行搅拌摩擦焊工艺试验,探讨焊缝成形、组织及性能变化规律. 结果表明,在300和400 r/min的转速,50 mm/min的焊接速度下可获得无缺陷接头;焊缝主要由搅拌区和热力影响区组成,具有明显的马氏体淬硬组织特征;高温热影响区为淬硬马氏体和回火马氏体混合组织,低温热影响区为过回火马氏体组织. 焊缝区具有晶粒细化特征,其晶粒尺寸约为母材69.2%. 焊缝区产生明显硬化,最高硬度约为母材硬度值的2.0倍. 焊接接头抗拉强度达到母材98%以上,搅拌区和热影响区冲击吸收能量分别达到母材的77.8%和87.4%,表明搅拌摩擦焊接头仍具有较好强韧匹配.