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金属磁记忆检测技术是一种新型的利用铁磁材料内在信息对材料进行检测和评价的无损检测方法,对裂纹类缺陷进行早期检测具有潜在的优势.利用小波包分析技术,对水压试验条件下API 5L X70管线钢焊缝中有无焊接裂纹的金属磁记忆信号能量特征进行了分析,确定了焊接裂纹金属磁记忆信号的小波包能量特征,并利用其作为输入特征向量建立了BP(back propagation)神经网络,对焊缝中是否含有裂纹等缺陷进行智能识别.结果表明,利用小波包能量和神经网络技术可以较好的实现焊接裂纹的识别. 相似文献
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焊接裂纹应力与磁记忆信号关系的实验研究 总被引:1,自引:0,他引:1
焊接裂纹产生的应力集中区是焊接构件在服役过程中最为危险的一个薄弱环节,对这个环节进行有效的安全评估,具有重要意义。金属磁记忆技术是近年来发展的一种全新的无损检测方法,它可以在地磁环境下检测铁磁构件的应力集中,从而诊断出产生(或可能产生)裂纹的危险区域。利用磁场中的高斯方程,对管线钢焊接裂纹的应力和金属磁记忆信号之间的关系模型进行了初步探讨,然后利用预制的焊接裂纹对此关系模型进行了研究预测,分析结果表明:此关系模型可满足应力检测的精度要求。 相似文献
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金属磁记忆检测技术是一种新型的无损检测方法,在焊接裂纹的检测和监测方面具有独特的优势.在提取焊接裂纹金属磁记忆信号特征的基础上,建立了用于焊接裂纹定量化分析识别的BP神经网络,利用Visual Basic和Matlab混合编程技术建立了焊接裂纹的金属磁记忆定量化分析软件. 相似文献
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金属磁记忆在焊接缺陷检测领域的研究现状及发展 总被引:1,自引:0,他引:1
金属磁记忆检测技术是一种新型的无损检测方法,它具有能够对焊接结构中的微观缺陷进行早期诊断,防止突发性破坏事故发生的潜在优势,在焊接缺陷检测领域具有广阔的发展前景,被认为是迄今为止能够对材料的内部损伤进行早期诊断的惟一可行的无损检测方法.文中首先对金属磁记忆检测技术进行了简要的介绍,随后指出了该技术在焊接裂纹检测方面的独特优势.并与传统焊接缺陷检测方法进行了比较,然后就其在焊接检测领域的研究和应用进行了分析.最后指出了金属磁记忆检测技术在焊接检测领域的发展方向. 相似文献
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液化石油气储罐焊疤表面裂纹的磁记忆信号研究 总被引:2,自引:4,他引:2
采用磁记忆检测发现液化石油气储罐焊疤部位存在较强的磁记忆信号。通过对储罐进行0~4.0MPa的加载试验,研究磁记忆信号的幅度和梯度随载荷的变化。最后采用磁粉探伤复验发现磁记忆信号部位存在大量3-5mm长的焊疤表面裂纹。试验结果表明,在0~2.0MPa的加压过程中,磁记忆信号的幅度和梯度均逐渐增大,到2.0MPa时达到峰值,在2.0~4.0MPa的加载过程中迅速下降,在此期间采用声发射监测,发现了七个声发射信号,证明该部位应力产生了迅速释放。由此证明磁记忆信号的幅度和梯度既与材料所处的整体应力有关,也与该部位的局部应力集中度有关。 相似文献
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Jae Hak Kim Jun Seok Seo Hee Jin Kim Hoi Soo Ryoo Ka Hee Kim Moo Young Huh 《Metals and Materials International》2008,14(2):239-245
The effect of microstructures on weld metal cold cracking has been studied using flux-cored are welding (FCAW) wires with
a 600 MPa strength level. Two FCAW wires were prepared by controlling the Ni content to allow a sufficient variation in weld
microstructures, but with little change in the weld metal strength. The microstructural analysis showed that there was a significant
difference in the proportions of the microstructural constituents of the weld microstructure. The 1.5%Ni wire resulted in
a weld microstructure with a lower grain boundary ferrite (GF) content associated with an increased proportion of acicular
ferrite (AF) than the 0% Ni wire. The GF contents of 0%Ni and 1.5%Ni weld metal were measured to be 19% and 6%, respectively.
The cold crack susceptibility of these two FCAW wires was evaluated using the gapped bead-on-plate (G-BOP) test at the two
different levels of diffusible hydrogen content As a result of the G-BOP tests, it was demonstrated that the 1.5%Ni wire had
better resistance to cold cracking than the 0% Ni wire because its weld deposit had a lower GF phase content. This implies
that, in addition to the hydrogen control approach, microstructural modification can be pursued to develop new welding consumables
with an improved resistance to cold cracking. In the discussion, the detrimental effect of GF against cold cracking is addressed
based on the microstructural characteristics of cold cracks in ferritic weld metal. 相似文献
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Study on magnetic memory signals of medium carbon steel specimens with surface crack precut during loading process 总被引:2,自引:0,他引:2
Static tensile test and tensile-tensile fatigue test of medium carbon steel sheet specimens with surface crack precut were performed on MTS810 hydraulic testing machine to clear the meaning of the point of Hp( y ) value zero. Magnetic memory signals were measured during the test process. The results show that only one point of Hp( y ) zero value exists in all measured magnetic signal curves during the loading process, which should be a sign of intersection of positive-negative magnetic poles after magnetic ordered state appears and does not indicate the position of surface crack precut. The analysis shows that the surface crack precut can not interrupt the magnetic ordered state occurred during the test completely, hence its Hp( y ) value is not zero. However, the crack extending to a penetrated defect at the instant of specimen's fracture leads to the discontinuance of magnetic ordered state. 相似文献