大型LNG储罐关键技术

论述了大型LNG储罐的建造标准、罐体材料、罐体设计、焊接、绝热、施工。指出9Ni钢强度、韧性需改进,可尝试细化晶粒、提高纯净度、添加合金元素等方法。9Ni钢焊接不当易造成电弧磁偏吹、焊接裂纹及焊接接头低温韧性差,可通过选用合适的焊材、减小弧坑、控制焊接线能量来改善。针对储罐的特殊结构及绝热要求,应进行详细的结构设计及计算,选用合适的绝热材料及施工方案。为尽快提升我国大型LNG储罐建造水平,制定相关标准十分必要。     

Verification of possibility for controlling welding distortion generated by laser-arc hybrid welding

For predicting welding distortion and residual stress generated by laser-arc hybrid welding (HYBW) with high accuracy by the 3D thermal elastic-plastic analysis based on FEM, a heat input model considering the dual heat source of HYBW was proposed. By using the proposed model, welding distortion and residual stress generated by HYBW on the general structural steel under several welding conditions, in which the heat input ratio of laser and arc were variously changed, were obtained. Comparing with the results obtained by experiments and analyses, the validity and generality of the proposed heat input model could be verified. The tendency and magnitude of welding distortion varied with the heat input ratio of laser and arc. The results indicated the possibility for controlling welding distortion generated by HYBW with the optimum heat input ratio of laser and arc.     

考虑焊接热影响区软化的高强钢对接接头强度

为研究焊接热输入对调质态高强钢对接焊缝接头强度的影响,设计了对接焊缝接头的静力拉伸试验,进行了对接接头熔敷金属及热影响区(HAZ)硬度分布测试,并对影响接头强度的关键因素进行了参数分析。试验材料选取Q550和Q690两种调质态高强钢,采取气体保护焊分别以1.0、1.5kJ/mm和2.0kJ/mm三个等级焊接热输入,以涵盖常用焊接工艺参数。静力拉伸试验结果表明：对接焊缝接头的强度随焊接热输入的增大而下降;在焊接热输入1.0kJ/mm下,接头的破坏模式为母材处断裂,而在热输入1.5kJ/mm和2.0kJ/mm下,接头断裂均发生在热影响区处。通过硬度分布测试发现,接头的热影响区存在硬化区和软化区。随着热输入的增加,接头软化区范围增大、最小硬度下降,导致接头强度降低。静力拉伸试验的强度测试结果与硬度分布测试结果在宏观上相互印证。参数分析结果表明,热影响区中软化区与母材强度之比、相对软化宽度是决定接头强度的主要因素,且其与接头强度呈近似线性相关关系。     

HRBF400钢筋手工电弧焊焊接接头组织性能分析

手工电弧焊因为其稳定的性能特点而被广泛用于各种焊材的焊接。通过分析手工电弧焊中不同焊接方法焊接接头的切口形貌、显微组织与硬度分布着重讨论了不同的焊接方法对热轧带肋钢筋组织性能的影响,为进一步优化其性能与工艺提供了理论依据。实验结果表明:由于焊接方法的差别及焊接过程中热输入不同,使得焊接接头的宏观形貌各不相同,具体表现在焊缝的深宽比、热影响区的大小及焊接缺陷等。接头的微观组织主要以先共析铁素体,低碳马氏体、回火索氏体、细晶铁素体和珠光体组成。不同的焊接方法,焊接接头的轴线方向及横截面的维氏硬度值也是各不相同,这就导致了其性能的差异。     

The effects of electro slag welding on material properties of box column plates

The effects of electro slag welding (ESW) on the material properties of box column plates, which is ASTM A572 Gr. 50 steel, were investigated experimentally and numerically. The material properties of the column plates before and after ESW were evaluated by macro-etching observation, micro-structural observation, and CVN impact tests. The temperature distribution of the column plates, with the ESW heat cycle as the heat input, was simulated by using the ANSYS FEM software. It was found that: (1) The CVN values in the through thickness direction of the base metal can be as low as 14J, 8.1J, and 8.1J at 0°C for plate thicknesses of 32, 40, and 50 mm respectively; (2) During the ESW process, the measured peak temperature for a 25×50 mm column plate surface was as high as 1033, 880 and 744°C for plate thicknesses of 32, 40 and, 50 mm respectively; (3) After the ESW heat cycle, the through thickness CVN value decreased by 68% for the coarse grain heat affected zone (HAZ) of the column pate; (4) The FEM thermal conduction model developed was able to simulate the temperature distribution of the steel plate during the ESW process with reasonable accuracy; (5) To avoid welding penetration due to ESW, a minimum plate thickness is suggested; (6) The impact of ESW heat cycle is more significant for thin column plates compared to thick ones.     

压型钢板电弧点焊连接的试验研究

本文通过对136个电弧点焊受剪连接试件的试验数据的整理分析,提出了电弧点焊连接焊点有效直径、折减直径的计算公式以及两种破坏模式极限承载力的计算方法,并给出了这种连接的刚度取值范围。通过试验研究,提出了保证电弧点焊连接质量的一些技术措施。     

埋弧焊线能量对Q345qD钢焊接接头性能的影响

以板厚为16mm的Q345qD为母材,采用埋弧自动焊工艺,通过改变焊接电流和焊接速度来改变焊接线能量,对3组试板进行拉伸和冲击试验,并观察了焊缝金属显微金相组织,分析了焊接线能量对焊缝金属强度和韧性的影响。结合实验数据,得出如下结论:线能量过高将严重损害接头韧性,适当降低线能量可以得到强度和韧性均优良的焊接接头。     

焙烧炉锚固件的螺柱焊接施工

阐述了气体悬浮焙烧炉锚固件的结构特点 ,分析了螺栓电弧焊的原理 ,介绍了螺柱焊机的焊接参数及操作 ,并针对焊接施工中的问题提出了相应的解决方法     

Design proposal of butt welded joints of high strength steel considering mismatch ratio and softened zone

针对高强度结构钢在焊接热循环作用下热影响区域可能产生软化现象，且高强钢焊接时将遇到焊材强度匹配的问题，基于高强钢对接焊缝的试验研究、数值分析和理论研究的结果，对考虑焊接软化和焊材强度匹配的强度模型进行简化，进而提出便于设计的简化公式。通过对试验数据、欧洲规范EC3预测值、强度模型预测值和简化公式预测值的对比，得出强度模型和简化公式对接头强度的预测值较为准确，而欧洲规范EC3高估了对接接头强度。为了进一步地将简化公式应用于工程设计，通过搜集和汇总焊缝加工尺寸、高强钢力学性能以及试件实际的工作性能等三方面的数据，对简化公式进行可靠度分析，当安全系数为4.5时，抗力分项系数取为0.84。对我国规范中高强钢对接焊缝连接的设计方法提出设计建议，即在对接焊缝受拉承载力计算式中考虑接头的综合强度，该综合强度取决于钢材强度、焊材强度、软化区情况和约束情况。     

考虑匹配比和软化效应的高强钢对接焊缝的设计建议

针对高强度结构钢在焊接热循环作用下热影响区域可能产生软化现象,且高强钢焊接时将遇到焊材强度匹配的问题,基于高强钢对接焊缝的试验研究、数值分析和理论研究的结果,对考虑焊接软化和焊材强度匹配的强度模型进行简化,进而提出便于设计的简化公式。通过对试验数据、欧洲规范EC3预测值、强度模型预测值和简化公式预测值的对比,得出强度模型和简化公式对接头强度的预测值较为准确,而欧洲规范EC3高估了对接接头强度。为了进一步地将简化公式应用于工程设计,通过搜集和汇总焊缝加工尺寸、高强钢力学性能以及试件实际的工作性能等三方面的数据,对简化公式进行可靠度分析,当安全系数为4.5时,抗力分项系数取为0.84。对我国规范中高强钢对接焊缝连接的设计方法提出设计建议,即在对接焊缝受拉承载力计算式中考虑接头的综合强度,该综合强度取决于钢材强度、焊材强度、软化区情况和约束情况。     

An experimental study of ultimate compressive strength of transversely stiffened aluminium panels

An experimental investigation was carried out to determine the ultimate strength of welded stiffened aluminium panels in alloy 6082 T6 subjected to in-plane compressive loads normal to the directions of the stiffeners. This load case is not treated in the European standard for aluminium structures, Eurocode 9. A total of 21 panel specimens with various side aspect ratios and both open and closed stiffener sections were tested in a purpose made test rig. Great care was taken to ensure the rig gave very precise boundary conditions. The panels were manufactured by metal inert gas arc welding and friction stir welding. An extensive measurement program was carried out to determine the distribution of material strength and initial geometric imperfections. Small imperfection amplitudes were found. Tensile tests revealed variation in material properties, but the strength values were on average higher than the values stated in Eurocode 9. The panels failed by two different deformation modes; global flexural buckling and local buckling of the plate elements between the stiffeners.     

铁路桥梁用321-Q345q-D复合钢板焊接工艺研究

合肥铁路枢纽南环线钢桁桥采用321-Q345q-D复合钢板作为桥面板,通过分析321-Q345q-D复合钢板的化学成分和设计要求,选择焊接材料,按照焊接工艺评定试验的要求,分别采用手工电弧焊和CO2气体保护焊两种方法进行试验。试验结果表明:321-Q345q-D复合钢板具有良好的焊接工艺性能,其焊接接头具有良好的耐蚀性,强度、韧性和塑性均能够满足设计要求。为321-Q345q-D复合钢板应用于铁路钢桥,提供了有效的焊接数据。该桥面复合钢板为首次在铁路上应用。     

组合热源电弧焊残余应力数值模拟

用大型有限元分析软件ANSYS,对钢材平板坡口电弧焊的温度场和应力场进行数值模拟。有限元模型选用三维实体单元,考虑材料物理性能随温度变化和对流边界等。采取表面高斯热源与焊缝区体热源相结合的组合热原模型模拟电弧焊的焊接热源。获得了三维电弧焊的焊接温度场和残余应力场,并对计算结果进行了分析,为准确求解焊缝强度、变形及指导钢结构施工设计和合理利用残余应力奠定了理论基础,提供了一种新的思路。     

Investigation of thermal effects on mechanical properties of 9Cr-1Mo to 9Cr-1Mo welded joints for high-temperature applications

Modified 9CR-1MO usage has been highly increased in recent years mainly under high-temperature application. This paper focusses on microstructure without post heat treatment and hardness, stress analysis of weld zone, heat affected zone and parent metal with and without post heat treatment. Here, among many suitable welding processes, we have been chosen Tungsten Inert Gas Welding with an appropriate filler rod ER308L.The post heat treatment is been carried out by an annealing process. The study of microstructure for 9cr-1mo steel mainly describes size and shape of grains by the Scanning Electronic Microscope, micro, and macro structure examination. The tensile and hardness strength of the 9cr-1mo steel has been determined by using suitable equipment throughout the base metal and weld zone. The microstructure is uniform and free from a dendritic pattern, the ductility of material more after annealing and the hardness of material become uniform overall except in HAZ.     

Effect of welding on local mechanical properties of stainless steels for concrete structures using universal hardness tests

This study analyses the effect of welding on mechanical properties of ribbed bars of two cold-deformed austenitic stainless steels (new, low-nickel AISI 204Cu and traditional 304L types) and two duplex stainless steels (SAF 2205 type, cold and hot-worked). Welds have been carried out using shielded metal arc welding. The effect of welding on local mechanical properties has been studied using a universal hardness equipment, measuring universal and Vickers hardness, elastic and plastic energies and Young modulus. Measured values are correlated with the microstructure of base materials and heat-affected zone. Results show that heat during welding promotes recrystallisation of the microstructure, effect that depends on the degree of deformation. These phenomena can be easily studied with universal hardness. Results suggest that hot-worked 2205 duplex stainless steel can be welded in construction without meaningful modification of its properties. Cold-deformed grades will comply ductility requirements of Eurocode 2 after welding, although reductions of yield strength can be found in 2205 and 304.     

PTFE膜材力学性能及抗力不定性分析

对PTFE膜材的基本力学性能进行了试验研究,分析了膜材的拉伸破坏机理;进行了膜材的抗力不定性分析,研究了循环拉伸、温度、损伤、接缝连接、人工加速老化等对PTFE膜材拉伸性能的影响规律.结果表明：膜材的经向断裂延伸率小于纬向断裂延伸率,经向抗拉强度略大于纬向抗拉强度;随着温度的升高,膜材拉伸强度逐渐减小;不同温度下搭接膜材接缝拉伸强度能够达到母材拉伸强度的90%以上;损伤膜材的拉伸强度有明显的折减,折减程度同取样位置、折叠次数有直接关系;循环应力幅较大时,经循环拉伸后的膜材拉伸曲线更接近线性;人工加速老化使膜材的拉伸强度有一定程度的折减,但并不明显.     

广东清远水利枢纽船闸人字门总装焊接技术

针对广东清远水利枢纽船闸人字门总装焊接工程焊接量大,焊接强度高,焊缝形式多样,施工空间小等特点,通过焊接方案比选,确定采用先焊边柱,后焊中间梁格,最后焊梁格和面板的焊接方法。并详细介绍了人字门焊接技术,包括焊接材料、焊接流程、焊缝处理、焊接工艺参数选择等。结果表明,通过严格控制,人字门焊接变形和焊接质量满足要求。     

低温地区超高层钢结构施工技术

黑龙江农科院国际农业科技创新中心工程地处低温地区,为超高层钢结构建筑,因工程量大、施工作业面局限性等特点,安装工程施工工期较长,低温施工难度大。重点针对倾斜钢柱、桅杆安装施工和焊接采用了相关技术。特别是低温焊接,通过选择合理的焊材,严格控制焊接工艺中的预热温度、层间温度和焊接热输入,并对焊完的焊口进行焊后加热和采用保温等措施,有效地避免了低温环境下焊接冷裂纹的产生。     

负载下焊接加固钢结构压弯构件受力性能的影响因素分析

为研究负载下焊接加固钢结构压弯构件的受力性能,采用考虑焊接热影响的有限元分析方法,对不同初始负载、偏心距、长细比及焊接热输入等级等影响因素进行分析。完成了包括未加固压弯钢柱及加固压弯钢柱共72个构件的受力全过程模拟分析,获得了各因素影响规律,并验证了考虑二阶效应的新的名义应力比计算公式。结果表明:未加固构件的初始负载水平可通过二阶式反映;初始几何缺陷模式及大小影响失稳破坏方向及焊接残余变形大小;影响加固构件极限承载力的主要因素依次为偏心距、长细比、焊接热输入、初始应力比;影响焊接残余变形的主要因素依次为焊接热输入、初始应力比、长细比;为新编《钢结构加固设计规范》关于负载下焊接加固压弯构件设计计算方法提供了参考和依据。     

The characterisation of friction stir welding process effects on stiffened panel buckling performance

The introduction of advanced welding methods as an alternative joining process to riveting in the manufacture of primary aircraft structure has the potential to realise reductions in both manufacturing costs and structural weight. However, welding processes can introduce undesirable residual stresses and distortions in the final fabricated components, as well as localised loss of mechanical properties at the weld joints. The aim of this research is to determine and characterise the key process effects of friction stir welding assembly methods on stiffened panel static strength performance. Utilising experimentally validated finite element modelling methods, it is demonstrated that welding induced residual stresses have a significant influence, and that collapse behaviour is less sensitive to advanced process effects and process effect magnitudes than panel initial buckling behaviour.