许泽建
,
李玉龙
,
李朋洲
金属学报
利用带有正四棱锥形金刚石压头的Vickers显微硬度计对0Cr18Ni10Ti不锈钢焊接接头的焊
缝、母材、熔合区及热影响区的压痕尺寸效应进行了研究,
实验载荷为0.098---4.9 N, 载荷保持时间均为10 s. 结果表明,
接头各区域的显微硬度在较小的载荷下随实验载荷的增加而减小, 当载荷
超过1.96 N时各区域硬度值基本保持恒定.
采用PSR模型对接头各区域硬度值随载荷的变化规律进行了较为准确的描述,
得到的HV PSR与1.96 N载荷下的实验结果间的误差小于3 %. 在2.94
N的 实验载荷下沿垂直接头方向连续进行了微压痕测试,
得到接头在不同位置处的显微硬度分布曲线,
并对接头的金相组织进行了观察和分析.
关键词:
0Cr18Ni10Ti不锈钢
,
welded joint
,
heat-affected zone
,
microhardness
NI Yushan CHENG Guangxu KUANG Zhenbang Xi'an Jiaotong University
,
China doctorate student
,
Institute of Engineering Mechanics
,
Xi'an Jiaotong University
,
Xi'an 710049
,
China
金属学报(英文版)
Hausdorff dimension of fracture surface roughness of welded joint,both welding metal and heat-affected zone.of pressure vessel steel 16MnR,tested under strain-controlled low-cycle fatigue,was examined with computer vision srstem and by two-dimensional variation method. Results show that it decreases with the increase of cyclic hysteresis energy.The Hausdorff di- mension variation at heat-affected zone is greater than that of weld metal.It is believed that the greater the fractal dimension is,the longer the fatigue life will be.
关键词:
welded joint
,
null
,
null
,
null
X. Y. Li
,
X. T. Tian and H. C. Zhu( 1)Weldng Division
,
Beijing Polytechnic University
,
Beijing 100022
,
China 2)National ho. of Advanced Welding Technology
,
HIT
,
Harbin 150001
,
China)
金属学报(英文版)
Mismatching is one of the basic characteristics of welded joints.Overmatched welded joint with a crack in hard weld is simplified as a cracked body of CCP type SHS (a hard bar sandwiched between two soft material with a crier perallel to the interface ) in this paper.Effects of mechanical heterogeneity on fatigue crack growth and crack closure of this model are studied by experimental and elastic - plastic finite element methods. It is found that, residual plastic deformation remaining in the wake of a growing crack tip, which cases crack closure,is affected the plastic deformation in adjacent soft mate- rial near by the crack tip. Both the shape of crack tip plastic zone and stress distribution ahead of crack tip in heterogeneous cracked body are different from that of homogeneous one. Crack closure (open- ing) loads are estimated by investigating the changes of crack tip opening displacement during fatigue loading, and a new model of crack oening process is presented. Because of the difference in the effect of mechanical heterogeneity on displacement of non - fatigue crack and fatigue crack, conventional CTOD can not reflect the real deformation at crack tip of SHS specimens.
关键词:
welded joint
,
null
,
null
,
null
Yukio TAKAHASHI，Masaaki TABUCHI
金属学报(英文版)
Strength of welded joints of high chromium steels is one of the important concerns for fabricators and operators of ultra supercritical thermal power plants. A number of creep as well as creep-fatigue tests with tensile hold have been carried out on the welded joints of two types of high chromium steels widely used in Japan, i.e. Grade 91 and 122 steels. It was found that failure occurred in fine grain heat-affected zone in all the creep-fatigue tests, even at a relatively low temperature and fairly short time where failure occurred in plain base metal region in simple creep testing. Four procedures were used to predict failure lives and their results were compared with the test results. A newly proposed energy-based approach gave the best estimation of failure life, without respect of the material and temperature.
关键词:
Creep
H.Hongo
金属学报(英文版)
Evaluation of creep properties of the welded joint through taking local fluctuation of the mechanical properties into consideration is experimentally or analytically seldom carried out. The purposes of the present study are to examine the surface strain distribution in the weld metal of a full thickness welded joint specimen and subsequently to investigate the local variation in the properties of the all-weld metal part of the joint using miniature specimens. A welded joint was prepared for 316FR steel plates by gas tungsten arc welding process using Mod. 316L filler wire. Creep tests were conducted at 823K in air using full thickness large welded joint specimens, HAZ and all-weld metal miniature specimens. From the results obtained, it is concluded that the creep properties of multi-layer welded joints strongly depend on the location of specimen sampling.
关键词:
creep properties
,
null
,
null
F.Q.Tian
金属学报(英文版)
Welded joint is a mechanical heterogeneous body, and mechanical heterogeneity has great effect on dynamic fracture behaviour of welded joints. In the present investigation, dynamic response curve and dynamic J-integral of practical undermatched welded joint and whole base and whole weld three-point-bend (TPB) models containing longitudinal crack are computed. Dynamic J-integral is evaluated using virtual crack extension (VCE) method and the computation is performed using MARC finite element code. Because of the effect of inertia,dynamic load response curve of computed model waves periodically. Dynamic J-integral evaluated by VCE method is path independent. The effect of inertia has little influence on dynamic J-integral curve. The value of dynamic J-integral of undermatched welded joint is lower than that of whole base metal and higher than that of whole weld metal. The results establish the foundation of safety evaluation for dynamic loaded welded structures.
关键词:
virtual crack extension
,
null
,
null
杨光
,
孔德军
,
叶存冬
,
谢春洋
,
郭皓元
材料热处理学报
利用扫描电镜对X70管线钢焊接接头微观结构进行了观察,采用中性5％连续盐雾试验考察了其焊接接头表面的腐蚀性能,分析了X70管线钢焊接接头在盐雾介质中腐蚀行为,对点蚀坑内腐蚀产物进行EDS分析,探讨了X70管线钢焊接接头表面点蚀机理.结果表明,X70管线钢焊接接头在盐雾环境中耐蚀性低,容易诱发局部点蚀,Cl-对X70管线钢焊接接头的腐蚀起主导作用;其腐蚀过程主要由表面点蚀、形成腐蚀产物层、裸露的焊接接头表面腐蚀等3个部分组成,其中点蚀是裂纹萌生和扩展的主要来源;腐蚀产物主要是由Fe的氧化物和少量Fe的氯化物构成,其形成的氧化膜提高了其防盐雾腐蚀能力.
关键词:
X70管线钢
,
焊接接头
,
盐雾腐蚀
,
腐蚀产物
冯向阳
,
齐彦昌
,
彭云
,
田志凌
,
薛群虎
钢铁研究学报
从互感器误差校验、电能计量统计和电能计量系统整体校验3个方面对光学电流互感器的现场运行性能进行客观评价。投运前和运行中期的误差校验数据显示,变差小于0.1%,满足0.2S级要求。建立2套独立计量系统,在实际现场运行条件下进行长期数据比对,反映数字电能计量系统在各种环境因素影响下的长期运行稳定性。通过对数字电能计量系统的整体校验,在额定功率条件下不确定度达到9.0×10-5,置信概率达到97.15%,系统综合误差为1.013%,满足规程要求。
关键词:
互感器
,
光学电流互感器
,
运行性能
,
电能计量
,
试验
,
误差分析
,
稳定性
