共查询到17条相似文献,搜索用时 109 毫秒
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研究了预置镍基合金片对15CrMo/1Cr18Ni9Ti异种钢超窄间隙焊接接头组织及性能的影响。结果表明,预置镍基合金片厚度小于0.6 mm时,15CrMo熔合线附近焊缝区部分区域以A模式凝固并形成奥氏体胞状晶,而其它区域仍以FA模式凝固,其组织为等轴晶奥氏体+枝晶状铁素体,并且焊缝中心无凝固裂纹形成。预置0.9~1.2 mm厚的镍基合金片时,焊缝中心因镍偏聚而以A模式凝固,形成粗大的奥氏体柱状枝晶,并有凝固裂纹形成。预置镍基合金片厚度在0.6~0.9 mm时,可使15CrMo熔合线附近焊缝区的Ni质量分数比填充金属(ER347L)的提高约2%,明显比未预置镍基合金片的接头具有更好的抑制碳扩散效果,但当镍基合金片厚度在0.3~1.2 mm范围内变化时接头抑制碳扩散的效果并无明显变化。焊态的异种钢接头不均匀混合区内存在马氏体层,而热时效后在熔合线附近会形成一定宽度的富碳硬化区及贫碳软化区。 相似文献
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分析了Cr15Mn9Ni1N奥氏体不锈钢钨极氩弧焊接头的组织.结果表明:在靠近熔合线的热影响区,经过高温焊接热循环后析出较多的δ铁素体.大线能量时其范围增大;靠近熔合线焊缝金属的组织为奥氏体胞晶中分布着残留蠕虫状δ铁索体:焊缝中心区域为奥氏体树枝晶中分布着残留骨架状δ铁素体;大线能量接头的熔合线处的组织为奥氏体晶粒上分布侧板条形8铁素体,而小线能量时为奥氏体品粒.分析认为:焊缝金属的凝固模式为δ铁素体先从液相中析出,随后通过固态相变转变为奥氏体,未转变的残留δ铁素体以蠕虫状、骨架形或侧板条的形态分布于奥氏体中.Hammar-Svensson Cr、Ni当量公式适于预测这种钢焊缝金属的凝固模式. 相似文献
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利用K110型电子束焊机焊接50 mm厚的304不锈钢板,并对焊接接头深度方向的微观组织及硬度进行分析. 结果表明,利用电子束焊接方法能够一次性焊透50 mm厚不锈钢板,得到成形良好的焊接接头. 焊缝深宽比较大,约为18:1. 焊缝组织由奥氏体和铁素体组成. 从焊缝上表面到深约39 mm处,铁素体形态依次为网状,板条状/骨架状和树枝状分布于奥氏体枝晶间或晶界处. 在焊缝的下层,亚稳的胞状奥氏体将取代稳定铁素体相作为初生相直接从熔体中析出. 沿焊缝中心深度方向,接头的凝固模式由primary ferrite with second-phase austenite,FA转变成primary austenite with second-phase ferrite,AF模式,晶粒尺寸减小,硬度呈波动性增加趋势. 相似文献
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《焊接技术》2017,(8)
使用CMT,MIG这2种焊接方法对X2CrNiN18-7不锈钢焊接,对得到的焊缝进行了外观形貌、组织构成、力学性能等方面的对比分析。结果表明:2种焊接方法焊缝外观形貌相似,CMT焊所得焊缝熔宽小于MIG焊的熔宽,CMT焊所得焊缝先析出δ铁素体,以FA模式凝固。室温组织由γ奥氏体、少量δ铁素体构成。接头由母材、热影响区、部分熔化区、焊缝柱状晶区构成,熔合线在母材部分熔化区和焊缝柱状晶区之间,靠近部分熔化区的热影响区部分析出条状平行铁素体,可抑制此区域热影响区晶粒的长大。相比CMT焊所得焊缝,MIG焊的特征区域缺少了部分熔化区以及等轴晶区。CMT焊接所得接头力学性能明显优于MIG焊。 相似文献
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T92/HR3C异种钢焊接接头的组织结构和力学性能 总被引:2,自引:1,他引:1
采用ERNiCr-3和ERNICrMo-3两种镍基焊丝,用气体保护钨极电弧焊(GTAW)法实现T92/HR3C异种钢管焊接.研究了接头的显微组织及其力学性能,以及焊后热处理对接头组织结构及力学性能的影响等.结果表明:T92/HR3C异种钢接头焊缝为胞状树枝晶组织,T92侧热影响区(HAZ)主要由过热区、粗晶区及细晶区构成;HR3C侧HAZ没有明显晶粒长大的现象,但晶界、晶内有碳、氮化物析出.ERNiCrM0-3焊接接头的强度、塑性及硬度较高,拉伸断裂位于母材;而ERNiCr-3焊接接头强度、硬度较低,但冲击韧性较高,拉伸断裂位于焊缝.760℃、30 min焊后热处理,有助于改善两种焊接接头的综合力学性能. 相似文献
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采用超细颗粒焊剂约束电弧超窄间隙焊接方法进行了1Cr18Ni9Ti奥氏体不锈钢的超窄间隙焊接试验,并对所得超窄间隙焊接接头的组织及性能进行了测试和分析。结果表明,1Cr18Ni9Ti奥氏体不锈钢超窄间隙焊接接头的根焊焊缝区晶粒为等轴晶,而填充焊和盖面焊的焊缝区晶粒则为粗大的柱状晶。等轴晶和柱状晶的基体均为奥氏体,晶粒内部均分布有少量板条状铁素体。超窄间隙焊接接头的填充焊缝和根焊焊缝具有与母材相当的硬度,而盖面焊缝的硬度则略低于母材。超窄间隙焊接接头除了收缩率和冲击功比母材的略低外,抗拉强度、屈服强度及伸长率明显高于母材所对应性能的最低值。此外,试验还测得超窄间隙焊接接头的腐蚀速率为0.417 g/(m2·h),该值明显低于母材的腐蚀速率。 相似文献
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为了研究电磁检测技术检测铁素体与奥氏体异种钢焊接接头表面开口裂纹的能力,制作了Q235R与S30408异种钢横向刻槽对比试样和纵向刻槽对比试样,开展了涡流阵列检测和交流电磁场检测试验。结果表明:涡流阵列检测技术能够检测异种钢焊接接头的横向裂纹和远离铁素体与奥氏体熔合线处的纵向裂纹,但无法检出熔合线处的纵向裂纹;交流电磁场检测技术能够检测熔合线处的纵向裂纹,但无法检测出远离铁素体材料的纵向刻槽;涡流阵列检测技术与交流电磁场检测技术的组合,可以解决铁素体与奥氏体焊接接头的表面开口裂纹的检测问题。 相似文献
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通过对Q235-B和316L异种钢I形和Y形坡口埋弧焊对接接头Q235-B一侧熔合区显微组织和元素分布及显微硬度的观测和分析,指出了在碳素结构钢与不锈钢异种金属的焊接接头中,碳素结构钢一侧出现硬而脆的熔合区;提出了减小熔合区的宽度是提高异种钢焊接接头抗弯曲性能的关键.此外研究了不同焊接工艺对焊接接头抗弯曲性能的影响机制,采用小尺寸的Y形坡口和使用含镍量高的焊丝,既有效地减小了熔合区的宽度,提高了异种钢焊接接头的抗弯曲性能,避免在对接接头双面埋弧焊时发生烧穿焊接缺陷. 相似文献
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对2 mm厚的LF2铝合金和Q235钢平板试件进行了加入中间过渡层金属Cu的电子束对接焊接试验,利用光学金相、扫描电镜及能谱分析等方法研究了接头各区域的组织结构和成分分布.结果表明,接头可分为三个焊缝组织区域,其中靠近钢侧的焊缝区主要为Fe基固溶体,并含有少量金属间化合物;靠近铝侧的焊缝区为含有Fe-Al系及Al-Cu系金属间化合物的Al基固溶体;焊缝中部区为呈层带状分布的多种Fe-Al以及Al-Cu脆性金属间化合物混合区.分析认为虽然引入了铜过渡层,但在焊缝中依然有较多金属间化合物生成,特别是焊缝中部区域上,呈连续层带状分布的多种脆性金属间化合物的产生是影响接头强度的主要因素.在对接头组织结构分析的基础上,建立了描述LF2/Q235异种金属电子束对接接头形成过程的物理模型. 相似文献
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M.M.A. Khan L. RomoliM. Fiaschi G. DiniF. Sarri 《Journal of Materials Processing Technology》2012,212(4):856-867
This paper investigates laser beam welding of dissimilar AISI 304L and AISI 430 stainless steels. Experimental studies were focused on effects of laser power, welding speed, defocus distance, beam incident angle, and line energy on weld bead geometry and shearing force. Metallurgical analysis was conducted on a selected weld only to show various microstructures typically formed at different zones and consequent change in microhardness. Laser power and welding speed were the most significant factors affecting weld geometry and shearing force. All the bead characteristics but radial penetration depth decreased with increased beam incident angle. The focused beam allowed selecting lower laser power and faster welding speed to obtain the same weld geometry. Weld shape factor increased rapidly due to keyhole formation for line energy input ranging from 15 kJ/m to 17 kJ/m. Fusion zone microstructures contained a variety of complex austenite-ferrite structures. Local microhardness of fusion zone was greater than that of both base metals. 相似文献
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Xinjie Di Dudu Geng Shipin Wu Dongpo Wang Zhi Zhang 《Science & Technology of Welding & Joining》2013,18(2):148-155
The solidification behaviour and microstructure of welding transition zone between low-transformation-temperature deposited metals and high-strength low-alloy steels were investigated. It was found that the steep composition gradient provided driving forces for the diffusion of carbon from base metal to weld metal, leading to the hardened and softened regions near fusion boundary. In weld metal near fusion boundary, there were retained δ-ferrites when the base metal dilution rate below 35% and Creq/Nieq value larger than 2.62. Compared with martensite, the mixed microstructures of martensite?+?δ-ferrite obtained less strain localisation, dislocation density and more percentages of large misorientation, which were more liable to resist microcrack initiation and propagation during deformation. 相似文献
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M.M.A. Khan L. Romoli M. Fiaschi F. Sarri G. Dini 《Journal of Materials Processing Technology》2010,210(10):1340-1353
This paper presents experimental investigation of laser beam welding of martensitic stainless steels in a constrained overlap configuration. Experimental studies were focused on the effects of laser power, welding speed and fiber diameter on bead geometry and mechanical properties of the weld. Metallurgical study of a selected welded joint was done only to show various microstructures typically formed at different zones. Laser power and welding speed were found the most significant factors affecting the weld geometry and shearing force. The contour plots showing constant response lines indicated the evidence of two-factor interaction effects of laser power-welding speed, welding speed-fiber diameter, and fiber diameter-laser power on all the responses except the weld width. Moreover, energy density plots illustrated its linear relationship with penetration depth and limited nonlinear effects on others. Additionally, metallurgical analysis of fusion zone showed dendritic structures consisted of martensitic with eutectic ferrite along solidification grain and subgrain boundaries. 相似文献
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采用LHM-200等离子弧焊机对1 mm紫铜与低碳钢异种材料进行了熔透型等离子弧焊试验,得到了内部无缺陷、外观成形良好的接头.观察了接头的显微组织,并分析了工艺参数对接头力学性能的影响.结果表明,焊缝区中心显微组织呈细胞群状,界面两侧的组织特征呈现显著的不同,焊缝与铜侧界面没有明显的熔合线,局部呈漩涡状,钢侧与焊缝连接处出现了明显的分界线;最佳工艺为焊接电流为65 A,焊接速度为0.4 cm/s,离子气流量为0.7 L/min,此时接头抗拉强度可达176 MPa,试样断裂于铜母材热影响区. 相似文献
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Over the last 40 years of laser welding practice, weld bead geometry always experiences a section of the weld bead slightly above or below the parent material surface. In this paper, a new concept – net shape welding is introduced, whereby the weld joint fusion zone is flat to the parent material surface. Experimental work was carried out to demonstrate net shape laser square butt welded mild steels sheets. Tensile test results show that the net-shape welds well outperform those with traditional weld bead geometry. Computational fluid dynamic and finite element models have been used to assist in the understanding of net-shape weld geometry formation and the superior mechanical properties. 相似文献