本文選題：60Si2Mn彈簧 + 應力松弛��； 參考：《天津大學》2012年碩士論文

【摘要】：應力松弛是彈簧在服役過程中的主要失效方式之一。它使機器的工作效率,儀器儀表的精度、靈敏度,穩(wěn)定性和可靠性受到極大影響。因此系統(tǒng)研究彈簧應力松弛問題,探討松弛機理,并對室溫使用的彈簧的服役壽命做出準確預測具有現(xiàn)實和理論意義。 本文研究了60Si2Mn淬火回火態(tài)彈簧和正火態(tài)彈簧在靜載荷下的應力松弛性能。分別考察了溫度、載荷和試驗時間對彈簧應力松弛行為的影響。利用動態(tài)彈簧應力松弛試驗機對不同溫度和不同載荷下彈簧應力松弛數(shù)據(jù)進行了采集,并基于溫度加速應力松弛理論對兩種組織彈簧的室溫服役壽命進行了預測。 借助顯微硬度儀、宏觀殘余應力儀、X射線衍射儀、金相顯微鏡、掃描電子顯微鏡和透射電子顯微鏡研究了不同溫度、不同載荷、不同試驗時間對淬火回火態(tài)和正火態(tài)兩種組織彈簧的顯微硬度、宏觀殘余應力、點陣畸變以及微觀組織的影響,并分析了彈簧應力松弛的微觀機理。 試驗結(jié)果表明,彈簧應力松弛曲線分為兩個階段,第一階段松弛速率快持續(xù)時間短;第二階段松弛速率慢,持續(xù)時間長。淬火回火態(tài)彈簧和正火態(tài)彈簧室溫服役10年的負荷損失率預測值分別為0.8%和2.97%,表明淬火回火組織具有較好的抗松弛性能。彈簧顯微硬度在低溫應力松弛過程中變化不大。宏觀殘余應力松弛是彈簧應力松弛的原因之一。引起點陣畸變的微應力在整個松弛過程中都不起決定性作用,而是組織內(nèi)的宏觀內(nèi)應力起作用。微觀結(jié)構(gòu)觀察和分析表明,淬火回火態(tài)彈簧松弛過程中由于位錯的運動會有條帶組織生成;正火態(tài)彈簧在松弛過程中片層結(jié)構(gòu)會有細化、寬化、扭轉(zhuǎn)、碎化等結(jié)構(gòu)變化。隨著松弛時間的延長條帶結(jié)構(gòu)和片層結(jié)構(gòu)都會消融,組織向均勻化發(fā)展。
[Abstract]:Stress relaxation is one of the main failure modes of spring in service. It greatly affects the efficiency of the machine, the precision, sensitivity, stability and reliability of the instrument. Therefore, it is of practical and theoretical significance to study the stress relaxation problem of spring, to discuss the relaxation mechanism, and to predict the service life of spring used at room temperature. In this paper, the stress relaxation properties of 60Si2Mn quenched tempered spring and normalizing spring under static load are studied. The effects of temperature, load and test time on the stress relaxation behavior of spring were investigated. The data of spring stress relaxation under different temperatures and loads were collected by using dynamic spring stress relaxation test machine, and the service life of two tissue springs at room temperature was predicted based on the theory of temperature accelerated stress relaxation. By means of microhardness instrument, macroscopical residual stress analyzer, X-ray diffractometer, metallographic microscope, scanning electron microscope and transmission electron microscope, different temperatures and loads have been studied. The effects of different test time on microhardness, macroscopic residual stress, lattice distortion and microstructure of quenching tempered and normalizing spring are discussed. The microcosmic mechanism of spring stress relaxation is analyzed. The experimental results show that the spring stress relaxation curve can be divided into two stages: the first stage is a short fast relaxation rate and the second stage is a slow relaxation rate with a long duration. The predicted load loss rates of quenched and tempered springs for 10 years at room temperature are 0.8% and 2.97, respectively, indicating that quenched and tempered structures have good relaxation resistance. The microhardness of spring does not change much during low temperature stress relaxation. Macroscopic residual stress relaxation is one of the reasons of spring stress relaxation. The microstress which causes lattice distortion does not play a decisive role in the whole relaxation process, but the macroscopic internal stress in the tissue plays an important role. The microstructure observation and analysis show that during the relaxation process of quenched and tempered spring there will be striped structure due to the movement of dislocation, and the lamellar structure of normalizing spring will change in the process of relaxation, such as thinning, broadening, torsion, fragmentation and so on. With the extension of relaxation time, both the strip structure and lamellar structure will melt, and the tissue will develop homogeneously.
【學位授予單位】：天津大學
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：TH135

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本文編號：1781757