本文選題：管線鋼　切入點：焊接熱循環(huán)　出處：《重慶科技學院》2017年碩士論文　論文類型：學位論文

【摘要】：石油與天然氣是國民經(jīng)濟發(fā)展的主要能源和重要戰(zhàn)略資源,采用管道輸送石油與天然氣目前是國內(nèi)外首選的技術(shù)方案。無論在制管成型、管道現(xiàn)場鋪設(shè)安裝,還是在管道維修過程中,管道用管線鋼均需依賴焊接來實現(xiàn)。然而,經(jīng)歷焊接這一快速的不均勻加熱和冷卻的復雜熱循環(huán)過程后,往往會發(fā)生管線鋼焊接接頭尤其是焊接熱影響區(qū)(HAZ)的性能與管材本身性能嚴重不匹配的現(xiàn)象,引發(fā)服役安全可靠性問題。因此,如何獲得顯微組織和力學性能優(yōu)異的管線鋼焊接接頭,長期以來是油氣輸送中備受關(guān)注的熱點與焦點問題。管線鋼SHCCT曲線是一種把焊接工藝條件與焊接后獲得的組織性能聯(lián)系起來的關(guān)系圖,能夠有效指導管線鋼焊接生產(chǎn)和施工。本論文以X80、X90和X100三種高級別管線鋼為研究對象,加工制備出精細的實心和空心管線鋼試樣,采用高精度DIL805A/D淬火膨脹儀,采集四川石油天然氣建設(shè)工程有限責任公司(簡稱四川油建公司)工程現(xiàn)場熔化極氣體保護焊(GMAW)焊接工藝參數(shù)作為依據(jù),制定三種不同焊接熱循環(huán)工藝(熱循環(huán)工藝一:以10℃/s加熱至950℃,保溫10min后以3~600s的不同t_(8/5)冷卻到室溫;熱循環(huán)工藝二:以150℃/s和200℃/s加熱至1100℃,保溫10s后以100℃/s冷卻到900℃保溫1min,再以1.5~600s的不同t_(8/5)冷卻到室溫;熱循環(huán)工藝三:以200℃/s加熱至900℃(1100℃或1350℃)保溫10s后以1.5~600s的不同t_(8/5)冷卻到室溫),通過光學顯微分析技術(shù)、電子顯微分析技術(shù)(SEM)以及顯微硬度測試等研究方法與實驗手段,獲得不同焊接熱循環(huán)下管線鋼的焊接顯微組織、力學性能和CCT曲線(SHCCT曲線),并進一步對三種管線鋼進行了對比分析,得到的主要研究結(jié)論如下:(1)在熱循環(huán)工藝一條件下,X80、X90、X100三種管線鋼顯微組織變化相似,均是多邊形鐵素體(PF)+珠光體(P)→多邊形鐵素體(PF)+準多邊形鐵素體(QF)→細小粒狀貝氏體(GB)+貝氏體鐵素體(BF),晶粒尺寸隨t_(8/5)增大而變小,顯微硬度隨t_(8/5)減小而增大。(2)在熱循環(huán)工藝二條件下,加熱速度不同,三種管線鋼出現(xiàn)貝氏體鐵素體(BF)的t_(8/5)也不同,加熱速度越大,X80管線鋼出現(xiàn)貝氏體鐵素體的t_(8/5)越大,X90與X100管線鋼的t_(8/5)越小,且三者顯微組織演變規(guī)律相似。(3)在熱循環(huán)工藝三條件下,當t_(8/5)=300~600s時,X80、X90、X100三種管線鋼模擬焊接臨界晶區(qū)與細晶區(qū)的室溫顯微組織組成不同;當t_(8/5)=1.5~120s時,X80、X90、X100管線鋼在模擬焊接臨界晶區(qū)、細晶區(qū)和粗晶區(qū)時的顯微組織演變規(guī)律相同,但顯微組織大小和顯微組織的臨界t_(8/5)不同,三種管線鋼的顯微硬度在該三種熱循環(huán)工藝中均隨t_(8/5)的減小而增加。此外,本論文獲得的三種熱循環(huán)工藝條件下的X80、X90、X100三種管線鋼的CCT曲線與SHCCT曲線,它們不僅為熱處理工藝和焊接工藝的制定提供參考依據(jù),同時也為X80、X90、X100管線鋼的實際應用提供有效的實驗數(shù)據(jù)。
[Abstract]:Oil and natural gas are the main energy and important strategic resources in the development of national economy. Pipeline transportation of oil and natural gas is currently the preferred technical scheme at home and abroad. Also in the process of pipeline maintenance, pipeline steel for pipeline depends on welding. However, after welding, which is a complicated thermal cycle of rapid uneven heating and cooling, The serious mismatch between the properties of welded joints of pipeline steel, especially the HAZ) and the properties of the pipe itself will often occur, which will lead to the problem of safety and reliability in service. How to obtain welded joints of pipeline steel with excellent microstructure and mechanical properties, The SHCCT curve of pipeline steel is a kind of relation diagram which relates welding process conditions with microstructure and properties obtained after welding. In this paper, three kinds of high grade pipeline steel X80, X90 and X100 are taken as the research object, the fine solid and hollow pipeline steel samples are prepared, and the high precision DIL805A/D quenching expander is used. The welding process parameters of GMAW in Sichuan Petroleum and Natural Gas Construction Engineering Co., Ltd (Sichuan Oil Construction Company) are collected as the basis. Develop three different welding thermal cycling processes (heat cycling process I: heating to 950 鈩，

本文編號：1591500