摘 要
鋁合金淬火后，開發(fā)殘余應(yīng)力會導(dǎo)致后續(xù)機(jī)加工中失真。結(jié)果會是，機(jī)加工零件可能會失去忍受性和不得不冷加工或是重新加工。殘余應(yīng)力的測量實(shí)驗(yàn)是漫長的、乏味的、和非常昂貴的，例如中子X射線衍射技術(shù)的最新發(fā)展。所以，在這項(xiàng)研究中，Al7050鍛造塊淬火以后，使用數(shù)量方法區(qū)預(yù)測殘余應(yīng)力，而且比較預(yù)測結(jié)果和實(shí)驗(yàn)結(jié)果。結(jié)果表明了預(yù)測值與實(shí)驗(yàn)結(jié)果有很好的一致性，最壞的情況下，偏差也只有10-15%。兩種不同的冷加工（壓縮和拉伸）方法常常被用來減少殘余應(yīng)力。結(jié)果比較好顯示了，壓縮和拉伸工藝減少的殘余應(yīng)力有90%之多?？墒菃螕魤嚎s鋁合金方法減少殘余應(yīng)力比其別低水平的方法更加有效和經(jīng)濟(jì)。也研究了彈性模的影響效果。模具偏轉(zhuǎn)被發(fā)現(xiàn)對減少殘余應(yīng)力的量從90%降到70%左右。

Residualstressesdevelopedafterquenchingofaluminumalloyscausedistortionduringsubsequentmachining.Asaresult,machinedparts
maybeoutoftoleranceandhavetobecoldworkedorre-machined.Experimentalmeasurementofresidualstressesislengthy,tediousandvery
expensiveevenwiththelatestdevelopmentsinneutronX-raydiffractiontechniques,forinstance.Therefore,inthisstudy,numericaltechniques
areusedtopredictresidualstressesafterquenchingofAl7050forgedblock,andthepredictionswerecomparedwithexperimentalmeasurements.
Theresultsindicatedthatthepredictedvaluesareinverygoodagreementwiththeexperimentalmeasurementswitharound10¨C15%deviationin
theworstcase.Twodifferentmethodsofcoldworking(compressionandstretching)areusedtoreducetheresidualstresses.Thecomparisonof
resultsshowedthatbothcompressionandstretchingprocessesreducedtheresidualstressesmorethan90%.However,single-strikecompression
ofaluminumblocksisfoundtobemoreefcientandcost-effectiveforreducingtheresidualstressestoverylowlevels.Theeffectsofelasticdie
werealsoinvestigated.Diedeectionwasfoundtoaffecttheresidualstressreductioncapabilitynegativelybydecreasingthemagnitudeofstress
reductionfrom90%toabout70%.