【摘要】：本課題研究了生產(chǎn)熱水器內(nèi)膽所用的低C釉化用鋼,因熱水器內(nèi)膽在使用時(shí)需承受一定的溫度和壓力,故對(duì)釉化用鋼的屈服強(qiáng)度有一定的要求。在實(shí)際的釉化燒結(jié)過(guò)程中,釉化用鋼會(huì)經(jīng)歷晶粒粗化、相變和溶質(zhì)擴(kuò)散等過(guò)程,其力學(xué)性能也會(huì)相應(yīng)地發(fā)生變化,而熱軋工藝和合金成分在很大程度上決定了釉化用鋼軋制態(tài)和釉化燒結(jié)后的性能,因此研究熱軋工藝和合金成分對(duì)釉化用鋼組織性能的影響具有重要意義。本文采用實(shí)驗(yàn)、有限元模擬和熱力學(xué)計(jì)算相結(jié)合的方法,對(duì)不同成分和軋制工藝的釉化用鋼進(jìn)行了深入研究,分析討論了連軋和形變誘導(dǎo)鐵素體相變(DSIT)工藝、以及合金元素Si和Mn含量對(duì)釉化用鋼在釉化燒結(jié)前后的力學(xué)性能和顯微組織的影響,為進(jìn)一步改進(jìn)軋制工藝和合金成分提供指導(dǎo)。主要的研究結(jié)果如下:與傳統(tǒng)的連軋工藝相比較,由DSIT工藝軋制的鋼板因經(jīng)歷了反復(fù)的形變誘導(dǎo)鐵素體相變而獲得了較細(xì)小的晶粒。但當(dāng)后三道次開(kāi)軋溫度較高時(shí),由于應(yīng)變誘導(dǎo)鐵素體相變形核的不均勻性以及組織中出現(xiàn)的較多的塊狀相,使得鋼板的軋制態(tài)屈服強(qiáng)度與連軋鋼板無(wú)明顯差別,且屈服平臺(tái)變窄;當(dāng)控制后三道次開(kāi)軋溫度接近Ar3時(shí),DSIT工藝軋制的鋼板的組織均勻性得到改善,屈服強(qiáng)度有一定的提高。經(jīng)815℃～871℃不同溫度的熱處理后,連軋鋼板的屈服強(qiáng)度出現(xiàn)了明顯的下降,降幅在20～30MPa之間;而DSIT軋制的鋼板熱處理后屈服強(qiáng)度有不同程度的提高。熱處理過(guò)程中鋼板屈服強(qiáng)度的變化與顯微組織的演變相對(duì)應(yīng)。有限元模擬結(jié)果顯示:在軋制初期,鋼板表面溫度均低于心部溫度,隨著軋制過(guò)程的進(jìn)行,兩者趨于一致。在DSIT軋制過(guò)程中,鋼板所承受的軋制力更大,溫度波動(dòng)也更為明顯。對(duì)于不同Si、Mn含量的鋼板,Si含量較低的鋼板無(wú)明顯的屈服平臺(tái),且組織中存在較多尺寸較大的珠光體相,鐵素體晶粒增大;經(jīng)815℃～871℃熱處理后,鋼板的拉伸曲線出現(xiàn)了明顯的屈服平臺(tái),屈服強(qiáng)度增加,但受熱處理溫度影響較大,熱處理溫度較高時(shí)屈服強(qiáng)度發(fā)生下降,可能與高溫?zé)崽幚砗箐摪屣@微組織中的珠光體尺寸較大有關(guān)。根據(jù)熱力學(xué)計(jì)算結(jié)果,降低Si含量和增加Mn含量均會(huì)使鐵素體-奧氏體轉(zhuǎn)變溫度降低,保溫過(guò)程中鋼板中的奧氏體量增多,這可能是鋼板組織中珠光體形態(tài)受熱處理溫度影響較大的原因。此外,提高M(jìn)n含量后,組織中的Mn23C6析出相將會(huì)增多,相應(yīng)地將消耗更多的C原子,使得固溶在鐵素體基體中的C減少,間隙原子釘扎位錯(cuò)形成的"柯氏氣團(tuán)"數(shù)量也相應(yīng)減少,這可能是Mn含量較高的鋼板在熱處理后屈服強(qiáng)度較低的原因。
[Abstract]:In this paper, the low C glazed steel used in the production of inner tank of water heater is studied. Because the inner tank of water heater needs to bear a certain temperature and pressure when it is used, there are certain requirements for the yield strength of glazed steel. In the actual glazing sintering process, the glazed steel will go through the process of grain coarsening, phase transformation and solute diffusion, and its mechanical properties will also change accordingly. The hot rolling process and alloy composition determine the rolling state and properties of glazed steel to a great extent, so it is of great significance to study the effect of hot rolling process and alloy composition on the microstructure and properties of glazed steel. In this paper, the glazed steel with different composition and rolling process has been deeply studied by means of experiment, finite element simulation and thermodynamic calculation, and the (DSIT) process of continuous rolling and deformation induced Ferrite transformation has been analyzed and discussed. The effects of Si and Mn contents on the mechanical properties and microstructure of glazed steel before and after glazing sintering provide guidance for further improvement of rolling process and alloy composition. The main results are as follows: compared with the traditional continuous rolling process, the steel plate rolled by DSIT process has obtained finer grains due to repeated deformation-induced Ferrite phase transformation. However, when the temperature of the last three passes is high, the rolling yield strength of the steel plate is not significantly different from that of the continuous rolling steel plate due to the inhomogeneity of the deformed nucleus of the strain-induced ferrite phase and the appearance of more bulk phases in the microstructure. And the yield platform becomes narrower; When the three-pass rolling temperature is close to Ar3, the microstructure uniformity and yield strength of the steel plate rolled by DSIT process are improved to a certain extent. After heat treatment at different temperatures from 815 鈩，

本文編號(hào)：2474334