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Effect of Post-weld Heat Treatment on Mechanical Characteristics of AZ31 Magnesium Alloy Welded Joints 被引量:1
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作者 闫志峰 张红霞 +2 位作者 DUAN Jinwen LIU Fei WANG Guilei 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2017年第5期1205-1212,共8页
Tungsten inert gas(TIG) welding was performed on 2.7 mm thick commercial extruded AZ31 B magnesium alloy plates. We investigated the effect of post-weld heat treatment(PWHT) on the microstructure, mechanical prope... Tungsten inert gas(TIG) welding was performed on 2.7 mm thick commercial extruded AZ31 B magnesium alloy plates. We investigated the effect of post-weld heat treatment(PWHT) on the microstructure, mechanical properties and precipitated phase of the weld joints. The results showed that during the annealing treatment(200 ℃-1 h, 250 ℃-1 h, 300 ℃-1 h, 350 ℃-1 h, 400 ℃-1 h, and 450 ℃-1 h), the average grain size in the weld seam was the minimum after annealing at 400 ℃ for 1 hour, and then abnormally grew up after annealing at 450 ℃ for 1 hour. The mechanical properties enhanced when the joints were processed from 200 ℃-1 h to 400 ℃-1 h but sharply decreased with increasing annealing temperature. In contrast to the annealing treatment, solution treatment(250 ℃-10 h, 300 ℃-10 h, 350 ℃-10 h, 400 ℃-10 h, and 450 ℃-10 h) exhibited a better ductility but a slight deterioration in tensile strength. Especially speaking, no eutectic compounds(such as Mg17 Al12) were observed in the weld seam. The supersaturated Al atoms were precipitated in a coarse spherical shape dispersed in the weld seam. The precipitated Al atoms dissolved in the matrix substances at the condition(400 ℃-1 h) or(250 ℃-10 h). The solution treatment caused grain coarsening and precipitated Al atoms dissolved in the weld seam substantially, which resulted in a drop in micro-hardness at the weld seam compared to the area of the annealed joints. 展开更多
关键词 magnesium alloy welded joint heat treatments microstructure mechanical properties
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Welding technique studies on the “West-East” pipeline project 被引量:1
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作者 隋永莉 杜则裕 +1 位作者 黄福祥 祁励春 《China Welding》 EI CAS 2006年第2期73-76,共4页
This paper described the work of welding process design for the " West-East" pipeline project, which is high pressure, large diameter and heavy wall thickness. According to the different geographical situation, clim... This paper described the work of welding process design for the " West-East" pipeline project, which is high pressure, large diameter and heavy wall thickness. According to the different geographical situation, climate, culture and the flexibility of the welding methods, this work recommended the semi-automatic process at the east and middle sections and automatic process at the west section of the pipeline project. The manual process is recommended on the tie-in joints and repairs. The double joint pipe and the 3 joint pipe are recommended at the water net place and some in-ditch welding place to reduce the welding volume. Also the special redesigned bevels are recommended for the automatic process and the semiautomatic process. Through all destructive tests, the results shows the welds are meet the requirements of related standards, specifications and design documents. 展开更多
关键词 "West-East" welding technique process design mechanical properties of welded joint
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Microstructure and properties in dissimilar/similar weld joints between DP780 and DP980 steels processed by fiber laser welding 被引量:9
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作者 Hongshuang Di Qian Sun +1 位作者 Xiaonan Wang Jianping Li 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2017年第12期1561-1571,共11页
The microstructure and mechanical properties(strength, fatigue and formability) of dissimilar/similar weld joints between DP780 and DP980 steels were studied. The microstructure in fusion zone(FZ) was lath martens... The microstructure and mechanical properties(strength, fatigue and formability) of dissimilar/similar weld joints between DP780 and DP980 steels were studied. The microstructure in fusion zone(FZ) was lath martensite(LM), and alloying elements in the FZ were uniformly distributed. The hardness in the FZ of dissimilar weld joint was similar to the average value(375 HV) of the two similar weld joints. The microstructural evolution in heat affected zone(HAZ) of dissimilar/similar weld joints was as follows:LM(coarse-grained HAZ) →finer LM(fine-grained HAZ) →M-A constituent and ferrite(intercritically HAZ) →tempered martensite(TM) and ferrite(sub-critical HAZ). Lower hardness in intercritically HAZ and sub-critical HAZ(softening zones) was observed compared to base metal(BM) in dissimilar/similar weld joints. The size of softening zone was 0.2-0.3 mm and reduction in hardness was ~7.6%-12.7% of BM in all the weld joints, which did not influence the tensile properties of weld joints such that fracture location was in BM. Formability of dissimilar weld joints was inferior compared to similar weld joints because of the softening zone, non-uniform microstructure and hardness on the two sides of FZ. The effect of microstructure on fatigue life was not influenced due to the presence of welding concavity. 展开更多
关键词 Dual phase steel Laser welding Dissimilar weld joints Microstructure mechanical properties Formability
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Development and application of software packages in welding engineering 被引量:3
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作者 Yan-Hong WEI Xiao-Hong ZHAN Zhi-Bo DONG 《Frontiers of Materials Science》 SCIE CSCD 2011年第2期160-167,共8页
The weldabiUty of some material is analyzed with simple calculating program in this paper, and weldability testing data are shared through database system. The welding procedures are designed with help of expert syste... The weldabiUty of some material is analyzed with simple calculating program in this paper, and weldability testing data are shared through database system. The welding procedures are designed with help of expert systems, and the knowledge is shared among welding engineers. Not only the preparing progress of the welding documents is completed with database systems but also the complex decision on the necessity of the qualification test according to the present procedure qualification records (PQRs) and manufacture codes is made. Moreover, the artificial neural network (ANN) technique is proven to be one of the effective ways to predict mechanical properties of welded joints when there are enough tested data to train the models. Finally, the achievements in modeling microstructure of welded joints are introduced, especially in solid transformation and grain growth in both heat-affected zone (HAZ) and welded molten pool. 展开更多
关键词 welding software package finiteelementmethod (FEM) welding procedurequalification mechanical properties of welded joints expert system database system
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