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目的采用无熔滴电弧热丝GTAW堆焊技术,在Q235钢表面堆焊具有自润滑功能的含石墨相耐磨合金。方法设计含有镍包石墨粉的药芯焊丝,并使用无熔滴电弧热丝GTAW堆焊技术和传统GMAW两种方法进行对比堆焊。焊后,采用销盘式摩擦磨损试验机对堆焊层进行对比摩擦磨损性能测试,利用光学显微镜、SEM和EDS研究堆焊层的微观结构及成分,并对磨损面形貌进行对比分析,探究自研焊接系统制备含石墨相堆焊层的工艺特点和堆焊层自润滑耐磨性能。结果无熔滴电弧热丝GTAW可以有效降低母材的稀释率,保证药芯焊丝自润滑石墨相过渡,且能提高熔敷率。堆焊层形成了Fe-Cr-B耐磨基体,并在晶界处分布大量的颗粒状石墨相。摩擦磨损实验中,堆焊层摩擦系数可低至约0.65,随着摩擦时间的延长,摩擦系数进一步减小,磨损面未发现典型犁沟,表面平滑且呈黑色,堆焊层具有自润滑功能,且摩擦系数与焊接参数有关。传统GMAW方法制备的堆焊层的摩擦系数为1.4左右,且随着磨损时间的延长,摩擦系数略有增大。结论无熔滴电弧热丝GTAW堆焊技术低热输入和高熔敷率的工艺特点适合堆焊,尤其适合防止焊丝化学成分烧损的堆焊。在合理控制工艺参数,焊接稳定的前提下,选择低辅助电流,可以成功制备含石墨相的自润滑耐磨堆焊层。 相似文献
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《焊接》2016,(11)
针对热锻模具工作条件及其失效形式,采用药芯焊丝气体保护堆焊方法制备Fe-Cr-Mo-W-V系热锻模具堆焊合金,采用金相组织观察、硬度测试、回火热处理、抗热疲劳裂纹和力学性能等多种试验方法,分析了W含量对堆焊合金显微组织、焊态硬度、热稳定性、热疲劳性能以及力学性能的影响。结果表明:Fe-Cr-Mo-W-V系堆焊合金的显微组织由板条马氏体+残余奥氏体组成。随着W含量的增加,堆焊合金焊态及550℃回火处理后所对应的硬度值逐渐增加,随着热处理时间的延长,堆焊层硬度逐步降低并趋于平缓。随着堆焊合金中W元素的增加,堆焊合金抗热疲劳裂纹性能逐渐降低,Fe-Cr-Mo-W-V系堆焊合金的抗拉强度略高于国外焊接材料Weld Mold 9650,断后伸长率略低于焊接材料Weld Mold 9650。 相似文献
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压力容器或配管的焊接方法主要为药皮焊条电弧焊(SMAW)、钨极气体保护焊(GTAW)、埋弧焊(SAW),一部分采用实心线半自动焊(GMAW)。目前仍然主要采用SMAW,GTAW,SAW焊接方法。从1975年开始探讨采用带焊剂芯电弧焊接方法(FCAW),现在约有60%的材料焊接是用FCAW方法施焊的,与SAW方法相组合,提高了焊接效率。现在,压力容器有关本体的焊接用SAW方法,管嘴以及管嘴与筒体的焊接,其它几乎所有焊接接头都用FCAW法施焊。每个焊工焊材用量,以1960年为100计,现在已达到175~180,配管的预装配焊接也用GTAW和FCAW以及GTAW和… 相似文献
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V. Balasubramanian V. Ravisankar G. Madhusudhan Reddy 《Journal of Materials Engineering and Performance》2008,17(2):224-233
This article reports the effect of postweld aging treatment on fatigue behavior of pulsed current welded AA 7075 aluminum
alloy joints. AA7075 aluminum alloy (Al-Zn-Mg-Cu alloy) has gathered wide acceptance in the fabrication of light weight structures
requiring high strength-to weight ratio, such as transportable bridge girders, military vehicles, road tankers, and railway
transport systems. The preferred welding processes of AA7075 aluminum alloy are frequently gas tungsten arc welding (GTAW)
process and gas metal arc welding (GMAW) process due to their comparatively easier applicability and better economy. Weld
fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification.
This often results inferior weld mechanical properties and poor resistance to hot cracking. In this investigation, an attempt
has been made to refine the fusion zone grains by applying pulsed current welding technique. Rolled plates of 10 mm thickness
have been used as the base material for preparing multipass welded joints. Single V butt joint configuration has been prepared
for joining the plates. The filler metal used for joining the plates is AA 5356 (Al-5Mg (wt.%)) grade aluminum alloy. Four
different welding techniques have been used to fabricate the joints and they are: (i) continuous current GTAW (CCGTAW), (ii)
pulsed current GTAW (PCGTAW), (iii) continuous current GMAW (CCGMAW), and (iv) pulsed current GMAW (PCGMAW) processes. Argon
(99.99% pure) has been used as the shielding gas. Rotary bending fatigue testing machine has been used to evaluate fatigue
behavior of the welded joints. Current pulsing leads to relatively finer and more equi-axed grain structure in GTA and GMA
welds. Grain refinement is accompanied by an increase in fatigue life and endurance limit. Simple postweld aging treatment
applied to the joints is found to be beneficial to enhance the fatigue performance of the welded joints. 相似文献
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Gas tungsten arc welding (GTAW) process was used for remelting of the top clad layers of austenitic stainless steel 316L deposited on low-carbon steel using gas metal arc welding (GMAW) process. Different electrochemical techniques were used for assessing and comparing sensitization and pitting corrosion performance of these clads (both in the as-welded as well as aged condition), besides comparing their passive film characteristics. Top clad layer remelting was influential upto a penetration depth of around 2.34 mm. Aging of clads at 750°C/24 hr accelerated the precipitation of carbides, which suppressed partially due to their remelting as indicated by electron probe microanalysis studies. Due to this GTAW remelted clads exhibited a relatively lesser degree of sensitization and higher pitting corrosion resistance as compared to the conventional GMAW clads. X-ray photoelectron spectroscopy studies revealed a relatively higher concentration of O, Cr, Ni, and Mo in the passive film of remelted clad surfaces than the conventional ones, which accounted for enhanced protectiveness of passive film on remelted surfaces as indicated by electrochemical impedance spectroscopy studies. 相似文献
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高效化焊接技术是目前焊接领域研究的热点,其应用领域越来越广泛和深入.针对轻型车辆广泛采用的高强高硬合金钢,采用高效双丝熔化极气体保护焊系统,进行了高强高硬合金钢高效化双丝共熔池对接焊缝焊接技术研究.试验采用奥氏体不锈钢焊丝进行高强高硬合金钢的焊接工艺试验,并与相同热输入的单丝熔化极焊接接头进行了对比分析,进行了金相组织、显微硬度、力学性能分析.结果表明,采用高效双丝共熔池熔化极气体保护焊工艺,获得良好的高强高硬合金钢对接焊缝焊接接头,力学性能满足使用要求. 相似文献
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A.M. TorbatiR.M. Miranda L. Quintino S. WilliamsD. Yapp 《Journal of Materials Processing Technology》2011,211(6):1112-1116
Autogenous gas tungsten arc welding (GTAW) and pulse rapid arc gas metal arc welding (GMAW) of butting bimetal (Bubi) pipelines were studied. GMAW was carried out from the outside of the pipe while GTAW was done from the inside to prevent lack of penetration and to promote a smooth internal weld bead surface. Current, welding speed, electrode diameter, shielding gas and orbital positions were defined as variables. The requirement for the GTA weld was to achieve 2 mm penetration depth without undercutting. The required penetration was difficult to achieve due to the outwards flow pattern in the molten pool driven by the Marangoni effect as a result of low sulphur content. It was shown that, under optimised conditions, it was possible to obtain sound welds with proper geometry and defect free. The conditions needed were a combination of current of 170 A, welding speed of 200 mm/min and an electrode angle of 30°, with shielding gas protection of He-25%Ar for narrow groove welding of a J-beveled pipe. 相似文献
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K. Sampath 《Journal of Materials Engineering and Performance》2009,18(9):1218-1225
AA2195, an Al-Cu-Li alloy in the T8P4 age-hardened condition, is a candidate aluminum armor for future combat vehicles, as
this material offers higher static strength and ballistic protection than current aluminum armor alloys. However, certification
of AA2195 alloy for armor applications requires initial qualification based on the ballistic performance of welded panels
in the as-welded condition. Currently, combat vehicle manufacturers primarily use gas metal arc welding (GMAW) process to
meet their fabrication needs. Unfortunately, a matching GMAW consumable electrode is currently not commercially available
to allow effective joining of AA2195 alloy. This initial effort focused on an innovative, low-cost, low-risk approach to identify
an alloy composition suitable for effective joining of AA2195 alloy, and evaluated transverse-weld tensile properties of groove
butt joints produced using the identified alloy. Selected commercial off-the-shelf (COTS) aluminum alloy filler wires were
twisted to form candidate twisted filler rods. Representative test weldments were produced using AA2195 alloy, candidate twisted
filler rods and gas tungsten arc welding (GTAW) process. Selected GTA weldments produced using Al-4wt.%Cu-2wt.%Si alloy as
filler metal consistently provided transverse-weld tensile properties in excess of 275 MPa (40 ksi) UTS and 8% El (over 25 mm
gage length), thereby showing potential for acceptable ballistic performance of as-welded panels. Further developmental work
is required to evaluate in detail GMAW consumable wire electrodes based on the Al-Cu-Si system containing 4.2-5.0 wt.% Cu
and 1.6-2.0 wt.% Si. 相似文献
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为了解决镀锌板上锌层易受热烧损,无法使用大电流MIG焊接方法进行高速焊接的问题,采用了一种低热输入高效率的焊接方法——单旁路耦合电弧GMAW(DE-GMAW)用于镀锌板的焊接。搭建了该焊接方法的试验平台,对镀锌板堆焊和搭接接头的高速焊接方法进行试验研究。结果表明,通过调整旁路电流值,单旁路耦合电弧GMAW方法降低了镀锌板上的焊接热输入,并可以在大电流和高焊速的条件下实现镀锌板堆焊和搭接接头的焊接,所得焊缝成形良好,母材变形小,焊接过程稳定无飞溅。焊后镀锌层的烧损与同等热输入条件下的普通MIG焊相比明显降低,保证了镀锌板焊后的耐腐蚀性能。 相似文献
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为探究旋转电弧GMAW堆焊短路过渡时熔池的温度和对流分布规律,利用Flow-3D软件建立三维数学模型,采用球形旋转热源模型,考虑重力、熔滴拖拽力、表面张力、浮力作用,模拟了堆焊状态下,工件材料为Q235的旋转电弧GMAW短路过渡的熔池成形规律. 采用流体体积法追踪熔滴过渡和熔池表面的自由变形,并分析熔滴进入熔池时熔池内部温度场和流场的变化. 结果表明,熔池形成过程中,旋转熔滴对熔池有搅拌作用,并使熔池内部液态金属活性增强,流速变快,熔池内部液态金属体积变大,熔池的宽度变大. 模拟预测的焊缝尺寸、形状与试验吻合良好. 为优化焊接工艺参数、改善旋转电弧GMAW堆焊焊缝质量提供参考依据. 相似文献
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《Science & Technology of Welding & Joining》2013,18(1):67-75
AbstractAn experimental Al–Cu–Li–Mg–Ag–Zr type alloy in the form of 13.7 mm thick plates was studied for its fusion characteristics using gas metal arc welding (GMAW) and pulsed gas metal arc welding (P-GMAW). High copper 2319 filler of 1.6 mm diameter was used. The burn-off characteristics of 2319 filler wire in GMAW and P-GMAW were experimentally determined, including the relation between pulse current and pulse duration for the desired one-drop detachment per pulse (ODPP) condition and feasible range of pulse parameters. The effect of welding parameters on bead geometry and shape relationships was investigated through beadon-plate experiments in the welding current range above the spray transition current. Reasonably good weld beads were obtained in P-GMAW at currents as low as 194 A and welding speeds of 45 cm min–1. P-GMAW yielded significantly higher weld penetration compared to GMAW. 相似文献