本文選題：CSP工藝　切入點：奧氏體晶粒　出處：《武漢科技大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：合金結(jié)構(gòu)鋼30CrMo因其具有良好的力學(xué)性能而在石油化工、機械制造、刀具模具等工業(yè)領(lǐng)域得到了廣泛的應(yīng)用。已有研究表明,與傳統(tǒng)熱連軋工藝相比,采用CSP工藝生產(chǎn)的30CrMo帶鋼在表面脫碳、成分偏析、組織性能穩(wěn)定性等方面具有明顯的優(yōu)勢。然而,對于30CrMo鋼而言,其最終的使用性能往往取決于熱處理工藝�；诖�,本文以CSP工藝生產(chǎn)的30CrMo熱軋帶鋼為研究對象,系統(tǒng)研究了其在不同熱處理工藝條件下組織和性能的變化規(guī)律,為其熱處理工藝的制定提供了理論依據(jù)。對CSP熱軋30CrMo帶鋼淬火工藝的研究表明:試驗鋼初始組織由細小均勻的珠光體和鐵素體組成。在再加熱過程中,初始組織奧氏體化,且隨著淬火溫度的升高以及保溫時間的延長,奧氏體晶粒不斷長大,其奧氏體長大動力學(xué)模型為D=392189.3exp(-1.02×105/RT)t0.031;經(jīng)水淬或油淬后均得到馬氏體組織,但不同工藝條件下馬氏體的類型、尺寸和力學(xué)性能不同。當(dāng)淬火溫度較低且保溫時間較短時,基體中的馬氏體組織主要由板條馬氏體和片狀馬氏體組成。隨著淬火溫度的升高以及保溫時間的延長,片狀馬氏體的含量逐漸減少,板條馬氏體的含量不斷增加,尺寸增大,強度和硬度值下降。不同加熱工藝下經(jīng)油淬后的屈服強度可表示為:σs=-4050.4+16272.2d-1/2;對CSP熱軋30CrMo帶鋼在淬火保溫階段脫碳行為的研究表明:脫碳層厚度隨淬火溫度的升高和保溫時間的延長逐漸增大,但是在1000-1200℃時脫碳層厚度先減小后增大,并建立了脫碳層厚度變化的數(shù)學(xué)模型;對CSP熱軋30CrMo帶鋼回火工藝的研究表明:隨著回火溫度升高和時間延長,馬氏體回復(fù)加劇,亞結(jié)構(gòu)粗化,450℃時界面開始有滲碳體析出,強度值和硬度值逐漸降低,斷后伸長率增大,在5h出現(xiàn)二次硬化現(xiàn)象;綜上所述,對于本文中所研究的CSP熱軋30CrMo帶鋼而言,其最佳的熱處理工藝為淬火溫度860-900℃、保溫15 min、油淬后在400-500℃的范圍內(nèi)回火5h。
[Abstract]:Alloy structural steel 30CrMo has been widely used in petrochemical, mechanical manufacturing, tool mould and other industries because of its good mechanical properties. The 30CrMo strip steel produced by CSP process has obvious advantages in surface decarburization, composition segregation, microstructure and mechanical stability, etc. However, for 30CrMo steel, the ultimate performance often depends on the heat treatment process. In this paper, the microstructure and properties of 30CrMo hot rolled strip produced by CSP process were studied systematically under different heat treatment conditions. The study on quenching process of CSP hot rolled 30CrMo strip shows that the initial microstructure of the test steel is composed of fine and uniform pearlite and ferrite, and the initial microstructure is austenitizing during reheating. With the increase of quenching temperature and the prolongation of holding time, the austenite grain grows continuously. The austenite growth kinetic model is DX 392189.3exp-1.02 脳 10 5 / RTT 0.031. The martensite structure is obtained by water quenching or oil quenching, but the martensite type is obtained under different technological conditions. When the quenching temperature is low and the holding time is short, the martensite structure in the matrix is mainly composed of lath martensite and lamellar martensite. With the increase of quenching temperature and the prolongation of holding time, the microstructure of martensite in matrix is mainly composed of lath martensite and sheet martensite. The content of lamellar martensite decreases gradually, the content of lath martensite increases and the size increases. The strength and hardness value decreased. The yield strength of oil quenched under different heating process can be expressed as: 蟽 -4050.4 16272.2d-1 / 2. The decarburization behavior of CSP hot-rolled 30CrMo strip during quenching and heat preservation is studied. The results show that the decarburization layer thickness increases with the increase of quenching temperature and preservation. The prolongation of temperature time gradually increased, However, at 1000-1200 鈩，

本文編號：1632463