霍立兴
焊接结构断裂、强度与评定科研工作
个性化签名
- 姓名:霍立兴
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学术头衔:
博士生导师
- 职称:-
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学科领域:
机械制造自动化
- 研究兴趣:焊接结构断裂、强度与评定科研工作
长期从事焊接结构断裂、强度与评定科研工作。改革开放以来,至今先后主持过7项国家自然科学基金项目、3项博士点基金项目、一项国防科工委项目。主持了一项国家经委“六五”攻关项目和参加了冶金部“六五”“七五”及劳动部“八五”“九五”国家重大课题攻关项目。另外与众多部委所属企业和研究所合作进行课题研究和试验解决了生产实际问题。主持完成的项目“全面屈服准则在焊接结构中的应用”通过天津市科委鉴定并获90年国家教委科技进步甲类成果一等奖。主持完成的项目“焊接结构的强度与断裂”85年获国家教委首届科技进步一等奖。主持完成的“六五”攻关项目“采油平台焊接结构抗脆性破坏研究”通过国家经委鉴定并获国家教委科技进步甲类成果二等奖并由船检局发往各有关分局应用。参加的国家“九五”攻关项目“体积型缺陷安全评定”获劳动部科技进步一等奖等。 最近与博士生一起自行开发研制出超声冲击装置,用其对焊接接头进行冲击处理后可以大幅度提高接头疲劳性能(疲劳强度提高60~70%、疲劳寿命可提高20~30倍)。该项成果受到国内外专家的重视,除被推荐在国际焊接学会期刊上发表外,一些国外研究所提出购买该装置的意向,国内已通过国家自然科学基金委主持的鉴定(目前为该委机械学科主持的唯一鉴定项目),且国家船级社已将其纳入在编的规范中推荐使用等,并获国家教委高校发明二等奖。另外所开发的功能焊条也可提高接头疲劳强度正准备推广。在国内外重要期及国际会议上发表论文百余篇。
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489
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成果数
10
【期刊论文】An Improved FOSM Method for Calculating the Failure Probability of Welded Pipes with Cracks1
霍立兴, Huo Lixing, Min Liu, Zhang Yufeng, Fangjuan Qi
,-0001,():
-1年11月30日
To increase the accuracy of R-F method, it is necessary to solve the problems of the linear expansion of failure function and non-normal variables. In this paper, the improved FOSM method was applied to calculate the failure probability of welded pipes with cracks. The examples show that this method is simple, efficient and accurate for reliability safety assessment of welded pipes with cracks. It can save more time than the Monte Carlo method does, so that the improved FOSM method is recommended for general engineering reliability safety assessment of welded pipes with cracks.
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【期刊论文】Study on Fracture Characteristic of Welded High-density Polyethylene Pipe*
霍立兴, Fangjuan Qi, Lixing Huo, Yufeng Zhang, Hongyang Jing, Xinqi Yang
,-0001,():
-1年11月30日
Crack opening displacement(COD) was applied to characterize the fracture initiation of the tough high density polyethylene, for the concepts of linear fracture mechanics(LEFM) are inapplicable for reasonably sized specimens due to extensive plasticity. In this paper normal single side notched three-point bend specimens and silica rubber replica techniques were used to study the characteristic COD of high-density polyethylene pipe and its butt-fusion joints including the weld fusion zone and heat effected zone at different temperature from -78℃ to 20℃. Testing results show that characteristic COD appears to depend on structural features that are determined by welding process and on testing temperature. As the temperature is lowered, characteristic COD of every zone studied decreases. Because welding process significantly changes some structural feature of HDPE material, characteristic COD of weld fusion zone is the smallest among three zones. Testing results can be used for the engineering design and failure analysis of HDPE pipe.
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霍立兴, Lixing Huo, Furong chen, Yufeng Zhang, Li Zhang, Fangjun Liu Gang Chen
,-0001,():
-1年11月30日
To improve the microstructure and properties of the electron beam welded joints, the vacuum or furnace whole post weld heat treatment (FWPWHT) usually should be done on it. The electron beam local post weld heat treatment (EBLPWHT) is a rather new heat treatment procedure that provides the advantages of high precision, flexibility and efficiency, energy saving and higher productivity. In this paper, the microstructure, mechanical properties, fracture toughness and fatigue properties of electron beam welded joints of 30CrMnSiNi2A steel in as-welded (AW) and EBLPWHT conditions have been investigated respectively. The results show that the microstructures of different zones of joints in as-welded condition are changed by EBLPWHT procedure, in which the welds from coarse needle martensite into lath-shaped martensite; the main structures of heat affected zones (HAZ) from lath-shaped martensite into lower bainite. The properties of welded joints can be improved by the EBLPWHT in some extent, especially the fracture toughness of the welds and the fatigue crack resistance of welded joints can be saficicantly improved. However a more appropriate heat treatment parameters of the EBLPWHT have to be studied in order to increase the mechanical properties of base metal near by the HAZ.
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【期刊论文】Study on Fracture Properties of High-density Polyethylene (HDPE) Pipe
霍立兴, Fangjuan Qi*, Lixing Huo, Yufeng Zhang, Hongyang Jing
,-0001,():
-1年11月30日
Butt-fusion welding is the main technology to join high-density polyethylene (HDPE) plastic pipes, which are widely used in transport the water, gas and corrosive liquid. Investigation shows that one of the failure modes of HDPE pipe is the crack slowly grows across the thick direction and leads to failure at last, so that it is very important to study the resistance to crack initiation of HDPE pipe and its butt-fusion welded joint. In this study, the elastic-plastic fracture mechanics parameter, crack opening displacement (COD) is used to describe the fracture initiation behaviors for the HDPE materials and its butt-fusion welded joints. The resistance to initiation fracture of HDPE pipe materials and butt-fusion welded joints were investigated at different temperature by using multiple specimen resistance curve method and silicon-rubber replica method. The results show that saturation initial crack COD-δis of HDPE pipe materials and butt-fusion welded joints decreases with the decreasing temperature. The δis of butt-fusion welded joints is lower than that of HDPE pipe materials. Investigation also proved that the silicon-rubber replica method is more suitable for HDPE engineering material than the multiple specimen method. At the same time the statistic distribution of the δis of HDPE butt-fusion welded joint was conducted. The results show that the value of the δis has the statistic variance inherently. The optimum fitting distribution of COD δis is Weibull distribution with three parameters.
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【期刊论文】Safety Assessment for the DONGFANG 1-1 Pipeline Installation
霍立兴, Li Zhang, Lixing Huo, Yufeng Zhang, Caiyan Deng, Bingren Bai, Xiaowei Li, Jun Cao
,-0001,():
-1年11月30日
In this investigation, the mechanical properties and low-temperature fracture toughness of API 5L X65 steel welded joints used for Dong Fang 1-1 gas export pipeline were studied. Structure Integrity Assessment Procedure (SINTAP)-Failure Assessment Diagram (FAD) method was applied to estimate the pipe structure with surface flaw at the weld toe. According to the ISO standard (BS7448), the CTOD fracture toughness of the welded joints were determined at the temperature of 0℃. For the heat affected zone (HAZ) specimens, post-test metallographic analysis was performed to insure that the tip of the crack was located in the coarse crystal zone in order to obtain valid and reliable results. The failure lines of analysis level 1 and 3 of weld metal were derived from the results of the mechanical property. The assessment was performed, considering the maximum lay stress, residual stress conservatively assumed to be uniform tensile stress, and minimum CTOD value. The results of the assessment showed that pipeline structure with surface flaw having the height and length respectively 2.2mm and 5mm at the weld toe is safe. This study lays the foundation of application of SINTAP to pipeline structure assessment.
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395下载
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霍立兴, Wang Wenxian, Huo Lixing, Wang Dongpo, Zhang Yufeng Jing, Hongyang, Yang Xinqi
,-0001,():
-1年11月30日
For a longitudinal welded joint, the tensile residual stresses are as high as the yield stress of the metal, so that the weld toes are sensitive to fatigue load. In this case a low transformation temperature electrode (LTTE) is one of the most useful methods used to improve the fatigue strength of the longitudinal welded joint, because the tensile residual stress is reduced or changed into compressive stress. Three kinds of longitudinal welded joints were selected to conduct fatigue tests. The tests results show that the fatigue strengths at 2
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霍立兴, Furong Chen *, Lixing Huo, Yufeng Zhang, Zhang Li, Liu Fangjun, ChenGang
,-0001,():
-1年11月30日
The effects of two post-weld heat treatment processes on the microstructure and fatigue properties of the electron beam welded joints of 30CrMnSiNi2A steel were studied. Electron beam local post-weld heat treatment (EBLPWHT), in a vacuum chamber, immediately after welding and a traditional furnace whole post weld heat treatment (FWPWHT) were accepted. The experimental results show that, after EBLPWHT, the main microstructure of weld is changed from coarse acicular martensite into lath martensite, and base metal is changed from ferrite and perlite into upper bainite and residual austenit, however the microstructures of different zones of joints in FWPWHT conditions are tempered sorbite. The fatigue crack growth rate da/dN of welds and base metal are not obviously differences among EBLPWHT, FWPWHT test and as-welded (AW) test, as the mechanical properties of materials have a certain but not large effect on the da/dN of welded joints. The resistance to near threshold fatigue crack growth data of welded joints can be largely improved by EBLPWHT and it is related to microstructure and crack closure effect.
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霍立兴, Lixing Huo, Furong chen, Yufeng Zhang, Li Zhang, Fangjun Liu, Gang Chen
,-0001,():
-1年11月30日
A three-dimensional finite-element model (FEM) used for calculating electron beam (EB) welding temperature and stresses fields of thin plates of BT20 titanium alloy have been developed in which the non-liner thermo-physical and mechanical properties of the material depending on the temperature has been considered. The welding temperature field, the distributions of residual stresses in as welded (AW) and electron beam local post-weld heat treatment (EBLPWHT) conditions have been successfully simulated. The results show that: (1) In the weld center, the maximum magnitude of residual tensile stresses of BT20 thin plates of titanium alloy is equal to 60~70% of its yield strengthσs; (2) The residual tensile stresses in weld center can be even decreased after EBLPWHT and the longitudinal tensile stresses are decreased about 50% compared to joints in AW conditions; (3) The numerical calculating results of residual stresses by using FEM are basically in agreement with the experimental results. Combined with numerical calculating results, the effects of electron beam welding and EBLPWHT on the distribution of welding residual stresses in thin plates of BT20 has been analyzed in detail.
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霍立兴, Lixing Huo, Furong chen, Yufeng Zhang, Li Zhang, Fangjun Liu, Gang Chen
,-0001,():
-1年11月30日
The electron beam local post weld heat treatment (EBLPWHT) is a rather new heat treatment that provides the advantages of high precision, flexibility and efficiency, energy saving and higher productivity. This paper studies the effect of two post-weld heat treatment processes on the microstructure, mechanical properties and fracture toughness of an electron beam welded joints in 30CrMnSiNi2A steel. EBLPWHT, in a vacuum chamber, immediately after welding and a traditional furnace whole post weld heat treatment (FWPWHT) were compared. The experimental results show that, after EBLPWHT treatment, the main microstructure of weld was changed from coarse acicular martensite into lath martensite, HAZ was changed from lath martensite, bainite into lower bainite, and base metal was changed from ferrite and perlite into upper bainite and residual austenit. The microstructures of different zones of joints in FWPWHT condition were tempered sorbite. The properties of welded joints can be improved by the EBLPWHT in some extent, especially the fracture toughness of welded joints can be largely improved. However the value of fracture toughness of base metal is comparatively low, so a more appropriate heat treatment parameters should be explored in the future.
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【期刊论文】New Developed Welding Electrode for Improving the Fatigue Strength of Welded Joints1
霍立兴, Wang Wenxian, Huo Lixing, Zhang Yufeng, Wang Dongpo, Jing Hongyang
,-0001,():
-1年11月30日
A new welding electrode, low transformation temperature electrode (LTTE), was introduced in this paper. It was described in design principle, mechanics, chemical compositions of their deposited metal and manufacturing methods. It was proved that the best transformation starting temperature from austenite to martensite of the deposited metal of LTTE was at about 190℃ and it was obtained by adding alloy elements such as Cr, Ni, Mn and Mo. The microstructure of the weld metal of the LTTE was low carbon martensite and residual austenite. The compressive residual stress was induced around the weld of the LTTE and the -145 MPa in compression could be obtained in middle of weld metal. The fatigue tests show that the fatigue strength of the longitudinal welded joints welded with the LTTE at 2×106 cycles was improved by 59% compared with that of the same type of welded joints welded with conventional E5015 and the fatigue life was increased by 47 times at 162MPa. It is very valuable method to improve the fatigue performance of welded joints.
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