焊接工艺对690镍基合金焊丝熔敷金属高温失塑裂纹敏感性影响研究

针对690镍基合金熔敷金属高温失塑裂纹敏感性问题,采用基于Gleeble-3500热力耦合试验机的STF试验,开展焊接工艺对国产化690镍基合金焊丝WHS690M熔敷金属高温失塑裂纹敏感性的影响研究,并与进口Inconel 52M焊丝试验结果进行对比分析。试验表明,熔敷金属高温失塑裂纹最小临界应变出现在1 050℃附近,焊接热输入对最小临界应变影响较小,相比于大面积堆焊熔敷层,对接焊缝熔敷金属临界应变降低,高温失塑裂纹敏感性提高。     

镍基合金复合钢板的焊接

环化塔预热器壳体的设计材料是Hastelloy C-276、Monel 400两种镍基合金复合不锈钢板,焊接是制造这台设备的关键技术.通过分析镍基合金复合钢板的焊接特点,指出镍基合金复合钢板焊接的关键是控制基层根部焊接时,焊缝金属中不要熔入复层合金成分;复层堆焊后的合金成分接近或达到焊材的化学成分,满足耐蚀要求.采用台阶式坡口形式,是避免根部焊缝金属互熔的最好措施;控制焊接线能量的多层焊是保证堆焊复层耐蚀性的关键.     

镍基合金焊接裂纹研究现状

近年来,镍基合金焊接件在航空航天、核电、火电和石油化工等工程领域的应用需求快速增长。本文介绍了镍基合金的分类以及镍基合金焊接方法的研究,由于成本以及技术等的限制,镍基合金的焊接主要采用熔化焊焊接方法。重点综述了镍基合金焊接裂纹的产生机理以及各元素对裂纹的影响。镍基合金熔化焊焊接过程中易产生4种焊接裂纹:结晶裂纹、液化裂纹、失塑裂纹和应变时效裂纹。总体上,结晶裂纹和液化裂纹产生机理已较为明确,焊接过程中低熔点液态薄膜的出现是结晶裂纹和液化裂纹产生的主要因素。失塑裂纹目前仍没有对其明确的定义,镍基合金失塑裂纹产生机理也存在着较大的分歧。镍基合金应变时效裂纹是沉淀强化镍基合金所特有的,裂纹产生与沉淀相的沉淀速率密切相关。杂质元素和添加元素对镍基合金焊接裂纹敏感性有着重要影响,元素的影响虽然已经进行了大量的研究,但元素单独或者协同对裂纹敏感性的具体影响仍需进一步的研究。     

高温合金熔化焊焊接性的研究进展

综述镍基高温合金和钴基高温合金熔化焊的研究现状,并阐述了焊接裂纹形成机理以及焊接工艺和合金成分对其焊接性的影响.镍基高温合金可以通过调整合金成分、析出相和晶界形貌、焊接工艺等来提高其焊接性.与沉淀强化型镍基高温合金相比,固溶强化钴基合金焊接性能良好,展现出良好的界面熔合性和较高的抗裂纹敏感性.新型沉淀强化钴基合金中γ/...     

镍基合堆焊层焊接热裂纹研究

该文采用托马斯镶嵌块试样和镍基合金管与不锈钢堆焊层实样进行焊接试验，比较了空冷，水冷和－４０℃干冰酒精冷却条件下焊接对焊缝微裂纹的影响。结果表明焊缝的高速冷却有利于镍基合金焊缝热裂纹的减少。     

喷瓷管道焊接接头的自熔覆防护

通过分析焊接对喷瓷管道焊接接头处瓷层的影响，提出了用自熔覆法对焊接接头进行防护。试验结果表明，在合适的电流下采用TIG焊打底能够使焊口附近的瓷层重熔并向焊缝流布、熔覆，在焊缝区形成保护层，起到自熔覆防护作用；焊前管端预涂釉浆能有效增加焊后接头区自熔覆瓷层的厚度，提高瓷层的防护效果；焊后采用火焰加热对接头区进行重熔处理，可以消除瓷层中气泡、裂纹等缺陷。采用焊前管端预涂釉浆、TIG焊打底、焊条电弧焊填充、焊后接头区瓷层重熔处理等配套措施能够有效解决喷瓷管道焊接接头的防护问题，焊后不用进行内补口。     

镍基合金油管实物性能试样焊接工艺研究

油井管实物性能检测是油井管产品使用的前提.本文针对镍基合金油管实物制备装配工艺进行研究,通过焊接方式将镍基合金油管与密封堵头进行连接,采用双相不锈钢焊条进行打底焊、抗拉强度高的不锈钢焊条进行填充盖面焊,焊后对其接头的显微组织、力学性能及全尺寸实物性能进行试验与分析.结果表明,焊接接头在靠近密封堵头侧为回火索氏体组织及上贝氏体组织,在镍基合金侧为奥氏体组织,焊缝组织为奥氏体和铁素体双相组织及少量碳化物.焊接接头的抗拉强度达到725MPa,断裂发生在镍基合金热影响区.焊缝具有较高的塑性,弯曲试验中焊缝未出现裂纹.焊缝区硬度最高,其次是镍基合金热影响区,镍基合金及密封堵头母材硬度分布均匀,镍基合金基体出现低硬度区,而在密封堵头侧熔合线附近靠近焊缝侧出现低硬度峰值.对采用焊接工艺制备的镍基合金油管进行全尺寸复合载荷实物性能检测试验,结果表明焊缝性能能够满足实物性能检测要求,未出现裂纹、泄漏、断裂等现象.     

镍基自熔性合金喷焊涂层的组织与性能研究

用两种镍基自熔性合金粉末,采用火焰喷焊技术在STB A22钢管基体表面制备了两种喷焊层,利用光学显微镜和扫描电镜观察了镍基合金喷焊钢管的表面形貌和喷焊层的断面组织,测定了喷焊层与基体之间的结合强度,利用扫描电镜和能谱仪测定了喷焊层与基体的界面组织以及成分分布,研究了喷焊层的成分分布、组织与性能.结果表明,镍基喷焊层与钢管基体形成了良好的冶金结合,合金元素在喷焊层与基体界面附近连续分布,保证了采用火焰喷焊技术得到的涂层与基体之间具有较高的结合强度.     

核电设备用690镍基合金气体保护焊丝国产化研究

针对核电设备用690镍基合金焊接材料依赖进口的现状,开展690镍基合金焊接材料的国产化研制。研制的690镍基合金气体保护焊焊丝WHS690M满足CAP1000及CAP1400核电站的要求,焊接工艺性良好,在不同焊接规范参数下,焊缝金属室温及高温力学性能波动较小,350℃抗拉强度≥485 MPa。对WHS690M及进口Inconel 52M焊丝熔敷金属进行高温失塑裂纹敏感性评估,并结合光学显微镜(OM)、扫描电子显微镜(SEM)及电子背散射衍射技术(EBSD),对晶粒取向和晶界特征进行观察。试验表明,焊缝金属DDC最小临界应变出现在1 050℃附近,进口Inconel 52M最小临界应变约为2.1%,WHS690M最小临界应变约为3.2%。     

镍基高温耐磨无渣堆焊焊条及其热处理工艺

针对镍基合金具有优良的高温综合性能,且目前市场上几乎没有这类手工电弧堆焊材料等实际情况,研制开发了一种抗高温耐磨损的镍基无渣堆焊焊条.该焊条具有焊接烟尘小,烟尘中含对人体有害气体极少;焊后焊道上几乎没有熔渣,连续多层焊无需敲渣;价格便宜(与钴基合金相比),高温(650℃左右)性能优良等特点.此外,该焊条由于熔敷金属中含合金元素量较一般堆焊焊条的熔敷金属多,成分复杂,焊后焊缝中存在的内应力较大,且焊缝在快速冷却条件下产生的组织不稳定,从而影响到熔敷金属的综合性能.为了能更好地推广和更合理地应用这种高温无渣耐磨堆焊焊条,对其熔敷金属的热处理工艺也进行了初步探讨.     

Plasma spraying of self-fluxing alloys with a remote arc with melting of the coating

One of the most advanced and efficient methods of increasing the service life of machine components and mechanisms is the deposition of hardening coatings on the working surfaces. The coatings of nickel-based self-fluxing alloys deposited by plasma spraying are used widely in various branches of engineering. The properties and bonding strength of plasma coatings produced from nickel-based self-fluxing alloys can be improved by melting the surface layer at a specific temperature. In this work, the authors propose a method of calculating the depth of penetration in spraying the coatings of self-fluxing alloys with a remote arc taking into account the changes of the heat conductivity of the material which depends on porosity and temperature. The experimental results are used to determine the values of the heat conductivity coefficient for the nickel-based self-fluxing alloys. The dependence can be used for the more accurate selection of the power of the remote arc. The difference between the calculated and experimental values is smaller than 10%.     

稀释率对ENiCrFe-7焊材熔敷金属隔离层中凝固裂纹的影响机理

采用ENiCrFe-7镍基焊材作为填充金属对Q345B钢进行焊接,在熔敷金属的隔离层中发现存在较大尺寸的微裂纹. 通过光学显微镜、扫描电子显微镜及能谱仪等手段,对隔离层内裂纹的分布、形态及裂纹内析出相等进行分析,并与不存在裂纹的熔敷金属区域进行对比. 结果表明,裂纹只存在于隔离层中,该区域中的稀释率较高,导致Fe含量较高;隔离层中富Nb析出物数量高于无裂纹的熔覆金属区域;裂纹表面呈现出典型的凝固裂纹形态,并存在大量富集Nb,S元素的析出相;焊接过程中,富Nb,S低熔点相析出是导致隔离层中形成凝固裂纹的主要原因.     

Research on Prediction Method of Liquation Cracking Susceptibility to Magnesium Alloy WeldsEI北大核心CSCD

Magnesium alloys has a wide application prospect due to their good properties, such as high specific strength and specific stiffness, but the susceptibility of liquation cracking is also pretty high. The liquation in partially melted zone of AZ-series magnesium alloys were investigated with circular-patch welding test. The AZ91, AZ31 base alloys were welded with AZ61 and AZ92 filler wires by using the cold metal transter metal inert-gas (CMT-MIG) welding. The results show that, the liquation occurred along the weld edge of AZ91 with the eutectic reaction occurring between gamma(Mg17Al12) phase and Mg-rich phase. The liquation susceptibility of AZ31 was pretty low as gamma(Mg17Al12) was not present in base metal of AZ31. Meanwhile, a new method for predicting liquation cracking based on binary phase diagram was proposed. When the initial solidification temperature of weld is higher and the solidification temperature range of weld is shorter than those of base metal, the liquation crack susceptibility of weld is mostly higher. When the initial solidification temperature of weld is close to or below that of base metal, and the solidification temperature range of weld is close to or longer than that of base metal, the liquation cracking susceptibility of weld is lower. This method worked well on predicting the effect of composition of base metal and filler wires on liquation cracking, and the predicting results are consistent with the experimental results. That is, the liquation cracking susceptibility is higher with AZ91 base metal used than that with AZ31 base metal. And, the liquation cracking susceptibility is lower with AZ92 filler wire than that with AZ61 filler wire.     

超厚板TC4钛合金电子束焊接接头应力腐蚀敏感性

针对100 mm超厚板TC4钛合金电子束焊接接头,采用慢应变速率拉伸方法评价接头在人造海水中的应力腐蚀敏感性,分析接头的显微组织和断口形貌,对接头的腐蚀机制进行研究. 结果表明,室温条件下应变速率为ε=1×10-6 s-1时,母材在海水中未表现出应力腐蚀敏感性;焊缝上部、中部和下部具有轻微应力腐蚀敏感性. 焊缝在海水中发生阳极溶解,产生氢吸附,导致裂纹的萌生. 同时氢扩散诱导α'相界及α'相内发生位错塞积,进而使裂纹在更低的应力水平下发生扩展.     

焊接加热对SHS复合材料组织的影响

采用电弧焊接方法焊搠铁资内衬复合钢管,探讨了焊接加热对热影响区组织的影响,结果表明,采用电弧焊方法焊接瓷内衬复合钢管,可以使复合材料经历一次热处理,热影响区陶瓷层由原来的树枝晶向等轴晶转化,焊接熔合区,在陶瓷与金属之间形成了一过渡层,过渡层与金属呈微冶金结合方式,过渡层与陶瓷呈现出原位结合方式。     

X65管线钢焊缝金属裂纹分析

Ｘ６５管线钢在焊接过程中,内侧焊疑金属出现横向和纵向沿熔合线方向的裂纹,横向裂纹惯穿焊缝金属横截面。有扫描电镜分析断口,发现裂纹处的焊缝金属与母材有较严重的化学成分偏析,内侧缝金属的熔合线基本垂直于母材。分析结果表明：局部成分偏析、工艺参数不适宜是造成焊缝裂纹的主要原因。     

AZ31B镁合金TIG焊裂纹形成机理及其预防措施

分析了AZ31B镁合金TIG焊接头裂纹形成机理,并提出了相应的预防措施。试验表明,焊接裂纹与填充材料的化学成分有一定关系。采用锌含量较低的AZ40M作为填充材料时,焊缝没有出现裂纹;采用AZ31B作为填充材料或直接对焊时,焊缝均有裂纹。     

Effects of alloy elements on microstructure and crack resistance of Fe-C-Cr weld surfacing layer

0　IntroductionFe C Crsurfacingalloysarewidelyusedinindustries ,mainlyduetotheirhighwearresistance .Underconditionsofabrasiveenvironments,theeffectofcompositionandmi crostructureontheabrasionresistancehasbeenextensivelystudied[1～4 ] .TheauthorsalsoevaluatederosionresistanceofFe C Crweldsurfacinglayersbecausealargenumberofma chinecomponentssufferedfromsevereerosion ,suchasper cussiveplate ,rotorbladeandexhaustpipe ,etc .However,thelowcrackresistanceofFe C Crweldsurfacinglayershasbecomethei…     

A J-INTEGRAL ANALYSIS OF CRACKS IN OVERMATCHED WELDED JOINTS

The effects of material inhomogeneity and weld width of the overmatched welded joints with alongitudinal crack or flaw upon the J-interal,a characterizing parameter for elastoplasticfracture,have been studied.The overmatched weld is idealized to be a parallelly cracked andsandwiched hard layer,the yieht stress of which is higher than that of the base metal.Numeri-cal solutions were obtained by using elastoplastic finite element method under the assumptionof plane stress.The resuits show that the values of J-integral are remarkably affected by thematerial inhomogeneity ant the weld width especially when the nominal stress or nominalstrain is comparatively high,which,therfore,should be taken into account when evaluatingthe crack driving force for an overmatched joint.     

高匹配焊接接头裂纹的J积分研究

本文研究了含有纵向裂纹或缺陷的高匹配焊接接头材料不均匀性和焊缝宽度对弹塑性断裂表征参量J积分的影响规律.高匹配焊缝被理想化为含有一平行裂纹的一个硬夹层,其屈服应力高于母材.在平面应力条件下利用弹塑性有限元计算得到数值解.研究结果表明,材料不均匀性和焊缝宽度对J积分值有显著影响,特别当名义应力或名义应变较高时影响更大.因此,估算高匹配接头的裂纹推力时必须对此加以考虑.