模拟焊后热处理温度对Q345R钢板焊接接头的焊接残余应力及力学性能的影响

通过热处理试验、残余应力测试、拉伸试验、弯曲试验、硬度试验等方法,分析了模拟焊后热处理温度对Q345R钢板焊接接头的残余应力及力学性能的影响.结果表明:随模拟焊后热处理温度由400℃提高至620℃,Q345R钢板焊接接头的残余应力逐渐减小,经620℃热处理后,可基本消除其焊接残余应力;随着模拟焊后热处理温度的提高,Q3...     

焊前及焊后热处理对TC11钛合金线性摩擦焊接头组织性能的影响

目的 研究焊前及焊后热处理（950 ℃+1 h+AC/540 ℃+6 h+AC）对TC11钛合金线性摩擦焊接头组织演变和力学性能的影响。方法 采用光镜、扫描电镜、显微硬度及拉伸试验对不同热处理条件下的接头进行了组织分析和力学性能测试。结果 金相结果表明,焊前热处理对焊接过程中接头的组织演变影响较小。在焊态和焊前热处理接头的焊接中心区域（WCZ）观察到类似的马氏体组织,但明显的热影响区域只能在焊前热处理接头中找到。焊后热处理后,WCZ中的马氏体组织转变为网篮组织,热力影响区（TMAZ）的初生α和转变β晶粒均有一定程度的长大。力学性能结果表明,焊前热处理可以提高整个接头的显微硬度,但硬度分布趋势与焊态接头的分布趋势相似。结论 焊后热处理可以降低WCZ和TMAZ的显微硬度,但母材的显微硬度有所提高。焊前和焊后热处理都可以提高接头抗拉强度,但会降低接头伸长率,特别是在焊前热处理条件下。     

焊后热处理对TC11钛合金线性摩擦焊接头组织与性能的影响

焊后热处理可以改善线性摩擦焊接头的组织与性能。对TC11钛合金线性摩擦焊接头进行双重退火(950+530)℃处理，利用光学显微镜、扫描电子显微镜等微观分析技术研究双重退火对焊接接头组织的影响。结果表明：热处理后接头焊缝区的动态再结晶晶粒完全消失，被粗针状、条状和球状α相取代。热力影响区组织变形程度减小，晶粒长大，部分α组织球化。母材中次生α相长大，呈粗针及短棒状。接头焊缝区及热力影响区的晶粒取向在热处理后更加随机，择优取向明显降低。力学性能测试表明，焊后双重退火处理消除接头中心高硬度区，接头中心硬度较焊态接头硬度下降约50HV,热力影响区硬度较焊态接头硬度上升约30HV;焊后热处理对接头拉伸强度没有显著影响；热处理后接头冲击韧性达到61.3 J·cm^-2,相比焊态提高约80%,与母材的冲击韧性接近。     

铁铝焊接界面组织与性能的研究

为了研究热处理对铁铝焊接界面组织和性能的影响,本文采用电容储能焊得到铁铝焊接接头,并对部分焊接接头进行热处理。利用显微镜、X射线能谱仪和显微维氏硬度仪对未热处理和热处理的焊接接头界面处的微观组织、化学成分和性能进行对比和分析。结果表明:热处理后焊接接头界面处有Fe-Al金属间化合物生成;热处理后的焊接接头融合区的铝含量比未热处理的低;焊接接头界面处由于铁铝原子的互扩散,硬度较铁、铝基体有所提高;热处理的焊接接头界面处的硬度高于未热处理的界面处硬度。热处理促使金属间化合物的生成,有利于改善焊接接头性能。     

Ti-22Al-25Nb合金惯性摩擦焊接头显微组织与力学性能EI北大核心CSCD

采用惯性摩擦焊技术焊接Ti-22Al-25Nb合金,研究热处理前后焊接接头微观组织和显微硬度的变化,分析接头在650℃和750℃高温拉伸力学性能.结果表明:接头原始态焊合区由B2相和极少量残余α2相构成,热处理后焊合区由B2相和O相构成,O相由B2相直接相变产生,相变过程无成分变化.原始态焊合区的显微硬度高于母材,780℃/3 h热处理后焊合区的显微硬度陡升,大量析出的细小O相促进硬度升高,800℃/3 h热处理后焊合区显微硬度介于原始态和780℃/3 h热处理之间.高温拉伸断裂位置均位于母材区域,650℃拉伸断口微观形貌呈韧性断裂特征,断口存在较多浅而小的韧窝.     

ER5356焊丝用于7075铝合金MIG焊接头热处理性能

采用MIG焊使用ER5356焊丝进行3 mm厚7075铝合金对接焊,焊后接头进行T6热处理。通过光学显微镜、X射线衍射仪、扫描电镜与能谱仪结合室温拉伸、显微硬度与电化学腐蚀分析接头组织、力学性能与耐蚀性。结果表明：焊接时熔池流动将母材熔化部位的Zn,Cu等合金元素带入焊缝,析出MgZn₂与AlCuMg相,成为焊缝进行热处理强化的基础;热处理后,大部分析出相溶入基体形成固溶+时效强化,接头抗拉强度提升20%,焊缝硬度提升18.4%,耐蚀性提高。但由于从母材流入焊缝的合金元素含量有限,焊丝与母材力学性能的差异与热影响区软化现象无法消除。     

Ti-22Al-25Nb合金惯性摩擦焊接头显微组织与力学性能

采用惯性摩擦焊技术焊接Ti-22Al-25Nb合金,研究热处理前后焊接接头微观组织和显微硬度的变化,分析接头在650℃和750℃高温拉伸力学性能。结果表明:接头原始态焊合区由B2相和极少量残余α_2相构成,热处理后焊合区由B2相和O相构成,O相由B2相直接相变产生,相变过程无成分变化。原始态焊合区的显微硬度高于母材,780℃/3 h热处理后焊合区的显微硬度陡升,大量析出的细小O相促进硬度升高,800℃/3 h热处理后焊合区显微硬度介于原始态和780℃/3 h热处理之间。高温拉伸断裂位置均位于母材区域,650℃拉伸断口微观形貌呈韧性断裂特征,断口存在较多浅而小的韧窝。     

转速对 7075-T651 铝合金搅拌摩擦焊接件内部残余应力分布的影响

目的掌握铝合金搅拌摩擦焊接板内部残余应力的分布,为控制焊接残余应力、改进焊接工艺和提高焊接件质量。方法以13.6 mm厚的7075-T651铝合金为研究对象,用短波长X射线衍射技术,对在不同搅拌头转速下搅拌摩擦焊接板内部的残余应力进行了无损测试,并对焊接接头在板厚中心层上的微观组织和显微硬度进行了研究。结果在垂直于焊缝截面上的显微硬度均呈"W"型分布,焊核区的显微硬度高于其两侧的热机械影响区和热影响区,但低于母材区的硬度;随着转速的增大,接头硬度的最小值减小,低硬度区的范围越大。横向残余应力绝对值整体小于焊接方向;焊核区为正应力,热机械影响区残余应力减小且变化梯度最大;残余应力的极大值位于热影响区和热机械影响区的交界处;残余应力极大值与硬度最小值的位置重合。结论通过残余应力的无损检测分析,不仅可以直接获得加工件内部应力分布,还可以间接获得加工件内部的加工缺陷情况,为改进加工工艺、提高成形精度提供依据。     

1Cr18Ni9与16MnR异种金属接头的耐腐蚀性能

为了研究1cr18Ni9和16MnR异种金属焊接接头的耐腐蚀性能,将焊态和经650℃、2 h焊后热处理的异种金属焊接接头试样放在浓度为10%NaOH溶液中进行腐蚀试验,分别对焊态和经650℃、2 h热处理后的腐蚀试样进行了EDS分析、腐蚀速度计算、电化学腐蚀以及显微硬度测试.研究结果表明:经650℃、2 h焊后热处理的金属接头的腐蚀速度比焊态金属接头的腐蚀速度显著增加;焊接接头在经过650℃、2 h焊后热处理,熔合区金属中有新合金相析出,使接头的耐腐蚀性能显著降低.     

喷丸改性对7050铝合金FSW接头性能的影响

对5 mm厚的7050铝合金搅拌摩擦焊接头进行喷丸表面改性处理,并对喷丸前后的接头进行残余应力测量、低周疲劳裂纹扩展试验,研究喷丸改性对焊接接头残余应力分布和焊核区、热影响区疲劳裂纹扩展速率的影响。结果表明,喷丸处理提高了接头表面粗糙程度,但接头表层及近表层产生硬化层,二次喷丸处理后的表层硬度值达198HV。二次喷丸最高硬度值比焊接态高33.1%。喷丸引入的残余压应力随喷丸次数增加而增大,最大压应力值位置也移向板材更深处。焊核区、热影响区疲劳裂纹扩展速率相对焊接态均降低,表明喷丸改性提高了接头两微区抗疲劳断裂的能力。     

Effect of electric contact surface treatment on microstructure and wear behaviour of ductile iron

Abstract

A study of electric contact surface treatment to ductile iron has been carried out. This technology was based on the application of the contact resistance heating between the electrode and workpiece. For comparison, the experiments of induction hardening to ductile iron were studied. The microstructure, microhardness, surface residual stress and wear properties were investigated using optical microscope, scanning electron microscope, X-ray diffraction, Vickers microhardness and rolling contact wear tests. Electric contact surface treatment resulted in the formation of fine ledeburite (white bright layer) and martensite in the ductile iron surface, in which the hardness in these areas was higher than that of induction hardened surface. The wear test results showed that the ductile iron surface after electric contact surface treatment had better wear resistance owing to the fine microstructure, high hardness and residual compressive stress.     

Influence of electron beam deflection techniques used during the cladding process on the wear and corrosion behaviour of cobalt‐based protective coatings on austenitic stainless steel

The present work aims to improve the wear resistance of the austenitic stainless steel X6CrNiMoTi17‐12‐2. In view of the potential use of this alloy, however, corrosion resistance should be maintained where possible. An electron beam surface treatment (cladding) was performed, and the cobalt‐based alloy Stellite® 12 was used as the wear‐resistant material. The presented results show the effects of several electron beam oscillation figures during the cladding process with regard to layer bonding, microstructure formation and hardness. The surface hardness achieved was 576±18 HV 0.3, almost three times higher than that of the base material (203±3 HV 0.3). The scratch energy density – which represents the resistance to abrasive wear – could be increased by a factor of 1.5. Under abrasive‐adhesive stress loading conditions, the determined wear volume decreased by a factor of almost 5. Based on the corrosion investigations carried out, it was possible to prove that in comparison to the base material, the tendency towards pitting corrosion could be almost completely suppressed.     

Effects of ultrasonic impact treatment on weld microstructure,hardness, and residual stress

Layered ultrasonic impact treatment (LUIT) was used on V-groove welds in 55?mm Q345 steel plate. Two welds were prepared, one by conventional gas metal arc welding (GMAW) and the other by GMAW and LUIT, where impact treatment was performed at nine stages during filling of the 28-pass weld. Microstructure, hardness, and residual stress in the welds were compared. While residual stress is very similar, there are significant differences in microstructure and hardness. The LUIT weld has mainly equiaxed grains and uniform hardness, while the conventional weld has columnar grains and a hardness gradient. It appears that beads in the LUIT weld did not exhibit columnar grain growth, and instead equiaxed grains grew from the fusion boundary into the weld.     

离焦量对激光熔覆层组织及性能的影响

目的改善40 Cr钢表面性能,提高其表面硬度、耐磨性及耐蚀性。方法利用扫描电子显微镜、显微硬度计、磨损试验机、电化学测试系统等对激光熔覆层组织及性能进行观察和分析。结果离焦量越大,熔覆粉末及基体表面熔化深度越浅,通过控制适当的离焦量可以获得结合良好的涂层;离焦量为110 mm时,激光束的快热快冷作用能获得细小均匀的组织,细晶能保证较高的硬度,耐磨性及耐蚀性均较好。结论 40Cr钢经激光熔覆处理后可显著改善其表面性能,适宜的离焦量有利于获得最佳性能。     

不锈钢低温盐浴表面氮化技术发展与现状

不锈钢具有良好的耐蚀性、韧性和可加工性,但其硬度低、耐磨性差,严重制约了其在有磨损腐蚀要求环境体系中的应用.为了提高不锈钢的抗磨损性能,通过低温活性盐浴表面处理技术提高其耐磨性的同时不降低其耐蚀性,使得其在具有磨损的腐蚀介质环境中能够提高其抗磨损性能而不被腐蚀,可延长其使用寿命.本文系统地介绍了低温活性盐浴表面氮化处理技术的发展、原理及应用和处理后表面氮化层的特点、组织和表面性能.低温活性盐浴表面处理后,表层活性N原子扩散在奥氏体间隙中形成过饱和固溶体的S-相,产生特殊的位错-应力FCC结构,使得奥氏体晶格发生严重变形,不但提高了其腐蚀性,同时大大提高了其硬度,使得不锈钢硬度能够达到1 000 HV0.1,其抗磨损性能亦得到了显著提高.     

Strength enhancement of the welded structures by ultrasonic peening

Residual stresses exist in all manufacturing processes which use heat and/or force such as casting, forming, machining and welding. Sometimes they cause decrease in strength and life of components especially under dynamic loads and vibration conditions. To improve fatigue strength, a number of post treatment operations are being used such as grinding, shot peening, re-melting and heat treatment. Ultrasonic peening is a newly developed method for the improvement of fatigue strength of, mainly, welded joints and structures. By employing this process, geometry of weld toe can be modified for reducing the stress concentration. In addition, elimination of tensile residual stresses, exertion of compressive residual stresses and closing of cracks, voids and cavities are expected, too. The extra advantage of this technology is its application on massive and large structures which cannot be treated by other procedures. For investigating the effect of ultrasonic peening on stainless steel-304 welded parts, a series of experiments were designed and implemented. Ultrasonic peening is mostly used as a mechanical surface treatment method in the automotive and aerospace industries. However, this paper comprises the results of experimental fatigue strength tests along with metallography, micro hardness and corrosion resistance tests of welded pieces with and without processing by ultrasonic peening. Experiments proved that under post treatment by ultrasonic peening, a better mechanical and corrosion resistance is achieved.     

不同热处理对钻杆材料硫化氢应力腐蚀性能的影响

随着酸性油气田的陆续出现,钻杆在酸性环境下腐蚀性能的研究显得尤为重要。通过拉伸试验、冲击试验、硬度测试及硫化氢应力腐蚀试验(SSC)等对不同热处理后V150钻杆材料的硫化氢应力腐蚀性能进行了研究。结果表明:热处理可以提高V150钻杆材料的抗硫化氢应力腐蚀性能;在淬火温度一定的情况下,抗拉强度、屈服强度及硬度随回火温度的升高呈逐渐降低的趋势,冲击韧性呈逐渐升高的趋势;抗SSC性能随着回火温度的升高逐渐提高;夹杂和缺陷是导致V150钻杆材料抗SSC性能降低的主要原因。     

纳米材料对TIG焊Q235接头组织及性能的影响

目的研究添加不同纳米材料对TIG焊缝组织及性能的影响。方法在试验板材表面钻一定深度小孔并在表面涂覆不同纳米材料,在TIG熔焊后对添加不同种纳米材料后焊接接头的微观组织、力学性能、断口形貌进行分析,并与未添加纳米材料的TIG焊缝进行比较分析。结果添加纳米TiC和Al_2O_3焊缝晶粒得到细化,硬度和耐磨性都有一定提高,而添加纳米SiO_2焊缝晶粒尺寸无明显变化,并且硬度与耐磨性能都有少量降低。结论在低碳钢的TIG焊结过程中添加纳米TiC和Al_2O_3能够提高焊接接头的力学及耐磨性能,而添加纳米SiO_2不利于接头性能的提高。     

1Cr5Mo钢管道焊后热处理质量评定指标研究

以１Ｃｒ５Ｍｏ钢管道为例,讨论了焊后热处理质量评定指标,通过对实际接头不同热处理制度下及热处理前后残余应力,硬度的测定和显微组织的观察,认为对于１Ｃｒ５Ｍｏ钢,以接头的硬度最大值２２５ＨＢ作为热处理质量评定指标较为恰当。在焊接质量保证合格的前提下,一般可仅校验热处理温度记录曲线合格,判定热处理质量合格。     

T10钢的脉冲爆炸-等离子体表面改性

为了提高T10钢的耐磨性和表面硬度,通过脉冲爆炸-等离子体(PDP)对T10钢进行表面改性,使用光学显微镜(OM)、扫描电镜(SEM)分析PDP处理前后T10钢的组织形貌,使用X射线衍射仪分析PDP处理后的试样的结构变化,使用显微维氏硬度计检测试样PDP处理前后的显微硬度,使用磨损试验机检测PDP处理前后的耐磨性能,使用电化学工作站检测试样PDP处理前后的耐腐蚀性能。结果表明:PDP处理T10钢后,在材料表层形成了外层为柱状区、内层为组织细化区双层结构的改性层,厚度约为70.71μm,显微硬度约为PDP处理前的2倍,磨损质量损失较基体减少,磨痕宽度明显减小; PDP处理前后T10钢自腐蚀电位无明显变化; PDP处理过程中试样快速加热、快速冷却且空气中N₂参与,使改性层有残余奥氏体出现,并生成新相Fe₃N,从而提高了T10钢的硬度和耐磨性; PDP前后试样耐蚀性变化不大。