共查询到20条相似文献,搜索用时 15 毫秒
1.
《Journal of Materials Processing Technology》2014,214(2):229-237
Welding residual stresses, Vickers hardness and microstructure of welded high-strength low-allow steel, known for high strength and low carbon content, were studied under the following conditions: as-received high-strength low-alloy steel, welded high-strength low-alloy steel without a buffering layer, and welded high-strength low-allow steel with various thickness buffering layer. A soft buffering layer with a modest thickness between the parent metal and the weld metal could be incorporated to welded high-strength low-alloy steel to effectively reduce the widths of tensile residual stress zone and welding softening zone, to change the residual stress (in y-direction) nature at the weld root from tensile to compressive, and to refine the grains of the welded high-strength low-alloy steel. The width of the tensile residual stress (in x-direction) zone was approximately equivalently to that of the welding softening zone for those welded high-strength low-alloy steel with and without buffering layers. 相似文献
2.
A.G.Huang Y.S.Wang Z.Y.Li J.G.Xiong Q.Hu 《金属学报(英文版)》2004,17(2):147-154
The size of austenite grain has significant effects on components and proportions of various ferrites in low-alloy steel weld metal.Therefore, it is important to determine the size of austenite grain in the weld metal. In this paper, a model based upon the carbon diffusion rate is developed for computing austenite grain size in low-alloy steel weld metal during continuous cooling. The model takes into account the effects of the weld thermal cycles,inclusion particles and various alloy elements on the austenite grain growth.The calculating results agree reasonably with those reported experimental observations.The model demonstrates a significant promise to understand the weld microstructure and properties based on the welding science. 相似文献
3.
4.
以超超临界锅炉SA213?T23钢水冷壁失效管为试验对象,通过宏观检查、化学成分分析、金相检验和硬度试验,分析失效原因。结果表明:该水冷壁管化学成分正常,材质性能未发生明显劣化;水冷壁失效原因为鳍片焊缝开裂,该裂纹为沿晶界扩展的再热裂纹,起源于焊缝熔合线附近的热影响区粗晶区域,先沿热影响区横向扩展,然后扩展至母材区域,最终导致管壁泄漏失效;热影响区粗晶区域显微组织为粗大的马氏体和贝氏体组织,硬度明显偏高于焊缝熔合线另一侧的焊缝区域,脆性增大。两者在显微组织和硬度上的明显差别,使焊缝熔合线附近的热影响区粗晶区域容易产生应力集中,在高温运行中发生晶间开裂。 相似文献
5.
6.
7.
Jian Lin Ninshu Ma Yongping Lei Hidekazu Murakawa 《Journal of Materials Processing Technology》2013,213(8):1303-1310
Higher shear strength and fusion line failure were measured in CMT brazed lap joint of aluminum alloy 6061 and zinc coated steels with high strength (DP600) or thick plate (1.2 mm). Lower shear strength and interface failure were observed only if aluminum was brazed with low strength (270 MPa) and thin steel sheet (0.7 mm). A numerical model was developed for the prediction of shear strength and failure modes of the CMT lap joints. The maximum principle stress and deformation energy at the interface layer of the CMT joints were adopted as failure criteria for interface failure prediction. The equivalent plastic strain in the weld metal, HAZ and base metal of aluminum side of the CMT brazed joints was used as a criterion for failure prediction occurred on the fusion line. The shear strength of CMT joints and the two failure modes can be accurately estimated by the developed numerical model. 相似文献
8.
Hongliang Li Qiang Ma Ning Guo Xiaoguo Song Jicai Feng 《Science & Technology of Welding & Joining》2019,24(1):1-7
Dissimilar joint between 304L austenitic stainless steel and low-alloy steel 16Mn was underwater wet welded using self-shielded nickel-based tubular wire. Microstructure, mechanical properties and corrosion behaviour of dissimilar welded joints were discussed. Ni-based weld metal was fully austenitic with well-developed columnar sub-grains. Type II boundary existed between Ni-based weld metal and ferritic base metal in underwater welds similar to that in air welds. Major alloying elements distributed non-uniformly across the austenitic weld metal/16Mn interface. Maximum hardness values in wet welding appeared in a coarse-grained heat-affected zone at the 16Mn side, which possessed very low impact toughness. Underwater Ni-based welded joints fractured at Ni-based weld metal under tensile test. Ni-based weld metal had favourable corrosion resistance similar to 304L base metal. 相似文献
9.
10.
11.
12.
P. D. Antunes E. O. Correa R. P. Barbosa E. M. Silva A. F. Padilha P. M. Guimaraes 《工业材料与腐蚀》2013,64(5):415-421
The influence of the weld metal chemistry on the susceptibility of AISI 444 ferritic stainless steel (FSS) weldment to stress corrosion cracking (SCC) in hot chloride was investigated by constant load tests and metallographic examination. Two types of filler metal of austenitic stainless steel (E316L and E309L) were used in order to produce fusion zones of different chemical compositions. The SCC test results showed that the interface between the fusion zone (FZ) and the heat affected zone (HAZ) was the most susceptible region to SCC. Results also showed that the AISI 444 stainless steel weldment with E309L weld metal presented the best SSC resistance. Microstructural examinations indicated that the cracks initiated in the weld metal and propagated to the HAZ of the AISI 444 FSS, where the fracture occurred and it was observed a considerable amount of precipitates. Additionally, the higher SCC resistance of the AISI 444 FSS weldment with E309L weld metal may be attributed to the presence of a discontinuous delta‐ferrite network in its microstructure, which acted as a barrier to cracks propagation from the fusion zone to the HAZ/fusion zone interface of AISI 444 FSS. Fractrography analyses showed that the transgranular quasi‐cleavage fracture mode was predominant in the AISI 444 weldment with E316L weld metal and the mixed fracture mode was the predominant in the AISI 444 weldment with E309L weld metal. 相似文献
13.
He Enguang Gong Shuili Wu Bing Chen Li Science Technology on Power Beam Processes Laboratory AVIC Beijing Aeronautical Manufacturing Technology Research Institute Beijing China 《稀有金属材料与工程》2011,(Z4):130-133
The residual stress of T-joints for SUS304 stainless steel by YAG laser welding was measured by the method of hole-drilling,and the effects of heat treatment and hardness distribution of weld joints on the distribution of residual stress for T-joints were analyzed.The results showed that the maximum of longitudinal residual tensile stress for T-joints was about 140MPa.The maximum of residual stress was not more than 40MPa after heat treatment,the peak of residual stress reduced obviously.The gradient of residual stress distribution was also reduced significantly.Strain hardening phenomenon occurred for T-joints,and the hardness of weld and heat affected zone was both higher than the hardness of base metal,the peak of hardness occurred in the fusion line.The effect of strain hardening phenomenon of weld and heat affected zone on the residual stress distribution of T-joints for SUS304 stainless steel was obvious,which made longitudinal residual tensile stress become higher. 相似文献
14.
以ABAQUS软件为平台,开发了热-弹-塑性有限元计算方法用于模拟Q345/SUS304异种钢多层多道焊对接接头的温度场、残余应力和焊接变形. 同时,采用试验方法测量了焊接接头的残余应力、横向收缩和角变形. 计算得到的残余应力、横向收缩和角变形与实测值吻合良好,验证了计算方法的妥当性. 结果表明,Q345母材与焊缝交界处的应力分布有明显的不连续性,靠近交界处Q345侧的较窄范围内纵向拉伸应力明显低于该区的两侧;SUS304侧的高纵向拉伸应力区明显宽于Q345侧. 此外,试验和数值分析表明,Q345/SUS304异质接头有较明显的角变形. 相似文献
15.
On the base of the methods of predicting weld metal microstructures of pearlitic dissimilar steel welded joints using austenitic type filler materials by Schaeffler Diagram, the other new methods of predicting and expressing weld metal microstructures of two kinds of dissimilar steel welded joints (pearlite/pearlite and austenite/pearlite) using austenitic filler materials by Schaeffler Diagram are suggested. Those new methods resolve some difficult problems which the microstructure kinds in two heterogeneous mixture zones of weld metal neighbouring two kinds of welded base metals are difficult to be accurately ascertained and the fluctuations of weld metal microstructures across fusion line are difficult to be conveniently expressed according to the traditional predicting method. The new predicting methods are more concise and practical. 相似文献
16.
根据对接接头的应力分布特点,提出了低匹配接头焊缝与母材具有相等静载承载能力的条件,即焊根处应力集中因子与接头匹配比(焊缝金属与母材的屈服强度的比值)相等。通过有限元计算及其结果的回归分析,建立了对接接头几何参数与焊根处应力集中因子经验方程。针对高强钢焊接结构的应用,以焊缝与母材静载等强承载为原则,进行了低匹配对接接头的几何形状设计。结果表明,该几何形状设计不仅可在较大范围内选择匹配比而不必降低应用载荷,而且接头断裂模式由局部屈服断裂向整个接头的全面屈服断裂转变,该接头设计对于高强钢低匹配接头的应用具有重要意义。 相似文献
17.
Austenitic stainless steel is welded as a cladding on the inner surface of a reactor pressure vessel (RPV) made of low alloy steel. In order to assess the structural integrity of the RPV precisely, the residual stress distribution caused by weld-overlay cladding and post-weld heat treatment (PWHT) is evaluated. Since the cladding layer is very thin compared to the vessel wall, it is necessary to evaluate the residual stress distribution around the weld fusion line, which can be very steep. In this study, cladded specimens were fabricated using different welding methods. Residual stress measurements using both sectioning and deep hole drilling (DHD) methods were then performed to evaluate the residual stress distributions through the weld fusion line. Three-dimensional thermal-elastic-plastic-creep analyses based on the finite element method were also conducted to evaluate the residual stress caused by weld-overlay cladding and PWHT. It was shown that analytical results provided reasonable agreements on weld residual stress with experimental results. It was also clarified that the main cause of residual stress due to welding and PWHT was the difference of thermal expansion between weld and base metals. 相似文献
18.
Influence of zirconium on microstructure and toughness of low-alloy steel weld metals 总被引:1,自引:0,他引:1
V. B. Trindade R. S. T. Mello J. C. Payão R. P. R. Paranhos 《Journal of Materials Engineering and Performance》2006,15(3):284-286
The influence of zirconium on microstructure and toughness of low-alloy steel weld metal was studied. Weld metals with different
zirconium contents were obtained adding iron-zirconium alloy in the welding flux formulation. Weld metal chemical composition
proved that zirconium was able to be transferred from the flux to the weld metal. The addition of zirconium refined the weld
metal microstructure, increasing the acicular ferrite content. Weld metal toughness, determined by means of impact Charpy-V
tests, showed that the zirconium addition is beneficial up to a content of 0.005 wt.%. Above this level, zirconium was not
able to produce further microstructure refinement, although the toughness was reduced, possibly due to the formation of microconstituent
such as the martensite-austenite constituent (M-A), which is considered to be deleterious to the weld metal toughness. 相似文献
19.
20.
The rupture behavior of the modified 10Cr–1Mo steel multi-layer welded joint is determined by the fine-grain zones of the weld metal adjacent to the fusion line during the long-term creep test at 620 °C. The microstructures of multi-layer weld metal before and after the creep tests were characterized in detail, and its role in creep behavior was systematically investigated. Most grain boundaries of subgrains represented the low-angle boundaries in the weld metal adjacent to the fusion line both before and after the creep test. The widths of grains in the fine-grain zones were about 0.5–1 μm. The fracture morphology appeared as "wave" structure due to the cracking initiating from multi-layer grain boundaries in the fine-grain zones. Some W elements that melted into weld metal adjacent to the fusion line altered the thermodynamic and kinetic conditions of the Laves phase formation during long-term creep exposure. Laves phase particles mainly distributed along the grain boundaries due to the faster diffusion and segregation of Mo, W, and Si elements. Moreover, higher-density grain boundaries in the fine-grain zones led to easier nucleation and growth of Laves phase particles. Compared with other areas in the welded joint, the size of Laves phase particles in the fine-grain zones of the weld metal adjacent to the fusion line was the largest ones. The interface between Laves phase particles and the matrix acted as the nucleation site of creep micro-cavities. The creep micro-cavities grew up at the expense of fine-grain boundaries and even grew across the grain boundary deeply into adjacent grains, and then developed to cracks in the fine-grain zones. 相似文献