本文選題：高頻電阻焊　切入點(diǎn)：正火　出處：《燕山大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：石油和天然氣采用管道輸送是最經(jīng)濟(jì)安全、環(huán)境友好的運(yùn)輸方式,為了滿足應(yīng)用過程對(duì)高頻電阻焊管性能的嚴(yán)格要求,對(duì)焊縫處采用正火處理來改善其性能。本文設(shè)計(jì)了正火工藝的預(yù)熱溫度、峰值溫度和保溫時(shí)間三個(gè)不同參數(shù),通過微觀組織觀察和性能分析,為確定最佳工藝提供實(shí)驗(yàn)依據(jù)。在Gleeble-3500熱模擬試驗(yàn)機(jī)上進(jìn)行熱處理工藝的模擬,預(yù)熱溫度對(duì)各試驗(yàn)鋼組織和性能的研究結(jié)果顯示:不同預(yù)熱溫度對(duì)組織和性能的影響均較小,在比較平緩的變化趨勢中,各試驗(yàn)鋼在730℃預(yù)熱時(shí)取得了韌性和強(qiáng)度的最佳配合。采用斷口掃描、金相分析和疲勞性能測試、沖擊試驗(yàn)等手段就峰值溫度對(duì)試驗(yàn)鋼的影響進(jìn)行了研究,結(jié)果表明:三種試驗(yàn)鋼隨著峰值溫度升高其組織與性能的變化趨勢不盡相同。在峰值溫度為950℃時(shí),X52鋼組織明顯細(xì)化,晶粒大小均勻,彌散分布;L415鋼大角度晶界百分?jǐn)?shù)較高,鐵素體晶粒等軸且大小均勻,珠光體含量較少。隨著溫度升高,這兩種鋼硬度與抗拉強(qiáng)度的變化趨勢相同且與各自韌性變化相反,峰值溫度為950℃時(shí)強(qiáng)度稍低,韌性較好,疲勞試驗(yàn)顯示X52鋼在950℃正火時(shí)疲勞壽命最長。X65鋼在925℃正火時(shí),鐵素體晶粒細(xì)小均勻,珠光體含量較少且沖擊功較高,斷口的韌性特征明顯,其強(qiáng)度的變化幅度較小。在生產(chǎn)實(shí)際中,根據(jù)鋼種設(shè)定正火溫度在925~950℃區(qū)間內(nèi)能夠有效改善組織,獲得最佳的性能配合。根據(jù)生產(chǎn)實(shí)際,設(shè)定了在峰值溫度進(jìn)行保溫的工藝,研究結(jié)果顯示:X52鋼經(jīng)保溫后晶粒粗化致韌性下降明顯;X65鋼的韌性以微弱幅度提升;L415鋼組織細(xì)化,強(qiáng)度上升,韌性提高。
[Abstract]:Pipeline transportation of oil and natural gas is the most economical, safe and environmentally friendly mode of transportation. In order to meet the strict requirements for the performance of high-frequency resistance welded pipe in the application process, In this paper, the preheating temperature, peak temperature and holding time of normalizing process are designed. In order to provide the experimental basis for determining the best technology, the heat treatment process was simulated on Gleeble-3500 thermal simulator. The results of the study on the microstructure and properties of each test steel showed that the influence of different preheating temperature on the microstructure and properties was small. In the gentle trend, the best combination of toughness and strength was obtained when the test steel was preheated at 730 鈩，

本文編號(hào)：1632994