2195铝锂合金焊接性能研究

采用手工氩弧焊焊接工艺,通过十字搭接裂纹敏感性试验方法来测定焊接裂纹敏感性,以此研究了焊丝成分变化对2195铝锂合金焊接结晶裂纹率、液化裂纹率的影响.试验过程综合优化了2195铝锂合金焊丝成分、焊接方式及焊接工艺参数,并对焊接接头的宏观形貌及微观组织、断裂特征和焊接接头力学性能等进行了测试和分析.研究结果表明:在焊接电...     

2195铝锂合金热处理制度工艺研究

随着航空航天工业的发展,对于低密度、高强度的铝合金材料需求越来越多,铝锂合金势必是一种发展趋势。近期,公司开展了2195铝锂合金试验研究,本文通过正交试验研究确定了最佳的热处理工艺,最终确定了2195铝锂合金挤压材的最优热处理制度。     

TiAl合金建筑材料焊后热处理组织及性能研究

对建筑用TiAl合金电子束焊接接头进行了两种热处理试验研究,借助金相显微镜(OM)分析了接头不同区域的显微组织,并对焊接接头进行显微硬度测试,分析了两种热处理方式对建筑TiAl合金焊接接头组织及硬度带来的变化.研究表明,TiAl合金电子束焊接后焊缝组织主要为α2相,B相与O相.焊接接头局部热处理后接头硬度较高的区域有所增加,但整体呈下降趋势;热处理后,TiAl合金电子束焊接后合金焊缝区的B2相尺寸减小,但B2相分解的O相板条尺寸变大.整体热处理后焊接接头的显微硬度整体有所降低.两种热处理均能降低焊缝区显微硬度,并分布较为平稳.     

激光冲击喷丸对2195铝锂合金组织结构及抗应力腐蚀性能的影响

研究了激光冲击喷丸(LSP)对2195铝锂合金组织结构及抗应力腐蚀性能的影响。研究结果表明激光冲击处理后,2195铝锂合金表层晶粒细化到纳米量级,多次冲击能使表层晶粒进一步细化。残余应力测试结果表明激光冲击喷丸能够引入残余压应力,多次冲击后残余压应力数值更大。此外,应力腐蚀实验结果表明激光冲击喷丸能够有效提升2195铝锂合金的抗应力腐蚀性能。在应力腐蚀环境中,激光冲击喷丸诱生的表层残余压应力和晶粒细化层能够阻碍裂纹的萌生和扩展,防止应力腐蚀断裂。     

厚板2195铝锂合金搅拌摩擦焊缝组织及性能研究

采用搅拌头转速800r/min、焊接速度150mm/min、搅拌头倾角2.5°的工艺参数焊接了10mm厚2195铝锂合金,并对接头组织及性能开展分析研究。结果表明:厚板2195铝锂合金搅拌摩擦焊接头组织分为焊核区、热机影响区、热影响区及轴肩影响区四个区域,且焊核中心也有明显的"洋葱环"结构;接头抗拉强度及延伸率分别达到母材的70%与60%,力学性能良好;接头各区域受搅拌作用及热循环影响的不同,晶粒组织尺寸存在差异,焊核区硬度最低,热机影响区次之,母材区硬度最大;接头断口以等轴韧窝为主,属于典型韧性断裂。     

2195铝锂合金轧制工艺研究

通过2195铝锂合金热轧、中间退火及冷轧试验，确立了合金适宜的热轧加热温度和退火温度，认为该合金冷轧变形量在不大于60％范围内对成品板材力学性能影响不大。     

铝锂合金材料研究应用现状与展望

铝锂合金是一类具有广阔应用前景的航空航天结构材料，已经历经90余年的发展历程.从铝锂合金的研发、生产和应用角度看，我国与国外仍存有不小差距.按成型方式铝锂合金可分为变形和铸造2大类, 目前研究较多和广泛应用的是变形铝锂合金.文中从析出相、热处理、腐蚀性和焊接性等方面介绍了变形铝锂合金的研究现状.同时从发展应用以及合金开发等方面, 总结了铸造铝锂合金的研究现状.结合当前国内外铝锂合金的研究现状对铝锂合金的未来发展做出了展望.      

时效及预拉伸变形对喷射成形2195铝锂合金性能和组织的影响

采用透射电子显微镜、拉伸试验等分析检测手段研究了用喷射成形2195铝锂合金铸锭挤压型材的预拉伸变形工艺和热处理工艺。结果表明,当预拉伸变形达到3%时,工艺能够满足型材力学性能的要求,型材的时效主要析出强化相为T1相、δ′相和θ′相。     

铝锂合金电子束焊缝超塑性变形行为与显微组织

通过高温拉伸试验研究了5A90铝锂合金电子束焊接头超塑性变形行为,并采用光学显微镜(OM)对接头变形前后的显微组织进行观察。研究结果表明,5A90铝锂合金电子束焊接头具有良好的超塑性变形能力,接头的延伸率随温度的升高和应变速率的增大而先增大再减小,试样的最佳变形参数为450℃,5×10~(-3)s~(-1),在此参数下试样的延伸率达到最大171.1%。变形后焊缝的组织由细小的等轴枝晶转变为较为粗大的等轴晶,焊缝的变形由扩散导致的晶界迁移和动态再结晶共同协调;而接头热影响区(HAZ)的组织发生较为明显的细化,主要变形机制为动态再结晶。温度的升高和应变速率的降低都有利于增强晶界迁移对焊缝变形的协调作用,同时会造成晶粒的长大,所以温度过高和应变速率过低都会使试样的延伸率下降。     

铝合金/Q235镀锌钢板异种金属CMT焊接接头组织分析

采用ER4043铝硅焊丝和ER5083铝镁焊丝对5083铝合金与Q235镀锌钢板进行CMT焊接实验;通过对焊缝界面组织的SEM和EDS观察分析,研究不同焊丝对5083铝合金和Q235镀锌钢板异种金属焊接接头的影响。结果表明:采用ER4043铝硅焊丝得到的焊接接头性能比采用ER5083铝镁焊丝得到的焊接接头性能更优。     

钪对AZ91合金组织和性能的影响

研究钪在AZ91合金中的相组成、形貌及其对合金组织和性能的影响。结果表明,钪在合金中生成Al3Sc高温耐热相,细化了枝晶组织。钪添加量为0.6%时,室温和200℃的抗拉强度分别为265.4MPa和161.1MPa。钪可显著降低合金自腐蚀电流密度,但腐蚀电位只有轻微增加。     

Effect of heat input on microstructure and mechanical properties of dissimilar joints of AISI 316L steel and API X70 high-strength low-alloy steel

The microstructure and mechanical properties of dissimilar joints of AISI 316L austenitic stainless steel and API X70 high-strength low-alloy steel were investigated.For this purpose,gas tungsten arc welding(GTAW)was used in three different heat inputs,including 0.73,0.84,and 0.97 kJ/mm.The microstructural investigations of different zones including base metals,weld metal,heat-affected zones and interfaces were performed by optical microscopy and scanning electron microscopy.The mechanical properties were measured by microhardness,tensile and impact tests.It was found that with increasing heat input,the dendrite size and inter-dendritic spacing in the weld metal increased.Also,the amount of delta ferrite in the weld metal was reduced.Therefore,tensile strength and hardness were reduced and impact test energy was increased.The investigation of the interface between AISI 316L base metal and ER316L filler metal showed that increasing the heat input increases the size of austenite grains in the fusion boundary.A transition region was formed at the interface between API X70 steel and filler metals.     

微量钪(Sc)对5A01合金性能与显微组织的影响

研究了在5A01合金基础上添加0．2％Sc和0．3％Sc后合金的显微组织、力学性能、腐蚀性能及焊接性能。结果表明，微量Sc的加入，初生Al3Sc或Al3（Sc，Zr）粒子可成为有效的非均质晶核，大大地细化合金的铸态晶粒，次生Al3Sc或Al3（Sc，Zr）粒子，能有效地钉轧位错和亚晶界，稳定亚结构并强烈抑制合金的再结晶。因此，加入Sc后的试验合金基体及焊接强度提高，腐蚀性能和焊接性能与5A01合金相当甚至更好。     

Welding character of the cryogenic and non-magnetic steel Fe-23Mn.4Al-5Cr-0.3C

The cold-rolled sheet of cryogenic and non-magnetic steel Fe-23Mn-4Al-5Cr-0.3C was welded by means of argon tungsten arc welding with the filler wire containing 26.65Mn, 3.06Al, 5.31 Cr and 0.31 C (wt.-%). The mechanical properties and microstructure of welded joints were examined at 300 and 77 K. The experimental results indicate that the weld metal and the heat affected zone are possessed of satisfactory mechanical properties suitable for cryogenic use and its austenitic structure is quite stable. No cooling delta-ferrite was observed in the weld metal or the heat affected zone. Thus, it is suggested that the Fe-23Mn-4Al-5Cr-0.3C steel can be used as a new material for weldments at cryogenic temperatures.     

Effect of Scandium and Chromium on the Structure and Heat Resistance of Alloys Based on γ-TiAl

It is established that microalloying of γ-titanium aluminides with scandium provides an increase in heat resistance, structure refinement and modification, and formation of a dispersion-strengthened structure with a coherent bond between the strengthening and matrix phases. Proceeding from this an improvement might be expected in strength characteristics over a wide temperature range. The effect in scandium consists in changing the ratio of Al:Ti thermodynamic activities in the direction of forming aluminum oxide at the alloy surface during oxidation as a result of the deoxidizing effect of scandium and the formation of fine oxide inclusions. As a result of this aluminum does not form oxides within the alloy. The distribution of elements within the microstructure of γ-Ti ― Al with 5%Cr after oxidation at 900°C for 300 h is studied. It is established that the surface scale layer that forms sometimes contains Cr in addition to Al and O. A diffusion mechanism is suggested for realizing the Cr-effect according to which chromium and aluminum ions participate in place of titanium ions in forming Al₂O₃ ― Cr₂O₃ scale at the metal ― air atmosphere interface.     

微量Nd和Sc对A1-6．5Mg-0．5Mn合金组织及力学性能的影响

采用拉伸力学性能测试、扫描电镜及透射电镜观察等手段研究了微量Nd和Sc对Al-6．5Mg-0．5Mn合金的显微组织及力学性能的影响。结果表明：分别单独添加Nd,Sc使合金的抗拉强度均有所提高;同时添加Nd和Sc可使合金的抗拉强度、屈服强度分别提高65MPa、55MPa,但合金的伸长率有所降低;合金中晶界上形成含Nd或Sc的化合物,这些化合物钉扎亚晶界、从而抑制合金的再结晶晶粒的形成。     

热处理工艺对含Nb微合金钢焊缝组织与性能的影响

采用含Nb焊丝对S355钢板进行焊接,分析了焊后热处理制度对含Nb焊缝组织和性能的影响。结果表明:经退火处理后,焊缝的强度升高,延伸率和冲击功降低。随着正火温度的升高,焊缝强度明显升高,延伸率和冲击功显著降低。随着正火次数的增加,焊缝强度、延伸率及冲击功均先增加而后降低,经3次正火处理后,焊缝组织和性能达到最佳值。     

Effect of GTAW Parameters on Structure and Mechanical Properties of C86300 Weld Joint

In this study, the effects of heat input variation in gas tungsten arc welding (GTAW), on structure and mechanical properties of commercially C86300 (containing addition of 0.6 wt% silicon) weld joint were investigated. Following microstructural characterization of Base metal, GTAW has been performed at welding currents 50 and 60 A and flow rates of argon shielding gas (10, 14 and 18 l/min) using the same filler metal composition. Therefore six GTAW samples were performed with various welding specifications. By structural investigations and hardness profiles, effects of increasing heat input on increasing average grain size in weld zone, heat affected zone width, penetration depth and alloying element losses were indicated. However increasing heat input increases penetration depth and has a positive effect on hardness and strength of the joint. In considering wear application of this alloy castings and probable GTAW for them, pin-on-disc wear test was performed and revealed better wear resistance of weld metal in comparison with base metal. Hence the optimum values of welding current and argon flow rates (in GTAW with the same composition filler) was determined for this alloy.     

Microstructure and mechanical property correlations in AA 6061 aluminium alloy friction stir welds

The influence of friction stir welding on the microstructure development and its role on residual stress distribution in the weldment and mechanical properties has been investigated. The study also focused on the impact of post weld heat treatment on the microstructure and mechanical properties as well as on residual stress distribution. The weld nugget region contained fine equiaxed grains as a result of thermo-mechanical working. Hardness survey showed that nugget region is soft due to precipitates dissolution. Weld joint exhibited lower strength as compared to the parent metal. Post weld Solution Treatment and Aging (STA) of longitudinal welds resulted in strength and ductility equivalent to that of parent metal while transverse weld tensile strength and ductility were lower than that of parent metal even after post weld STA. Residual stress distribution profiles across the weld region are asymmetric with respect to weld centerline, with the largest residual; stress gradients occurring on the advancing side of the weld. Within the region inside the shoulder diameter, residual stress is entirely compressive. Welds exhibited tensile residual stresses in post weld STA condition     

Al?Zn?Mg?Cu?Zr?(Sc)合金搅拌摩擦焊接头组织和性能

利用光学显微镜、透射电子显微镜、显微硬度计和万能拉伸试验机等分析手段,表征了Al?Zn?Mg?Cu?Zr?(Sc)合金搅拌摩擦焊（FSW）接头的显微组织和性能,探究了Sc元素对改善超高强Al?Zn?Mg?Cu?Zr合金焊接性能的作用机制。结果表明:Al?Zn?Mg?Cu?Zr?(Sc)合金焊接接头具有相似的组织特征,焊核区为动态再结晶组织,由细小均匀的等轴晶组成,包含较高密度的位错线,大部分时效析出相回溶;热力影响区晶粒被拉长,位错密度更高,残留的时效析出相显著粗化;热影响区保留与母材相同的晶粒形态,大部分时效析出的η'相发生长大,少部分粗化成η相。添加质量分数0.17%的Sc,可以使合金FSW接头抗拉强度提升43 MPa,屈服强度提升23 MPa,断后伸长率改善2.3%,焊接系数达到74.1%。Al₃(Sc,Zr)二次析出相可以强烈抑制位错、亚晶界、晶界的移动,细化晶粒的同时保留大量的亚结构,且自身可发挥Orowan弥散强化作用。因此,可通过细晶强化、亚结构强化和弥散强化三种方式显著提高合金FSW接头的力学性能。