共查询到20条相似文献,搜索用时 156 毫秒
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QP980淬火-配分钢属于第三代先进高强钢,具有强塑积高、成形性好等优点而成为汽车轻量化发展的重要材料。对国内某公司生产的1.5 mm厚的QP980淬火-配分钢采用机器人MAG焊(熔化极活性气体保护焊)进行焊接,分析焊接工艺参数对其焊接接头组织和力学性能的影响。考虑到焊接的淬火作用以及焊接接头的等强匹配原则,采用ER50-6焊丝作为填充材料。研究结果表明,在合适的焊接工艺窗口内,减小焊接热输入有利于提高焊接接头的强度,但对其塑性有不利影响。焊接接头横截面的组织和力学性能变化非常大,焊缝金属区主要由铁素体和珠光体组成,硬度较低,但能达到原始母材的硬度值;靠近焊缝的热影响区主要是完全相变区,该区是由原始母材组织发生奥氏体转变后冷却产生的以板条马氏体为主的组织,硬度较母材有较大提升,该区成为焊接接头的硬化区,而靠近母材的焊接热影响区主要包括两相区和回火区,两相区中部分组织发生了奥氏体转变,冷却后转变的组织较原始组织中的马氏体含量有所降低,硬度略有下降,而回火区是由原始组织中的铁素体、少量奥氏体以及发生了回火的马氏体组成,由于马氏体的回火作用,硬度也略有降低。在该钢的MAG焊中,焊接接头软化现... 相似文献
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对6082-T6铝合金焊接接头进行固溶+时效和时效两种热处理,研究不同热处理制度对其组织和性能的影响.实验结果表明:未处理的6082-T6焊接接头抗拉强度为225?MPa,断裂位置位于热影响区,接头硬度最低值均在热影响区;经时效处理后的6082-T6焊接接头处强化相分布更加均匀,焊缝区组织无明显变化,熔合区和热影响区组... 相似文献
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研究了固溶温度、时效温度及时间对10Ni2Cr2MnCuMoVAl塑料模具钢热处理后的微观组织和力学性能的影响。结果表明:固溶处理后,10Ni2Cr2MnCuMoVAl钢的组织主要是板条马氏体构成,且随固溶温度的升高,马氏体板条发生明显宽化,并在890℃固溶后达到硬度最高值。时效处理后的组织由板条马氏体、粒状贝氏体和析出碳化物构成。当时效温度区间为460~520℃,随着时效温度的升高,材料的强度逐渐升高,韧性逐渐降低,并在520℃达到强度峰值;时效温度高于520℃时,随着温度升高,材料硬度降低,冲击韧性升高。分析在540℃不同时效时间处理后的性能可知,试验钢在8h达到力学性能峰值。通过比较试验钢在不同时效处理后的力学性能数据,10Ni2Cr2MnCuMoVAl钢的最佳热处理工艺为:880℃固溶处理2h+空冷,随后在520℃时效处理4h+空冷。 相似文献
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利用金相(OM)、扫描电子显微镜(SEM)、电子背散射衍射(EBSD)以及能谱(EDS)等手段研究了FH40低温钢焊接接头显微组织演变及其对低温冲击韧性的影响.结果表明,FH40低温钢母材具有优异的综合力学性能,其屈服强度为420 MPa,抗拉强度为518 MPa,-60℃夏比冲击功为162 J,而焊接接头熔合线位置及热影响区的低温韧性急剧降低至16 J.显微组织分析表明,低温钢母材为细小的多边形铁素体+珠光体组织,在心部位置珠光体组织呈带状分布.焊接热影响区的显微组织主要为针状铁素体,但是心部存在明显的马氏体带.针状铁素体硬度为229.7 HV0.05,比原来的多边形铁素体高约40 HV0.05,而马氏体的硬度为313.7 HV0.05,较原来的多边形铁素体高约140 HV0.05.EBSD结果显示在马氏体带存在较高的内应力,这是造成焊接接头低温韧性急剧下降的主要原因.EDS表明,中心偏析导致热轧低温钢母材形成C、Mn富集的珠光体带,这些C、Mn富集的珠光体带在焊接热影响作用下重新奥氏体化,并在冷... 相似文献
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以航空用7075铝合金为焊接母材,采用航空专用铝合金ER5056焊丝对其进行TIG焊接,将焊后接头进行固溶处理+时效处理,研究焊接电流为130 A条件下的接头在不同固溶温度与固溶时间、不同时效温度与时效时间下进行热处理,通过对接头的硬度、拉伸力学性能、断口形貌及能谱进行表征发现,当固溶温度与时间为470℃×2 h、时效温度与时间为120℃×24 h条件下得到的接头具有较好的综合力学性能。 相似文献
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采用电子探针、XRD和透射电镜等研究了热等静压态、固溶态、固溶+时效处理过程中,粉末冶金不锈钢33Cr9Ni2Mo0.96N第二相的析出行为。结果表明:热等静压态的33Cr9Ni2Mo0.96N组织主要由γ+Cr2N+σ组成,经过固溶淬火后,组织主要由奥氏体+少量铁素体组成,经500℃和600℃时效后,33Cr9Ni2Mo0.96N中没有观察到第二相析出,经700℃时效,残余铁素体转变为σ相,同时在奥氏体晶粒及晶界处也开始析出σ相,经过800℃时效,有大量的Cr2N沿晶界析出,然后向晶内长大,经900℃时效后,Cr2N不断向晶内生长,最终几乎布满整个晶粒,而σ相趋于稳定。 相似文献
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Yutaka S. Sato Hiroyuki Kokawa Masatoshi Enomoto Shigetoshi Jogan Takenori Hashimoto 《Metallurgical and Materials Transactions A》1999,30(12):3125-3130
The precipitation sequence in friction stir weld of 6063 aluminum during postweld aging, associated with Vickers hardness
profiles, has been examined by transmission electron microscopy. Friction stir welding produces a softened region in the weld,
which is characterized by dissolution and growth of the precipitates. The precipitate-dissolved region contains a minimum
hardness region in the aswelded condition. In the precipitate-dissolved region, postweld aging markedly increases the density
of strengthening precipitates and leads to a large increase in hardness. On the other hand, aging forms few new precipitates
in the precipitate-coarsened region, which shows a slight increase in hardness. The postweld aging at 443 K for 43.2 ks (12
hours) gives greater hardness in the overall weld than in the as-received base material and shifts the minimum hardness from
the as-welded minimum hardness region to the precipitate-coarsened region. These hardness changes are consistent with the
subsequent precipitation behavior during postweld aging. The postweld solution heat treatment (SHT) and aging achieve a high
density of strengthening precipitates and bring a high hardness homogeneously in the overall weld. 相似文献
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Distribution of tensile property and microstructure in friction stir weld of 6063 aluminum 总被引:2,自引:0,他引:2
Dominant microstructural factors governing the global tensile properties of a friction-stir-welded joint of 6063 aluminum
were examined by estimating distribution of local tensile properties corresponding to local microstructure and hardness. Yield
and ultimate tensile strengths of the as-welded weld were significantly lower than those of the base material. Postweld aging
and postweld solution heat-treatment and aging (SHTA) restored the strengths of the weld to the levels of the base material.
Elongation was found to increase with increasing strength. Hardness tests showed that the as-welded weld was soft around the
weld center and that the aged weld and the SHTA weld had relatively homogeneous distributions of high hardness. Hardness profiles
of the welds were explained by precipitate distributions and precipitation sequences during the postweld heat treatments.
The strengths of the welds were related to each minimum hardness value. In a weld having a heterogeneous hardness profile,
the fracture occurred in the region with minimum hardness. When a weld had a homogeneous hardness profile, its fracture site
depended on both crystallographic-orientation distribution of the matrix grains and strain tensor of the imposed deformation,
i.e., it fractured in the region with a minimum average Taylor factor. 相似文献
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Abu Syed H. Kabir Xinjin Cao Javad Gholipour Priti Wanjara Jonathan Cuddy Anand Birur Mamoun Medraj 《Metallurgical and Materials Transactions A》2012,43(11):4171-4184
The effects of postweld heat treatment (PWHT) on 3.2-mm- and 5.1-mm-thick Ti-6Al-4V butt joints welded using a continuous wave (CW) 4-kW Nd:YAG laser welding machine were investigated in terms of microstructural transformations, welding defects, and hardness, as well as global and local tensile properties. Two postweld heat treatments, i.e., stress-relief annealing (SRA) and solution heat treatment followed by aging (STA), were performed and the weld qualities were compared with the as-welded condition. A digital image correlation technique was used to determine the global tensile behavior for the transverse welding samples. The local tensile properties including yield strength and maximum strain were determined, for the first time, for the laser-welded Ti-6Al-4V. The mechanical properties, including hardness and the global and local tensile properties, were correlated to the microstructure and defects in the as-welded, SRA, and STA conditions. 相似文献
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摘要:通过连续冷却实验研究了Nb Ti微碳深冲双相钢在不同冷却速率下的显微组织变化规律。并结合显微组织、热膨胀曲线以及实验钢的硬度值绘制出实验钢的CCT曲线。结果表明,实验钢的CCT曲线由铁素体、珠光体与贝氏体区组成,其中铁素体和贝氏体的区域较大,覆盖冷却速度范围较广。实验冷却速率下未出现马氏体组织。在05~1℃/s的慢冷速下,组织由铁素体和珠光体组成;当冷速增加至3℃/s时,贝氏体开始出现,珠光体消失。当冷速在5~10℃/s范围内时,获得铁素体+贝氏体双相组织;当冷速大于10℃/s时,铁素体相变消失,此时为纯贝氏体转变。热处理过程中若想获得一定量的马氏体组织,退火温度宜设置在820~900℃双相区较低温度范围,使合金元素充分富集于少量奥氏体中,在随后冷却过程中此奥氏体转变为马氏体组织。 相似文献
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《钢铁研究学报(英文版)》2011,(Z1):769-772
The weldability of 12MnNiVR was examined in terms of the simulated HAZ continuous cooling transformation (SH-CCT) diagram,microstructure and mechanical properties of the simulated coarse grain heat-affected zone (CGHAZ).When t 8/5 is shorter,the microstructure mainly consists of lath bainite.When t 8/5 is 60 s,the microstructure becomes coarser bainite.Some acicular ferrite appears beside lath bainite when t 8/5 =100s.Finally,a microstructure composed of polygonal ferrite,acicular ferrite,and small amount pearlite is obtained with a small amount of bainite at t 8/5 >100s.With the increase of t 8/5,the hardness of CGHAZ decreases considerably.The minimum impact toughness of CGHAZ appears at t 8/5 =100s.The hardness and the toughness of CGHAZ remain above the specified values for steel 12MnNiVR. 相似文献
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��С����������� 《钢铁研究学报》2013,25(9):52-57
Electro-slag welding with heat input of 530kJ/cm was applied to 60mm thick shipbuilding plate EH40, and microstructure and mechanical properties of the weld joint were characterized. Different regions such as heat affected zone, fusion zone, weld metal and base metal are found across the weld joint by microstructure analysis. A narrow coarse grain heat affected zone consisting of acicular ferrite, polygonal ferrite and grain boundary ferrite is found, width of which is less than 1mm. Acicular ferrite (?? 10??m) and grain boundary ferrite is observed at weld metal, while fusion zone have a complex structure of acicular ferrite, grain boundary ferrite and ferrite side plate. Mechanical property tests show that the absorbed energy of WM, FL and CGHAZ at -20?? during Charpy impact test is more than 60J, no evident softening phenomenon occurred at heat affected zone, and other properties met the requirement. 相似文献
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H. Shaikh H. S. Khatak S. K. Seshadri J. B. Gnanamoorthy P. Rodriguez 《Metallurgical and Materials Transactions A》1995,26(7):1859-1868
This article deals with the effect of the microstructural changes, due to transformation of delta ferrite, on the associated
variations that take place in the tensile and stress corrosion properties of type 316 L stainless steel weld deposits when
subjected to postweld heat treatment at 873 K for prolonged periods (up to 2000 hours). On aging for short durations (up to
20 hours), carbide/ carbonitride was the dominant transformation product, whereas sigma phase was dominant at longer aging
times. The changes in the tensile and stress corrosion behavior of the aged weld metal have been attributed to the two competitive
processes of matrix softening and hardening. Yield strength (YS) was found to depend predominantly on matrix softening only,
while sig-nificant changes in the ultimate tensile strength (UTS) and the work-hardening exponent, n, occurred due to matrix
hardening. Ductility and stress corrosion properties were considerably affected by both factors. Fractographic observations
on the weld metal tested for stress-corrosion cracking (SCC) indicated a combination of transgranular cracking of the austenite
and interface cracking. 相似文献
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V. S. Raghunathan V. Seetharaman S. Venkadesan P. Rodriguez 《Metallurgical and Materials Transactions A》1979,10(11):1683-1689
Microstructures of welds of AISI type 316 stainless steel have been examined with a view to establishing the changes that
occur during postweld heat treatments in the temperature range 900 to 1100°C. The ferrite content of the weld zone has been
estimated using a point count technique in the as-welded condition as well as after heat treatments. In addition, the compositional
changes occurring in the ferrite phase have been determined using an electron microprobe analyzer. The ferrite content of
the weld decreases continuously with an increase in the aging time. At the same time, the morphology of the ferrite changes
from a dendritic network into a distribution of isolated near spherical particles. An analysis of the kinetics of the dissolution
and the spheroidization of ferrite suggests that both these processes are controlled by interface diffusion; activation energies
for these processes are 132 and 140.5 kJ/mol respectively. The influence of the heat treatment variables on the morphology
and composition of the ferrite phase have been discussed. 相似文献
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The effects of solution and aging treatment on microstructure and mechanical properties of 10Ni2Cr2MnCuMoVAl plastic mold steel were experimentally studied. The results show that the dominant microstructure of 10Ni2Cr2MnCuMoVAl steel after solid solution treatment is lath martensite, and higher solution temperature results to larger width of martensite, while the highest value of hardness could be obtained after solution treatment at 890??. After aging, the microstructure consists of lath martensite, granular bainite and carbides. For steel aged at 460-520??, the strength of the material gradually increased with higher aging temperature, while the toughness decreased gradually. When the temperature exceeded 520??, higher temperature led to decreased hardness and increased toughness. Compared the mechanical properties of steel aged at 540?? for different time, the test steel reached the peak of mechanical properties at 8h. By comparing the mechanical properties of the test steels after different aging treatments, the optimized heat treatment process of 10Ni2Cr2MnCuMoVAl steel is solution treatment at 880?? for 2h with air cooling and tempering temperature at 540?? for 4h with air cooling. 相似文献