共查询到20条相似文献,搜索用时 203 毫秒
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超细晶粒钢的强度和韧性比普通晶粒钢有大幅度的提高,其焊接性是该钢能否获得广泛应用的关键。通过采用实际焊接和焊接热模拟方法,研究了焊接热输入对超细晶粒钢组织和力学性能的影响。研究结果表明,超细晶粒钢的奥氏体晶粒长大倾向与普通晶粒钢相近,在热影响区和母材之间存在一再结晶软化区,板厚小于3mm时,粗晶热影响区的裂纹扩展吸收能大于母材,板厚大于5mm时,粗晶热影响区韧性比母材有较大幅度降低。对影响粗晶热影响区韧性的机理进行了探讨。 相似文献
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采用普通电弧焊方法(手工电弧焊、二氧化碳气体保护焊、埋弧焊)对400MPa级超细晶粒钢进行焊接,并对不同工艺条件下的焊接接头进行了组织性能分析.研究结果表明:400MPa级超细晶粒钢电弧焊焊接接头热影响祆区存在着明显的晶粒长大现象;手工电弧焊和埋弧焊焊接接头性能明显下降,而二氧化碳气体保护焊焊接接头性能下降不明显.根据试验结果,实际生产中可以利用二氧化碳气体保护焊方法焊接400MPa级超细晶粒钢. 相似文献
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采用STT焊接电源进行了400 MPa级超细晶粒钢焊接试验.结果表明,在表面张力过渡CO2气保焊条件下,超细晶粒钢热影响区宽度极窄约为1 mm,随着线能量增大,热影响区中过热区的晶粒尺寸随之增大,但低线能量的表面张力过渡使晶粒长大的程度得到控制.各焊接线能量下,热影响区各区平均硬度不低于母材,不存在软化现象.过热区为多相组织混合形貌,为低碳马氏体、贝氏体、珠光体、铁素体的不平衡混合组织.对线能量3.68 kJ/cm时的焊接接头进行综合力学试验,发现超细晶粒钢的热影响区硬度、强度和韧性均高于母材. 相似文献
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采用激光-MIG复合焊对X80管线钢和X100管线钢进行焊接,研究了激光功率对复合焊接头的焊缝形貌、显微组织、硬度、强度和韧性的影响规律.结果表明,激光功率从2.0 k W增大至3.5 k W时,盖面焊缝熔宽和熔深增加,激光区熔深明显增加;激光区焊缝中AF含量增加、LB含量减少,X100侧粗晶热影响区和细晶热影响区中条状贝氏体含量减少,X80侧粗晶热影响区和细晶热影响区中准多边形铁素体含量增加.复合焊接头硬度分布并不对称,最高硬度出现在X100侧熔合区部位.复合焊接头的抗拉强度基本不随激光功率变化,拉伸试样断裂位置均为X80侧母材.随着激光功率增大,焊接接头最高硬度和韧性均下降. 相似文献
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激光焊接DP1000双相先进高强钢的过程中,普遍存在焊接热影响区的软化现象,热影响区的软化严重影响了焊接结构的成形和使用性能. 为了能提高焊接接头的成形和使用性能,采用快速冷却的方式来改善其焊接热影响区的软化问题. 通过拉伸试验、显微硬度测试、扫描电镜和光学显微镜等手段对比研究了1.5 mm厚DP1000双相钢板有无快速冷却的焊接接头中组织和性能的变化. 结果表明,在快速冷却条件下,激光焊接DP1000双相钢的接头热影响区软化区较空冷焊接的窄,软化现象有所改善,强度和塑性均有所提高. 相似文献
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Wang Weibin Shi Yaowu Sha Peng Lei Yongping Tian Zhiling 《Journal of Materials Engineering and Performance》2003,12(5):581-583
A 400 MPa ultra-fine grain steel possesses high strength and toughness. Due to its fine grain size, the heat affect zone (HAZ)
of the weld joint will soften during welding. The weldability of 400 MPa ultra-fine reinforced steel bar of flash butt welding
is investigated by using the micro metallographical examination and macro-mechanical-property tests. The joint of flash butt
welding has a superior mechanical property. The HAZ in the weld joint does not show apparent softening. There is only a localized
softening spot inside the weld seam, which does not affect the property of the whole joint. Therefore, flash butt welding
is appropriate for joining the 400 MPa ultra-fine grain reinforced steel bars. The resulting weld joint has excellent mechanical
properties. 相似文献
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A. K. Lakshminarayanan V. Balasubramanian 《Journal of Materials Engineering and Performance》2012,21(4):530-539
This article presents the comparative evaluation of microstructural features and mechanical properties of friction stir welded
(solid-state) and laser beam welded (high energy density fusion welding) AISI 409M grade ferritic stainless steel joints.
Optical microscopy, microhardness testing, transverse tensile, and impact tests were performed. The coarse ferrite grains
in the base material were changed to fine grains consisting duplex structure of ferrite and martensite due to the rapid cooling
rate and high strain induced by severe plastic deformation caused by frictional stirring. On the other hand, columnar dendritic
grain structure was observed in fusion zone of laser beam welded joints. Tensile testing indicates overmatching of the weld
metal relative to the base metal irrespective of the welding processes used. The LBW joint exhibited superior impact toughness
compared to the FSW joint. 相似文献
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采用焊接热模拟的方法,研究一种980 MPa级低碳贝氏体高强钢焊接接头HAZ不同区域,通过对各个区域的组织及相的分析,以及相应的拉伸及冲击试验研究了此类高强钢的组织和性能.结果表明,粗晶区的冲击性能最好,细晶区的冲击性能最低,为热影响区的薄弱环节.粗晶区组织为均匀粗细相间的板条贝氏体组织;在板条贝氏体上弥散析出碳化物;板条贝氏体界面上的奥氏体薄膜的存在是粗晶区韧性提高的原因.细晶区为孪晶马氏体+少量的板条马氏体,孪晶马氏体是导致细晶区性能下降的主要原因.Abstract: Microstructure and mechanical properties of HAZ of 980 MPa low carbon bainite high strength steel joints were studied . The different regions of welded joint HAZ were simulated by welding thermal simulation technique. Microstructure observation, phase analysis, and corresponding tensile and impact test for different regions of welded joint HAZ were taken. The results indicate: the impact property of coarse grain zone is the best, while the impact property of fine grain zone is the worst. So the fine grain zone is the weakest part of the welded joint. Microstructure of coarse grain zone is uniform interweaved coarse and fine lath martensites, and precipitation acicular ferrite are distributed between the lath martensites. Toughness of coarse grain zone is increased owing to the austenite thin film adherent lath martensite interface. Microstructure of fine grain zone are twin martensite and a small number of lath maarten-site, only minor acicular ferrite are distributed in the twin martensite . Toughness of fine-grained zone was decreased owing to twin martensite. 相似文献
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《Science & Technology of Welding & Joining》2013,18(4):448-454
AbstractThis paper describes friction welded joint properties of super fine grained steel (SFGS) and discusses improvements in these joint properties. The average grain size diameter of the SFGS base metal is ~0·6 μm, and its ultimate tensile strength is 660 MPa. The joint, made by a continuous drive friction welding machine (conventional method), fractured at the welded interface even though it possessed 100% joint efficiency. This was due to both the coarsening of the grain size and the softening of the welded interface with its adjacent region caused by heat input during braking times. The authors developed a joining method using a continuous drive friction welding machine that has an electromagnetic clutch to eliminate heat input during braking time, which was called the 'low heat input friction welding method' (LHI method). The joint obtained by the LHI method had the same tensile strength as the base metal at the friction time when the friction torque reached the initial peak. That is, the joint obtained 100% joint efficiency and fractured at the base metal, although the adjacent region of the welded interface softened only slightly. The grain size of this joint was smaller than that obtained by the conventional method. It was clarified that the optimum friction welded joint of the SFGS could be obtained by the LHI method in comparison with the conventional method. 相似文献
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研究了400 MPa级超细晶粒钢基于表面张力过渡、CO2气体保护焊、特殊窄间隙坡口、不同热输入条件下的焊接接头的成形与力学行为.结果表明,热输入在3~4 kJ/cm范围时可获得熔合良好、单面焊双面成形、热影响区极窄(1 mm左右)的焊接接头.该接头的硬度、抗拉强度高于母材,未见热影响区脆化与软化现象;弯曲塑性合格;焊接热影响区平均冲击韧性高于母材约60%.焊接热影响区冲击韧性高于母材的原因与粒状珠光体组织生成、多相非平衡组织共存和更高的屈服应力有关. 相似文献
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厚板转子钢多层多道焊接头不同微区断裂韧度的分析 总被引:1,自引:1,他引:0
文中研究了厚板转子钢多层多道窄间隙焊接接头不同微区的断裂韧度,主要包括接头中热影响区粗晶区及细晶区,焊缝中的柱状晶区和等轴晶区.结果表明,焊缝内柱状晶区断裂韧度(Jm)最低,断裂韧度最小值为195 kJ/m2,而热影响区的细晶区断裂韧度最高,Jm为1 265 kJ/m2.热影响区细小的等轴晶粒(1~12 μm)和晶内均匀分布的碳化物是其断裂韧度较好的主要原因.焊缝内组织主要为回火索氏体,以柱状晶形式分布在焊缝中,裂纹容易沿柱状晶晶界扩展,导致焊缝的断裂韧度较低.整个接头柱状晶与等轴晶组织交替分布,提高抗裂纹扩展能力,保证了整个焊接接头的安全可靠. 相似文献