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1.
采用TIG焊方法对纳米贝氏体钢板进行表面堆焊并快速进行再纳米化处理,通过SEM和TEM观察了焊接接头不同区域的组织特征和形态,使用XRD和TEM电子衍射花样对各种相进行鉴定,并获得相应相的含量,采用拉伸试验和硬度测试获得了再纳米化焊接接头的力学性能.结果表明,经过再纳米化处理,纳米贝氏体钢焊缝区和淬火区组织转变为纳米级片层状的贝氏体和奥氏体,其中焊缝奥氏体含量为13%,而且淬火区片层厚度与母材相当约为70 nm,焊缝区片层厚度大于母材约为300 nm.力学性能测试结果表明,再纳米化焊接接头抗拉强度为1500 MPa,硬度为7000 MPa,与母材相差无几,其中接头断裂位置为回火区,是由于回火区析出大量碳化物导致的. 相似文献
2.
采用TIG焊方法对纳米贝氏体钢板进行表面堆焊并快速进行再纳米化处理,通过SEM和TEM观察了焊接接头不同区域的组织特征和形态,使用XRD和TEM电子衍射花样对各种相进行鉴定,并获得相应相的含量,采用拉伸试验和硬度测试获得了再纳米化焊接接头的力学性能.结果表明,经过再纳米化处理,纳米贝氏体钢焊缝区和淬火区组织转变为纳米级片层状的贝氏体和奥氏体,其中焊缝奥氏体含量为13%,而且淬火区片层厚度与母材相当约为70 nm,焊缝区片层厚度大于母材约为300 nm.力学性能测试结果表明,再纳米化焊接接头抗拉强度为1500 MPa,硬度为7000 MPa,与母材相差无几,其中接头断裂位置为回火区,是由于回火区析出大量碳化物导致的. 相似文献
3.
采用扫描电镜、透射电镜TEM和电子背散射衍射EBSD分析了焊接偏析对纳米贝氏体钢再纳米化焊缝中的残余奥氏体的影响.结果表明,焊接偏析导致了粗大奥氏体的形成,该粗大奥氏体集中分布于枝晶间位置.粗大奥氏体的含碳量低于块状奥氏体,稳定性降低.母材残余奥氏体尺寸为亚微米级且均匀分布,而焊缝残余奥氏体的平均晶粒尺寸为微米级,且分布不均匀.焊接偏析导致的焊缝残余奥氏体的变化对焊缝延伸率有重要影响.力学测试结果表明再纳米化焊缝强度与母材相当,延伸率明显小于母材. 相似文献
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采用ф1.2 mm实芯焊丝对CrMo耐热钢进行了热输入量为8和18 kJ/cm的富氩气体保护焊试验,对焊板整体进行焊后热处理后,研究了焊缝金属的组织与性能。结果表明,随着热输入量从8 kJ/cm增加至18 kJ/cm,焊缝金属组织由板条贝氏体(LB)+粒状贝氏体(GB)转变为GB+少量多边形铁素体(PF);随着回火温度从620℃升高至660℃,焊缝金属中M-A组元逐渐分解,碳化物在基体上弥散析出;同时,焊缝金属韧性随热输入增加和回火温度降低而降低,硬度随热输入增加和回火温度升高而减小。 相似文献
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采用搅拌摩擦焊(FSW)和变极性等离子弧焊(VPPA),在2219铝合金6 mm板上沿着相互垂直的方向施焊以形成FSW-VPPA交叉焊缝.对交叉焊缝的组织形貌进行了观察分析,并对交叉焊缝和单一VPPA焊缝的拉伸力学性能及断口形貌进行了对比研究.结果表明,交叉焊缝微观组织呈现不对称、不均匀的特征,其焊缝区组织主要由α-Al基体和(α-Al+CuAl2)共晶组成,熔合区以及近熔合区的热影响区易于出现聚集性气孔;熔合区附近气孔发生率增加导致交叉接头抗拉强度及断后伸长率明显下降. 相似文献
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通过沿垂直于搅拌摩擦对接焊缝的方向进行变极性等离子弧对接立焊获得交叉焊缝,研究了6mm厚的2219铝合金交叉焊缝的微观组织和拉伸性能.并利用扫描电镜对焊缝断口的形貌进行了观察.结果表明,交叉焊缝呈现出铸态组织的特征,但是与单纯变极性等离子弧焊焊缝相比组织更不均匀.交叉焊缝的力学性能具有方向性,沿变极性等离子弧焊方向抗拉强度为254.5 MPa,沿搅拌摩擦焊方向的性能是207.53MPa,仅为母材的50%,满足使用要求.气孔是造成焊缝性能降低的主要原因. 相似文献
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采用自主开发的抗拉强度690 MPa级埋弧焊丝对16.3 mm厚同等强度级别钢板进行了双面双丝埋弧焊接试验,研究了焊接接头的组织和性能。焊缝组织性能测试结果表明,先焊面焊缝由针状铁素体、粒状贝氏体、上贝氏体及少量M-A组元和晶界铁素体组成,而后焊面焊缝则由针状铁素体、多边形铁素体、上贝氏体及少量M-A组元组成;先焊面硬度值(247 HV5)高于后焊面(232 HV5)与先焊面存在的粒状贝氏体组织有关;先焊面和后焊面的-20 ℃小试样冲击吸收能量分别为106 J和119 J,先焊面较低的冲击吸收能量与其较低含量的针状铁素体及粒状贝氏体的存在有关。全焊缝力学性能测试结果表明,焊缝的抗拉强度768 MPa,-20 ℃韧性≥ 165 J,断后伸长率为20 %。热影响区组织性能测试结果表明:先焊面和后焊面的热影响区组织特征相似,其中粗晶区和临界再热粗晶区均由上贝氏体和粒状贝氏体组成,细晶区和临界区分别由多边形铁素体和M-A组元,以及上贝氏体、粒状贝氏体、多边形铁素体和M-A组元构成;上述各区域(粗晶区、临界再热粗晶区、细晶区和临界区)的硬度值分别为236、232、229和234 HV5,其中粗晶区硬度值最高、其-20 ℃冲击吸收能量≥ 169 J。上述焊缝区和热影响区的组织和性能测试表明:焊接接头具有较好的强度与低温冲击韧性匹配。 相似文献
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使用熔化极气体保护焊对变形镁合金板材对接。在不同焊接工艺参数下观察焊缝中的气孔特征,分析气孔成因以及气孔对接头微观组织和力学性能的影响。显微组织检测结果表明:气孔主要分布在焊缝顶部或底部,而且气孔能相互连接甚至产生裂纹。然而,在合适的焊接工艺参数下,气孔的产生可以得到有效控制。拉伸测试结果表明:接头的平均抗拉强度接近甚至高于母材。由于第二相β-Mg17(Al,Zn)12的强化作用,焊缝区的硬度高于母材。 相似文献
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采用ER4043和ER4047焊丝,对厚度为12 mm的舰船用6082铝合金进行了TIG焊接试验研究,测试了焊缝强度并对其显微组织进行了观察分析.结果表明,在采用文中推荐的焊接参数条件下,使用Al-Si系焊丝的焊接接头力学性能优良,焊缝区组织为树枝状晶的铸态组织,熔合区出现异于焊缝中心的胞状晶;热影响区受焊接热循环作用组织有所粗化.使用ER4043焊接的接头抗拉强度略低于使用ER4047的接头,但塑性相对较好并且生成大气孔的倾向相对较低. 相似文献
12.
采用搅拌摩擦焊(friction stir welding,FSW)技术对氧化物弥散强化(oxide dispersion strengthen,ODS)铁素体钢进行了焊接,并对焊接工艺进行了优化. 当转速为150 r/min,焊接速度为30 mm/min时可以获得无焊接缺陷的ODS钢焊接接头. 结果表明,采用FSW焊接的ODS钢接头的微观组织出现明显的洋葱环结构,搅拌区为等轴再结晶晶粒,前进侧热机影响区表现出明显的塑性流动的特征,热影响区的晶粒较母材也发生了明显改变. 接头的高温拉伸性能偏低,但经过温度1 150 ℃,时间1 h的热处理后,其高温拉伸性能得到大幅提高,与母材拉伸性能接近. 相似文献
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含钪与不含钪铝镁钪合金焊接接头的组织与性能 总被引:2,自引:0,他引:2
分别采用Al-Mg-Zr和Al-Mg-Zr-Sc合金焊丝为填充材料,对2 mm厚的Al-Mg-Sc合金薄板进行惰性气体保护焊接,然后对两种焊接接头的显微组织和力学性能进行对比研究。结果表明:采用两种焊丝焊接的Al-Mg-Sc合金薄板的焊接接头强度系数均大于0.9。但采用Al-Mg-Zr-Sc合金焊丝为填充材料时,焊缝晶粒组织明显细化,熔合区形成的细小等轴晶层提高了基材与焊缝填充材料的结合力,焊接接头的屈服强度比采用Al-Mg-Zr合金焊丝为填充材料时提高了100 MPa,显著提高了Al-Mg-Sc合金焊接构件的许用强度,因此焊接Al-Mg-Sc板材更宜采用Al-Mg-Sc-Zr焊丝。 相似文献
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M. Sireesha S. Sundaresan Shaju K. Albert 《Journal of Materials Engineering and Performance》2001,10(3):320-330
Modified 9Cr-1Mo steel finds increasing application in power plant construction because of its excellent high-temperature
properties. While it has been shown to be weldable and resistant to all types of cracking in the weld metal and heat-affected
zone (HAZ), the achievement of optimum weld metal properties has often caused concern. The design of appropriate welding consumables
is important in this regard. In the present work, plates of modified 9Cr-1Mo steel were welded with three different filler
materials: standard 9Cr-1Mo steel, modified 9Cr-1Mo, and nickel-base alloy Inconel 182. Post-weld heat treatment (PWHT) was
carried out at 730 and 760 °C for periods of 2 and 6 h. The joints were characterized in detail by metallography. Hardness,
tensile properties, and Charpy toughness were evaluated. Among the three filler materials used, although Inconel 182 resulted
in high weld metal toughness, the strength properties were too low. Between modified and standard 9Cr-1Mo, the former led
to superior hardness and strength in all conditions. However, with modified 9Cr-1Mo, fusion zone toughness was low and an
acceptable value could be obtained only after PWHT for 6 h at 760 °C. The relatively poor toughness was correlated to the
occurrence of local regions of untransformed ferrite in the microstructure. 相似文献
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《稀有金属(英文版)》2019,(11)
Zigzag line is a common defect in friction stir welding(FSW) joint.The formation mechanism of the zigzag line in Al-Cu alloy FSW joint and its influence on the microstructure and mechanical properties during post weld heat treatment(PWHT) were studied by scanning electron microscopy(SEM),microhardness and tensile tests.It is found that the occurrence of zigzag line for PWHT joint is determined by PWHT process which in nature depends on residual stress and thermal stress of FSW joint.The optimization of PWHT process to reduce the residual and thermal stress can trigger for the deterioration of mechanical properties of PWHT joints with zigzag line.No obvious decrease of tensile properties is observed for T6-450 and T6-495 joints although zigzag line appears in the weld.PWHT determines the sizes of zigzag line cracks and consequently determines the fracture location and characteristics of FSW joint. 相似文献
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利用光学显微镜、扫描电镜分析了某厂生产的X90钢管线钢焊接接头的显微组织,通过硬度试验和冲击试验测试了其硬度和韧性变化规律。试验结果显示,其焊缝为针状铁素体和粒状贝氏体组织,熔合区和粗晶区为粗大粒状贝氏体组织,细晶区为多边形铁素体、珠光体和MA组织,混晶区为粒状贝氏体、多边形铁素体、珠光体和MA的混合组织;热影响区有局部硬化和软化现象,且内焊缝硬度高于外焊缝;试验温度高于-20 ℃时,热影响区的冲击吸收能量和剪切断面率高于焊缝,低于-40~-20 ℃区间某个值后,冲击性能将降低至焊缝性能以下;热影响区的韧脆转变温度约在-50 ℃附近,而焊缝的韧脆转变温度约在-70 ℃附近。 相似文献
18.
In this paper, the state-of-the-art progress in research on novel mechanical properties of nanocrystalline materials and carbon
nanotubes is reviewed. There is evidence that the relation between the strength of nanocrystalline materials and grain size
does not observe the classic Hall-Petch plot. Lowtemperature and high-strain rate superplasticity have been found in some
nanocrystalline materials. Theoretical prediction and experimental data indicate that carbon nanotubes are materials with
high stiffness, high strength, great toughness, and low density. There are already some application examples for novel mechanical
properties of nanocrystalline materials and carbon nanotubes.
For more information, contact P.K. Liaw, University of Tennessee at Knoxville, Materials Science and Engineering Department,
427-B Dougherty Engineering Building, Knoxville, Tennessee 37996; (865) 974-6356; fax (865) 974-4115; e-mail pliaw@utk.edu. 相似文献
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《Science & Technology of Welding & Joining》2013,18(4):259-266
Underwater friction taper plug welding for X65 pipeline steel was performed using Q345 structural steel and 316L stainless steel plugs. Weld microstructures, defects formation and mechanical properties were investigated. Using Q345 plugs can produce defect free and overmatching welded joints whose impact toughness was also favourable. Lower bainite and lath martensite in the weld zone resulted in high hardness with maximum value up to 418?HV10. Using 316L plugs can significantly reduce weld zone hardness due to austenite dominated microstructure. Microcracks can easily emerge at and may propagate along γ–δ phase boundaries to form macrocracks. Intermittent cracks were found along the bonding interface of all the 316L plug welds, which should be caused by the relief of the residual stress. 相似文献