共查询到20条相似文献,搜索用时 93 毫秒
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采用W-Re合金搅拌工具对4 mm厚409L铁素体不锈钢板进行搅拌摩擦焊(FSW),利用光学显微镜、扫描电镜、电子万能试验机和显微硬度仪等研究了焊接接头的焊缝形貌、微观组织和力学性能。结果表明:采用转速为1000 r/min,焊速为80 mm/min的工艺参数可以获得力学性能良好、无缺陷的409L铁素体不锈钢搅拌摩擦焊接接头。接头焊核区组织为高度细化的等轴铁素体晶粒,平均晶粒尺寸为17.3μm,并形成了大量的小角度晶界,是母材的3.66倍。焊缝的显微硬度分布呈“抛物线”形态,焊核区的硬度最高,为143 HV0.2,焊缝各区域的力学性能均高于母材。焊接接头的拉伸断裂在母材处,断裂形式为韧性断裂。 相似文献
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采用搅拌摩擦焊方法对5 mm厚7050铝合金进行了焊接,利用光学金相对接头缺陷及其形成原因进行了分析.结果显示,在参数不当的情况下出现的缺陷有飞边、孔洞、沟槽以及未焊合四种:飞边由表层金属过度软化导致;孔洞的产生则是焊速/转速比过大,焊缝中、下部材料塑性流动不充分引起;而沟槽是由于焊具下压量不足时,表面材料流动不充分产生;未焊合发生在焊缝底部,其产生原因是焊接热输入不足,焊缝底部再结晶程度低使得原始对接面材料间没有融合而存留.其中未焊合为主要的焊接缺陷,会严重降低接头力学性能,改变接头拉伸时的断裂位置和断裂模式. 相似文献
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建立了搅拌摩擦焊接过程中焊缝表面弧形纹形成过程模型,解释了弧形纹弧峰、弧谷的形成原因。焊接过程中,轴肩与母材表面间所形成的软化层沿着搅拌头的转动方向缓缓向轴肩后方流动。形成了软化薄层,并不断增厚。当轴肩与流动到轴肩后侧的软化层两者界面处的分子间吸附力不足以带动软化层整体向前运动时,软化层外侧的薄层与轴肩脱离,并在随后的冷却过程中硬化而形成弧峰。上述行为在搅拌摩擦焊接过程中反复发生,导致相邻弧峰间产生一凹陷,形成弧谷。焊缝表面相邻弧峰间距与搅拌头行走速度成正比,与搅拌头的转速、轴肩/母材间的摩擦系数成反比。 相似文献
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不锈钢搅拌摩擦焊摩擦头磨损机理研究 总被引:2,自引:0,他引:2
搅拌摩擦头技术是搅拌摩擦焊工艺的关键技术.在探讨不锈钢搅拌摩擦焊工艺的基础上,对不锈铜搅拌摩擦焊过程中硬质合金搅拌摩擦头的磨损机理进行了比较系统的试验研究.通过对实验研究结果的分析,初步将搅拌摩擦头的磨损归结为粘结磨损、氧化磨损、扩散磨损、脆性剥落和脆断. 相似文献
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通过对搅拌摩擦焊接焊缝中的缺陷进行分析研究,认为其缺陷主要分为外观缺陷与内部缺陷,并进一步对其缺陷位置、形态及出现原因给予了说明. 相似文献
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采用不同搅拌头转速,研究了搅拌头转速对4 mm厚2205双相不锈钢板材搅拌摩擦焊接头组织及性能的影响. 结果表明,当焊接速度为50 mm/min时,搅拌头转速在600 ~ 800 r/min的范围内,均可获得表面成形良好且内部无缺陷的接头.接头搅拌区在动态再结晶的作用下组织得到细化,硬度值较高,热影响区在焊接热作用下组织粗化,硬度值较低.整个接头的铁素体含量在50% ~ 60%范围内,且随着转速的升高搅拌区的铁素体含量有所增加. 当转速为600 r/min时,接头的抗拉强度达到最大824 MPa,为母材的97.3%,断裂位置为接头的热影响区. 相似文献
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Rapid formation of the sigma phase in 304 stainless steel during friction stir welding 总被引:1,自引:0,他引:1
Seung Hwan C. Park Yutaka S. Sato Hiroyuki Kokawa Kazutaka Okamoto Satoshi Hirano Masahisa Inagaki 《Scripta materialia》2003,49(12):1175-1180
Rapid formation of sigma phase occurred in 304 stainless steel during friction stir welding. A possibility was suggested that the sigma formation can be accelerated by the emergence of delta-ferrite at high temperature and the subsequent decomposition of the ferrite under the high strain and recrystallization induced by friction stirring. 相似文献
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采用ER-309焊丝焊接了TCS345,T4003,Nirosta 4003,JFE410RW四种铁素体不锈钢,用金相方法分析了四种母材、接头的显微组织,通过电化学极化曲线测量,对母材和焊接接头的耐腐蚀性能进行了评价.结果表明,TCS345和T4003铁素体不锈钢与Nirosta 4003和JFE410RW铁素体不锈钢的主要区别是钛和锰含量偏低,尤其是钛含量少,导致TCS345和T4003铁素体不锈钢的晶粒长大倾向较Nirosta 4003和JFE410RW铁素体不锈钢的明显.铁素体不锈钢焊接接头存在较大的热影响区,热影响区的组织与母材晶粒相比,其晶粒明显粗大;TCS345铁素体不锈钢的晶粒长大严重,Nirosta 4003和JFE410RW铁素体不锈钢的铁素体晶粒尺寸比TCS345略小,晶粒长大不明显.在1mol/L Na2SO4溶液中,TCS345和JFE410RW不锈钢母材的腐蚀性能优于T4003和Nirosta 4003. 相似文献
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Repair welding process of friction stir welding groove defect 总被引:1,自引:0,他引:1
The groove defect formed in the friction stir welding dramatically deteriorates weld appearances and mechanical properties of the joints owing to its larger size and penetration. Therefore, the friction stir repair welding was utilized to remove such a groove defect, and the focus was placed on the mechanical properties and microstructural characteristics of the repair joints so as to obtain an optimum repair welding process. The experimental results indicate that the groove defect can be removed by friction stir repair welding, and the offset repair welding process is superior to the symmetrical repair welding process. In the symmetrical repair welding process, a large number of fine cavity defects and an obvious aggregation of hard-brittle phase Al2Cu occur, accordingly the mechanical properties of the repair joint are weakened, and the fracture feature of repair joint is partially brittle and partially plastic. A good-quality repair joint can be obtained by the offset repair welding process, and the repair joint is fractured near the interface between the weld nugget zone and thermal-mechanically affected zone. 相似文献
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采用钨铼合金搅拌工具对新型9Cr-1Mo钢进行搅拌摩擦焊工艺试验,探讨焊缝成形、组织及性能变化规律. 结果表明,在300和400 r/min的转速,50 mm/min的焊接速度下可获得无缺陷接头;焊缝主要由搅拌区和热力影响区组成,具有明显的马氏体淬硬组织特征;高温热影响区为淬硬马氏体和回火马氏体混合组织,低温热影响区为过回火马氏体组织. 焊缝区具有晶粒细化特征,其晶粒尺寸约为母材69.2%. 焊缝区产生明显硬化,最高硬度约为母材硬度值的2.0倍. 焊接接头抗拉强度达到母材98%以上,搅拌区和热影响区冲击吸收能量分别达到母材的77.8%和87.4%,表明搅拌摩擦焊接头仍具有较好强韧匹配. 相似文献
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铝/钢异质金属复合结构具有轻质节能、降低成本、可以满足不同的工作条件等特点,在航空航天、船舶制造等领域的应用日益受到重视。由于铝和钢的物理化学性质存在巨大差异,铝和钢的连接成为焊接领域的难点问题。搅拌摩擦焊作为一种固相连接方法,具有热输入低、高温停留时间短、焊接变形小等特点,对克服铝/钢异质金属性能差异带来的焊接困难具有优势,已成为铝/钢异质金属焊接的研究热点。综述了铝/钢异质金属搅拌摩擦焊国内外研究现状,主要涉及搅拌头材料选择与结构设计、焊缝成形、焊接工艺窗口、力学性能、接头冶金结合、连接机制以及外源辅助搅拌摩擦焊新技术,可以为铝/钢异质金属结构的轻量化设计提供新思路,最后对其发展趋势进行了展望。 相似文献
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This study investigated the influence of preheating temperature and welding speed on the microstructure of dissimilar lapped friction stir welding (FSW) of ductile cast iron FCD450 and 304 stainless steel. The stainless steel was placed on FCD450, and then FSW was carried out at a tool rotational speed of 200, 400, and 600 rpm and welding speed between 1 and 10 mm/s. Preheating was conducted at 573 and 773 K. Martensitic structure was formed in HAZ of FCD450 without the preheating, while the preheating resulted in the formation of a pearlite structure. Even when the preheating was employed, however, stir zone (SZ) of FCD450 had the chill structure at a lower welding speed, because the SZ temperature exceeded the eutectic temperature. Formation of the chill structure in the SZ could be prevented at a higher welding speed. This study showed that FSW would be available as a dissimilar welding method between ductile cast iron and stainless steel. 相似文献
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采用搅拌摩擦焊对镁合金(AZ31B)和钢(Q235)异种材料进行焊接,通过优化工艺参数获得最佳成形接头,并采用光学显微镜对接头显微组织进行观察,通过SEM沿板厚方向分析焊核与钢侧界面不同位置的微观形态.结果表明,镁/钢连接紧密,焊核勺子状区与镁侧分界面明显,晶粒较母材晶粒明显长大;钢侧热力影响区受机械和热的复合作用,组织不均匀,既有等轴晶组织也有条状组织,镁侧热力影响区不明显;镁热影响区晶粒粗化较钢侧严重.接头横截面钢侧显微硬度距离焊核越近硬度值越高,焊核硬度分布不均,局部区域硬度很高,最高为324.7 MPa,镁侧硬度值较均匀. 相似文献