Comparison of Linear and Nonlinear Ultrasonic Parameters in Characterizing Grain Size and Mechanical Properties of 304L Stainless Steel

Abstract

Ultrasonic nondestructive techniques can be used to characterize grain size and to evaluate mechanical properties of metals more practically than conventional destructive optical metallography and tensile tests. Typical ultrasonic parameters that can be correlated with material properties include ultrasonic velocity, ultrasonic attenuation coefficient, and nonlinear ultrasonic parameters. In this work, the abilities of these ultrasonic parameters to characterize the grain size and the mechanical properties of 304L stainless steel were evaluated and compared. Heat-treated specimens with different grain sizes were prepared and tested, where grain size ranged from approximately 40 to 300 μm. The measurements of ultrasonic velocity and ultrasonic attenuation coefficient were based on a pulse-echo mode, and the nonlinear ultrasonic parameter was measured based on a through-transmission mode. Grain size, elastic modulus, yield strength, and hardness were measured using conventional destructive methods, and their results were correlated with the results of ultrasonic measurements. The experimental results showed that all the measured ultrasonic parameters correlated well with the average grain size and the mechanical properties of the specimens. The nonlinear ultrasonic parameter provided better sensitivity than the ultrasonic velocity and the ultrasonic attenuation coefficient, which suggests that the nonlinear ultrasonic measurement would be more effective in characterizing grain size and mechanical properties than linear ultrasonic measurements.

Microstructural Characterization of Additively Manufactured Metal Components Using Linear and Nonlinear Ultrasonic Techniques

“…Furthermore, these random textures owing to the fast cooling rate have been reported to contain a high dislocation density, which can also contribute to the increased [ 33 ]. In addition, a previous study [ 37 ] reported that a decrease in the grain size increases the number of grain boundaries in a unit volume, in which the grain boundaries often act as interfacial discontinuities and generate higher harmonics for the propagating ultrasonic wave. To further substantiate this observation, the high-angle grain-boundary maps for the 0.92 m/s (grain size: 75 μm) and 1.16 m/s (grain size: 59 μm) LBS conditions were obtained using EBSD and compared, as shown in Figure 10 , where grain boundaries with a misorientation angle exceeding 15° are illustrated by gray lines [ 57 ].…”

“…The parameter , which is another linear ultrasonic property, quantifies the ultrasonic amplitude loss due to scattering, absorption, or friction when ultrasonic waves propagate through a material [ 16 ]. is often dependent on microstructural features such as grain size, boundary [ 37 ], textures [ 38 ], pores [ 12 ], and inclusions [ 39 ]. For conventional metals, nondestructive evaluation of various microstructural features using ultrasonic forward or backscattering has been extensively reported [ 40 ].…”

“…This parameter depends on the monochromatic fundamental ultrasonic wave and the higher harmonic components generated by the distortion of the fundamental wave. Because is known to be sensitive to the material microstructural characteristics, such as dislocations [ 19 ], precipitates [ 42 ], microscale cracks [ 14 ], and grain boundaries [ 37 ], its application has recently been actively investigated. can be derived as [ 17 ]: where is the ultrasonic wavenumber and and are the displacement amplitudes of the fundamental and second-order harmonic frequency components of the propagating ultrasonic wave, respectively.…”

Effect of the Grain Sizes on the Ultrasonic Propagation and Attenuation on Different Types of Steels Microstructure During Non-Destructive Testing

“…Samples used in this study are hot rolled steel plates S355, S275, Corten B and S275N with chemical composition shown in Table 1 that have been based on the European standards and recent research work [10][11][12][13][14][15][16]. Figure 1 depicts the dimension of the prepared samples which correspond to 160mm x 60mm x 30mm for the analysis and characterizations of their microstructure with ultrasonic testing NDT.…”

The Characterization of Fatigue Damage of 316L Stainless Steel Parts Formed by Selective Laser Melting with Harmonic Generation Technique

“…Nonlinear ultrasonic detection methods can be divided into the high-order harmonics detection method [24,25], the mixing modulation method [26][27][28], and the ultrasonic phased array imaging detection method [29], of which the high-order harmonics detection method is the most mature and widely used. Addressing the problem that SLM 316L stainless steel parts are prone to fatigue damage in multiple working conditions, and based on the nonlinear acoustics theory, in this study, the nonlinear ultrasonic test for the SLM 316L stainless steel specimen, which was subjected to fatigue loading, was carried out using the high-order harmonics detection method.…”