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哈尔滨理工大学学士学位论文I焊缝超声波检测时ＤＡＣ曲线的制作与应用摘要在超声波检测时，为了避免漏检，超声检测人员通常用较高的灵敏度（二次波或三次波的灵敏度）作为扫查灵敏度。当在扫查过程中发现缺陷时，根据缺陷波距一次波、二次波（三次波）的水平位置远近选用水平差值最小的波次的灵敏度对缺陷进行定量。因此在超声波检测时应用DAC曲线，不仅可灵敏的监测出缺陷的位置所在，而且简单方便。本文分析了超声波检测在检测时对检测结果的分析，应用DAC曲线和DAC曲线的多种制作方法，并对比分析了各种DAC曲线的制作方法优缺点如：直线连接法；最小二乘拟合法；拉格朗日拟合曲线法等，并且还介绍了增益型波检测DAC曲线与衰减型检测DAC曲线。DAC曲线在实际工程中的应用很是广泛。其中本文以TC4大直径钛合金棒材超声波探伤为例证明DAC曲线可以对保证准确的灵敏度及建立曲线进行声程补偿，可有效解决材料探伤杂波较高的问题，保证大直径棒材的有效检测，以保证探伤结果的准确性、可靠性。关键词超声波检测；DAC曲线；缺陷定量；评定依据哈尔滨理工大学学士学位论文IIProductionandApplicationofDACCurveinUltrasonicTestingofWeldsAbstractInultrasonictesting,inordertoavoiddetection,ultrasonictestingpersonnelusuallywithhighsensitivity(sensitivityoftwotimeswaveorthreetimesthewave)asthescanningsensitivity.Whenthefinddefectsduringscanningprocess,accordingtothedistanceofdefectwavefromawave,thetwowave(thethreewave)levellocationselecttheleastleveldifferencebetweenwavesensitivityasthequantifydefects.TheapplicationofDACcurveinultrasonictesting,notonlycansensitivelydetectthelocationofdefects,butalsobesimpleandconvenient.Thispaperanalyzedtheultrasonictestinginthedetectionoftheanalysisonthetestresults,makingawidevarietyofapplicationsofDACcurveandDACcurve,andanalyzedtheadvantagesanddisadvantagesofvariousmethodsofDACcurveanalysissuchas:linearconnectionmethod;leastsquaresfitting;Lagrangefittingcurvemethod,andalsointroducesthegainwavedetectionofDACcurveandDACcurveofattenuationmeasurement.ApplicationofDACcurveinengineeringpracticeisveryextensive.WhichbasedontheTC4largediametertitaniumalloybars-ultrasonictestingasanexampletodemonstratethatDACcurvecanbeusedforacousticsensitivitytoensuretheaccuracyofcompensationandestablishmentofcurve,whichcaneffectivelysolvetheproblemofhighmaterialtestingnoise,ensuretheeffectivedetectionoflargediameterbars,inordertoguaranteetheaccuracy,reliabilityoftestingresults.KeywordsUltrasonictesting;DACcurve;Defectquantitative;Assessmentbasis哈尔滨理工大学学士学位论文III目录摘要......................................................................................................................IAbstract...............................................................................................................II第1章绪论...................................................................................................-1-1.1课题背景............................................................................................-1-1.2超声波检测时应用曲线....................................................................-2-1.2.1焊缝超声波检测时DAC曲线...............................................-2-1.2.2焊缝超声波检测时AVG曲线................................................-3-1.3我国超声波检测时曲线的现状及发展............................................-6-1.4本文主要研究内容............................................................................-6-第2章超声波检测DAC曲线的制作........................................................-7-2.1DAC曲线分类...................................................................................-7-2.1.1dB-S曲线（实测DAC曲线）...............................................-7-2.1.2DAC面板.................................................................................-8-2.2各种绘制方法在标准中的使用........................................................-8-2.2.1直接连线法..............................................................................-9-2.2.2最小二乘法曲线拟合..............................................................-9-2.2.3拉格朗日插值法....................................................................-10-2.2.4结论........................................................................................-12-2.3衰减型和增益型探伤DAC曲线绘制...........................................-12-2.3.1衰减型DAC曲线的绘制.....................................................-12-2.3.2增益型数字超声探伤仪DAC曲线的绘制.........................-16-2.4绘制DAC曲线注意事项...............................................................-17-2.5本章小结..........................................................................................-18-第3章DAC曲线在大直径钛合金棒材超声检测中的应用...................-19-3.1简介..................................................................................................-19-3.2探伤原理..........................................................................................-19-3.3探伤工艺的选择..............................................................................-20-3.3.1探伤仪....................................................................................-20-3.3.2探头........................................................................................-20-3.3.3对比试块................................................................................-20-3.3.4扫查........................................................................................-22-3.4试验过程..........................................................................................-22-3.4.1前期试验................................................................................-22-哈尔滨理工大学学士学位论文IV3.4.2不同探头对比试验................................................................-22-3.4.3DAC曲线试验.......................................................................-24-3.4.4实验结果..............................