本文選題：細(xì)晶高強(qiáng)IF鋼 + 奧氏體晶粒　； 參考：《遼寧科技大學(xué)》2015年碩士論文

【摘要】：近年來(lái),由于人們對(duì)環(huán)境污染和能源問(wèn)題越來(lái)越重視,要求汽車生產(chǎn)向輕量化方向發(fā)展,汽車用鋼的高強(qiáng)度化是實(shí)現(xiàn)汽車生產(chǎn)輕量化的有效途徑。無(wú)間隙原子鋼(IF鋼)兼具較高的強(qiáng)度與優(yōu)異的深沖性能,在現(xiàn)代汽車生產(chǎn)中得到了大量的應(yīng)用。隨著汽車產(chǎn)業(yè)的蓬勃發(fā)展,對(duì)IF鋼性能的要求也在不斷提高,因此對(duì)IF鋼做進(jìn)一步的研發(fā)顯得尤為重要。本文以細(xì)晶高強(qiáng)IF鋼為研究對(duì)象,在不同的加熱溫度和保溫時(shí)間條件下對(duì)實(shí)驗(yàn)鋼進(jìn)行回溶實(shí)驗(yàn),然后利用光學(xué)顯微鏡觀察實(shí)驗(yàn)鋼中顯微組織的變化規(guī)律,并采用透射電子顯微鏡對(duì)實(shí)驗(yàn)鋼中第二相粒子的固溶析出規(guī)律與無(wú)沉淀析出區(qū)的形成機(jī)制進(jìn)行研究,同時(shí)對(duì)實(shí)驗(yàn)鋼進(jìn)行力學(xué)性能檢測(cè)。主要研究結(jié)果如下:1.細(xì)晶高強(qiáng)IF鋼在加熱過(guò)程中,隨著加熱溫度的升高、保溫時(shí)間的延長(zhǎng),第二相粒子的數(shù)量逐漸減少且尺寸逐漸增大,同時(shí)奧氏體晶粒逐漸長(zhǎng)大。對(duì)OM實(shí)驗(yàn)數(shù)據(jù)進(jìn)行非線性回歸,擬合得到加熱過(guò)程中奧氏體晶粒長(zhǎng)大的數(shù)學(xué)模型為:2.由OM實(shí)驗(yàn)結(jié)果可知,細(xì)晶高強(qiáng)IF鋼的奧氏體晶粒粗化溫度為1050℃,奧氏體晶粒粗化時(shí)間為40 min。因此,實(shí)際生產(chǎn)中最好將加熱溫度控制在1050℃~1100℃、保溫時(shí)間控制在30 min~40 min。3.TEM實(shí)驗(yàn)結(jié)果顯示,實(shí)驗(yàn)鋼中未溶的第二相粒子在低溫時(shí)主要是呈圓形、橢圓形的富Nb析出相,在高溫時(shí)主要是呈方形、長(zhǎng)方形的富Ti析出相,當(dāng)加熱溫度達(dá)到1150℃時(shí),Nb元素基本完全固溶于鐵基體中。理論計(jì)算表明,含Nb第二相粒子的全固溶溫度為1130℃,理論計(jì)算結(jié)果與實(shí)驗(yàn)現(xiàn)象基本吻合。4.實(shí)驗(yàn)鋼中由于析出相粒子的固溶和粗大化與晶界遷移造成的掃動(dòng)效應(yīng),導(dǎo)致僅在晶界遷移方向的后方,形成獨(dú)特的無(wú)沉淀析出區(qū),且在退火過(guò)程中無(wú)沉淀析出區(qū)優(yōu)先在晶界經(jīng)過(guò)的區(qū)域形成。5.在退火過(guò)程中,隨著退火溫度的升高,細(xì)晶高強(qiáng)IF鋼的屈服強(qiáng)度逐漸降低,n值逐漸增加,無(wú)沉淀析出區(qū)的平均寬度逐漸增大。因此可以推測(cè),無(wú)沉淀析出區(qū)的平均寬度是影響細(xì)晶高強(qiáng)IF鋼屈服行為和加工硬化行為的原因之一。
[Abstract]:In recent years, because people pay more and more attention to the environmental pollution and energy problems, the automobile production is required to develop to the direction of light weight. The high strength of automobile steel is an effective way to realize the light weight of automobile production.Non-gap atomic steel (if steel) has both high strength and excellent deep drawing performance, and has been widely used in modern automobile production.With the rapid development of automobile industry, the requirements of if steel properties are also increasing, so it is very important to further develop if steel.In this paper, the high-strength if steel with fine grain was used as the research object. The experimental steel was redissolved at different heating temperature and holding time, and the microstructure of the steel was observed by optical microscope.The rule of solid solution precipitation of the second phase particles and the formation mechanism of the precipitation zone without precipitation were studied by transmission electron microscope, and the mechanical properties of the experimental steel were tested.The main results are as follows: 1.With the increase of heating temperature and the prolongation of holding time, the number and size of the second phase of fine grained high strength if steel decrease gradually and the austenite grain grows gradually.The mathematical model of austenite grain growth during heating is obtained by nonlinear regression of OM experimental data.The results of OM experiment show that the austenite grain coarsening temperature is 1050 鈩，

本文編號(hào)：1772519