【摘要】：本文以III級熱軋鋼筋(HRB400)為實(shí)驗(yàn)對象,通過查閱文獻(xiàn)及實(shí)驗(yàn)分析,分析其不同溫度下不同保溫時(shí)間的組織演變情況及再結(jié)晶行為的研究,確定了熱軋螺紋鋼相變動(dòng)力學(xué)及再結(jié)晶動(dòng)力學(xué)方程,為建立組織預(yù)報(bào)系統(tǒng)提供了理論基礎(chǔ)。采用熱分析法與膨脹法相結(jié)合測定III級螺紋鋼的CCT曲線,通過實(shí)驗(yàn)分析,當(dāng)實(shí)驗(yàn)的冷速低于3℃/s時(shí),冷卻的最終產(chǎn)物為鐵素體與珠光體,當(dāng)冷速為3~8℃/s時(shí),冷卻產(chǎn)物中出現(xiàn)貝氏體組織,當(dāng)冷速為8~15℃/s時(shí),冷卻產(chǎn)物中開始出現(xiàn)馬氏體組織,隨著冷速的不斷增加,材料的硬度也在不斷提高。根據(jù)不同冷速下的相變點(diǎn),繪制熱軋鋼筋的CCT曲線,為等溫淬火實(shí)驗(yàn)方案提供基礎(chǔ)。為獲得熱軋鋼筋再結(jié)晶動(dòng)力學(xué)方程,本文通過Gleeble熱模擬機(jī)模擬單道次及雙道次壓縮實(shí)驗(yàn),以模擬動(dòng)態(tài)再結(jié)晶及靜態(tài)再結(jié)晶的過程。對于動(dòng)態(tài)再結(jié)晶,通過擬合曲線計(jì)算其激活能Q=283.3854KJ/mol,進(jìn)而得到動(dòng)態(tài)再結(jié)晶動(dòng)力學(xué)方程。通過二次微分計(jì)算不同溫度及變形速度下的臨界應(yīng)變,為靜態(tài)再結(jié)晶提供理論依據(jù)。對于靜態(tài)再結(jié)晶,在低于臨界應(yīng)變情況下計(jì)算不同道次間隔時(shí)間下的道次軟化率,計(jì)算t0.5表達(dá)式,最后確立靜態(tài)再結(jié)晶的動(dòng)力學(xué)方程。為確立熱軋鋼筋相變動(dòng)力學(xué)方程中的參數(shù),本文以螺紋鋼的CCT曲線為基礎(chǔ),在不同溫度下進(jìn)行等溫淬火實(shí)驗(yàn),計(jì)算不同保溫時(shí)間下的組織轉(zhuǎn)變情況。通過CCT曲線確定鐵素體(600~730℃)、珠光體(470~580℃)、貝氏體(350~450℃)轉(zhuǎn)變區(qū)間。保溫不同時(shí)間(1~15min),計(jì)算不同溫度下的相轉(zhuǎn)變體積分?jǐn)?shù),隨著保溫時(shí)間的增加,相變體積分?jǐn)?shù)也在不斷增加,通過線性擬合確定鐵素體、珠光體、貝氏體相變動(dòng)力學(xué)方程。
[Abstract]:In this paper, the microstructure evolution and recrystallization behavior of III grade hot rolled steel bar (HRB400) at different temperature and different holding time were analyzed by consulting literature and experimental analysis. The transformation kinetics and recrystallization kinetics equations of hot rolled rebar are determined, which provides a theoretical basis for the establishment of microstructure prediction system. The CCT curves of III grade rebar were measured by means of thermal analysis and expansion method. By experimental analysis, the final product of cooling was ferrite and pearlite when the cooling rate was less than 3 鈩，

本文編號：2254256