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ID:32472594
大小:3.64 MB
页数:62页
时间:2019-02-06
《热轧双相钢疲劳及冲击行为的研究》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、辽宁科技大学工程硕士论文摘要摘要近年来,汽车工业发展迅速,对汽车用钢提出更高的要求。双相钢以其优越的性能引起了人们的重视,在汽车用钢板中具有广阔的应用前景。本文以热轧双相钢为研究对象,对其疲劳和冲击等行为进行了研究,主要内容如下:1.通过对实验钢种进行高周和低周疲劳实验可以发现:疲劳裂纹起源于试样的表面,裂纹源沿断口周边分布,为多源特征。材料本身的缺陷(内部微裂纹、夹杂物和第二相粒子等)也可成为裂纹源;在疲劳扩展区可以清晰的观察到塑性疲劳条带,伴随着疲劳条带的形成,产生与条带平行相间的二次裂纹,同时可以观察到疲劳辉纹、疲劳台阶等一些疲劳断裂的微观特征;2.通过对实验钢种的
2、低温冲击实验可以发现:夹杂物以及微裂纹存在破坏了钢基体的连续性,在外加载荷的作用下造成了该处的应力集中导致断裂,使得材料冲击性能下降。通过不同终轧温度、卷取温度下实验用钢的冲击实验得知:随着终轧温度降低和卷取温度的升高,晶粒细化,冲击性能增加。3.通过热轧双相钢疲劳寿命和冲击性能的实验可以得知,提高冶金质量、细化晶粒和优化工艺参数等手段可以改善材料的疲劳性能和冲击性能。关键词:热轧双相钢,高周疲劳极限,低周疲劳极限,冲击韧性Thestudyonthefatigueandimpactbehaviorforas-hotrolleddual-phasesteelAbstract
3、demandsforautomotiveplatesarebeingincreaseddramaticallywiththenationaleconomydevelopment.Recently,Peoplepaymoreandmoreattentionondual-phasesteelforitssuperiormechanicalproperties.fatigueandimpactbehaviorwerestudiedbasedontheC··Si·-Mnas·-hotrolleddual—phasesteel.Themaincontentsareasfollows
4、:1.Fromthetestofthehi曲一frequencyfatigueandlow-frequencyfatigue,itisfoundthatthefatiguecracksstartfromthesurfaceofthesample,andthesourceofthecrackisalongtheedgeoffracture.Thedefectsofsample(micro—fracture,impurities,thesecondphase)Canbethecauseofcrack.Theplasticfatiguebandcanbeobservedinth
5、efatigueextendregion,andthesecondcrackwhichisparalleltOthebandOCCurSwiththeformationoffatigueband.Themicro—features:suchasfatiguelinesandfatiguestepsearlalsobefound2.Fromtheimpactductllitytestatlowtemperature,itisfoundthattheimpuritiesandmicro-fracturesCandestroythecontinuityofsteelmatrix
6、,andthecapturecausedbystressconcen仃atlonwilldecreasetheimpactproperties.ThegrainCanberefinedandimpactpropertiesincreasedwiththedecreasingofthefinishingtemperatureandtheincreasingofthecoilingtemperaturebytheimpacttestunderthedifferentfinishingtemperatureandcoilingtemperature.3.Fromtheresul
7、tofthefatigueandimpactductilitytest,itisshowntheimprovedfatigueandimpactpropertiesCanbeobtmnedbytheincreasingthequalityofmetallurgy,refininggrainandimprovingtheparametersofhotrolling,etc.Keywords:as-hotdual—phasesteel,high-frequencyfatiguelimit,low—frequencyfatiguel
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