Start Date

2016 12:00 AM

Description

We use steel materials for a car, an industrial machine, a building and so on. The steel materials are used for the main parts of the machine. The steel materials have good mechanical characteristics, however, higher mechanical characteristics by special treatment are often demanded. In this case, some evaluation methods are also required to monitor and control the mechanical characteristics of steel materials. Normally, mechanical destructive testing is used for the evaluation of them, however, all products on line cannot be evaluated because destructing samples are needed by mechanical testing. Therefore, non-destructive evaluation by electromagnetic method is focused on in this paper. We have developed a non-destructive evaluation for hardening steel named as a frequency sweep excitation and spectrogram (FSES) method [1]. This proposed method can evaluate mechanical characteristics non-destructively by using several frequency components of magnetic flux depending on hardening conditions [1].

Figure 1 shows the measured magnetic coercive force Hc and maximum magnetic field strength Hmax. The sample were hardened by induction heating with the current of 80[A]. As shown in Figure 1, in the 8 - 12 [mm] and 16 - 22 [mm] sections, the spectrogram of the maximum magnetic field strength Hmax was changed locally in comparison of the one of the magnetic coercive force Hc. It has been made clear that the magnetic coercive force Hc could evaluate the hardening strength qualitatively and quantitatively [1]. Moreover, it is obvious that the local material changes can be evaluated by the maximum magnetic field strength Hmax as shown in Figure 1.

Language

en

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Jan 1st, 12:00 AM

Local Hardening Evaluation of Carbon Steels by Using Frequency Sweeping Excitation and Spectrogram Method

We use steel materials for a car, an industrial machine, a building and so on. The steel materials are used for the main parts of the machine. The steel materials have good mechanical characteristics, however, higher mechanical characteristics by special treatment are often demanded. In this case, some evaluation methods are also required to monitor and control the mechanical characteristics of steel materials. Normally, mechanical destructive testing is used for the evaluation of them, however, all products on line cannot be evaluated because destructing samples are needed by mechanical testing. Therefore, non-destructive evaluation by electromagnetic method is focused on in this paper. We have developed a non-destructive evaluation for hardening steel named as a frequency sweep excitation and spectrogram (FSES) method [1]. This proposed method can evaluate mechanical characteristics non-destructively by using several frequency components of magnetic flux depending on hardening conditions [1].

Figure 1 shows the measured magnetic coercive force Hc and maximum magnetic field strength Hmax. The sample were hardened by induction heating with the current of 80[A]. As shown in Figure 1, in the 8 - 12 [mm] and 16 - 22 [mm] sections, the spectrogram of the maximum magnetic field strength Hmax was changed locally in comparison of the one of the magnetic coercive force Hc. It has been made clear that the magnetic coercive force Hc could evaluate the hardening strength qualitatively and quantitatively [1]. Moreover, it is obvious that the local material changes can be evaluated by the maximum magnetic field strength Hmax as shown in Figure 1.