發(fā)布時間：2019-03-24 11:19

【摘要】：本文在鋁熱反應(yīng)的基礎(chǔ)上通過添加過量的Fe_2O_3制備出單相微納結(jié)構(gòu)304奧氏體不銹鋼,并研究了軋制溫度對所制備單相微納結(jié)構(gòu)304不銹鋼組織和性能的影響;以及退火時間對軋制后的組織和性能的影響及作用機(jī)制。通過分析不銹鋼中的納米晶奧氏體、亞微米晶奧氏體晶粒尺寸、體積分?jǐn)?shù)的變化,以及鐵素體體積分?jǐn)?shù)的改變等,根據(jù)研究結(jié)果表明了微納結(jié)構(gòu)組織的演化機(jī)制以及對相應(yīng)的力學(xué)性能的影響。1.當(dāng)Fe_2O_3過量比例由2.5%逐漸增加到7.5%時,所制備出的微納結(jié)構(gòu)304不銹鋼XRD顯示主要相為奧氏體,其中包含有少量的鐵素體,且鐵素體含量在Fe_2O_3過量5%時達(dá)到了最小值,其中少量的鐵素體分布在胞狀奧氏體的晶界處。EDS顯示隨著Fe_2O_3過量比例的增加,合金中的Al元素含量先下降后又有所回升,同時也會引起Cr、Ni等其他合金元素含量的下降。2.Fe_2O_3過量5%的微納結(jié)構(gòu)304不銹鋼在高溫1000℃、低溫700℃下不同變形量軋制時,都未發(fā)生相變,組織中包含主要的奧氏體相和少量的鐵素體相。不同軋制情況時,鐵素體體積分?jǐn)?shù)無明顯變化,納米晶奧氏體在軋制過程中發(fā)生長大,引起其晶粒尺寸增大,體積分?jǐn)?shù)減小。亞微米晶在軋制過程中長大和破碎同時進(jìn)行,其晶粒尺寸與體積分?jǐn)?shù)與軋制溫度、變形量有關(guān)。軋制后相比鑄態(tài),材料力學(xué)性能大幅上升。在高溫軋制時可達(dá)到最大抗拉強(qiáng)度1410MPa。當(dāng)在700℃變形量為60%軋制時,受微納結(jié)構(gòu)晶粒尺寸影響,材料的屈服強(qiáng)度相比于高溫1000℃時有所提高,但是延伸率略微偏低。3.Fe_2O_3過量5%的微納結(jié)構(gòu)304不銹鋼在1000℃-40%-700℃-60%軋制后再在800℃經(jīng)不同時間退火處理,結(jié)果表明晶粒尺寸從軋制態(tài)到退火態(tài)迅速升高然后緩慢增加,晶粒尺寸長大行為更多依賴于溫度,隨退火時間延長,晶粒尺寸增長比較緩慢。退火過程中材料中沒有新相生成,退火后的試樣組織中包含奧氏體和少量鐵素體。退火后材料強(qiáng)度有所下降,但是塑性得以提升。其中,在800℃退火8h后材料良好的綜合性能,歸因于組織中形成的雙尺度結(jié)構(gòu)。
[Abstract]:In this paper, single-phase micronano-structure 304 austenitic stainless steel was prepared by adding excess Fe_2O_3 on the basis of aluminothermic reaction, and the effect of rolling temperature on the microstructure and properties of single-phase micro-nano-structure 304 stainless steel was studied. And the effect of annealing time on the microstructure and properties after rolling and its mechanism. The changes of grain size, volume fraction and ferrite volume fraction of nanocrystalline austenite and submicron austenite in stainless steel are analyzed. Based on the results of the study, it is shown that the evolution mechanism of micro / nano structure and its influence on the corresponding mechanical properties. 1. When the excess ratio of Fe_2O_3 increased from 2.5% to 7.5%, the micronano-structural stainless steel XRD showed that the main phase was austenite, which contained a small amount of ferrite. The ferrite content reaches the minimum when the Fe_2O_3 excess is 5%, and a small amount of ferrite is distributed at the grain boundary of cellular austenite. EDS shows that with the increase of Fe_2O_3 excess ratio, the content of ferrite increases with the increase of Fe_2O_3 excess ratio. The content of Al in the alloy decreased first and then increased, but also led to the decrease of the content of other alloying elements, such as Cr,Ni. The content of 2.Fe_2O_3 excess 5% in stainless steel with micro / nano structure was 1000 鈩，

本文編號：2446278