TA23合金不同焊接方法接头组织性能研究

采用CMT、TIG和EBW焊对TA23合金进行焊接,对比分析了不同焊接方法下接头微观组织和力学性能的差异。结果表明,焊接热输入直接影响焊缝晶粒尺寸和焊接接头宽度,TIG焊缝晶粒尺寸最大,CMT次之,EBW最小;EBW接头宽度为5 mm,CMT接头宽度为7 mm,TIG接头达14 mm;3种焊接方法焊缝区域组织均由马氏体α相、片层状α相和残余β相组成,热影响区组织形态介于焊缝和母材组织形态之间;3种焊接方法焊缝区显微硬度和接头抗拉强度均大于母材,其中EBW焊缝区显微硬度值最大,TIG焊接头抗拉强度最高,CMT焊缝显微硬度和接头抗拉强度均居中。     

深潜器用Ti80厚板电子束焊接接头组织性能研究

采用电子束焊接方法焊接深潜器用56 mm厚Ti80合金,并对焊接接头的组织结构和力学性能进行研究。结果表明,焊接接头成形良好,无缺陷;焊缝组织为马氏体α相和残余β相组成的网篮组织;熔合区界线明显,过热区十分窄;热影响区组织由初生α相、马氏体α相和β相组成;焊接接头各区域显微硬度值分布不均匀,由焊缝至母材显微硬度值逐渐下降;拉伸断裂发生在远离焊缝的母材处,接头抗拉强度为935.3 MPa,大于原始母材的911.8 MPa;焊缝冲击吸收功为36.3 J,由焊缝至母材冲击吸收功值逐渐增大,接头各区域冲击断裂方式均为韧性断裂。     

钛合金激光焊及其接头的显微组织与力学性能

采用光纤激光器对3.5 mm厚TC4合金板材进行焊接,并对焊接接头的显微组织与力学性能进行分析测试,确定了试验条件下的最佳激光焊参数。结果表明,焊缝熔合区组织主要为针状α′马氏体及少量β相,热影响区由α相及少量α′马氏体组成;接头区域的显微硬度在熔合区变化平缓,而热影响区的硬度下降明显。在激光功率为4.0 kW、焊接速度为3.0 m/min时,获得接头的力学性能最佳,焊缝强度与母材本身的强度接近。接头拉伸断口表面存在大量韧窝,呈明显的韧性断裂特征。     

超窄间隙激光焊接TC4钛合金接头组织及性能研究

以TA2为焊丝,采用超窄间隙激光焊接方法焊接了10 mm的TC4钛合金板,间隙为2 mm。利用光学显微镜(OM)、扫描电镜(SEM)和拉伸试验机分析了TC4钛合金接头的组织与性能。结果表明,选取合适的工艺可以实现TC4钛合金超窄间隙激光填丝焊接,获得无缺陷的焊接接头。接头由母材、热影响区、熔合区、焊缝组成,界线清晰。其中热影响区为网篮状组织,焊缝由大β晶粒组成,大晶粒内部为杂乱的α+α′相针状组织,热影响区晶粒明显细化。由于超窄间隙的啮合效应,接头最大抗拉强度为893 MPa,达到母材的84.7%,断裂位置在焊缝中心。焊缝区和热影响区的显微硬度高于母材,且在热影响区的显微硬度最大,接头整体显微硬度呈马鞍状分布。     

AZ31/7005异种材料填丝GTAW焊接接头的组织与性能

采用ER4043,ER4047铝硅合金焊丝对AZ31镁合金和7005铝合金异种材料进行填丝钨极氩弧焊(GTAW),并对AZ31/7005接头进行微观组织观察和显微硬度分析。结果表明:采用填丝钨极氩弧焊工艺,可以获得表面成形良好的焊接接头;镁侧熔合区是接头力学性能的薄弱区,镁侧熔合区不同结晶区域Mg和Al的成分较为接近,组织主要为Mg17Al12+Mg共晶体组织;靠近镁侧熔合区无高硬度脆性相产生,焊缝区的硬度稍高于镁母材区,但远低于铝母材区。     

固溶时效态GH925/Inconel625异种合金焊接力学性能研究

采用氩气保护焊(MIG)和625专用焊丝,研究GH925合金圆柱搭接焊接电流、道次间隔时间(T=1～2 s)对焊结区组织成分、析出相对焊接接头力学性能的影响。研究表明,固溶时效态GH925合金采用625专用焊丝可以得到熔合良好的焊接接头,接头抗拉强度最高达到830 MPa,达到焊丝抗拉强度的1.15倍。焊缝区组织由奥氏体γ相和弥散析出δ相组成,焊接电流50 A时焊缝区以平面晶析出为主,出现晶界多边化现象;焊接电流65 A时焊缝为胞晶组织,焊接电流65和80 A时靠近熔合线母材一侧2～3 mm处出现δ相带状剧烈析出区,与δ析出温度范围有关。能谱分析表明析出相为(NiFeCr)固溶型复杂化合物。增加道次间隔时间T有利于获得力学性能更好的焊缝组织。     

不同强度级别双相不锈钢激光焊接头的组织与力学性能

目的 为了合理制定不同强度等级DP钢同种和异种接头的激光焊接工艺,研究激光焊接工艺对接头组织性能的影响。方法 采用SEM、硬度试验、拉伸试验等手段,研究不同强度等级DP钢同种和异种激光焊接接头的微观组织和力学性能。结果 对于同种DP钢激光焊接,由于接头各个区域经历的热循环不同,因此其马氏体体积分数和形态、含碳量等存在明显差异。在焊缝熔合区,由于冷却速度较高,因此马氏体体积分数较高且为细条状,硬度高于母材硬度。在热影响区,由于马氏体发生了回火分解,因此其硬度值低于母材硬度,且软化的程度和范围大小与DP钢的强度级别相关。软化的热影响区成为接头的薄弱区域,降低了接头的拉伸性能。在异种DP钢激光焊接接头中,焊缝熔合区的硬度也明显高于母材硬度。靠近高强度级别母材侧的热影响区范围更大,软化程度更明显,接头硬度分布不再对称。接头的抗拉强度与低等级DP钢母材的抗拉强度基本一致。结论 激光焊接工艺对不同强度等级DP钢同种和异种接头组织性能的影响存在较大的差异,DP钢强度级别越高,接头或接头对应侧的热影响区软化程度越明显,这在制定焊接工艺以及焊后处理工艺过程中需要予以考虑。     

316L/S32101异种金属焊接接头的显微组织与力学性能研究

目的 研究乏燃料水池用钢板316L与覆板S32101双相不锈钢的焊接性、接头不同区域显微组织特征及接头与母材之间的性能差异.方法 利用氩弧焊接技术对5 mm厚的316L底板与3 mm厚的S32101覆板以搭接的形式进行焊接,利用金相显微镜、扫描电镜、维氏显微硬度仪和电子万能材料试验机对焊接接头的宏观形貌、显微组织以及力学性能进行研究.结果 316L/S32101焊缝组织主要由铁素体基体、晶界树枝状奥氏体以及晶内细小片状奥氏体所组成;316L侧靠近焊缝处存在一个较窄的熔合区,其组织由奥氏体基体和少许细小分散的铁素体组成,而S32101侧靠近焊缝处组织则由粗大铁素体晶粒和沿晶粒边界分布的若干小块状奥氏体组成.从316L母材区到焊缝区,硬度显著增大,而从焊缝区到S32101母材区,硬度变化很小;焊接接头的抗拉强度高达510 MPa,为两侧316L和S32101母材强度的87.9％和88.6％.结论 在焊接电流为240 A和焊接速度为300 mm/min的条件下,可以通过氩弧焊获得成形良好的搭接接头,且接头的力学性能优异.     

7075高强铝合金激光填丝焊接组织与力学性能研究

采用光纤激光器对4mm厚的7075铝合金进行激光填丝焊接,对焊接接头的显微组织、相结构、断口形貌、力学性能进行观察和分析。结果表明:焊缝(FZ)边缘组织为柱状枝晶组织,焊缝中心为等轴晶组织;热影响区(HAZ)保留了母材(BM)的轧制长条状形态,但晶粒有所长大。母材的相组成主要为α-Al固溶体、S-Al_2CuMg强化相和η-MgZn_2强化相,焊缝无强化相析出。焊缝区硬度值为各区中最低,热影响区显微硬度呈阶梯式增长。焊接速度为2~4m/min的接头拉伸试样均在焊缝处断裂,抗拉强度最大为母材的67.5%。接头拉伸试样均出现了颈缩现象,断口由大量的等轴状韧窝构成,为韧性断裂。     

Ti17合金电子束焊接接头的性能及组织分析

分析了Ti17合金真空电子柬焊接接头的显微组织结构及其显微硬度分布规律,并结合室温和高温拉伸试验结果分析了焊接接头的力学性能。结果表明,用电子束焊接方法焊接的Ti17合金其焊缝区和热影响区显微组织为β相基体上分布着细长针状α相,母材为典型的α＋β双相网篮组织,焊后焊缝晶粒细化,焊接接头的焊缝区硬度最高,焊缝的抗拉强度和缺口敏感性均高于母材。     

异种高熵合金CuCoCrFeNi和AlCoCrFeNi的激光焊接头组织和性能研究

为开展异种高熵合金激光焊接性研究,采用光纤激光对1.2 mm厚的异种高熵合金CuCoCrFeNi和AlCoCrFeNi实施了对接焊试验,利用金相观察、EDS、XRD和显微硬度计等方法对接头组织和性能进行测试.研究表明:在经历焊接热循环后,HAZ的金相组织没有发生明显变化;在FZ附近发现两种不同类型的显微组织(柱状晶和胞状晶),WM中心区由等轴晶组成;WM区内各元素均匀分布,FZ附近区域焊缝晶界处存在Cu、Al元素的偏聚,与母材相比,该偏聚现象明显减弱;焊缝横截面的显微硬度略高于CuCoCrFeNi合金,远低于AlCoCrFeNi合金;异种接头拉伸试样断裂位置发生在AlCoCrFeNi合金母材处,接头的抗拉强度σb为166 MPa,断口形式为解理断裂,其断口形貌为扇形花样与河流状花样(无撕裂棱).与母材组织相比,焊缝区晶粒明显细化,且焊缝仍为高熵合金.     

Microstructure and properties of the laser butt welded 1.5-mm thick T2 copper joint achieved at high welding speed

Laser welding of highly reflective materials, such as copper, has suffered problems such as spatter, underfill and undercut for a long time. This work analyzed the associated mechanism and suggested that appearance and integrity of laser welded copper joint could be improved by conducting the welding process at a high welding speed which is slightly below the critical welding speed for full-penetration welding at the specified laser power. The microstructure, mechanical properties and electrical conductivity of the T2 copper joint achieved under high welding speed were tested. Results show that copper joint and base material (BM) have similar electrical conductivity, the weld fusion zone (FZ) and the heat affected zone (HAZ) are softened; the tensile strength and elongation of the joint are approximately 20% and 84% below those of the BM respectively. The joint breaks near the interface between the longitudinal columnar grain structures (LC) growing along welding direction at the FZ center, and the horizontal columnar grain structures (HC) growing perpendicular to the welding direction at other area of FZ. Degradation of the mechanical properties of copper joint is attributed to the softening of the heated zone and the big angle between the growth directions of LC and HC.     

Microstructure and mechanical properties of a new Al–Zn–Mg–Cu alloy joints welded by laser beam

A new type of Al–Zn–Mg–Cu alloy sheets with T6 temper were welded by laser beam welding (LBW). Microstructure characteristics and mechanical properties of the joints were evaluated. Results show that grains in the heat affected zone (HAZ) exhibit an elongated shape which is almost same as the base metal (BM). A non-dendritic equiaxed grain zone (EQZ) appears along the fusion line in the fusion zone (FZ), and grains here do not appear to nucleate epitaxially from the HAZ substrate. The FZ is mainly made up of dendritic equiaxed grains whose boundaries are decorated with continuous particles, identified as the T (AlZnMgCu) phase. Obvious softening occurs in FZ and HAZ, which mainly due to the changes of nanometric precipitates. The precipitates in BM are mainly η′, while plenty of GPI zones exist in FZ and HAZ adjacent to FZ, in the HAZ farther away from FZ, η phase appears. The minimum microhardness of the joint is always obtained in FZ at different times after welding. The ultimate tensile strength of the joint is 471.1 MPa which is 69.7% of that of the BM. Samples of the tensile tests always fracture at the FZ.     

工艺参数对Al-Mg异种金属搅拌摩擦焊-钎焊复合焊接接头力学性能的影响

目的研究工艺参数对Al-Mg异种金属搅拌摩擦焊-钎焊复合焊接接头力学性能的影响。方法采用搅拌摩擦焊-钎焊方法,在不同焊接工艺参数下焊接2A12-T4铝合金和AZ31镁合金。结果当焊接速度为23.5mm/min、旋转速度为375 r/min时,焊接接头的抗拉剪力达到最大,为5.5 kN,比搅拌摩擦焊接头的最大抗拉剪力的5.0 kN提高了10%。结论搅拌摩擦焊-钎焊复合焊接的工艺参数会显著影响铝/镁异种金属接头力学性能,通过优化工艺参数能够获得力学性能优异的铝/镁异种金属焊接接头。复合焊接接头的抗拉剪力随着焊接速度的增大呈现先增大后减小的趋势。     

Influence of Heat Input on Microstructure and Mechanical Properties of Laser Welding GH4169 Bolt Assembly—Numerical and Experimental Analysis

By conducting the numerical and experimental analysis, the influence of heat input on the microstructures and mechanical properties of laser welding GH4169 bolt assembly is systematically investigated. The weld formation, temperature field, and residual stress distribution during laser welding by using the finite element modeling are consistent with experimental results. The numerical simulation results show that the increase of heat input imparts lower residual stresses and higher temperature gradient. During the process of laser welding, the steepest temperature gradient and the peak residual stress arise in the fusion zone (FZ). In addition, the dissolution of γ″ and γ′ toward the fusion line increases in heat affected zone (HAZ), but only Laves phase is observed in FZ. With increasing heat input from 24 to 48 J mm⁻¹, the ultimate tensile strength of welded joints decreases. Both the lowest microhardness values and tensile failure of GH4169 alloy laser welded joint are in FZ. Herein, it is that the relationship among the heat input, microstructures, and mechanical properties of GH4196 bolt assembly in laser welding is systematically established, which will be of guiding significance for the selection of welding parameters in aerospace.     

铝/镁搅拌摩擦焊-钎焊焊接接头微观组织结构

目的研究不同工艺参数下钎料Zn的添加对Al/Mg异种金属搅拌摩擦焊-钎焊焊接接头组织和性能的影响。方法以厚度为0.05 mm的纯Zn作为钎料,对3 mm厚的2A12-T4态铝合金和4 mm厚的AZ31变形镁合金,进行搅拌摩擦焊-钎焊的复合焊接,分析锌夹层的添加对接头微观组织与力学性能的影响。结果当添加Zn中间层时,接头钎焊区缓解了拉伸断裂趋势,在焊接速度为23.5 mm/min,旋转速度为375 r/min时,接头抗拉剪力达到5.5 k N,复合焊接接头的钎焊焊缝由搭接区、固相扩散区、钎焊区组成。结论钎料的添加有效阻止了Al-Mg系金属间化合物的形成。     

Effect of electron beam welding on the microstructures and mechanical properties of thick TC4-DT alloy

Electron beam welding (EBW) was applied to 50 mm thick damage-tolerant Ti–6Al–4V (TC4-DT) alloy, and microstructure, microhardness and tensile properties of the defect-free welded joints were examined. The results indicated that the microstructure of the base metal is composed of primary α phases and the lamellar (α + β) bimodal structure. For the EBW joint, martensite basketweave microstructure is formed in fusion zone (FZ). Moreover, the heat affected zone (HAZ) near FZ consists of acicular martensite and a small portion of primary α phase. The HAZ near base metal consists of primary α phase and transformed β containing aciculate α. It is found that the boundary of the two portions of the HAZ was dependent on the β phase transus temperature during weld cooling. Microhardness values for FZ and HAZ are higher than that of base metal, and there are the peak values for the HAZ near the weld metal. The fracture locations of all the EBW tensile specimens are in base metal, and the ultimate tensile strength of the joints may reach about 95% of the base metal. In addition, with the depth increasing along the weld thick direction, the grain size of the FZ decreases and microhardness increases.     

电弧电流对AZ31B/DP980激光诱导电弧焊接接头成形及力学性能的影响

采用激光诱导钨极惰性气体保护(tungsten inert gas, TIG)电弧焊接技术,在未添加任何夹层和镀层的条件下,通过优化工艺,获得了AZ31B镁合金和DP980高强钢高质量搭接焊接头,重点研究TIG电弧电流对焊接接头成形和力学性能的影响规律。结果表明：电弧电流的增大会提高镁合金在高强钢的润湿铺展能力,提升焊缝宽度的同时减小润湿角。镁合金/钢焊接接头的最大拉伸载荷随着电弧电流的增大先升高后降低,接头断裂模式由沿界面断裂转变为沿焊缝断裂。当TIG电流为80 A、激光功率为350 W时,焊接接头最大平均拉伸载荷达到279 N/mm。焊缝宽度和界面层厚度的增大以及激光匙孔的钉扎作用共同提升了镁合金/钢的接头性能。     

Effect of Zn content on the microstructures and mechanical properties of laser beam-welded ZK series magnesium alloys

The effect of Zn content on the microstructures and mechanical properties of laser beam welded ZK series magnesium alloys (ZK21, ZK40, and ZK60) has been studied. Owing to the lower heat input, laser beam welding can successfully be employed to weld ZK series magnesium alloys having Zn content up to 4 wt%, which are difficult to weld by means of conventional arc welding. However, ZK60 is susceptible to solidification cracking and presents a poor weldability, which may originate from the net-like distribution of more Mg₅₁Zn₂₀ precipitates along grain boundaries (GBs) in the fusion zone (FZ). With increasing Zn content, the amount and size of precipitates along GBs in the FZ increase, and the morphology of grains in the FZ adjacent to fusion boundary changes from cellular to equiaxed dendritic. The grains in the FZ of ZK40 alloy are the finest among the three alloys, whose size is only about 4.8 μm, and the ZK40-welded joint achieves the highest ultimate tensile strength of 312 MPa, which is up to 90.4% of the base metal.