Nondestructive inspection for cracks detection in welded joints of clad steel by radio wave techniques

巴西盐前地区石油开采的艰苦条件创造了一个具有挑战性的环境，使生产在经济上可行和安全。腐蚀性的环境和日益严重的高压和温度增加了对特殊钢材和合金的需求。在这种条件下使用的主要材料之一是复合钢，它由提供机械强度的基材和通常被称为CRA(耐腐蚀合金)的耐蚀合金组成。几个盐下油田已将这种材料用于建造深水开采系统设备的不同部件，其中包括将石油从海底输送到水面平台或船舶的管道。尽管复合钢具有优异的性能，但也存在一些相关的问题，主要是管道焊缝根部腐蚀疲劳裂纹的形核。为此，需要对用这种类型的钢制造的设备进行检查程序，以确保生产可靠的海上开采系统。IKTS和LNDC之间的双边合作将处理复合钢的检查方法问题。有关各方将战略性地分享他们的经验，以提高视察成功的可能性。无损检测、腐蚀和焊接实验室(LNDC/UFRJ)将利用其在石化行业实施无损检测方法开发方面的专业知识做出贡献，德累斯顿工业大学和弗劳恩霍夫陶瓷技术与系统研究所(IKTS)将利用无损检测技术方面的经验做出贡献。以下合并提案应被理解为合作伙伴之间未来长期合作的初始阶段。在一项已完成的前期研究中，Heuers Group的高分辨率射频涡流技术是一种很有前途的解决方案，可用于裂纹检测以及复合钢样品的应变和局部杂质表征。在对IN718航空发动机合金亚表面应变表征算法进行初步研究的基础上，发现了UFRJ提供的不同熔覆层界面处的人工裂纹。这项前期研究的实验需要在更广泛的实验工作中重复，并结合一个基本概念，从理论上描述不良导电层状材料中的无线电波EC相互作用及其失真现象。在这一短期启动项目内，将获得一个更合格的数据库a，以便评估其潜力和相关性。

The hard conditions for oil exploitation at Pre-salt region in Brazil created a challenging environment to turn production economically viable and safe. Corrosive environments and increasingly critical high pressures and temperatures raised the demand for special steels and alloys. One of the main materials being used in such conditions is the clad steel, which consists on the junction of a base material that provides mechanical strength and a corrosion resistant alloy, commonly called CRA (Corrosion Resistance Alloy). Several Pre-salt fields have used this material in the construction of different parts of equipments for the deep water exploitation system, among these, the pipes that conduct oil from the sea bed to the platforms or ships on the surface. Despite the excellent properties presented by clad steels, there are a few problems associated; the main one is the nucleation of corrosion fatigue cracks in the pipe weld root. For this reason, an inspection procedure of equipment manufactured with this type of steel is needed to ensure the production of a reliable offshore exploitation system. The bilateral collaboration between IKTS and LNDC will handle the problem of inspection methodologies in clad steels. The parties involved will share their experiences strategically in order to enhance the inspections success possibilities. The Laboratory of Nondestructive Testing, Corrosion and Welding (LNDC / UFRJ), will make its contribution with the expertise on implementing the development of nondestructive inspection methodologies for the petrochemical industry, and the Technische Universitaet Dresden together with Fraunhofer Institute for Ceramic Technologies and Systems (IKTS) with the experience on nondestructive testing technologies. The following conjoined proposal should be understood as an initialization of a future long term collaboration between the partners. Within a completed pre study it turns out, that the high resolving Radio Frequency Eddy Current technique of Heuers group is a promising solution for crack detection and the characterization of strain and local impurities of clad steel samples. Based on preliminary work on algorithms for sub surface strain characterization of IN718 aero engine alloys, artificial cracks at the interface of differed prepared claddings provided by UFRJ were found. The experiments of this pre study needs to be repeated within a more extended experimental work combined with a basic concept for theoretical description of phenomenas of radio wave EC interaction within poor conductive layered materials and its distortions. Within this short term initialization project a more qualified base of data a will be acquired in order to evaluate the potential and relevance.