【摘要】：當(dāng)前能源需求旺盛,為了滿足國民經(jīng)濟(jì)對電力的迫切需要,同時(shí)要應(yīng)對來自環(huán)境保護(hù)方面的要求和挑戰(zhàn),勢必要大力推廣大容量和高參數(shù)的超(超)臨界發(fā)電技術(shù),而發(fā)電機(jī)組的關(guān)鍵部件之一要選用高性能鍋爐管用耐熱鋼材料。鐵素體耐熱不銹鋼具有成本低、熱膨脹系數(shù)小、熱傳導(dǎo)率高、綜合力學(xué)性能好等優(yōu)點(diǎn)。然而,隨著火力發(fā)電技術(shù)的不斷發(fā)展,現(xiàn)有的鐵素體耐熱不銹鋼已很難滿足未來超(超)臨界發(fā)電大容量和高參數(shù)的要求,人們都在嘗試?yán)酶鞣N途徑來研制新型鐵素體耐熱不銹鋼,進(jìn)而提高其使用性能。X10CrAlSi18鋼是一種新型高Cr鐵素體耐熱不銹鋼,具有較優(yōu)的綜合性能,已在國外投入生產(chǎn),國內(nèi)同種材料的應(yīng)用幾乎完全依賴于進(jìn)口,且國內(nèi)外對該鋼組織和性能的研究較少,因此非常有必要對該鋼進(jìn)行系統(tǒng)地研究,以便更安全的使用。本文以工業(yè)化生產(chǎn)X10CrAlSi18耐熱不銹鋼板為研究對象,采用數(shù)值模擬計(jì)算、掃描電子顯微鏡(SEM)、能譜分析(EDS)、X-射線衍射分析(XRD)、拉伸試驗(yàn)以及沖擊試驗(yàn)等手段,主要從熱處理制度對組織和力學(xué)性能的影響以及X10CrAlSi18耐熱鋼的抗高溫氧化行為兩個(gè)方面進(jìn)行深入研究。得到的主要研究結(jié)果如下:利用Thermo-Calc軟件完成了熱力學(xué)平衡相圖的計(jì)算,可以輔助分析在不同熱處理制度條件下,顯微組織的變化情況。計(jì)算結(jié)果表明:X10CrAlSi18耐熱鋼相變過程中,基體中會有AlN相、M7C3碳化物、M23C6碳化物及Sigma相產(chǎn)生。為調(diào)整組織,消除內(nèi)應(yīng)力,提高其加工性能,特對該鋼進(jìn)行退火和回火處理。分析得出:在800~950℃退火時(shí),顯微組織主要由鐵素體相、M23C6碳化物、Sigma相以及AlN相組成。在850℃退火時(shí),該鋼組織較為均勻,平均晶粒尺寸為48.91μm,具有最優(yōu)的綜合力學(xué)性能。由于鐵素體不銹鋼具有低溫脆性,掌握其韌脆轉(zhuǎn)變溫度可以為實(shí)際生產(chǎn)和加工提供參考,因此對該鋼進(jìn)行韌脆轉(zhuǎn)變溫度試驗(yàn)。結(jié)果表明:X10CrAlSi18耐熱不銹鋼韌脆轉(zhuǎn)變溫度約為87℃�？垢邷匮趸允窃u定耐熱鋼性能優(yōu)劣的一項(xiàng)重要指標(biāo),本文采用恒溫氧化法對該鋼進(jìn)行了高溫氧化試驗(yàn),試驗(yàn)溫度分別為800℃、900℃和1000℃,取樣時(shí)間間隔為20 h。結(jié)果表明:X10CrAlSi18耐熱不銹鋼氧化增重曲線符合典型的拋物線規(guī)律。在1000℃時(shí),氧化增重量明顯高于800℃和900℃時(shí)的氧化增重量。根據(jù)不銹鋼的抗氧化性能評定標(biāo)準(zhǔn),800℃與900℃條件下,X10CrAlSi18耐熱不銹鋼屬于完全抗氧化,而在1000℃時(shí),屬于抗氧化級別鋼。利用XRD、SEM以及EDS等檢測手段分析了氧化膜的形貌及物相組成。分析表明:在800~1000℃氧化時(shí),氧化膜均由MnCr2O4,SiO2,Al2O3和(Fe0.6Cr0.4)2O3氧化物構(gòu)成。但在800℃和900℃,氧化膜中以尖晶石結(jié)構(gòu)的MnCr2O4氧化物為主;而在1000℃氧化時(shí),氧化膜中以尖晶石結(jié)構(gòu)的(Fe0.6Cr0.4)2O3氧化物為主。這種由Cr/Mn氧化物到Fe/Cr氧化物的轉(zhuǎn)變,是導(dǎo)致抗氧化性下降的主要原因。
[Abstract]:The current energy demand is exuberant. In order to meet the urgent needs of the national economy for electricity and to meet the requirements and challenges from the environmental protection, it is inevitable to vigorously promote the supercritical generation technology with large capacity and high parameters. One of the key components of the generator set is heat resistant steel material for high performance boiler tubes. Ferritic heat resistant stainless steel has the advantages of low cost, low thermal expansion coefficient, high thermal conductivity and good comprehensive mechanical properties. However, with the continuous development of thermal power generation technology, the existing ferrite heat-resistant stainless steel can hardly meet the requirements of large capacity and high parameters for future supercritical power generation. People are trying to develop a new type of ferrite heat-resistant stainless steel by using various ways, thus improving its performance. X10CrAlSi18 steel is a new type of high-Cr ferrite heat-resistant stainless steel, which has excellent comprehensive properties and has been put into production abroad. The application of the same material in China is almost dependent on imports, and there are few researches on the structure and properties of the steel at home and abroad, so it is very necessary to study the steel systematically in order to use it more safely. In this paper, the industrial production of X10CrAlSi18 heat-resistant stainless steel plate was studied by means of numerical simulation, scanning electron microscope (SEM), energy dispersive analysis (EDS), X-ray diffraction (XRD), tensile test and impact test. The effect of heat treatment on microstructure and mechanical properties and the oxidation resistance of X10CrAlSi18 heat-resistant steel at high temperature were studied. The main results are as follows: Thermo-Calc software was used to calculate the thermodynamic equilibrium phase diagram, which can be used to analyze the change of microstructure under different heat treatment conditions. The results show that during the phase transformation of the steel, the AlN phase M7C3 carbides, M23C6 carbides and Sigma phases can be produced in the matrix during the phase transformation of Heat-resistant Steel X10CrAlSi18. In order to adjust the microstructure, eliminate the internal stress and improve the processing property, the steel was annealed and tempered. The results show that when annealed at 800 鈩，

本文編號：2125958