【摘要】：ROF爐內(nèi)罩用鋼是高鉻-鎳奧氏體耐熱不銹鋼。ROF爐內(nèi)罩用鋼長(zhǎng)期工作在高溫及還原性氣氛中,要求在高溫下具有一定的強(qiáng)度及良好的抗氧化性。本文通過(guò)對(duì)服役20850h后的進(jìn)口 YUS701鋼鋼板與其供貨態(tài)鋼板進(jìn)行對(duì)比發(fā)現(xiàn),服役后鋼板中的奧氏體晶粒嚴(yán)重長(zhǎng)大,發(fā)生了晶界氧化,室溫強(qiáng)度降低;位錯(cuò)密度降低,晶界處析出大塊狀M23C6相;晶內(nèi)析出長(zhǎng)條狀的σ有害相,材料的高溫強(qiáng)度、塑性和韌性降低�，F(xiàn)役ROF爐內(nèi)罩用鋼主要存在高溫強(qiáng)度不足、密封處氧化嚴(yán)重及服役壽命不長(zhǎng)的問(wèn)題。為了改善和提高這些問(wèn)題,本文在進(jìn)口 YUS701鋼的成分基礎(chǔ)上添加合金元素進(jìn)行成分優(yōu)化,得到優(yōu)化成分。通過(guò)熱力學(xué)模擬計(jì)算、熱處理實(shí)驗(yàn)、氧化實(shí)驗(yàn),借助金相顯微鏡(OM)、掃描電子顯微鏡(SEM)及能譜分析(EDS)、透射電子顯微鏡(TEM)及X射線衍射(XRD)等顯微組織表征方法,研究了ROF內(nèi)罩用鋼的高溫抗氧化性及經(jīng)熱處理后的組織、性能,得出以下結(jié)論:1、加V、W的試驗(yàn)鋼中,奧氏體晶粒粗大;力學(xué)性能沒(méi)有明顯提高,甚至略有降低。試驗(yàn)鋼中加入Nb后,晶粒得以細(xì)化;且在室溫及高溫下的力學(xué)性能均較優(yōu);但因?yàn)棣蚁嗪蚙相在650℃時(shí)的析出量隨著Nb含量的增加而增長(zhǎng),故本文將Nb含量控制在0.2 wt%左右即可。C含量由0.09 wt%降低為0.05 wt%時(shí),有利于奧氏體晶粒細(xì)化及晶粒均勻化;同時(shí)減少了 M6C型碳化物及M2(C,N)相的析出。與此同時(shí),Ni含量為14.00 wt%左右有利于進(jìn)一步控制鋼中σ相、Z相及G相等有害相的析出。ROF爐內(nèi)罩用鋼優(yōu)化后的成分為:0.05 wt%C,14.00 wt%Ni,0.2 wt%Nb,0.30 wt%N,1.75 wt%Si,1.47 wt%Mn,0.67 wt%Mo。2、隨著固溶溫度的升高,試驗(yàn)鋼的晶粒尺寸逐漸增大,強(qiáng)度和硬度下降,而塑性和沖擊韌性則上升。在滿(mǎn)足所需晶粒尺寸要求(25～50μm)的條件下,試驗(yàn)鋼在1070℃時(shí)的綜合力學(xué)性能較好。試驗(yàn)鋼在1070℃保溫不同時(shí)間時(shí),奧氏體晶粒隨著保溫時(shí)間的延長(zhǎng)而逐漸均勻化。當(dāng)固溶保溫時(shí)間為60min時(shí),晶內(nèi)碳氮化物基本完全溶解,在晶內(nèi)僅有少量呈細(xì)小顆粒狀的富Cr碳化物析出,故經(jīng)過(guò)成分優(yōu)化后的ROF爐內(nèi)罩用鋼的熱處理工藝為:1070℃固溶60min,水冷。3、經(jīng)過(guò)成分優(yōu)化后的試驗(yàn)鋼在1100℃氧化100h后能夠形成較穩(wěn)定的氧化膜,氧化動(dòng)力學(xué)曲線在各個(gè)階段的瞬時(shí)氧化速率最低,具有與進(jìn)口料相當(dāng)?shù)母邷乜寡趸浴?、試驗(yàn)鋼經(jīng)過(guò)成分優(yōu)化及熱處理工藝優(yōu)化后,高溫強(qiáng)度與進(jìn)口料相當(dāng),同時(shí),其室溫抗拉強(qiáng)度和屈服強(qiáng)度分別為823MPa和460MPa;室溫韌性為448J;室溫及高溫延伸率分別為55%及114%,均優(yōu)于進(jìn)口料。
[Abstract]:ROF furnace cover steel is high chromium nickel austenitic heat resistant stainless steel. ROF furnace cover steel works in high temperature and reductive atmosphere for a long time and requires certain strength and good oxidation resistance at high temperature. In this paper, the austenitic grain of imported YUS701 steel plate after service 20850 h and its supplied steel plate are found to have grown seriously, resulting in grain boundary oxidation and decrease of room temperature strength. The dislocation density decreases and the bulk M23C6 phase is precipitated at the grain boundary, while the long stripe 蟽 harmful phase is precipitated in the crystal, and the high temperature strength, plasticity and toughness of the material decrease. The existing ROF furnace cover steel mainly has the problems of insufficient high temperature strength, serious oxidation in sealing area and short service life. In order to improve and improve these problems, the composition of imported YUS701 steel was optimized by adding alloying elements. Through thermodynamic simulation calculation, heat treatment experiment, oxidation experiment, (OM), scanning electron microscope (SEM) and energy spectrum analysis (EDS),). Transmission electron microscope (TEM) and X-ray diffraction (XRD) were used to characterize the microstructure of ROF inner cover steel. The oxidation resistance at high temperature and the microstructure and properties after heat treatment were studied. The following conclusions were obtained: 1. Coarse austenite grain; The mechanical properties were not obviously improved or even slightly decreased. After the addition of Nb into the test steel, the grain size can be refined, and the mechanical properties at room temperature and high temperature are better. But because the precipitation of 蟽 phase and Z phase increases with the increase of Nb content at 650 鈩，

本文編號(hào)：2377087