Material characterization of cast irons with an EMAT/EC dual probe
Material characterization of cast irons with an EMAT/EC dual probe
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DOI：
10.3233/jae-2010-1230
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发表时间：
2010
影响因子：
0.6
通讯作者：
Keita Ohtaki;T. Uchimoto;T. Takagi
中科院分区：
文献类型：
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作者：
Keita Ohtaki;T. Uchimoto;T. Takagi
铸铁的力学性能在很大程度上取决于石墨形态和基体结构，因此应同时评价石墨形态和基体结构。前者可通过超声检测（UT）进行评价，后者可通过涡流检测（ECT）进行评价。基于上述背景，本研究提出了一种利用电磁超声/涡流双探头对铸铁材料进行表征的方法。为此，我们用本探头对不同石墨形态和基体组织的铸铁进行了超声和ECT检测。结果表明，石墨球化率与超声速度、珠光体比与EC信号之间存在相关性。这些结果表明，EMAT/EC双探头是有效的铸铁材料表征。铸铁是一种铁碳基合金，其主要成分为铁，碳含量超过2%。它具有优良的机械性能，如强度、延展性、易切削性和生产率，是有用的工程材料。因此，它被广泛用于汽车、工业机械等的部件。但是，铸件的制造工艺复杂，组织控制困难。因此，对铸铁力学性能进行无损表征是铸造工业的关键问题之一。铸铁的组织由石墨和钢基体组成。铸铁的力学性能取决于石墨形态和基体结构，因此，应同时评价石墨形态和基体结构。本文建立了用超声波声速测定铸铁球化率的方法（1）。通过测量球墨铸铁的电致变色信号来估计铸铁的基体组织和硬度（2）。因此，石墨形态和基体结构可以分别通过超声检测（UT）和涡流检测（ECT）进行评价。我们提出了一种EMAT/EC双探头（3），它可以用一个探头结构获得超声和EC信号。将该探头应用于管道壁厚减薄的检测中，验证了基于ECT与UT互补的无损检测方法的可行性。本文提出了一种用电磁超声/涡流双探头对铸铁材料进行表征的新方法。铸铁的材料特性是不均匀的，应根据每个点进行表征。该双探头结构紧凑，可同时采集超声和电涡流信号
Mechanical properties of cast irons strongly depend on the graphite morphology and the matrix structure, thus both of them should be evaluated for their characterization. The former can be evaluated by ultrasonic testing (UT), and the latter can be evaluated by eddy current testing (ECT). Considering the background above, this study proposes a novel method for the material characterization of cast irons with an EMAT/EC dual probe. For this purpose, we conducted UT and ECT for cast irons with different graphite morphology and matrix structures with the present probe. As a result, correlations betwe en the nodularity of graphite and ultrasonic velocity, and between one the pearlite ratio and EC signals were obtained. These results imply that the EMAT/EC dual probe is effective for the material characterization of cast irons. Cast iron is an Fe-C base alloy that contains iron as the princ ipal ingredient and carbon more than 2%. It is useful engineering material due to its excellent mecha nical properties, such as strength, ductility, free cutting, and productivity. Accordingly, it is widely used f or the parts of automobiles, industrial machinery and so forth. However, the manufacturing process of casting is complex, and the microstructure control is difficult. Therefore, nondestructive characterization of mechanical properties of cast irons is necessary and one of key issues in the foundry industry. The structure of cast irons consists of graphite and a steel matrix. Mechanical properties of cast irons depend on the graphite morphology and the matrix structure, thus both of them should be evaluated for their characterization. The nodularity of cast irons is estimated by measuring the ultrasonic velocity, and the method is established (1). The matrix structure and hardness of cast iron are estimated by measuring the EC signals of ductile cast irons (2). Therefore, the graphite morphology and matrix structure can be evaluated by ultrasonic testing (UT) and eddy current testing (ECT), respectively. We have proposed an EMAT/EC dual probe (3) that can obtain ultrasonic and EC signals with a single probe structure. This probe was applied to the evaluation of wall thinning of pipes, and the feasibility of the nondestructive evaluation based on the complementarity between ECT and UT was verified. This paper proposes a new method for the material characterization of cast irons with an EMAT/EC dual probe. The material properties of cast irons are not uniform and should be characterized with respect to each point. The dual probe with a single and compact structure can acquire UT and EC signals