共查询到19条相似文献,搜索用时 93 毫秒
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热输入对2.25Cr1MoV钢粗晶热影响区再热裂纹敏感性的影响 总被引:1,自引:0,他引:1
再热开裂曾多次在2.25Cr1MoV钢反应器的焊接粗晶热影响区(Coarse-grained heat affected zone,CGHAZ)部位发生,却很少在"斜Y型坡口再热裂纹试验"中出现。考虑两者之间的热输入差异,通过Gleeble热模拟试验研究热输入对2.25Cr1MoV钢CGHAZ再热裂纹敏感性的影响,并结合显微组织观察、硬度测定及断口分析,讨论热输入、组织和性能之间的关系。结果表明,在5~100 kJ/cm的热输入范围内,CGHAZ的再热裂纹敏感性随热输入的升高而增大,当热输入为35 k J/cm时,CGHAZ在675℃对再热开裂"高度敏感",限制热输入在25 kJ/cm以内,将有效降低其再热裂纹敏感性。综合分析发现,模拟CGHAZ的高温塑性与其在高温拉伸试验后硬度的变化规律之间存在良好的对应关系。当软化现象发生时,拉伸试样的断裂模式为穿晶与沿晶的混合型断裂,具有较高的断面收缩率(Reduction of area,Ro A),当二次硬化现象发生时,其断裂模式为均一的微孔聚集型沿晶断裂,RoA显著降低。试验结果从二次硬化的角度反映了高热输入条件下CGHAZ的再热脆化机理。 相似文献
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本试验采用焊接热模拟技术,经过不同焊后热处理工艺,测定其冲击韧性变化,用扫描电镜观察断口形貌,做硬度测定和金相观察,以及热处理后的母材强度试验等,来评定15MnVR钢及其焊接热影响区经回火后的回火脆化倾向问题。试验表明,15MnVR钢有较严重的回火脆性,尤其以570~610℃为最明显的回火脆化区。 相似文献
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油气管线钢焊接局部脆化及断裂机理的研究 总被引:1,自引:0,他引:1
采用焊接热模拟方法和现代物理测试技术研究了管线钢焊接热影响区的韧性变化规律。结果表明,多道焊中,当二次热循环峰值温度处于(α+γ)临界区时,管线钢HAZ的韧性最低,表现为临界粗晶区局部脆化。拉伸试验和冲击试验结果表明,管线钢临界粗晶热影响区在断裂过程中,存在夹杂物形核、铁素体与M—A组元界面形核和M—A组元内部形核三种方式。M—A组元对裂纹扩展没有阻止作用。 相似文献
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常辉荣 《机械工人(热加工)》2007,(12):34-36
针对欧标S460NL钢板,按照ISO17642标准,进行了焊接性试验,确定了最小焊接热输入量,最低预热温度及焊后热处理温度,并在此条件下进行焊接力学性能试验,获得劳氏质量认证。 相似文献
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大线能量低焊接裂纹敏感钢的焊接(一)——热影响区强韧性机理研究 总被引:5,自引:1,他引:5
利用焊接热模拟技术对一种610MPa级大线能量低焊接裂纹敏感性钢的热影响区(HAZ)强韧化机理进行了研究。结果表明:在大线能量焊接条件下,该钢HAZ的强韧性决定了HAZ组织中针状铁素体的含量和形态,其含量越高,越细小,对HAZ的强韧性越有利;钢中TiN粒子的存在可促进HAZ针状铁素体的形核,且当钢中Ti/N比值接近理想化学配比3.42时,可明显细化针状铁素体,提高HAZ韧性。 相似文献
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为了能系统全面探究P92钢管焊条在焊接变形状态后焊缝内的焊缝热残余应力变化规律和其分布及规律情况,基于三维有限元分析及模拟分析的实验软件Abaqus建立起了实验数据库P92钢焊接模拟仿真模型的数据,研究的实验分析结果与分析模型表明,在钢管焊接变形的状态情况条件下,焊缝应力分布以及钢管焊缝受热温度影响区环向热应变分布和钢管焊缝内轴向应力变化主要体现呈拉应力,在焊缝热影响区出现了拉残余应力分布的最大值。随着距离焊缝中心距离的进一步的增加,焊接过程中拉残余的残余应力值也就逐渐减小。 相似文献
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4000 m3球罐用钢NK-HITEN610U2的焊接 总被引:1,自引:0,他引:1
低焊接裂纹敏感性高强钢NK -HITEN6 10U2具有良好的焊接性和抗裂性 ,焊接该类钢主要是防止产生冷裂纹和热影响区脆化 ,控制线能量是焊接工艺措施中的关键。另外 ,控制焊条熔敷金属扩散氢含量、选择适当的预热温度、焊后及时消氢处理 ,也是防止冷裂纹必不可少的措施。 相似文献
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Gyuyoung Lee Kwang Jin Park Dong Ho Bae 《Journal of Mechanical Science and Technology》2009,23(5):1244-1248
Sulfide stress corrosion cracking (SSCC) in crude oil field environment containing hydrogen sulfide (H2S) has been recognized as a material degradation and damage mechanism. Laboratory data and field experience have demonstrated
that extremely low concentration of H2S may be sufficient to lead to SSCC failure of susceptible materials. In some cases, sulfides may act synergistically with
chlorides to produce SSCC failures. SSCC mechanism is a form of hydrogen embrittlement that occurs in high strength steels
and in localized hard zones in weld of susceptible materials. In the heat-affected zones adjacent to the weld, there are often
very narrow hard zones combined with regions of high residual stress that may become embrittled to such an extent by dissolved
atomic hydrogen. On the basis of this understanding, SSCC tests were conducted with smooth specimens of the multi-pass welded
ASTM A106 Gr B steel pipe used in the oil industries. And SSCC resistance according to the welding processes was evaluated.
From the results, the weld by GTAW+FCAW showed the largest resistance against SSCC.
This paper was recommended for publication in revised form by Associate Editor Chongdu Cho
Gyuyoung Lee received the M.S. degree in Mechanical Engineering from Sungkyunkwan University in 2003 and 2005, respectively. Currently
he is in doctorate course in Sungkyunkwan University. He is currently serving as a Reliability member of the Korean Society
of Mechanical Engineers. Lee’s research interests are in the area of welding design, environmental strength of materials,
and life prediction and reliability assessment of the industrial facilities. 相似文献
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Sung-Wook Kang Beom-Seon Jang Jae-Woong Kim 《Journal of Mechanical Science and Technology》2014,28(9):3873-3883
In recent years, as interest in environmental protection and energy conservation rose, technological development for lightweight efficiency of transport equipment, such as aircrafts, railcars, automobiles and vessels, have been briskly proceeding. This has led to an expansion of the application of lightweight alloys such as aluminum and magnesium. For the welding of these lightweight alloys, friction stir welding has been in development by many researchers. Heat-flow analysis of friction stir welding is one such research. The flow and energy equation is solved using the computational fluid dynamic commercial program ‘Fluent’. In this study, a rotation affected zone concept is imposed. The rotation affected zone is a constant volume. In this volume, flow is rotated the same as the tool rotation speed and so plastic dissipation occurs. Through this simulation, the temperature distribution results are calculated and the simulation results are compared with the experimental results. 相似文献
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通过改变肋片的焊接尺寸以及焊接形状建立肋片传热模型,采用CFD(Computational Fluid Dynamic)模拟的方法,将模拟结果与传统铸造肋片的传热情况进行对比,研究不同焊接方式以及焊接尺寸对整个肋片的换热量以及换热系数的影响.结果显示,肋片焊接后,对整个肋片的换热量和换热系数有一定的影响,但影响较小.其中换热量根据焊接尺寸的增加先减小后增大;而换热系数呈波浪形变化,但有减小的趋势. 相似文献
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Heung-Shik Lee Sung-Ho Bang Tae-Won Kim 《Journal of Mechanical Science and Technology》2014,28(10):4037-4047
A corrosion fatigue crack propagation test for 430 stainless steel and its heat affected zone was conducted in pH buffer solutions, and the results were compared with model predictions. The bare corrosion effect on fatigue crack propagation, particularly in corrosive environments was evaluated by means of a modified Forman equation. As shown in the results, the average corrosion rate determined from the ratio of corrosion induced crack length to the entire crack length under a cycle load was 0.11 and 0.37 for the base metal and heat affected zone, respectively, with a load ratio of 0.5, frequency of 0.5, and a pH 10.0 environment. The modeling and experimental processes demonstrate a step towards a methodology enabling the corrosion effects on fatigue crack propagation behavior to be determined. 相似文献