概述
按一般法規或規章要求,一旦檢測出一個可疑的內孔表麵(ID)相連的裂紋,則必須對它進行鑒定。初始過程通常包括使用與檢測階段相同的1.5、2.25或5MHz斜探頭。進一步評估信號幅度、上升和降落時間、回波動態響應和脈衝持續時間,希望籍此能幫助確定該可疑信號是否來自內部相連幾何體、沉頭孔、根部或者是否是一個實際的缺陷。
另ling一yi種zhong方fang法fa,即ji使shi用yong單dan晶jing片pian爬pa波bo探tan頭tou也ye可ke用yong於yu鑒jian定ding過guo程cheng,這zhe種zhong方fang法fa逐zhu漸jian盛sheng行xing,因yin為wei它ta簡jian易yi而er且qie能neng對dui該gai可ke疑yi缺que陷xian提ti供gong檢jian測ce以yi及ji初chu步bu的de定ding量liang信xin息xi。
單晶片爬波探頭詳述
用於內孔(ID)爬波技術的單晶片探頭設計成能在感興趣的材料中產生70度的折射縱波。用於產生70度縱波的入射角也會生成其他波型的波。這些不同模式的波互相作用從而產生一個獨特的回波波型――波型變化決定於引起回波的缺陷材料中的深度。每種成分的行為可分為以下三種類型:
直接縱波:這是70度折射縱波,在快速簡易的校準程序後,隻有在裂紋非常深的時候才出現。
橫波(30-70-70):伴隨著70度的縱波,同時會產生一個30度的橫波。30度橫波傳播到試塊底麵,有一部分聲波能量將折射為70度縱波信號。這種“波型轉換”的70度波將撞擊反射體表麵然後傳播回到探頭。該往返信號也被認為是“30-70-70”信號來表示三角聲程的每一段的角度。這個信號出現在中間壁厚的或是很深的缺陷處。
內表麵爬波:zhezhongboxingshizhishangshiyizhongyanzheshikuaineibiaomianchuanbodebiaomianzongbo。dangchuxianneibiaomianpaboshi,weikenengcunzaineibiaomianxianglianquexiantigongqiangyoulidezhengju,suoyineibiaomianpaboxinhaobeirenweishiyizhong“標記”。
使用爬波探頭校準
爬(pa)波(bo)技(ji)術(shu)之(zhi)所(suo)以(yi)相(xiang)對(dui)容(rong)易(yi)實(shi)施(shi),歸(gui)因(yin)於(yu)校(xiao)準(zhun)和(he)信(xin)號(hao)評(ping)定(ding)很(hen)大(da)程(cheng)度(du)上(shang)基(ji)於(yu)波(bo)型(xing)識(shi)別(bie)的(de)簡(jian)單(dan)概(gai)念(nian)這(zhe)一(yi)事(shi)實(shi)。一(yi)般(ban)而(er)言(yan),這(zhe)三(san)種(zhong)波(bo)型(xing)模(mo)式(shi)產(chan)生(sheng)的(de)信(xin)號(hao)是(shi)否(fou)出(chu)現(xian)A-掃描顯示取決於反射體的種類和幾何形狀。
涉及這三種波形中的兩種波形的定位回波的校準:內表麵爬波和30-70-70xinhao。jianyixiaozhunzaiyubeijiancecailiaotongyanghoududexiaozhunshikuaishangjinxing。weilejiejinbeijiancedeliewen,xuyaozaishikuaineiqiegechuyixiliedeqiecao。juyoudaibiaoxingdeqiecaoshenduwei20%~80%bihou。youyunengchanshengzhesanzhongboxingmoshizhishi,shikuaicemiankeyiyongyuxiaozhun。dangcankaoshikuaiheceshicailiaohouduyiyangshi,meiyizhongxinhaodedaodashijiandechazhishiyiyangde。shishixiaozhunshi,laizishikuaibianyuande30-70-70xinhaoyinggaidingweiyutanshangyipingmudedisigeerneibiaomianpaboxinhaodingweiyudiwuge。yidanjianliqizhezhongguanxi,jiukeyikaishishiyongpabotantoujinxingtanshanghexinhaoshibieguocheng。youyuzaipabozujianzhongbaohandejiaogaodenengliang,yijipabozaikaojinneibiaomianchuchuanbodeshishi,taduiyuneibiaomianlianjieliewenfeichangerbuzunxunbiaomianjihexingzhuang,duiyushiyonghengbotantounengtigongqiangliezhishidehanfenggenbuzheyangdefansheti,pabodelingmindubijiaodi。yinweizhegeyuanyin,jianceyuankeyiduiyuanxianpandingweiquexiandezhongxinpingding,yekeduihuaiyiweineibiaomianlianjiezhishitibuchongsaozhajiancecailiao。yinweimeiyizhongboxingmoshizhizaitedingdetiaojianxiapabotantouyeyunxuyonghuhuodechubudechicunxinxi
圖1的A掃描隻顯示ID爬波信號,這表明有淺裂紋存在。圖2中的A-掃描同時顯示內表麵爬波和30-70-70往返信號,這表明有中間層內缺陷存在。圖3中的A-掃描顯示了所有的三種信號。ID爬波、30-70-70往(wang)返(fan)信(xin)號(hao)和(he)直(zhi)接(jie)的(de)縱(zong)波(bo)信(xin)號(hao)都(dou)存(cun)在(zai)。這(zhe)表(biao)明(ming)有(you)深(shen)裂(lie)紋(wen)存(cun)在(zai)。由(you)於(yu)任(ren)何(he)超(chao)聲(sheng)技(ji)術(shu)都(dou)存(cun)在(zai)局(ju)限(xian)性(xing)。來(lai)自(zi)三(san)種(zhong)波(bo)形(xing)模(mo)式(shi)的(de)信(xin)號(hao)可(ke)能(neng)有(you)不(bu)同(tong)的(de)幅(fu)值(zhi)關(guan)係(xi),這(zhe)取(qu)決(jue)於(yu)探(tan)頭(tou)頻(pin)率(lv)、阻尼特性、jingpianchicunhebeijiancailiaodehoudu。gengyoushenzhe,beijianjinshudeleixingheshijineibiaomianxingzhuangyekenenggaibianrushejiaocongergaibianhuibofuzhiguanxi。youyuzhexieyuanyin,duizhezhongjishujianyishiyongheshidexiaozhunshikuai。
zhezhongqianfudekebianxingyeshizhezhongjishuzhisuoyizuoweidingxingfangfadeyuanyin。huibodeguanxiduiyuquexiandazhideshendugeichuleyigefeichanghaodezhishi,danshibixushiyongjinyibudingliangjishulaiyanzhengfanshetideshendu。
定量技術
定量技術使用定量流程圖
使用內表麵爬波技術得到的結果可用一個定量流程圖來概括
尖端衍射技術
這種方法用於定量範圍約為5-35%壁bi厚hou深shen度du的de淺qian裂lie紋wen。在zai這zhe種zhong方fang法fa中zhong,來lai自zi裂lie紋wen尖jian端duan的de信xin號hao的de抵di達da時shi間jian用yong於yu確que定ding裂lie紋wen深shen度du。為wei了le簡jian化hua這zhe個ge過guo程cheng,儀yi器qi校xiao準zhun成cheng每mei一yi個ge屏ping幕mu格ge子zi對dui應ying用yong一yi個ge特te定ding的de裂lie紋wen深shen度du。典dian型xing地di,選xuan定ding屏ping幕mu的de最zui初chu五wu格ge中zhong的de每mei一yi格ge代dai表biao材cai料liao厚hou度du的de20%。因此,穿過20%壁厚深處的裂紋會在第4個屏幕分格上產生信號,穿過40%壁厚深處的裂紋會在第3個(ge)屏(ping)幕(mu)分(fen)格(ge)上(shang)產(chan)生(sheng)信(xin)號(hao)等(deng)等(deng)。同(tong)樣(yang)要(yao)注(zhu)意(yi)在(zai)這(zhe)個(ge)技(ji)術(shu)中(zhong)要(yao)把(ba)尖(jian)端(duan)信(xin)號(hao)和(he)角(jiao)反(fan)射(she)分(fen)離(li)開(kai),從(cong)這(zhe)種(zhong)分(fen)離(li)中(zhong)獲(huo)得(de)的(de)信(xin)息(xi)使(shi)操(cao)作(zuo)者(zhe)對(dui)裂(lie)紋(wen)深(shen)度(du)做(zuo)出(chu)最(zui)終(zhong)的(de)精(jing)確(que)的(de)判(pan)定(ding)。圖(tu)4顯示了一個穿過20%壁厚缺陷的A-掃描波形。
為了對來自裂紋尖端的信號提供良好的分辨率,典型的是使用高阻尼、5MHz、45或60度的斜探頭。由於裂紋尖端的信號可能比較弱,探傷儀應該有RF顯示模式。當信噪比比較差時,用這種顯示模式可以更容易地看到裂紋尖端信號,如圖5所示。
雙波型技術
這種方法用於對穿透30-70%壁厚深度範圍的裂紋進行定量。典型地使用3MHz雙晶片串列式的探頭。該探頭由前麵的晶片發射50度折射縱波和相應的橫波,並由後麵接收來自晶片的波形。
zhezhongtantoudexiaozhunheshiyongshizhishangshijianduanyanshehepabojishudejiehe。shiyongjianduanyanshejishu,tanshangyishizheyangxiaozhunde,shidelaiziliewenjianduandexinhaoweiyupingmutedingdefengeshang。zaipingding/定量過程中同樣使用這種衍射技術,來記錄和使用不同波型波的分離。
高角度縱波技術
最後的定量技術用於穿過約60-95%bihoushendufanweideliewenjinxingdingliang。zhezhongfangfazaicishiyonglaiziliewenjianduanxinhaodidashijianzuoweiliewenshendudezhishi。laizikaojinbiaomiandeliewendexinhaoxiaozhunzaiqianjigefengechuergengshenyidiandezhishixinhaoxiaozhunzaigengduoshumudefengechu。yinggaizhuyi:這zhe些xie指zhi示shi信xin號hao顯xian示shi了le保bao持chi試shi樣yang中zhong的de大da量liang的de好hao的de材cai料liao的de數shu量liang,而er不bu是shi裂lie紋wen的de實shi際ji深shen度du。我wo們men建jian議yi這zhe種zhong技ji術shu使shi用yong雙shuang晶jing片pian高gao角jiao度du縱zong波bo探tan頭tou。對dui於yu檢jian測ce幾ji乎hu完wan全quan沿yan著zhe壁bi厚hou方fang向xiang傳chuan播bo的de裂lie紋wen,內nei表biao麵mian爬pa波bo探tan頭tou是shi很hen有you用yong的de。
結論
zhexiejishuzuizhongyaodefangmianjiushitamendejianyixing。yidanlijieleshengshudexingwei,jiancehedingliangneibiaomianlianjiequexiandeguochengjiuchengweixiaozhunheboxingshibiedeyizhongjishu。ciwai,yinweigaidingliangjishujiyuhuibodedidashijian,yinci,zaibenzhishangjiugengjingque。erchuantongjishuzeliyongxinhaodefuzhi,huiyinouhetiaojianerzaoshouxuduobianhua。caiyongduyueshijianjibenjishu,huijiangdihuoxiaochuzhexiebianhuadeyingxiang。
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