發(fā)布時(shí)間：2018-02-05 01:20

  本文關(guān)鍵詞： Ti微合金鋼 Zr 奧氏體 固溶度 析出相 靜態(tài)再結(jié)晶　出處：《昆明理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著國(guó)家工業(yè)化水平的日益提高,對(duì)綜合性能優(yōu)異的鋼材需求越來越廣。Ti微合金鋼因其本身所具有的優(yōu)良性能以及相對(duì)低廉的價(jià)格,受到越來越多的關(guān)注。但是,由于Ti比較活潑,易與O、S等雜質(zhì)元素結(jié)合形成夾雜物,從而降低了Ti在鋼中作用的發(fā)揮;此外,TiC的析出具有較高的溫度敏感性,可能導(dǎo)致鋼板性能出現(xiàn)波動(dòng)。針對(duì)這些問題,研究者普遍采用Ti與Nb、V、Mo等復(fù)合微合金化的方式去改善。但同屬于微合金化元素,Zr對(duì)Ti微合金鋼影響方面的研究報(bào)道還很少。因此,本文針對(duì)Ti、Zr-Ti兩種微合金鋼,通過理論計(jì)算和熱處理、熱模擬的實(shí)驗(yàn)方法,利用金相顯微鏡(OM)、掃描電子顯微鏡(SEM)、透射電子顯微鏡(TEM)等,研究Zr對(duì)Ti微合金鋼奧氏體化及Ti的碳氮化物固溶的影響、Zr對(duì)形變奧氏體中析出與再結(jié)晶的影響規(guī)律。通過熱力學(xué)模型計(jì)算得到Zr-Ti鋼中相互作用系數(shù)為,εZrTI =-0.976 +166.15/T、εZrZr=-1.07 + 190.06/T、εCZR=-0.387-2.08/T、εNZr=18.9-184.41/T;說明Zr可以降低Ti、C在鐵基體中的活度,提高其在奧氏體中的固溶度;升高了 N在鐵基體中的活度,降低其在奧氏體中的固溶度。不同均熱溫度下Zr對(duì)Ti微合金鋼奧氏體化及Ti的碳氮化物固溶的影響實(shí)驗(yàn)結(jié)果表明,在1150℃時(shí),Ti鋼中的TiC可能仍處于溶解階段,1200～1250℃時(shí),兩種試驗(yàn)鋼中的TiC均完全溶解于奧氏體中,Zr·的加入促進(jìn)了試驗(yàn)鋼的奧氏體均勻化,同時(shí)也細(xì)化了奧氏體晶粒。Ti鋼中存在著Ti4C2S2,Zr-Ti鋼中存在著(Mn,Zr)S等硫化物;兩種試驗(yàn)鋼中均存在著大、小尺寸的氮化物;大尺寸氮化物導(dǎo)致試驗(yàn)鋼的塑性、韌性及成形性能惡化,要避免形成;小尺寸的氮化物則對(duì)細(xì)化奧氏體晶粒有重要作用。應(yīng)力松弛實(shí)驗(yàn)的結(jié)果表明,兩種試驗(yàn)鋼奧氏體中微合金碳氮化物的析出-時(shí)間-溫度(PTT)曲線均呈典型的“C”曲線;最快析出溫度均在925℃左右;低溫下Zr延遲了含Ti的碳化物析出。雙道次壓縮實(shí)驗(yàn)結(jié)果表明,兩種試驗(yàn)鋼的靜態(tài)再結(jié)晶動(dòng)力學(xué)模型分別為,Ti鋼:X =1-exp[-0.693(t/t0.5)0.715]、r-Ti鋼:Xs=1-exp(-0.693(t/t0.5)0.786];兩種試驗(yàn)鋼的靜態(tài)再結(jié)晶激活能分別為,Ti鋼:142.292KJ/mol,Zr-Ti鋼:115.052KJ/mol;形變奧氏體組織與軟化分?jǐn)?shù)—時(shí)間曲線保持較好的吻合性;Zr的加入可以提高Ti鋼的變形抗力,有效的抑制奧氏體變形。應(yīng)變誘導(dǎo)析出相的分析結(jié)果表明,Ti鋼中的應(yīng)變誘導(dǎo)析出相為TiC,Zr-Ti鋼中的應(yīng)變誘導(dǎo)析出相為(Zr,Ti)C;應(yīng)變誘導(dǎo)析出相以晶界形核為主,部分會(huì)在未溶相周圍形核長(zhǎng)大,應(yīng)變誘導(dǎo)析出相的存在阻礙再結(jié)晶的進(jìn)行;Zr加入到Ti鋼中得到尺寸較大的(Zr,Ti)C顆粒,相對(duì)于Ti鋼來說,靜態(tài)再結(jié)晶更易進(jìn)行。
[Abstract]:With the increasing industrialization of the country, the demand for the steel with excellent comprehensive properties is becoming wider and wider, because of its own excellent performance and relatively low price. More and more attention has been paid to it. However, because Ti is active, it is easy to form inclusions by combining with impurities such as OFS, thus reducing the role of Ti in steel. In addition, the precipitation of tic is highly temperature-sensitive, which may lead to the fluctuation of the properties of the steel plate. In view of these problems, Ti and NB V are widely used by researchers. The method of composite microalloying such as Mo has been improved. However, there are few reports on the effect of Zr on Ti microalloying steel. Therefore, this paper focuses on Ti. Two kinds of Zr-Ti microalloyed steels were studied by means of theoretical calculation, heat treatment, thermal simulation, metallographic microscope and scanning electron microscope (SEM). The effect of Zr on austenitization of Ti microalloyed steel and the solution of Ti carbonitride were studied by transmission electron microscope (TEM). The effect of Zr on precipitation and recrystallization in deformed austenite was studied. The coefficient of interaction in Zr-Ti steel was calculated by thermodynamic model. 蔚 ZrTI + -0.976 166.15 / T, 蔚 ZrZr=-1.07 190.06 / T, 蔚 CZR=-0.387-2.08/T. 蔚 NZr18.9-184.41 / T; The results show that Zr can decrease the activity of TiOC in iron matrix and increase its solution in austenite. The effect of Zr on the austenitization of Ti microalloyed steel and the solution of Ti carbides at different soaking temperatures were investigated. The results show that the effect of Zr on the austenitization of Ti microalloyed steel and the solid solution of Ti carbides. At 1150 鈩，

本文編號(hào)：1491705