马氏体相变对P91钢焊接残余应力的影响

基于仿真模拟软件SYSWELD,建立了P91钢材料属性数据库,设计开发了考虑马氏体相变的“热-冶金-力学”耦合计算方法,采用热循环曲线法对P91钢平板对接接头残余应力场进行数值模拟仿真分析。参照原始焊接工艺方案进行上下0.5mm/s焊接速度的调整,并进行残余应力仿真计算。结果表明,马氏体相变能抵消焊缝热收缩时产生的拉应力。后道焊缝焊接过程中施加的热载荷对前道焊缝应力变化和平板角变形有着显著的影响。考虑后道焊缝焊接过程中施加的热载荷对前道焊缝组织变化的影响时,焊接接头整体的拉应力大幅度下降,热影响区的拉应力上升,角变形起缓和作用。焊接速度越大,Von Mises残余应力和横向残余应力越大,纵向残余压应力越小。     

高强度核电用钢厚板手工焊性能研究

介绍了武钢首批试制的高强度核电用钢厚板手工电弧焊性能研究,按照第三代核电技术(AP1000)用钢提出的焊接技术条件,对36mm和48mm两种规格的核电用厚钢板进行了手工焊焊接性能试验,研究结果表明:采用E9018-G-H4R核电专用焊条匹配WHD585E钢厚板所得焊接接头综合力学性能优良,能满足第三代核电用钢提出的焊接技术条件。     

Improving the Fatigue Performance of the Welded Joints of Ultra-Fine Grain Steel by Ultrasonic Peening

Contrast tests were carried out to study the fatigue performance of the butt joints treated by ultrasonic peening, aiming at the improvement of ultrasonic peening treatment(UPT) on welded joints of a new material. The material is a new generation of fine grain and high purity SS400 steel that has the same ingredients as the traditional low carbon steel. The specimens are in two different states:welded and ultrasonic peening conditions. The corresponding fatigue testing data were analyzed according to the regulation of the statistical method for fatigue life of the welded joints established by International Institute of Welding(IIW). Welding residual stress was considered in two different ways: the constant stress ratio R = 0.5 and the Ohta method. The nominalstress-number (σ-N) curves were corrected because of the different plate thickness compared to the standard and because there was no mismatch or angular deformation. The results indicated that: 1 ) Compared with the welded specimens, when the stress range was 200 MPa, the fatigue life of the SS400 steel specimens treated by ultrasonic peening is prolonged by over 58 times, and the fatigue strength FAT corresponding to 106 cycles is increased by about 66％; 2) As for the SS400 butt joint ( single side welding double sides molding) , after being treated by UPT, the nominal S-N curve (m = 10) of FAT 100 MPa(R =0.5) should be used for fatigue design. The standard S-N curves of FAT 100 MPa (R = 0.5, m = 10) could be used for fatigue design of the SS400 steel butt joints treated by ultrasonic peening.     

Use of Plastic Correction Formula to Improve Accuracy of Welding Residual Stress Test with Blind-Hole Method

The blind-hole method is the most widely used approach to experimentally determine the distribution of residual stress. This paper aims to improve test accuracy of welding residual stress and conducts an experimental study on the strain release factors involved when using the blind-hole method for Q235 and Q345, two steels commonly used in building structures. The ranges of strain release factors A and B in the elastic stage, the effects of strain release factors on residual stress calculated values, and the plastic corrected strain release factors are analyzed considering of the effect of plastic deformation around the blind hole on measurement accuracy. Finally, a simplified calculation formula to determine strain release factors is proposed for use with the blind-hole method. Results show that in the elastic stage, strain release factor A for Q235 and Q345 ranges from-0.399 to-0.525 and strain release factor B from-0.791 to-0.960. Changing the strain release factors A and B shows that calculated residual tensile stress varies in relation to a decrease in both factor values. However, there is a increase in calculated residual compressive stress with a decrease in the strain release factor A value, but there is an decrease with a decrease in strain release factor B value. Calculated residual stress applied to elastic strain release factors is compared with that applied to amended plastic strain release factors for Q235 steel. The maximum deviation between calculated residual stress and test stress is reduced from 21.1 to 1.0%,and for Q345 steel from 26.5 to 1.2%. It is thus evident that the plastic correction formula proposed in this paper can be used in calculations when conducting a residual stress test.     

Behavior of axially loaded tubular X-joints using bolted connection: mechanical model and validation

X-joints are one of the fundamental joint configurations used in a wide range of transmission tubular structures. Experimental investigation of lbur tubular X-joints with bolted connection was conducted in this study, and it was found that the annular plate was the main yielding control member of such X-joints. Moreover, the portion outside the effective width of the chord member still had a restriction effect on the annular plate, which led to reducing the yielding strength of the joint, while the gusset plate could help to improve the yield strength capacity. In the current design code of steel structures, the contribution to the strength capacity of the gusset plate has not been taken into account. Therefore, based on some mechanical assumptions, a general mechanical model was proposed. After the introduction of the gusset plate strength capacity factor, the yield capacity simplified calculation method of such X-joints was derived. Through the analyses of such X-joints with various diameters and thicknesses, it was concluded that a simple mechanical model could predict test results very well and that the contribution of the gusset plate was also taken into account.     

H型钢梁埋弧自动焊变形控制分析

随着国民经济的发展，H型钢梁的应用范围不断扩大。为解决H型钢梁焊后易变形，分析和探讨了不同方法矫形功能以及消除焊缝残余应力的能力。试验结果表明，随焊连续碾压矫形法能有效地减小全焊接H型钢梁焊后应力和变形，焊缝表面无缺陷，平整光滑。     

A NEW PENETRATION CONTROL APPROACH FOR APPLICATION TO VARYING ROOT THICKNESS

研究了ＴＩＧ焊板厚变化对熔透的影响，并利用有限板厚焊接热过程计算公式研究了正面熔宽与背面熔宽的关系．在此基础上提出了利用正面熔宽在工件板厚变化的情况下进行熔透控制的方法．同时利用同轴视觉ＴＩＧ焊焊接系统和计算机图象处理系统测量和控制正面焊接熔宽，以实现熔透控制．试验结果表明，所提出的利用正面熔宽进行熔透控制的方法在１ｍｍ～３ｍｍ的工件变化范围内能够有效控制熔透．     

高强特厚板焊接施工工艺监造

通过对高强特厚板材料热影响区的脆化、冷裂纹和层状撕裂等焊接性能的分析,得出Q345GJC钢材焊接性能较差的结论.对高强特厚板焊接工艺质量控制要点进行了深入的研究,并应用于某超高层钢结构制作监造中,焊缝合格率达到100%,有效的保证了工程的质量.     

薄板结构振动声辐射特性分析及优化

利用有限元法与边界元法结合对薄板进行振动声辐射特性分析,研究了薄板结构在简谐力作用下表面声压分布状况,分析了不同边界条件、材料以及加筋形式等因素对薄板结构振动声辐射特性的影响,并对简支矩形薄板厚度进行了优化。研究表明,边界约束的增加会导致薄板刚度变大,进而导致薄板辐射声功率与辐射效率随之改变?不同材料对结构的辐射声功率均有影响,而对辐射效率影响很小?加筋对薄板声辐射特性影响显著,十字型加筋形式减震降噪效果最好?对薄板厚度进行优化,优化后薄板辐射声功率级下降了4.29dB。     

MSC.Marc有限元分析软件在焊接残余应力和变形模拟中的应用

焊接是工程制造领域广泛使用的一种高效构件成型制造技术,但焊接过程中因焊接局部加热而形成的残余应力和变形是在工程制造中不希望出现的。焊接数值模拟能较为准确预测焊接构件中的焊接残余应力和变形的分布情况,可用以指导制造过程中焊接工艺参数的优化和焊接顺序的选择,为降低试验成本和缩短产品制造周期提供了一种可行的方法。对MSC.Marc软件焊接模拟热源模型、材料模型以及其在焊接残余应力和变形模拟中的应用情况作了介绍。     

行李传送车车身设计及工艺

针对现有行李传送车车身为多片钢板拼焊而成,存在零件多、工序多、焊缝质量难保证、加工成本高等问题,通过对现有车身结构可折弯加工区域的整合分析,提出车身结构设计的新方案,并在保证工艺强度的前提下,减小了车身钢板厚度;结合新的车身结构设计方案,提出钣金折弯的生产工艺。     

A first order system model of fracture healing

INTRODUCTION Fracture healing is an important research subject in biomechanics. During the last years, many theories and simulation models have been proposed for de- veloping a comprehensive view of the mechanisms controlling bone morphogenesis. Pauwels (1960) was one of the first authors to propose a theory of tissue differentiation in response to local mechanical stress and strain. He assumed that deviatoric stresses com- prise the specific stimulus for the formation of fibrous connecti…     

新一代炉壳钢LK490埋弧焊性能研究

对新一代长寿命高炉炉壳用钢LK490两种规格（36mm和65mm）厚板,采用WQ-1焊丝匹配CHF101焊剂进行埋弧焊对接性能试验。结果表明,两种规格厚板焊接接头常温拉伸强度和高温拉伸强度均满足LK490钢焊接技术条件,焊缝、熔合线和热影响区低温冲击功有较大的富余量,接头综合性能指标满足新一代高炉炉壳用钢焊接技术要求。     

A first order system model of fracture healing

A first order system model is proposed for simulating the influence of stress stimulation on fracture strength during fracture healing. To validate the model, the diaphyses of bilateral tibiae in 70 New Zealand rabbits were osteotomized and fixed with rigid plates and stress-relaxation plates, respectively. Stress shielding rate and ultimate bending strength of the healing bone were measured at 2 to 48 weeks postoperatively. Ratios of stress stimulation and fracture strength of the healing bone to those of intact bone were taken as the system input and output. The assumed first order system model can approximate the experimental data on fracture strength from the input of stress stimulation over time, both for the rigid plate group and the stress-relaxation plate group, with different system parameters of time constant and gain. The fitting curve indicates that the effect of mechanical stimulus occurs mainly in late stages of healing. First order system can model the stress adaptation process of fracture healing. This approach presents a simple bio-mathematical model of the relationship between stress stimulation and fracture strength, and has the potential to optimize planning of functional exercises and conduct parametric studies. Project (No. 39470698) supported by the National Natural Science Foundation of China     

石油化工装置不锈钢复合钢板的焊接工艺

不锈钢复合钢板是一种由基层和复层组成的双层金属钢板,在石油化工装置中使用十分广泛。针对不锈钢复合钢板的焊接性特点,从坡口的选择、焊接方法、焊接材料、错变量的控制、焊后热处理和无损检测等工艺因素入手,阐述和提出了适合不锈钢复合钢板在石油化工设备制造生产中的焊接工艺措施。实践证明,这些工艺方法与措施在实际生产中可借鉴使用,并具有良好的针对性和实用效果。     

双层钢板混凝土组合剪力墙的抗剪性能(英文)

为深入了解双层钢板混凝土组合剪力墙的抗剪性能,采用数值模拟的方法研究了钢板厚度、混凝土厚度、混凝土强度及组合剪力墙的跨高比等主要参数对该组合剪力墙抗剪性能的影响规律,并提出了该组合剪力墙弹性抗侧刚度及抗剪极限承载力的简化计算公式.研究表明:随着钢板厚度、混凝土厚度、混凝土强度等级的增加,组合剪力墙的抗剪性能均有较显著的提高;组合剪力墙跨高比的变化对其弹性抗侧刚度影响较大,而对其抗剪极限承载力的影响并不明显.通过将公式计算结果与有限元计算结果进行对比分析,发现提出的简化计算公式较合理,能较好地反映双层钢板混凝土组合剪力墙的实际受力状态.该结论可作为双层钢板混凝土组合剪力墙初步设计的参考建议.     

Effect of direct quenching on microstructure and mechanical properties of medium-carbon Nb-bearing steel

The influence of direct quenching （DQ） on microstructure and mechanical properties of 0.19C-1.7Si-1.0 Mn-0.05Nb steel was studied. The microstructure and mechanical properties of reheat quenched and tempered （RQ＆T） steel plate were compared with those of direct quenched and tempered （DQ＆T） steel plates which were hot rolled at different finish rolling tem-peratures （1173 K and 1123 K）, i.e., recrystallization-controlled-rolled direct-quenched （RCR＆DQ） and controlled-rolled direct-quenched （CR＆DQ）, respectively. The strengths generally increased in the following order： RQ＆T〈RCR＆DQ＆T〈 CR＆DQ＆T. Strength differences between the CR＆DQ＆T and RQ＆T conditions as high as 14% were observed at the tempered temperature of 573 K. The optical microscopy of the CR＆DQ＆T steel showed deformed grains elongated along the rolling direction, while complete equiaxed grains were visible in RQ＆T and RCR＆DQ＆T steels. Transmission electron microscopy （TEM） and electron backscattering diffraction （EBSD） of the DQ steels showed smaller block width and higher density of dislocations. Inheritance of austenite deformation substructure by the martensite and differences in martensite block width were ruled out as major causes for the strength differences between DQ and RQ steels.     

36m吊车梁焊接变形的控制和矫正

在钢结构制造中焊接产生的残余应力,常以变形的形式表现出来,如不采取措施,将严重影响其质量及使用寿命,制定合理的焊接工艺,正确的施焊,适当的矫正是保证焊接质量所遵循的重要环节.     

正交异性钢桥面铺装有限元模拟和优化分析

为了确定正交异性钢桥面铺装受力状态并为设计提供参考,运用子模型有限元法分析了桥梁整体变形及局部轮载作用下铺装内部受力状态及应变分布特点.为优化设计铺装层结构,分析了铺装层模量对其应变状态影响.分析结果表明:大跨径钢桥整桥变形对铺装层受力状态影响很小,钢桥面铺装设计的控制受力因素是轮载局部作用下铺装层的横向应变,铺装层模量对铺装层的受力状态有显著影响,通过提高铺装层刚度过渡层的结构优化设计措施可以显著改善铺装层的受力状态,降低铺装层的应变水平.分别对环氧沥青混凝土、SBS改性沥青SMA和Rosphalt改性沥青混凝土的模量及疲劳性能进行了试验评价,可以为桥面铺装结构组合设计提供参考数据.     

X100管线钢埋弧焊焊接性能研究

X100管线钢屈服强度在690MPa以上,为了实现钢管埋弧焊缝的高强度高韧性匹配,研制了与X100管线钢相匹配的WS01焊丝,该焊丝匹配大西洋CHF105焊剂,焊接接头抗拉强度810MPa,20℃冲击功,焊缝的弯曲、硬度实验结果均达到AP15L钢管标准要求。