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超声背散射法可通过多晶体金属内部的空间方差信号，实现微观结构参数的无损评价，但表面粗糙度对评价模型的精度及实用性存在显著影响.基于高斯声束理论推导垂直入射粗糙界面的纵波声场，以此研究声能的Wigner分布规律；在超声的波长远大于粗糙度的前提下，构造表面粗糙度修正系数，并建立粗糙界面的单次散射响应模型，揭示粗糙度对超声波背向散射的影响规律.用304不锈钢制备轮廓均方根值为0.159 m的光滑试块和25.722 m的粗糙试块开展超声背散射实验，结果表明模型在粗糙度修正前后均可实现光滑试块的晶粒尺寸有效评价，但未经修正的传统模型对粗糙试块的晶粒尺寸评价结果与金相法结果的相对误差高达-21.35%，而本模型的评价结果与金相法结果符合得很好，相对误差仅为1.35%.可见，本模型能有效补偿粗糙度引起的超声背散射信号衰减，从而提高晶粒尺寸无损评价的精度.In the diffuse ultrasonic backscatter describing the scattering of elastic waves from polycrystalline metal material, the spatial variance of the signal is used as a primary measure of microstructure.Previously,theoretical singly-scattered response models have been developed for the diffuse backscatters of elastic waves within polycrystalline materials,which take into consideration both transducer beams and microstructural scattering information.However,the surface roughness of the liquid-solid interface induces a noticeable change of spatial variance amplitude,and its effect on the diffuse ultrasonic backscatter that can severely degrade the accuracy and practicability of the microstructure parameter evaluation was neglected in previous models.Therefore,a new singly-scattered response model for the rough surface polycrystalline samples is developed by following the forms similar to previous models for longitudinal-to-longitudinal scattering at normal incidence.In particular, we assume that the surface is slightly rough,specifically,the surface roughness value should not be larger than the magnitude of the wavelength.Hence,the modified expressions of ultrasonic reflection and transmission coefficients for the randomly rough interface can be applied to the singly-scattered response model.Then,with the modified transmission coefficient,a Gaussian beam is adopted to model the transducer beam pattern at normal incidence for longitudinal wave propagation through a rough liquid-solid interface to the polycrystal.Next,the Wigner transform of the displacement field is derived with a parameter of the surface roughness root mean square value.After that,a new expression of the calibration parameter including the modified reflection coefficient is given to provide a conversion between the displacement field and the experimental transducer voltage.Finally,the rough surface singly-scattered response model is built and the surface roughness correction coefficient is presented here to quantify the effect of the surface roughness on diffuse ultrasonic backscatter.The numerical results show that the Wigner distribution amplitude decreases and the acoustic energy coverage shrinks with the increase of the surface roughness.The theoretical spatial variance amplitude decreases by about 79.2% when the root mean square roughness value is set to be 40 m.The surface roughness correction coefficient is usually smaller than 1 when the reference calibration sample is smooth,but it can be bigger than 1 when the reference sample is rough.The results from the developed theory are then compared with the experimental measurements associated with a pulse echo transducer configuration for 304 stainless steel by using the smooth and rough surface samples.From these measurements,the mean grain size of the stainless steel can be determined.The experimental results show that although the corrected and uncorrected models both fit the experimental spatial variance curve from the smooth surface sample well,the uncorrected model fails to extract the grain size of the rough surface sample.The relative error of the grain size between optical microscopy and the uncorrected model can reach -21.35%.In contrast,good agreement with optical microscopy is observed by using the surface roughness corrected model,and the relative error is only 1.35%.In conclusion,the ultrasonic waves transmit though the rough interface twice,and the diffuse scattering which happens in these processes reduces the number of backscatter waves that can return to the transducer,so the spatial variance amplitudes drop dramatically.The correction coefficient presented here can describe the effect of surface roughness on diffuse ultrasonic backscatter.Moreover,it can improve the accuracy of grain size evaluation effectively.Thus,the surface roughness corrected ultrasonic backscatter model may be applicable for quality control of roughwrought castings or forgings during the manufacturing.
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Keywords:
- diffuse ultrasonic backscatter /
- surface roughness /
- grain size /
- nondestructive evaluation
[1] Bouda A B, Lebaili S, Benchaala A 2003 NDT&E Int. 36 1
[2] Liu Y G, Zhang S B, Han Z H, Zhao Y J 2016 Acta Phys. Sin. 65 104401(in Chinese)[刘英光, 张士兵, 韩中合, 赵豫晋2016物理学报65 104401]
[3] Panetta P D, Bland L G, Tracy M, Hassan W 2015 TMS 2014 Supplemental Proceedings San Diego, USA, February 16-20, 2014 p721
[4] Gayda J, Gabb T P, Kantzos P T 2004 Superalloys Champion, USA, September 19-23, 2004 p323
[5] Wang X H, Xiang J J, Hu H W, Xie W, Li X B 2015 Ultrasonics 60 27
[6] Li X B, Song Y F, Ni P J, Wang Z, Liu F, Du H L 2015 Nucl. Instrum. Meth. B 351 16
[7] nal R, Sarpn I H, Yalim H A, Erol A,Özdemir T, Tuncel S 2006 Mater. Charact. 56 241
[8] Laux D, Cros B, Despaux G, Baron D 2002 J. Nucl. Mater. 300 192
[9] Du H L, Turner J A 2014 Ultrasonics 54 882
[10] Li X B, Song Y F, Liu F, Hu H W, Ni P J 2015 NDT&E Int. 72 25
[11] Kersemans M, van Paepegem W, Lemmens B, van Den Abeele K, Pyl L, Zastavnik F, Sol H, Degrieck J 2014 Exp. Mech. 54 1059
[12] Margetan F J, Gray T A, Thompson R B 1991 Review of Progress in Quantitative Nondestructive Evaluation La Jolla, USA, July 15-20, 1990 p1721
[13] Rose J H 1992 Review of Progress in Quantitative Nondestructive Evaluation Brunswick, Maine, July 28-August 2, 1991 p1677
[14] Han Y K, Thompson R B 1997 Metall. Mater. Trans. A. 28 91
[15] Ghoshal G, Turner J A 2010 J. Acoust. Soc. Am. 128 3449
[16] Song Y F, Li X B, Wu H P, Si J Y, Han X Q 2016 Acta Metall. Sin. 52 378(in Chinese)[宋永锋, 李雄兵, 吴海平, 司家勇, 韩晓芹2016金属学报52 378]
[17] Margetan F J 2012 Review of Progress in Quantitative Nondestructive Evaluation Burlington, USA, July 17-22, 2011 p54
[18] Ghoshal G, Turner J A, Weaver R L 2007 J. Acoust. Soc. Am. 122 2009
[19] Kube C M, Du H L, Ghoshal G, Turner J A 2012 J. Acoust. Soc. Am. 132 EL43
[20] Du H L, Lonsdale C, Oliver J, Wilson B M, Turner J A 2013 J. Nondestruct. Eval. 32 331
[21] Hu P, Kube C M, Koester L W, Turner J A 2013 J. Acoust. Soc. Am. 134 982
[22] Xiao Q, Wang J, Guo X S, Zhang D 2013 Acta Phys. Sin. 62 094301(in Chinese)[肖齐, 王珺, 郭霞生, 章东2013物理学报62 094301]
[23] Shi F, Lowe M J S, Xi X, Craster R V 2016 J. Mech. Phys. Solids 92 260
[24] Guo Y 2003 Ph. D. Dissertation (Iowa:Iowa State University)
[25] Margetan F J, Haldipur P, Yu L, Thompson R B 2005 Review of Progress in Quantitative Nondestructive Evaluation Golden, USA, July 25-30, 2004 p75
[26] Cohen L 1995 Time-Frequency Analysis (Englewood Cliffs:Prentice-Hall) pp113-135
[27] Boashash B 1988 IEEE Trans. Acoust. Speech. Signal. Process. 36 1518
[28] Weaver R L 1990 J. Mech. Phys. Solids. 38 55
[29] Schmerr L W, Song S J 2007 Ultrasonic Nondestructive Evaluation System (New York:Springer) pp179-234
[30] Thompson R B, Lopes E F 1984 J. Nondestruct. Eval. 4 107
[31] Reed F A, Batzinger T J, Reed R W, Jönsson S 1993 Review of Progress in Quantitative Nondestructive Evaluation La Jolla, USA, July 19-24, 1992 p1265
[32] Nagy P B, Adler L 1987 J. Acoust. Soc. Am. 82 193
[33] Schmerr L W 2000 Mater. Eval. 58 882
[34] Kim A D, Ishimaru A 2000 BiOS 2000 The International Symposium on Biomedical Optics San Jose, USA, January 22-27, 2000 p423
[35] Ryzhik L, Papanicolaou G, Keller J B 1996 Wave Motion 24 327
[36] Carrier G F, Krook M, Pearson C E 1966 Functions of a Complex Variable:Theory and technique (New York:McGraw-Hill Inc.) pp301-375
[37] Rogers P H, van Buren A L 1974 J. Acoust. Soc. Am. 55 724
[38] Vitos L, Korzhavyi P A, Johansson B 2003 Nat. Mater. 2 25
[39] Lerch T P, Schmerr L W, Sedov A 1996 Res. Nondestruct. Eval. 8 1
[40] Duan X M, Zhao X Y, Sun H F 2014 Acta Phys. Sin. 63 014301(in Chinese)[段晓敏, 赵新玉, 孙华飞2014物理学报63 014301]
[41] Hu P, Turner J A 2015 J. Acoust. Soc. Am. 137 321
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[1] Bouda A B, Lebaili S, Benchaala A 2003 NDT&E Int. 36 1
[2] Liu Y G, Zhang S B, Han Z H, Zhao Y J 2016 Acta Phys. Sin. 65 104401(in Chinese)[刘英光, 张士兵, 韩中合, 赵豫晋2016物理学报65 104401]
[3] Panetta P D, Bland L G, Tracy M, Hassan W 2015 TMS 2014 Supplemental Proceedings San Diego, USA, February 16-20, 2014 p721
[4] Gayda J, Gabb T P, Kantzos P T 2004 Superalloys Champion, USA, September 19-23, 2004 p323
[5] Wang X H, Xiang J J, Hu H W, Xie W, Li X B 2015 Ultrasonics 60 27
[6] Li X B, Song Y F, Ni P J, Wang Z, Liu F, Du H L 2015 Nucl. Instrum. Meth. B 351 16
[7] nal R, Sarpn I H, Yalim H A, Erol A,Özdemir T, Tuncel S 2006 Mater. Charact. 56 241
[8] Laux D, Cros B, Despaux G, Baron D 2002 J. Nucl. Mater. 300 192
[9] Du H L, Turner J A 2014 Ultrasonics 54 882
[10] Li X B, Song Y F, Liu F, Hu H W, Ni P J 2015 NDT&E Int. 72 25
[11] Kersemans M, van Paepegem W, Lemmens B, van Den Abeele K, Pyl L, Zastavnik F, Sol H, Degrieck J 2014 Exp. Mech. 54 1059
[12] Margetan F J, Gray T A, Thompson R B 1991 Review of Progress in Quantitative Nondestructive Evaluation La Jolla, USA, July 15-20, 1990 p1721
[13] Rose J H 1992 Review of Progress in Quantitative Nondestructive Evaluation Brunswick, Maine, July 28-August 2, 1991 p1677
[14] Han Y K, Thompson R B 1997 Metall. Mater. Trans. A. 28 91
[15] Ghoshal G, Turner J A 2010 J. Acoust. Soc. Am. 128 3449
[16] Song Y F, Li X B, Wu H P, Si J Y, Han X Q 2016 Acta Metall. Sin. 52 378(in Chinese)[宋永锋, 李雄兵, 吴海平, 司家勇, 韩晓芹2016金属学报52 378]
[17] Margetan F J 2012 Review of Progress in Quantitative Nondestructive Evaluation Burlington, USA, July 17-22, 2011 p54
[18] Ghoshal G, Turner J A, Weaver R L 2007 J. Acoust. Soc. Am. 122 2009
[19] Kube C M, Du H L, Ghoshal G, Turner J A 2012 J. Acoust. Soc. Am. 132 EL43
[20] Du H L, Lonsdale C, Oliver J, Wilson B M, Turner J A 2013 J. Nondestruct. Eval. 32 331
[21] Hu P, Kube C M, Koester L W, Turner J A 2013 J. Acoust. Soc. Am. 134 982
[22] Xiao Q, Wang J, Guo X S, Zhang D 2013 Acta Phys. Sin. 62 094301(in Chinese)[肖齐, 王珺, 郭霞生, 章东2013物理学报62 094301]
[23] Shi F, Lowe M J S, Xi X, Craster R V 2016 J. Mech. Phys. Solids 92 260
[24] Guo Y 2003 Ph. D. Dissertation (Iowa:Iowa State University)
[25] Margetan F J, Haldipur P, Yu L, Thompson R B 2005 Review of Progress in Quantitative Nondestructive Evaluation Golden, USA, July 25-30, 2004 p75
[26] Cohen L 1995 Time-Frequency Analysis (Englewood Cliffs:Prentice-Hall) pp113-135
[27] Boashash B 1988 IEEE Trans. Acoust. Speech. Signal. Process. 36 1518
[28] Weaver R L 1990 J. Mech. Phys. Solids. 38 55
[29] Schmerr L W, Song S J 2007 Ultrasonic Nondestructive Evaluation System (New York:Springer) pp179-234
[30] Thompson R B, Lopes E F 1984 J. Nondestruct. Eval. 4 107
[31] Reed F A, Batzinger T J, Reed R W, Jönsson S 1993 Review of Progress in Quantitative Nondestructive Evaluation La Jolla, USA, July 19-24, 1992 p1265
[32] Nagy P B, Adler L 1987 J. Acoust. Soc. Am. 82 193
[33] Schmerr L W 2000 Mater. Eval. 58 882
[34] Kim A D, Ishimaru A 2000 BiOS 2000 The International Symposium on Biomedical Optics San Jose, USA, January 22-27, 2000 p423
[35] Ryzhik L, Papanicolaou G, Keller J B 1996 Wave Motion 24 327
[36] Carrier G F, Krook M, Pearson C E 1966 Functions of a Complex Variable:Theory and technique (New York:McGraw-Hill Inc.) pp301-375
[37] Rogers P H, van Buren A L 1974 J. Acoust. Soc. Am. 55 724
[38] Vitos L, Korzhavyi P A, Johansson B 2003 Nat. Mater. 2 25
[39] Lerch T P, Schmerr L W, Sedov A 1996 Res. Nondestruct. Eval. 8 1
[40] Duan X M, Zhao X Y, Sun H F 2014 Acta Phys. Sin. 63 014301(in Chinese)[段晓敏, 赵新玉, 孙华飞2014物理学报63 014301]
[41] Hu P, Turner J A 2015 J. Acoust. Soc. Am. 137 321
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