本文選題：H型鋼 + Q345�。� 參考：《山東大學(xué)》2017年碩士論文

【摘要】：熱軋H型鋼是一種具有高效節(jié)約、良好的綜合力學(xué)性能、截面設(shè)計(jì)合理的金屬材料,在建筑領(lǐng)域用途較為廣泛。但其抗火性能較差,當(dāng)建筑物遭受火災(zāi)時(shí),不僅室內(nèi)存放物品會(huì)遭到破壞,而且建筑物本身尤其是建筑物的鋼結(jié)構(gòu)也會(huì)遭到不同程度的損壞。目前,針對(duì)高層建筑鋼結(jié)構(gòu)抗火性能研究多集中于鋼結(jié)構(gòu)的高溫力學(xué)性能變化情況,而對(duì)于火災(zāi)后鋼結(jié)構(gòu)存在的隱患研究甚少。本課題針對(duì)這一研究現(xiàn)狀,對(duì)建筑領(lǐng)域中常用的Q345B、精煉Q345B和Q345E三種熱軋H型鋼材進(jìn)行模擬火災(zāi)實(shí)驗(yàn),探究其遭受不同條件的火災(zāi)后微觀組織和力學(xué)性能的變化情況,找出建筑物遭受火災(zāi)后未發(fā)生坍塌鋼結(jié)構(gòu)存在的安全隱患,為高層建筑火災(zāi)后未坍塌鋼結(jié)構(gòu)危險(xiǎn)評(píng)估和新型耐火鋼材開發(fā)提供理論支持。本課題利用實(shí)驗(yàn)室方法模擬火災(zāi)現(xiàn)場(chǎng),設(shè)置過火溫度為650℃、700℃、750℃、800℃、850℃、900℃、950℃條件下保溫1小時(shí)和2小時(shí)共14組熱處理實(shí)驗(yàn),對(duì)Q345B、精煉Q345B和Q345E三種試驗(yàn)材料分別進(jìn)行不同方式的過火處理。通過金相實(shí)驗(yàn),觀察過火處理前后材料微觀組織的變化;通過硬度實(shí)驗(yàn)探究試驗(yàn)材料過火處理前后表面與心部硬度變化情況;通過室溫拉伸實(shí)驗(yàn)探究實(shí)驗(yàn)材料屈服強(qiáng)度和抗拉強(qiáng)度等力學(xué)性能變化情況。利用統(tǒng)計(jì)方法,分析試驗(yàn)材料在不同過火條件下微觀組織中晶粒度、帶狀組織和魏氏組織等級(jí)變化情況;借助MATLAB等工具分析試驗(yàn)材料在過火前后組織組成變化情況。根據(jù)試驗(yàn)材料遭受過火前后微觀組織和力學(xué)性能變化情況,分析試驗(yàn)材料在過火前后力學(xué)性能變化與材料微觀組織變化之間的關(guān)系。分析實(shí)驗(yàn)結(jié)果可知,三種鋼材均在過火溫度達(dá)到750℃及以上時(shí)出現(xiàn)較明顯的脫碳現(xiàn)象,并伴有微觀組織和力學(xué)性能突變,試驗(yàn)材料心部力學(xué)性能優(yōu)于材料外部,高強(qiáng)度的精煉Q345B火災(zāi)后力學(xué)性能降低最多,災(zāi)后潛在危害最大,Q345B次之,Q345E強(qiáng)度硬度降低相對(duì)最少。此外,三種材料抗火性能強(qiáng)弱不僅與其抗火結(jié)構(gòu)設(shè)計(jì)有關(guān),還與材料原始成分和控軋控冷方式等有關(guān),Q345E因含有Nb、Ti、V、B等微合金元素抗火性較好,精煉Q345B因熱軋過程中產(chǎn)生部分魏氏組織,材料抗火性最差,Q345B介于兩者之間。綜上所述,火災(zāi)后鋼結(jié)構(gòu)力學(xué)性能變化是由鋼結(jié)構(gòu)微觀組織和成分發(fā)生了變化,但火災(zāi)過程中引起微觀組織變化的因素多為鋼結(jié)構(gòu)與火源接觸面積、過火溫度和過火時(shí)長(zhǎng)等。
[Abstract]:Hot rolled H-section steel is a kind of metal material with high efficiency and saving, good comprehensive mechanical properties and reasonable section design, which is widely used in the field of construction. But its fire resistance is poor, when the building is under fire, not only the indoor storage items will be damaged, but also the building itself, especially the steel structure of the building, will also be damaged to varying degrees. At present, the research on the fire resistance of steel structures in high-rise buildings is mainly focused on the change of high temperature mechanical properties of steel structures, but there is little research on the hidden dangers of steel structures after fire. In view of the present situation of this research, the fire simulation experiments were carried out on three kinds of hot rolled H-section steel, Q345B, refined Q345B and Q345E, which were commonly used in the field of construction, and the changes of microstructure and mechanical properties after the fire were investigated. To find out the hidden danger of the steel structure without collapse after the fire, and to provide theoretical support for the risk assessment of the steel structure without collapse after the fire and the development of new refractory steel. In this paper, the fire site was simulated by laboratory method, and 14 groups of heat treatment experiments were carried out under the conditions of 650 鈩，

本文編號(hào)：1977656