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X70管线钢焊接热影响区的连续冷却转变组织 总被引:1,自引:0,他引:1
利用热模拟技术并结合组织分析和硬度测试,测定出X70管线钢焊接热影响区连续冷却转变曲线并研究其组织转变规律.结果表明:当冷却速率大于15℃/s时,焊接热影响区组织由板条状贝氏体、粒状贝氏体和少量铁素体组成,细小的马氏体-奥氏体组元呈弥散分布;但随着冷却速率的减小,贝氏体比例逐渐减小,铁素体比例逐渐增大,晶粒明显长大,性能恶化.在实际焊接中将热输入控制在9.3~18.6 kJ/cm(壁厚14.6 mm)可获得强韧性良好的焊接热影响区组织. 相似文献
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Numerical simulation and experimental verification of the restraint intensity of pipeline girth welding joint 下载免费PDF全文
The restraint intensity (RI) of the pipeline girth welding joint was investigated using finite element method and experimental method to predict the cold cracking susceptibility of pipeline steel. The distribution of RI along the girth weld was investigated to study the influence of welding position on the RI. Subsequently, the effects of outer diameter (OD) and wall thickness of pipeline on the RI were studied with ABAQUS software. The results show that the RI is almost independent of welding position. The RI increased with the increasing wall thickness but decreased with the increasing OD. A prediction model of RI was developed based on the effects of the OD and the wall thickness. It has been found that the predicted RIs were in good agreement with the experimental values. The maximum fractional error between the predicted RI and the experimental values was just about 10%. It was indicated that the errors were mainly caused by the heterogeneous of the weld bead. 相似文献
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为确定纤维素焊条熔敷金属检测中是否需要提前在钢板坡口两侧作堆敷层进行研究,通过对方形试板进行不同层数的堆敷,观察出焊缝化学成分接近,与焊材本身化学成分相比有了不同比例的增加,说明母材的化学元素有稀释到焊缝中,但不会随着层数的增加而有明显的改变;通过加工距离坡口焊缝不同距离的化学试块进行分析,发现与母材试板堆敷结论相近,母材的化学成分有不同程度的稀释到焊缝,但距离坡口不同垂直距离的化学成分相差不明显;坡口不作堆敷层与堆敷1层力学性能相近,堆敷2层的力学性能优于不做堆敷层、堆敷1层,但相差不大. 相似文献
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国内外常用评定冷裂纹敏感性的试验方法有20多种,选择其中的斜Y形坡口试验、刚性拘束裂纹试验(RRC试验)和里海试验进行分析对比。通过对这3种冷裂试验方法拘束度的有限元计算以及管道对接环焊缝拘束度的模拟计算,得出以下结论:1同种材料、同样焊接工艺条件下,斜Y形坡口试验和平板对接试验焊缝拘束度远大于管道对接环焊缝的拘束度;2里海试验拘束度的大小与开槽的长度有关,槽越深,拘束度越小;同种材料、同样焊接工艺条件下,通过改变里海试样开槽长度可以模拟实际管道的拘束情况。 相似文献
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用插销试验法研究了实心焊丝CO2气保焊根焊条件下X80管线钢的冷裂纹敏感性及断口特征.结果表明,预热100℃条件下X80钢的抗冷裂性好,临界断裂应力σcr为624 MPa,与其抗拉强度相当.当拘束拉伸应力高于抗拉强度时,将发生失效断裂,断裂性质为延性断裂断口.CO2气保焊进行根焊焊接时,X80钢的抗冷裂性好,与该方法能得到超低氢的焊接条件有关,此外还与该钢的裂纹敏感系数(0.17%)不高,HAZ淬硬不明显有关.焊接接头过热区的组织主要为块状铁素体,最高硬度297 HV. 相似文献
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