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研发了抗HIC(Hydrogen Induced Cracking,氢致开裂)压力容器用Q345R(R-HIC)钢,并研究其焊接接头区域的显微组织及性能。结果表明,焊缝区、熔合区和热影响区显微组织主要由铁素体、贝氏体和珠光体组成。各区域热力学过程不同,焊接后显微组织存在明显差异:焊缝区显微组织主要由先共析铁素体、针状铁素体和粒状贝氏体组成;熔合区显微组织中贝氏体逐渐增多,铁素体逐渐减少;热影响区中的粗晶区显微组织几乎全部由贝氏体组成,细晶区和不完全重结晶区显微组织为等轴铁素体和珠光体组织。焊接接头具有良好的力学和抗氢致开裂性能。焊接接头微区硬度和冲击性能与显微组织关系密切:热影响区存在贝氏体组织导致其平均硬度最高、冲击功最低;针状铁素体具有良好的抗裂纹扩展能力,使得焊缝区具有良好的冲击韧性,冲击功最高。各区域差异的显微组织未对抗氢致开裂性能造成影响。 相似文献
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对18Ni无Co马氏体时效钢进行了真空电子束焊接,用金相显微镜观察了焊接接头的组织形貌,并测定了焊缝区、热影响区、基体的显微硬度.结果表明,18Ni无Co马氏体时效钢组织为板条马氏体组织,材料焊接性能良好,焊缝区凝固组织为胞状树枝晶,熔合线附近热影响区晶粒发生了再结晶,晶粒长大明显.硬度分布有明显的规律性,焊缝区硬度最低,细晶区硬度最高,熔合线附近的热影响区,离熔合线越远,硬度值越高.在距熔合线2.5 mm处有一个马氏体与奥氏体两相混合的狭窄区域,硬度较其两侧有明显降低. 相似文献
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Zhanpeng Lu Tetsuo Shoji Fanjiang Meng He Xue Yubing Qiu Yoichi Takeda Koji Negishi 《Corrosion Science》2011,(5):1916-1932
Microstructure and local deformation in 316NG weld heat-affected zones were measured by electron-back scattering diffraction and hardness measurements. With increasing the distance from the fusion line, kernel average misorientation decreases and the fraction of Σ3 boundaries increases. Stress corrosion cracking growth rates in high temperature water were measured at different locations in the heat-affected zones that correspond to different levels of strain-hardening represented by kernel average misorientation and hardness distribution. Intergranular cracking along random boundaries as well as extensive intergranular crack branching is observed in the heat-affected zone near the weld fusion line. 相似文献
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采用插销试验进行了12Cr10Co3W2Mo耐热钢在室温以及预热100,200和300℃条件下焊接接头粗晶区临界断裂应力试验研究,测试了热影响区最高硬度,观察了粗晶区微观组织,并对插销试样断口进行了扫描电镜观察.结果表明,随着预热温度升高,临界断裂应力呈线性增加趋势;热影响区最高硬度出现在粗晶区,该区域组织为板条马氏体,随着预热温度升高,粗晶区硬度呈小幅下降趋势;在各预热温度下,插销试样起裂区断口均呈解理+准解理氢致开裂特征,随着预热温度提高,氢致开裂的断口特征逐步消失. 相似文献
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Heterogeneous microstructure-induced mechanical responses in EH420 shipbuilding steel welded joint by electro-gas welding processed have been systematically studied by scanning electron microscopy,electron backscatter diffraction and mechanical testing.Comparing with the coarse-grained heat-affected zone (CGHAZ),the weld metal presents higher toughness (129.3 J vs.37.3 J) as it contains a large number of acicular ferrites with high-angle grain boundaries (frequency 79.2%) and special grain boundary Σ3 (frequency 55.3%).Moreover,coarse austenite grains in CGHAZ and slender martensite-austenite constituents between bainite laths may likely facilitate crack propagation.Polygonal ferrites and tempered pearlites formed at the junction of the fine-grained heat-affected zone and the intercritical heat-affected zone induced a softened zone with an average hardness of 185 HV0.5,which is the main reason for the occurrence of tensile fracture. 相似文献
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Metallurgical modeling of microcrack repairment during welding nonferrous materials: non-equilibrium solidification behavior of weld pool (I) 下载免费PDF全文
Metallurgical modeling of synergistic microcrack self-repairmen during welding single crystal and polycrystalline superalloys of high-temperature aerospace materials has been properly established.The idea of improvement of nickel-based superalloys weldability through non-equilibrium solidification behavior of backfill to self-repair arterial crack network is usefully proposed.Crystallographic control strategy of crack self-repairmen of fusion zone interdendritic solidification cracking and heat-affected zone (HAZ) intergranular liquation cracking is technically achievable,indicating that optimal niobium alloying beneficially refines weld microstructure,stabilizes the primary solidification path,increases the solidification temperature and concomitantly decreases the weld pool geometry.High-carbon grain boundary is more thermal stable and less contributes to incipient intergranular liquid film than that of low-carbon grain boundary.The theoretical predictions of cracking susceptibility are indirectly verified in a rather satisfactory manner.Additionally,the metallurgical modeling enhances predicative capabilities and thereby is readily applicable for other alloy systems. 相似文献
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Microstructures and hardness of flat overhead weld of the high strength steel thick plate using double-sided arc welding 下载免费PDF全文
High strength steel thick plate is widely used in shipbuilding, pressure vessels, etc., the balance between weld quality and welding efficiency is becoming a research focus. In this paper, double sided double arc flat-overhead welding experiments for high strength steel thick plate were conducted. Microstructures of weld have been observed through optical microscope (OM) and scanning electron microscope (SEM). Transformation of microstructures under thermal cycles of multi peaks was analyzed. Macro and micro hardness were also tested. The results show that the heat-affected zone (HAZ) near the fusion line experiences thermal cycles up to three times. The microstructures there are the most complex, including coarse lath martensite in original coarse-grained zone, and net like structure along grain boundaries in critical reheat coarse grained zone. After several times of tempering for backing welding, the features of acicula and lath are weakened. Its microstructure approaches to the microstructure of base metal which is tempering sorbite. The hardness test shows that the maximum hardness occurs at critical reheat coarse-grained zone, the hardness of reticulation structure at grain boundary can be up to 450HV. 相似文献
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分析了T23/12Cr1MoV异种钢焊接接头焊后热处理裂纹的宏观和微观特征、断口形貌及接头的显微组织,测试了接头的硬度分布,在此基础上讨论了裂纹的性质及形成原因,并提出了防止裂纹的措施。结果表明,裂纹启裂于T23钢侧焊趾部位,沿粗晶粒热影响区(CGHAZ)晶界扩展,为典型的再热裂纹。焊后热处理明显降低了异种钢焊接接头两侧热影响区的硬度,T23钢侧CGHAZ产生再热裂纹与其在焊后热处理过程中晶界析出碳化物有关,其析出促进了孔洞的形成。在焊后热处理前,对异种钢焊接接头进行一次550 ℃×1 h的中间热处理有利于抑制再热裂纹的产生。 相似文献
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Metallurgical modeling of microcrack repairment during welding nonferrous materials: non-equilibrium solidification behavior of weld pool (Ⅰ) 下载免费PDF全文
《中国焊接》2017,(2)
Metallurgical modeling of synergistic microcrack self-repairmen during welding single crystal and polycrystalline superalloys of high-temperature aerospace materials has been properly established. The idea of improvement of nickel-based superalloys weldability through non-equilibrium solidification behavior of backfill to self-repair arterial crack network is usefully proposed. Crystallographic control strategy of crack self-repairmen of fusion zone interdendritic solidification cracking and heat-affected zone( HAZ) intergranular liquation cracking is technically achievable,indicating that optimal niobium alloying beneficially refines weld microstructure,stabilizes the primary solidification path,increases the solidification temperature and concomitantly decreases the weld pool geometry. High-carbon grain boundary is more thermal stable and less contributes to incipient intergranular liquid film than that of low-carbon grain boundary. The theoretical predictions of cracking susceptibility are indirectly verified in a rather satisfactory manner. Additionally, the metallurgical modeling enhances predicative capabilities and thereby is readily applicable for other alloy systems. 相似文献
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对影响水下焊条电弧焊扩散氢含量的主要因素和焊缝组织进行分析研究.结果表明,电弧周围的水对焊缝增氢的贡献并不大,仅仅使扩散氢含量增加0.4%,扩散氢来源的主体是药皮中的结晶水和防水层材料所携带的H元素,分别使扩散氢含量增加12.1%和21.8%,工件表面的铁锈也是焊缝增氢的一个不容忽视的因素,会使扩散氢含量上升达28.2%.焊缝组织为少量的侧板条铁素体和贝氏体,热影响区(HAZ)则含有大量马氏体组织.其焊接接头的最高硬度一般都超过0.4 GPa,硬度峰值出现在熔合线附近,在焊缝热影响区内会形成典型的焊道下裂纹缺陷. 相似文献