本文選題：低合金鑄鋼　切入點(diǎn)：脈沖電流　出處：《吉林大學(xué)》2017年碩士論文

【摘要】：低合金高強(qiáng)度鋼是現(xiàn)今社會使用量大且應(yīng)用范圍廣泛的重要金屬材料,但其傳統(tǒng)熱處理工序復(fù)雜,資源消耗量大,難以充分發(fā)揮材料的潛能。為了降低資源消耗,開發(fā)能夠提高資源利用率、縮短鋼鐵生產(chǎn)過程的新工藝勢在必行。電脈沖處理技術(shù)是在改善金屬材料的顯微組織和力學(xué)性能、提高能源利用率的背景下提出的一種新興技術(shù),已在材料加工的各領(lǐng)域內(nèi)有所應(yīng)用,并取得了顯著的效果。本論文將脈沖電流處理技術(shù)應(yīng)用于ZG25SiMn2Cr B鋼的固態(tài)相變和回火過程,通過檢測其顯微組織和力學(xué)性能的變化,系統(tǒng)地研究了脈沖電流處理對三種不同初始組織ZG25Si Mn2CrB鋼固態(tài)相變過程的影響規(guī)律及作用機(jī)制。對比不同初始狀態(tài)下的試樣,研究了電脈沖處理馬氏體逆相變機(jī)理,得到不同初始狀態(tài)下ZG25SiMn2CrB鋼的最佳脈沖電流處理工藝參數(shù)。(1)以退火態(tài)為初始狀態(tài)的試樣奧氏體化升溫過程為擴(kuò)散型轉(zhuǎn)變,隨脈沖電流處理時間的增加,室溫顯微組織由鐵素體/珠光體逐漸轉(zhuǎn)變?yōu)榘鍡l馬氏體組織,并于500 ms脈沖電流淬火處理后的組織達(dá)到最細(xì),力學(xué)性能最佳;以正火態(tài)為初始狀態(tài)的試樣奧氏體升溫轉(zhuǎn)變過程既有擴(kuò)散型轉(zhuǎn)變又有非擴(kuò)散型轉(zhuǎn)變,鋼的室溫組織逐漸由貝氏體/鐵素體和馬氏體的混相組織轉(zhuǎn)變?yōu)榘鍡l馬氏體和隱晶馬氏體組織,最佳淬火工藝參數(shù)為480 ms脈沖電流淬火處理;以淬火態(tài)為初始組織的試樣逆相變有位移型逆相變的特征,在380 ms脈沖電流處理后晶粒尺寸最細(xì),綜合力學(xué)性能最好。與退火態(tài)和正火態(tài)初始組織相比,淬火所得到的馬氏體初始組織更有利于脈沖電流處理工藝實(shí)現(xiàn)奧氏體晶粒超細(xì)化。(2)分別利用脈沖電流和傳統(tǒng)熱處理對電脈沖淬火態(tài)ZG25SiMn2CrB鋼進(jìn)行回火處理,研究ZG25Si Mn2CrB鋼回火后組織的演變過程和力學(xué)性能變化,研究發(fā)現(xiàn)瞬時脈沖電流回火處理可以避免回火脆性現(xiàn)象的產(chǎn)生。(3)在最佳參數(shù)脈沖電流淬、回火處理下ZG25SiMn2CrB鋼獲得比傳統(tǒng)箱式電阻爐熱處理更好的力學(xué)性能。高密度脈沖電流處理ZG25SiMn2Cr B鋼的相變是熱效應(yīng)和非熱效應(yīng)相耦合作用的結(jié)果,非熱效應(yīng)可以降低奧氏體的形核勢壘,瞬時升溫過程能夠提高形核率,抑制奧氏體晶粒的長大,最終使組織細(xì)化。
[Abstract]:High strength low alloy steel is an important metal materials in modern society and the use of a large quantity of a wide range of applications, but the traditional heat treatment process is complex, the consumption of resources, to give full play to the potential of material. In order to reduce the consumption of resources, development can improve the utilization rate of resources, it is imperative to shorten the process of steel production process. The electric pulse treatment technology is to improve the microstructure and mechanical properties of metal materials, a new technique is proposed to improve the energy utilization rate of the background, has been applied in the field of material processing, and achieved remarkable results. The solid phase and the tempering process the pulse current treatment technology application in ZG25SiMn2Cr B steel. By detecting the changes of the microstructure and mechanical properties of the system, to study the effect of electric current pulse on three different initial microstructure of ZG25Si Mn2CrB steel solid phase change process The law and mechanism. The sample comparison under different initial conditions, the electric pulse reverse martensitic transformation mechanism, obtained under different initial conditions of ZG25SiMn2CrB steel. The optimum pulse current treatment parameters (1) in the annealed samples for the initial state of austenite of the heating process for the diffusion transformation, with the increase of pulse current treatment the microstructure consists of ferrite / pearlite gradually transformed into lath martensite, and the microstructure after quenching pulse current to achieve the most fine at 500 ms, the optimum mechanical properties; normalizing state is the initial state, the sample temperature of austenite transformation process is diffusion transformation and change the diffusion type. The microstructure of steel gradually from bainite / ferrite and martensite mixed phase organization into lath martensite and martensite microstructure, the optimum process parameters for the 480 MS power flow quenching quenching pulse In the quenched samples for processing; the initial organization characteristic of inverse transformation of displacement inverse transformation, at 380 ms after electropulsing treatment the fine grain size, the best comprehensive mechanical properties. Compared with the annealed and normalized initial microstructure, quenching are martensite initial microstructure is more conducive to the current process of implementation of the austenite grain detailed pulse. (2) according to the pulse current and the traditional heat treatment on the electrical pulse quenched ZG25SiMn2CrB steel tempering, changes of evolution and mechanical properties of ZG25Si Mn2CrB steel after tempering organization, found that instantaneous pulse current can avoid the phenomenon of tempering temper brittleness. (3) the optimal parameters of pulse current quenching ZG25SiMn2CrB, tempering steel to obtain mechanical properties than the traditional box type resistance furnace heat treatment better. High density pulse current transformation processing ZG25SiMn2Cr B steel is thermal effect Due to the coupling effect with non thermal effect, the non thermal effect can reduce the nucleation barrier of austenite. The instantaneous heating process can improve the nucleation rate, inhibit the growth of austenite grain, and finally make the microstructure refined.

【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG142.1;TG161

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1 崔歆煒;脈沖電流處理對ZG25SiMn2CrB鋼組織及性能的影響[D];吉林大學(xué);2017年

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本文編號：1698248