TC17钛合金线性摩擦焊接头组织及性能

文中针对航空发动机风扇及压气机盘TC17钛合金材料,开展了接头组织分析、拉伸性能测试及硬度测试,分析了接头不同部位组织特征及形成原因.结果表明,接头明显分为母材区（BM）、热力影响区（TMAZ）和焊合区（WZ）,焊接接头中部热力影响区的组织表现为等轴晶粒,而靠近焊缝边缘处热力影响区的晶粒表现为沿着受力方向被拉长,焊合区发生了动态再结晶;接头的拉伸性能与母材相当;接头热力影响区的硬度高于母材和焊合区,平均硬度为486 HV.     

试样状态对线性摩擦焊接头组织及性能的影响

文中针飞机构件常用的TC4钛合金,分别研究了线切割表面、粗铣表面及磨制表面三种状态焊前试件状态对线性摩擦焊接头成形、显微组织、氧元素含量及力学性能的影响。结果表明三种状态试件接头成形良好。焊后的宏观组织均分为母材区、热力影响区、焊合区,其中热力影响区组织沿着受力方向被拉长并发生了初生α相溶解,焊合区发生了动态再结晶,晶粒内部为细小的片层组织。线切割及粗铣状态接头氧元素含量没有明显增加,与磨制状态接头相当。三种焊前状态接头的拉伸性能相当;K_t=1,R=0.06,550 MPa条件时三种接头的疲劳寿命相当。     

PM-TZM钼合金电子束焊接特性

为研究PM-TZM钼合金电子束焊接特性,对其进行了电子束焊接试验,分别对接头显微组织及力学性能进行了分析. 结果表明,PM-TZM钼合金电子束焊缝呈“钉状”几何特征,熔合线附近有链状气孔出现. 焊缝区由粗大的等轴晶及柱状晶组成,热影响区晶粒相比于母材明显长大. 接头各区域硬度值不同,焊缝区硬度与母材相当,硬度最低值出现在两侧热影响区.PM-TZM合金电子束焊接接头有较大的性能损失. 接头室温最高抗拉强度378 MPa,为母材抗拉强度的47%,1 000℃抗拉强度168 MPa. 接头拉伸断裂均发生于焊缝区,呈典型的脆性解理断裂特征.     

TC21+TC4-DT线性摩擦焊接头组织与力学性能试验

针对高强TC21和中强TC4-DT异种钛合金进行线性摩擦焊工艺研究,对接头进行不同热处理,接头微观组织和力学性能进行试验分析. 结果表明,TC21 + TC4-DT线性摩擦焊接头飞边成形良好,飞边表面光滑根部无明显缺陷存在;焊态条件下焊缝组织为典型的魏氏组织结构特征,热处理后焊缝组织析出弥散的针状α相,随着热处理温度的升高析出的针状α相逐渐长大粗化,致使接头冲击和断裂性能先上升后下降;接头拉伸性能与TC4-DT母材相当;700℃/3 h热处理接头、母材高周疲劳性能试验结果表明,接头的疲劳极限达到558 MPa,与TC4-DT基体相当,焊缝组织细化是提高接头疲劳极限的重要原因.     

大厚度TC21钛合金电子束焊接试验

对56mm厚TC21钛合金进行了电子束对接试验,对接头显微组织和力学性能进行了研究.结果表明,接头焊缝区组织形态以柱状β晶粒为基体,针状的马氏体弥散其中;热影响区从焊缝到母材分为三个区域,依次为等轴再结晶β晶粒区、片状和针状а相形成的魏氏组织区以及片状α相聚集长大的区域;熔合区内柱状晶与等轴晶联生.接头强度达到母材水平,断裂发生在母材内,接头厚度方向性能一致.接头塑性损失较大,只达到母材的50%左右.接头焊缝区硬度最高,其次是热影响区的等轴晶区和魏氏组织区,而热影响区内片状α相聚集长大的区域硬度值最低.

Abstract：

Electron beam welding of TC21 56 mm titanium alloy was carried out. The microstructure and the mechanical properties of welded joints were analyzed and tested. The results showed that the weld zone consisted of the columnar β gains, and in which the transgranular acicular α' martensite were dispersedly distributed. HAZ can be divided into three parts from base metal to weld zone, which are the equiaxed recrystallized β grain zone, Widmanstaten structure zone formed by lamellar and aeicular α phases and lamellar a phase coarsening zone. Fusion zone consists of the adnate columnar and equiaxed grains. Tensile strength of joints reaches to that of base metal and the failure appears in the base metal. The mechanical properties are uniform along the vertical direction. Plasticity in the welded joint is greatly decreased and only up to 50% of that of the base metal. The microhardness in weld zone is the highest, and that of the equiaxed grain zone and Widmanstaten structure zone in HAZ is higher, and the microhardness in columnar a phase coarsening zone is the lowest.     

异质钛合金线性摩擦焊接头微观组织

为了探明TC11与TC17异质钛合金线性摩擦焊接头微观组织形成机制,采用光学显微镜和扫描电镜研究接头不同区域的微观组织.结果表明,线性摩擦焊接头由TC11一侧的热力影响区(TMAZ)、TC11一侧的焊缝区、TC17一侧的焊缝区和TC17一侧的TMAZ所组成.在TMAZ未发现有动态再结晶发生,而材料的相变与变形是同时进行的.在焊缝区内发生了动态再结晶过程,摩擦停止后在摩擦界面上形成初生β共生晶粒.在振幅为3 mm、频率为40 Hz、摩擦压力为66.7 MPa条件下,随着摩擦时间的延长,初生β相动态再结晶晶粒尺寸和α相片层宽度增加.     

激光快速成形TA15钛合金氩弧焊接头组织及力学性能

对激光快速成形TA15钛合金与轧制TA15钛合金薄板进行了氩弧焊接试验,观察分析了焊接接头各区域组织特征,测试了焊接接头各区域的显微硬度以及室温拉伸性能.结果表明,激光快速成形件与轧制薄板氩弧焊焊缝凝固组织是具有粗大片状α+β组织特征外延定向生长的柱状晶.轧制件对焊接热影响敏感性强,热影响区晶粒发生严重长大现象,激光成形件靠近焊缝热影响区晶粒转变为等轴晶,距焊缝较远的热影响区仍保持柱状晶.激光成形件热影响区硬度最高,焊缝区及轧制件热影响区的硬度最低.焊接接头抗拉强度低于母材,塑性与轧制件相当,断裂位置位于轧制件热影响区.     

Mechanical and corrosion properties of 445J2 ultra pure ferritic stainless steel joint

The microstructure, mechanical and corrosion resistance properties of 445J2 ultra pure ferritic stainless steel thin plate joints conducted by the pulsed current gas tungsten arc welding (PCGTAW) were discussed in this paper. In order to avoid weld defects, the appropriate welding process was adjusted. The joints were subjected to optical microscopy, transverse static tensile, plastic deformation, intergranular corrosion and electrochemistry corrosion tests. The results indicated that the weld zone (WZ) is characterized with columnar grains and equiaxed grains and the heat-affected zone (HAZ) shows coarse ferrite grains due to the rapid solidification of thin plate welding. The PCGTAW joint exhibited acceptable mechanical properties and equivalent corrosion resistance properties as the base metal.     

FSS/ASS厚壁异种钢“TIG冷焊 + UNGW”组合焊的接头组织与力学性能

为了有效解决铁素体不锈钢的焊接热影响区晶粒易粗化问题，以及奥氏体不锈钢焊接时在接头部分熔合区及其附近热影响区内因易形成蠕虫状δ铁素体而显著降低该区域耐腐蚀性的问题，提出了“TIG冷焊 + UNGW”的组合焊接工艺，并进行了1Cr17/1Cr18Ni9Ti厚壁异种不锈钢的焊接，同时对所得接头的显微组织、力学性能及耐腐蚀性进行了测试与分析. 结果表明，组合焊接头的1Cr17母材热影响区晶粒未发生粗化，并且1Cr18Ni9Ti母材部分熔合区及其附近热影响区内未形成蠕虫状δ铁素体；组合焊接头的抗拉强度优于1Cr17母材，并且1Cr17母材热影响区的冲击吸收能量与1Cr17母材相当；组合焊接头的熔敷层、1Cr18Ni9Ti母材、1Cr17母材、UNGW焊缝区及完整接头的耐腐蚀性呈依次下降的趋势.     

热处理对TC17(α+β)/TC17(β)线性摩擦焊接头组织及力学性能的影响

针对热处理前后TC17(α+β)/TC17(β)钛合金线性摩擦焊接头组织和性能进行了对比分析. 结果表明,焊态时焊缝区组织发生动态回复和再结晶,两侧的热力影响区组织均被不同程度地拉长,热处理后焊缝中的亚稳相分解析出弥散的α和β相,TC17(α+β)侧热力影响区的初生α相有所长大. 焊态接头焊缝区显微硬度比母材低,接头的抗拉强度和屈服强度略低于母材,分别达到母材的91.9%,96.2%,接头拉伸性能试件断裂位置均在焊缝区;经过热处理,母材显微硬度未发生明显变化,焊缝区显微硬度显著提高,接头抗拉强度和屈服强度达到与母材相当,与焊态相比分别提高11.9%,8.2%,接头拉伸性能试件断于母材区.     

DD6/FGH96线性摩擦焊接头组织及性能

文中针对航空发动机涡轮盘的典型材料DD6单晶和FGH96粉末合金材料,开展了异种材料线性摩擦焊工艺研究.研究了DD6/FGH96的可焊性,并对DD6/FGH96线性摩擦焊接头进行了组织观察和力学性能测试.结果表明,焊接后FGH96侧组织有明显变形区,而DD6侧组织变形不明显.两种材料焊缝区的γ'相均发生了溶解,而且尺寸也发生变化.拉伸测试结果表明,断裂均发生在DD6单晶侧,接头抗拉强度可与DD6单晶母材相当.     

30 mm 7A05铝合金搅拌摩擦焊接头组织及力学性能

采用搅拌摩擦焊方法利用新型搅拌头对30 mm厚的7A05-T6铝合金进行了单道对接,焊后分析讨论了焊缝接头微观组织和力学性能.结果表明,接头焊核区发生动态再结晶,生成细小的等轴晶粒;焊缝两侧热力影响区受机械和热的双重作用,组织存在较大差异,前进侧为窄条状组织,后退侧为扁平状组织;热影响区晶粒粗化;在焊接30 mm板时,工艺参数范围较窄,旋转频率为360 r/min,焊接速度为100 mm/min时,可获得无缺陷、成形好的焊缝;接头抗拉强度为367.7 MPa、屈服强度为280.8 MPa、断后伸长率为14.4%高于母材,接头抗拉强度可达母材的95%.接头显微硬度的分布呈类似W形分布,热影响区软化趋势比较明显.     

Rotating arc horizontal narrow gap welding of high strength quenched and tempered steel

Rotating arc horizontal narrow gap welding of quenched & tempered ( Q&T) steel was innovatively performed for solving the bottleneck that the molten pool sagged due to the gravity. The shapely multilayer single pass horizontal joint could be obtained by using the rotating arc welding process. The cold crack was not observed in the joint without controlling the heat input and selecting the consumables intentionally. Mkrostructure of the joint could be divided into three zones:base metal zone ( BMZ) , heat-affected zone (HAZ) and weld zone ( WZ). Because of the characteristic of the rotating arc horizontal welding process, the defects in the joints were slag inclusion formed at the inUrlayer of lower side wall. The tensile strength and hardness of HAZ and WZ were larger than those of BMZ. The impact toughness in WZ, HAZ and BM at 0℃ is equal to 115, 212 and 236 J, respectively.     

Double-sided gas tungsten arc welding process on TC4 titanium alloy

TC4 titanium alloy was welded by double-sided gas tungsten arc welding（GTAW） process in comparison with conventional GTAW process, the microstructure and mechanical performance of weld were also studied. The results indicate that double-sided GTAW is superior over regular single-sided GTAW on the aspects of increasing penetration, reducing welding deformation and improving welding efficiency. Good weld joint was obtained, which can reach 96.14% tensile strength and 70.85% elongation percentage of the base metal. The grains in heat-affected zone（HAZ） are thin and equiaxed and the degree of grain coarsening increases as one moves to the weld center line, and the interior of grains are α and α′ structures. The coarse columned and equiaxed grains, which interlace martensitic structures α′ and acicular α structures, are observed in weld zone. The fracture mode is ductile fracture.     

Microstructural and mechanical characteristics of laser welding of Ti6Al4V and lead metal

Titanium alloy Ti6Al4V and lead metal were welded using a continuous wave Nd:YAG laser. The influences of laser power, scanning velocity, and laser beam offset on weld morphology were investigated. Microstructure, chemical composition and mechanical properties of the joints were evaluated. Experimental results showed that fusion weld formed at the upper part of the weld and brazing weld with solder of Pb formed at the lower part of the weld under appropriate process condition. Interfaces were formed between mixed fusion zone and liquid lead zone in molten pool during laser welding of Ti6Al4V and lead. Reasons for interface formation may be different driving force of various regions in molten pool, and the miscibility gap of Ti and Pb binary system. Ti-Pb intermetallic compound Ti₄Pb was detected at the fusion weld zone, which made the microhardness of the weld seam was higher than that of the base materials. The strength of the joint was at least equal to or larger than that of lead base material.     

130mm铝合金扫描激光填丝焊接头微区组织和性能

针对船用130 mm 5A06铝合金厚壁结构件的扫描激光填丝焊接头,对其焊缝（weld metal,WM）、热影响区（heat affected zone,HAZ）及母材（base metal,BM）的显微组织进行研究,并通过维氏硬度和微型剪切试验研究了接头各区力学性能差异.结果表明,5A06铝合金单激光焊缝以等轴晶为主,填丝焊焊缝以柱状晶为主,HAZ和BM晶粒比WM粗,母材及热影响区为轧制的纤维状组织;由于焊接热循环作用,接头热影响区硬度略高于母材,抗剪强度二者差别不大,单激光焊缝硬度和抗剪强度略高于填丝层.总体而言,焊缝区强度低塑性好,母材及热影响区强度高塑性低.     

高氧TC4/TC17钛合金线性摩擦焊接头组织特征及力学性能

对高氧TC4/TC17异质钛合金进行线性摩擦焊试验,研究了焊接接头各区域组织特征、焊接界面合金元素扩散行为及力学性能. 结果表明,焊接过程中焊缝区发生了相变及动态再结晶,形成细小的等轴晶粒. 高氧TC4侧焊缝区形成针状马氏体,TC17侧形成亚稳定β相;两侧热力影响区晶粒均发生了破碎,沿着振动方向拉长. 焊后冷却阶段在焊合线附近出现合金元素扩散现象,扩散区域狭窄. 焊缝中心处显微硬度值最高达到420 HV,高氧TC4侧显微硬度随着靠近母材而逐渐降低;TC17侧显微硬度随着远离焊缝中心迅速升高. 拉伸性能测试结果表明,接头抗拉强度与高氧TC4母材相当.     

Microstructure and Its Influence on the Mechanical Properties of Ni–28W–6Cr-Based Alloy-Welded Joints by GTAW

Microstructure and mechanical properties of Ni–28W–6Cr alloy-welded joints produced by gas tungsten arc welding were investigated in this work.Results showed that original fine-grain base metal near fusion line totally transformed into coarse heat affected zone after welding.Carbides with different shapes were found in the weld metal and base metal, which all were determined as M6C carbides.In comparison with carbides in base metal, M6C carbides in weld metal are rich in Si and Cr but deficient in W.Moreover, M6C carbides are extremely scarce and hard to be detected in weld metal.Mechanical tests show that the hardness value of weld metal is only about 60% of base metal; the yield strength and tensile strength of welded joint are much lower than those of base metal due to the absence of carbides in weld metal.     

7075/TC4异种金属CMT Advanced+P熔钎焊特性分析

基于CMT Advanced+P焊接方法,以ER5356铝合金焊丝对7075铝合金和TC4钛合金组成的搭接接头进行熔钎焊试验,并对接头进行微观组织及力学性能分析.结果表明,焊接接头主要由焊缝区、铝合金侧热影响区和钎焊界面区组成;焊缝区主要是等轴晶;铝合金侧热影响区的晶粒表现出轧制特性,并在晶界附近析出大量金属间化合物;...     

TC4钛合金线性摩擦焊接头组织和力学性能

文中阐述了线性摩擦焊的原理、特点,并针对TC4钛合金线性摩擦焊接头组织和力学性能进行了研究.对比分析TC4钛合金线性摩擦焊接头焊态和焊后热处理态的接头组织和力学性能.结果表明,焊接接头共分为母材、热力影响区和焊缝区三部分;TC4钛合金的接头(包括焊态和焊后热处理态)抗拉强度和屈服强度均达到母材的90%以上;焊缝中心的硬度值最高,焊后热处理能使接头的硬度分布更加均匀.