我国核电行业与机械行业换热管与管板接头焊接工艺评定标准比较与分析

介绍了我国核电行业换热管与管板接头焊接工艺评定标准与机械行业换热管与管板接头焊接工艺评定标准的情况,将两个行业的换热管与管板接头焊接工艺评定标准进行了比较与分析,并总结我国核电行业与机械行业换热管与管板接头焊接工艺评定标准的差异,对今后我国压水堆核电厂标准体系中换热管与管板接头焊接标准的制订提供参考与指导。     

304L管板式换热器换热管与管板接头的焊接

进行了304L换热管和304L管板接头不同焊接工艺方法(SMAW,TIG,MAG)以及在采用SMAW工艺方法时不同坡口深度的对比试验;指出了采用填丝TIG焊工艺焊接换热管和管板接头的质量稳定性好;阐述了MAG焊工艺焊接换热管和管板的应用前景:强调了管板坡口深度对于SMAW工艺焊接换热管和管板接头质量的重要性.     

电站锅炉水冷壁爆管失效分析

发电厂锅炉受热面管失效给发电企业带来了极大的经济损失,困扰着企业的安全生产.据粗略统计,炉内四管(过热器管、再热器管、水冷壁管、省煤器管)事故占国内锅炉事故的2/3左右[1].     

预应力隔热管的焊接

材质为高强钢的预应力隔热管是在石油开采中用于地下输送高温高压水蒸汽的绝热管。介绍了该管的内管焊接,内管与外管的焊接工艺及试件的性能试验。焊接的隔热管经油田现场试验,结果表明其性能良好。     

浅谈Assel轧管机与Accu Roll轧管机的性能对比

简要介绍了Asse轧管机和Accu Roll轧管机各自的特点和适用范围,重点对二者的性能优劣进行了对比分析。Accu Roll轧管机轧制薄壁管的速度快,轧制过程相对稳定;两种轧管机组所轧制的荒管精度都很高,但Accu Roll轧管机的导盘有时会影响荒管质量,且导盘和轧辊消耗大,更换耗时;Assel轧管机的设备重量轻,投资成本低,收回成本时间短。因此,Asse轧管机的综合性能指标优于Accu Roll轧管机。     

并排多通管内高压成形支管排列方式研究

以并排多通管内高压成形工艺为研究对象,在支管总间距一定的条件下,相邻支管间距由外到里成等差数列,对几种典型支管排列方式下并排多通管内高压成形工艺进行模拟分析.结果表明:在相同加载路径条件下,相邻支管间距由外到里逐渐增加时支管平均高度高于支管等间距排列和支管间距由外到里逐渐减小的排列方式,此时支管等间距排列时支管高度分布最均匀.加载路径修正后,相邻支管间距由外到里逐渐增加的支管排列方式得到的支管平均高度明显高于其他排列方式,且增加幅度越大,支管平均高度越高,各支管高度分布越均匀.不同支管排列方式最终得到的并排多通管壁厚分布规律基本相同.     

中国重型机械研究院股份公司签订大规格二辊伺服冷轧管机项目

2013年7月,中国重型机械研究院股份公司(简称中重院)中标浙江久立特材股份有限公司LG530大规格二辊伺服冷轧管机项目,并已正式签订供货合同。中重院近些年研制的二辊伺服冷轧管机已形成系列化,多项技术取得国家专利并获奖。其中,高速伺服冷轧管机已成功出口美国;另有多套冷轧管机已成功应用于第三代核电燃料管、核电蒸发器管、核电主管道用管、油井管、化工管、航空管     

三辊连轧管机的发展及分析对比

三辊连轧管机是当今世界上最先进的轧管机。介绍了三辊连轧管机的发展情况及主要优势,重点阐述了三辊连轧管机的结构特点,并着重对PQF连轧管机与FQM连轧管机以及PQF连轧管机的两种机型(轴向换辊和侧向换辊)进行了分析比较。     

钛复合换热管与双相钢管板的焊接工艺

本文通过合理选择钛-2205复合换热管与2205管板焊接工艺参数及制定合理有效的保护措施,较好的完成了钛-2205复合换热管与2205管板的焊接任务,保证了苯酚精制塔第二冷凝器管-管板的焊接质量。     

三项轧管工艺试验和第一台自动轧管机的诞生——《无缝钢管百年史话》(6)

简介了周期轧管工艺、自动轧管工艺和连续轧管工艺这三项轧管工艺试验情况。自动轧管采用二次穿孔工艺 ,管坯经锥辊式穿孔机穿孔 ,不经加热 ,再在盘式辊穿孔机上扩径减壁。继发明周期轧管机11年后 ,1903年11月 ,第一台自动轧管机在美国宾州的Greenville厂诞生 ,这是无缝钢管生产的第二项轧管工艺。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

冲压圆点连接机理初探

对冲压圆点连接的机理和圆点处的金相组织进行了分析。冲压圆点连接可分为4个阶段 ,即板料初压入阶段、冲压圆点成形初期阶段、冲压圆点形成阶段、保压阶段。由于被连接的板料在冲压连接圆点处受挤压 ,所以在材料的连接处产生压应力 ,提高了连接的抗疲劳强度。此外 ,对冲压圆点连接的特点、应用范围及影响因素进行了论述     

Simulation of 3-D Deformation and Material Flow During Roll Forging Process Using System of Oval-Round Groove

Basing on the analysis of the traits of the roll forging process, a system-model of computer simulation has been established. Three-dimensional rigid-plastic FEM has been used for the simulation of the deformation process in the oval and round pass rolling, including the entering, rolling, and separating stages. The analysis was conducted using the Deform-3D ver.5.0 code. The important information concerned with the deformation area characteristic, material flow, and velocity field has been presented. Otherwise,the location of the neutral plane in the deformation area was shown clearly.     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Numerical Simulation of the Thermo-Mechanical Process for Beam Blank Continuous Casting

The aim of this study was to simulate the solidification process of beam blank continuous casting, and then find the reasons for the typical defects of the beam blank. A two-dimensional transient coupled finite element model has been developed to compute the temperature and stress profile in beam blank continuous casting. The enthalpy method was used in the heat conduction equation. The thermo-mechanical property in the mushy zone was taken into consideration in this calculation. It is shown that at the mold exit the thickness of the shell had its maximum value at the flange tip and its minimum value at the fillet. The temperature had a great fluctuation on the surface of the beam blank in the secondary cooling zone. At the unbending point, the surface temperature of the web was in the brittleness temperature range under the present condition. To ensure the quality, it is necessary to weaken the intensity of secondary cooling. At the mold exit the equivalent stress and strain have higher values at the flange tip and at the web. From the spray 1 to the unbending point, the maximum values of stress and strain gradually moved to the internal section of the flange tip and the web. However, whenever, there were bigger stress and strain values near the flange tip and the web than in the other parts, it must be very easy to generate cracks at those positions. Now, online verification of this simulation has been developed, which has proved to be very useful and efficient to instruct the practical production of beam blank continuous casting.     

A CUMULATIVE FATIGUE DAMAGE RULE UNDER THE ALTERNATIVE OF CORROSION OR CYCLIC LOADING

Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.     

The Electrochemical Behavior of Oceanic Microbiological Influenced Corrosion on Carbon Steel

The corrosion behavior of carbon steel in the medium of marine microorganisms was investigated by electrochemical impedance spectra, polarization curves, and so on. Experimental results showed that the corrosion potential of carbon steel moved in a negative direction in the unpurified marine microorganism solution, and the polarization style of the cathodic process did not change. The electrochemical impedance spectra showed that the impedance value of the electrode decreased in the medium with bacteria, which indicated that the existence of microorganism could accelerate the corrosion progress of carbon steel.     

Structural Optimization of Electromagnetic Swirling Flow in Nozzle of Slab Continuous Casting

During the slab continuous casting process, the flow field of molten steel in the mold plays a decisive role in the quality of the slab. In this paper, electromagnetic swirling flow in nozzle technology is proposed to control the flow field in mold.This technology can drive molten steel to rotate inside the submerged entry nozzle by electromagnetic force, thereby controlling the flow field. This research shows that it can reduce the impact of molten steel on the bottom of nozzle and partly reduce the negative pressure at the upper part of nozzle outlet which is even eliminated by optimizing the structure and angle of nozzle. The area of heat flux of the mold wall becomes larger, and the crest value of heat flux gets lower than that without swirling in nozzle and any nozzle optimization. The meniscus fluctuates smoothly, and the flow velocity at the top surface is within a reasonable range. The temperature field distribution in the mold is uniform which was beneficial to the growth of equiaxed crystal and decreased element segregation.     

Effect of Structural Parameters on the Thermal Stress of a NiFe2O4-Based Cermet Inert Anode in Aluminum Electrolysis

Inert anode has been a hot issue in the aluminum industry for many decades. With the help of FEA(finite element analysis) software ANSYS,a model was developed to simulate the thermal stress distribution working condition of an inert anode. To reduce its thermal stress,the effect of some parameters on the thermal stress distribution was investigated,including the anode height,the anode radius,the hole depth,the hole radius,and the radius of inner chamfer and outer chamfer. The results showed that in the actual working condition of an inert anode,there existed a large axial tensile stress near the tangent interface between the anode and bath,which was the major cause of anode breaking. Increasing the anode height and reducing the hole depth properly seemed to be beneficial for the stress distribution. With the increase of anode radius,the stress distribution became better first and then deteriorated,the reasonable value was between 0.045 to 0.06m. The hole radius had a significant effect on the stress and a smaller radius would reduce the thermal stress. The effect of the radius of the inner chamfer and the outer chamfer was less than other parameters.     

RESEARCH ON THE FORMATION MECHANISM OF INTERNAL CRACK IN THE CONTINUOUS CASTING SLAB

In view of the periodic bending deformation of solid-liquid interface in the solidification process for continuous casting slab, the variation of temperature gradient and dendritic spacing in the front edge of the solid-liquid interface, and the nucleation and propagation process of crack were studied. It is shown that the bending deformation of the interface results in the temperature field change in the front edge of solid-liquid interface, and the occurrence of temperature gradient along drawing direction results in the growth of secondary dendrites. The initial crack formed during the middle and final stage of solidification may extend to the surface of the casting slab and become an internal crack. The results of the theoretical analysis are basically in agreement with that of the experiment.