共查询到20条相似文献,搜索用时 10 毫秒
1.
Junzhi Hu Sumei Wang Xiaoli Zhao Shilin Zhu Botao Yu 《Frontiers of Mechanical Engineering in China》2010,5(2):189-193
A self-propagating high-temperature synthesis (SHS) welding-pen that can weld steel workpiece from 6 to 10 mm is developed
and welds the Q235 steel. The structure and properties of the welding joint are studied. The result indicates that this type
of welding is melting and the fusion zone is clear. The tensile-strength of the welding joint is 283 MPa, flexural strength
is 628 MPa, impact toughness is 46.43 J·cm−2, and the microhardness of the welding joint and fusion zone are 230 HV0.1 and 255.6HV0.1, respectively. The mircohardness of the fusion zone and the welding line are higher than that of the matrix. 相似文献
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以镍粉和钛粉为原料,采用自蔓延燃烧合成技术制备了多孔NiTi形状记忆合金,研究了压坯压力、镍含量、钛粉粒径等参数对合金孔隙尺寸、孔隙均匀性和显微组织的影响。结果表明:自蔓延燃烧合成的NiTi合金为螺旋分层结构;压坯压力在100~200 MPa范围内再经自蔓延燃烧合成的NiTi合金的孔隙均匀,且为三维连通结构,比较理想;镍质量分数为40%左右时,孔隙的分布和三维贯通性均较理想;当钛粉粒径较大时,出现了大量的液相和NiTi2、Ni3Ti等杂质相,反应很不充分,钛粉粒径在50~100μm之间为好。 相似文献
4.
Lyu Dae Yeong You Hyo Sun Yoon Jai Young Chung Se Hi 《Journal of Mechanical Science and Technology》1992,6(2):73-80
It has been well known that the ductile-brittle transition temperature (DBTT) of each weld structure or its shift (ΔDBTT)
from parent material is one of the very useful measures of the fracture characteristics in steel weldment. In order to present
an applicability of small punch (SP) test technique to weldments, in this study, a fracture strength of microstructure at
any localized region of interest on HAZ, weld metal and parent material in two steels was evaluated by using DBTT or ΔDBTT
obtained from the SP test in relation to the data obtained from the COD test. The empirical correlation, (ΔDBTT)
SP
⋟0.55 (ΔDBTT)
COD
, was obtained from the SP and COD test. In addition, the effects of test materials, that is the microstructures of welded
region and the orientations of specimens etc, did not appear at the empirical correlation. 相似文献
5.
Effects of laser shock processing on mechanical properties of laser welded ANSI 304 stainless steel joint 总被引:1,自引:0,他引:1
Yongkang Zhang Lei Zhang Kaiyu Luo Guifang Sun Jinzhong Lu Fengze Dai Junwei Zhong 《机械工程学报(英文版)》2012,25(2):285-292
With the rapid development of engineering component with integration,high-speed and multi-parameter,traditional techniques haven’t met practical needs in extreme service environment.Laser welding,a new welding technology,has been widely used.However,it would generate the drop of mechanical properties for laser welded joint due to its thermal effect.Laser shock processing(LSP) is one of the most effective methods to improve the mechanical properties of laser welded ANSI 304 stainless steel joint.In this paper,the effects of LSP on the mechanical properties of laser welded ANSI 304 stainless steel joint have been investigated.The welded joint on the front of the tensile samples is treated by LSP impacts,and the overlapping rate of the laser spot is 50%.The tensile test of the laser welded joint with and without LSP impacts is carried out,and the fracture morphology of the tensile samples is analyzed by scanning electron microscope(SEM).Compared with the yield strength of 11.70 kN,the tensile strength of 37.66 kN,the yield-to-tensile strength ratio of 0.310 7,the elongation of 25.20%,the area reduction of 32.68% and the elastic modulus of 13 063.876 MPa,the corresponding values after LSP impacts are 14.25 kN,38.74 kN,0.367 8,26.58%,42.29% and 14 754.394 MPa,respectively.Through LSP impacts,the increasing ratio of the yield strength and tensile strength are 121.79% and 102.87%,respectively;the elongation and area reduction are improved by 5.48% and 29.38%,respectively.By comparing with coarse fracture surface of the welded joint,the delamination splitting with some cracks in the sharp corner of the welded joint and asymmetric dimples,LSP can cause brighter fracture surface,and finer and more uniform dimples.Finally,the schematic illustration of dimple formation with LSP is clearly described.The proposed research ensures that the LSP technology can clearly improve the yield strength,tensile strength,yield-to-tensile strength ratio,elongation,area reduction and elastic modulus of the welded joint.The enhancement mechanism of LSP on laser welded ANSI 304 stainless steel joint is mainly due to the fact that the refined and uniform dimples effectively delay the fracture of laser welded joints. 相似文献
6.
Keshav Prasad D. K. Dwivedi 《The International Journal of Advanced Manufacturing Technology》2008,36(5-6):475-483
This paper investigates the influence of the submerged arc welding (SAW) process parameters (welding current and welding speed)
on the microstructure, hardness, and toughness of HSLA steel weld joints. Attempts have also been made to analyze the results
on the basis of the heat input. The SAW process was used for the welding of 16 mm thick HSLA steel plates. The weld joints
were prepared using comparatively high heat input (3.0 to 6.3 KJ/mm) by varying welding current (500–700 A) and welding speed
(200–300 mm/min). Results showed that the increase in heat input coarsens the grain structure both in the weld metal and heat
affected zone (HAZ). The hardness has been found to vary from the weld centre line to base metal and peak hardness was found
in the HAZ. The hardness of the weld metal was largely uniform. The hardness reduced with the increase in welding current
and reduction in welding speed (increasing heat input) while the toughness showed mixed trend. The increase in welding current
from 500 A to 600 A at a given welding speed (200 mm/min or 300 mm/min) increased toughness and further increase in welding
current up to 700 A lowered the toughness. Scanning electron microscopy of the fractured surfaces of impact test specimen
was carried out to study the fracture modes. Electron probe micro analysis (EPMA) was carried out to investigate the variation
in wt.% of different elements in the weld metal and HAZ. 相似文献
7.
Ming-Der Jean Jen-Ting Wang 《The International Journal of Advanced Manufacturing Technology》2006,28(9):882-889
This paper presents the application of principal components analysis for Taguchi orthogonal experiments to develop a robust
electron beam welding treatment (EBWT) process with high efficiency multiple performance characteristics (MPCs). In this study,
the principal components analysis (PCA) design incorporating the correlation matrix of tested trials is employed. In the first
step, the MPCs are reduced to two independent components using PCA. Both components accounted for 98.8% of the total variance.
The first principal component (PC), which refers to the integrated hardening capability index of the EBWT process, accounts
for 70.7% of the total variation. The remaining 28.1% were contributed by the second PC, which can be interpreted as the penetration
capability index. In the second step, we identify the most important PC loading vectors using PCA, and estimate the importance
of the PCs. By using PCA, relationships between different MPCs can be investigated and the most important factors for the
variance of the EBWT process can be identified.
The experimental results show that redundant information could be eliminated by using principal components in conjunction
with Taguchi’s orthogonal array experiments. This proposed approach is simple, effective, and efficient for developing a robust
and high-efficiency EBWT process of high quality. In this study, the MPCs in the EBWT process are successfully optimized . 相似文献
8.
Effect of shielding gas mixture on gas metal arc welding of HSLA steel using solid and flux-cored wires 总被引:1,自引:0,他引:1
S. Mukhopadhyay T.K. Pal 《The International Journal of Advanced Manufacturing Technology》2006,29(3-4):262-268
In this work, gas metal arc welding of high strength-low alloy (HSLA) steel with solid- and flux-cored arc welding wires using
different shielding gas compositions was performed. The composition of filler wire and shielding gas in gas metal arc welds
of HSLA steel determines the inclusion characteristics, microstructure and mechanical properties. Thus, acceptable weld metal
properties in HSLA steel using gas metal arc welding (GMAW) process could be achieved with the proper combination of filler
wire and shielding gas composition. 相似文献
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本文主要阐述柳州机械厂为适应农用微车配套需要而研制的 LJ376QC型柴油机的技术性能 ,配车试验并对主要件结构特点作了分析 相似文献
11.
Q235与X70钢在新加坡土壤中的应力腐蚀行为现场试验研究 总被引:1,自引:0,他引:1
通过国产Q235钢与X70钢U形试样在新加坡现场埋样试验,应用腐蚀形貌观察、裂纹扩展形貌观察、腐蚀产物的分析以及土壤理化性质分析等手段研究Q235钢和X70钢在新加坡土壤中的应力腐蚀行为特征,初步研究国产钢在国外典型土壤环境中的耐蚀性。结果发现,新加坡土壤中含有较多的硫化菌,硫化菌降低了硫酸盐还原菌的破坏作用;Q235钢与X70钢U形试样在新加坡酸性土壤中埋样1年后均发现了应力腐蚀开裂(Stress corrosion cracking,SCC),表现出明显的SCC敏感性,X70钢应力腐蚀敏感性强于Q235钢,钢的强度对于应力腐蚀敏感性有一定的影响;点蚀的发生和酸性土壤环境促进了应力腐蚀的发生,其应力腐蚀过程主要受阳极溶解(Anodic dissolution,AD)控制,同时可能存在氢致开裂(Hydrogen induced cracking,HIC)的混合控制。 相似文献
12.
Jen-Ting Wang Ming-Der Jean 《The International Journal of Advanced Manufacturing Technology》2006,28(9):909-918
In this paper, we present the application of the fuzzy logic analysis to a Taguchi orthogonal experiment for developing a
robust model with high efficiency in multiple performance characteristics (MPCs) of the plasma transfer arc welding (PTAW)
hardfacing process. It eliminates uncertain information and is a simple, effective, and efficient approach. A fuzzy logic
system is used to simultaneously investigate relationships between various MPCs and to determine the efficiency of each trial
of the Taguchi experiments. From the fuzzy inference process, we are able to determine the optimal setting of factor-levels
for the MPCs. In addition, we also use the analysis of variance (ANOVA) to identify the significant factors, which coincide
with findings from the fuzzy logic analysis and are found to account for about 79% of the total variance. Furthermore, a confirmation
experiment of the optimal process is conducted, and it verifies that both individual performance characteristics and MPCs
are successfully optimized and satisfy our desired levels of MPCs. 相似文献
13.
为了减小成形误差,提高激光选区熔化成形复杂特征结构件的能力,实验采用Ti6Al4V金属粉末,设计了不同倾斜角度的悬垂结构模型,研究了倾斜角度、扫描策略对悬垂结构SLM成形质量的影响。结果表明:倾斜角度越小,悬垂面的边缘线宽度误差越大(>80μm),表面粗糙度值越大(>20μm),翘曲变形越严重;岛形随机扫描策略的整体成形质量要低于Z形正交扫描策略,但对不同角度的悬垂结构影响不同。结合QM-Meltpool监控系统,从熔池的角度分析了倾斜角度和扫描策略的影响,为悬垂结构SLM成形提供了参考依据。 相似文献
14.
China’s High-speed steel cutting tools hold a considerable share in the global market.However,the overproduction of low-end HSS tools causes serious resource waste and low efficiency,which has become one of the major problems in the tool industry in China.So a new Surface Modification technology is developed,which can make the low-end HSS tools into the high-end ones.On the analysis of the mechanism of cryogenic and quenching-polish-quenching(QPQ),the cryogenic and QPQ compound treatment are studied by using φ8 HSS(M2) drills.The nitriding layer and the base of the drill bit are Studied and analyzed,and the mechanism of compound treatment is discussed by the technological parameters adjustment and the combination test of cryogenic,nitrogen,tempering procedures,and several analysis methods such as the optics metallographic microscope,the scanning electronic microscope (SEM),X-ray diffraction and micro hardness.The cutting test is done on the drills by cryogenic treatment,QPQ treatment and cryogenic and QPQ compound treatment separately.The results indicates that the cutting life of HSS (M2) drill can be increased dramatically by cryogenic and QPQ compound treatment. 相似文献
15.
In optical communication systems which require the coupling of the light source to the fiber, efficient coupling can be practically realized either using a separate lens or by direct formation of the lens at the fiber end. A novel lensed plastic optical fiber (LPOF) is presented with efficient coupling of the plastic optical fibers with a light source. An aspherical plastic lens was bound with a flattened plastic fiber end by laser transmission welding (LTW) to form an aspherical fiber endface which can provide better coupling efficiency than a spherical fiberface. An analysis demonstrates that LTW can offer strong welding with small heat affected zones that are appropriate for commercial use. In this study a useful method for manufacturing lensed-end fibers is developed and demonstrated experimentally. 相似文献
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轿车白车身装焊单元,常采用多机器人同时焊接,设备多、机器人工作空间环境复杂,依靠经验方法的路径规划工作量大且难以优化。通过对装焊单元进行分析,在采用商品化的建模与仿真软件对装焊单元进行建模的基础上设计了Probabilistic Roadmap算法自动规划点焊机器人的运动路径。通过对一单机器人装焊单元进行路径规划与仿真验证说明了规划方法的有效性。 相似文献
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光纤机敏结构振动形态感知及其SMA致动控制 总被引:1,自引:0,他引:1
以模拟太空帆板结构为试验模型,针对振动状态监测与主动控制技术需求,着重进行柔性光纤机敏结构振动形态感知及其形状记忆合金(SMA)致动控制研究。技术方法上基于分布植入式FBG传感网络的信息感知特性与结构形态曲面拟合算法,实现结构分布多点曲率检测与形态重构,并为基于SMA致动的结构振动主动控制提供判决依据;基于结构表面分布配置的SMA驱动网络,采用分组交替驱动方式实现结构低阶模态大幅振动主动控制;设计试验模型结构与构建完整试验测控平台,并综合阐述了试验方案与试验过程。试验结果验证了结构振动形态感知的有效性,以及结构振动SMA致动控制的可行性和高效性,为航天柔性结构低阶模态振动主动监控提供了较好的技术探索思路。 相似文献
18.
采用非平衡磁控溅射沉积技术制备纯MoS2和不同Ti掺杂量的MoS2-Ti复合薄膜。用SEM和XRD对薄膜的形貌和结构进行分析,用纳米划痕仪测试薄膜与基底间的附着力,用球-盘摩擦试验机评价薄膜在大气和真空环境中的摩擦学性能。研究结果表明:在溅射沉积MoS2薄膜过程中掺杂金属Ti,有效地阻断了MoS2疏松、多孔柱状晶的优势生长,从而生成组织结构致密、无定形态的薄膜,提高了其与基底间的附着力。掺Ti复合薄膜在大气和真空环境中的摩擦学性能都得到显著改善,真空环境中10%Ti含量的薄膜耐磨寿命最长,是纯MoS2膜的37倍,大气环境中20%Ti含量的薄膜耐磨寿命最长,是纯MoS2膜的67倍。 相似文献
19.