本文選題：機(jī)器人雙絲MAG焊 + 低合金高強(qiáng)鋼�。� 參考：《上海交通大學(xué)》2014年碩士論文

【摘要】：隨著海洋鉆井平臺逐步向深海發(fā)展，平臺用鋼的強(qiáng)度等級越來越高、厚度越來越大。而鉆井平臺樁腿的焊接作為平臺建造最為關(guān)鍵的步驟之一，對焊接效率和焊接質(zhì)量的要求也越來越高。針對我國海洋平臺建設(shè)起步晚、技術(shù)水平相對落后的狀況，本文重點研究了自升式鉆井平臺樁腿用大厚度Q690E低合金高強(qiáng)鋼機(jī)器人雙絲MAG焊接工藝。 本文首先采用ABAQUS有限元分析軟件，模擬計算了不同焊絲間距的Q690E雙絲焊溫度場和焊接接頭熱循環(huán)曲線，并與單絲焊溫度場進(jìn)行對比分析，探索低合金高強(qiáng)鋼機(jī)器人雙絲MAG焊接接頭熱循環(huán)曲線特點，為后續(xù)工藝試驗提供理論指導(dǎo)。然后通過平板單層單道堆焊試驗，以及對焊道截面的宏觀分析，探索不同焊接電源模式（脈沖模式和恒壓模式）以及焊接速度對機(jī)器人雙絲MAG焊縫成形的影響。最后結(jié)合以上試驗結(jié)果，對50mm厚的Q690E高強(qiáng)鋼進(jìn)行機(jī)器人雙絲MAG對接焊工藝試驗，通過對焊接接頭的力學(xué)性能測試、微觀組織觀察以及沖擊斷口的掃描電鏡照片分析，研究了焊接熱輸入、焊接規(guī)范（大電流高速焊和小電流低速焊）以及保護(hù)氣體對Q690E機(jī)器人雙絲MAG焊焊接接頭組織性能的影響。 最終研究結(jié)果表明： （1）當(dāng)雙絲間距大于20mm時，焊接熔池中部出現(xiàn)縮頸，焊縫中心熱循環(huán)曲線出現(xiàn)了兩個波峰；當(dāng)雙絲間距為25mm時，焊縫區(qū)T8/3增大到71.6s，冷卻速度降低； （2）在其他焊接條件相同時，兩種電源模式所得焊縫的熔深均為4.7mm，但脈沖電源模式下焊縫熔寬為16.0mm，余高為3.5mm，均大于恒壓模式下所得焊縫熔寬和余高；隨著焊接速度的增大，雙絲脈沖MAG焊縫熔深先增大后減小，在焊接速度為9.2mm/s時，焊縫熔深最大，為5.9mm； （3）對于低合金高強(qiáng)鋼Q690E的機(jī)器人雙絲MAG焊接工藝，當(dāng)焊接電源采用脈沖模式，焊接熱輸入控制在1.57KJ/mm左右，保護(hù)氣體為20%CO2+80%Ar的混合氣體時，，能夠獲得滿足標(biāo)準(zhǔn)規(guī)定、綜合力學(xué)性能優(yōu)良的焊接接頭，接頭強(qiáng)度大于770MPa，-40℃低溫沖擊功大于69J。
[Abstract]:With the development of offshore drilling platform into the deep sea, the strength and thickness of platform steel are higher and higher. As one of the most critical steps in platform construction, the welding of pile leg of drilling platform requires more and more high welding efficiency and welding quality. In view of the situation that the construction of offshore platforms in China started late and the level of technology was relatively backward, In this paper, the welding process of large thickness Q690E low alloy high strength steel robot dual wire MAG for pile leg of jack-up drilling platform is mainly studied. Firstly, Abaqus finite element analysis software is used in this paper. The temperature field of Q690E double wire welding and the thermal cycle curve of welding joint were simulated and calculated with different wire spacing, and compared with single wire welding temperature field, the characteristics of thermal cycle curve of low alloy high strength steel robot double wire MAG welding joint were explored. To provide theoretical guidance for subsequent process testing. Then, through the single-pass surfacing test and the macroscopic analysis of the welding pass section, the effects of different welding power modes (pulse mode and constant voltage mode) and welding speed on the weld formation of robot double-wire MAG are explored. Finally, combined with the above experimental results, the robot double-wire MAG butt welding process of Q690E high-strength steel with 50mm thickness was tested. The mechanical properties of the welded joints, the microstructure observation and the SEM photos of the impact fracture were analyzed. The effects of welding heat input, welding specifications (high current high speed welding and low current low speed welding) and shielding gas on the microstructure and properties of Q690E robot double wire MAG welding joint were studied. The necking appears in the middle of the weld pool, and two peaks appear in the heat cycle curve of the weld. When the distance between the two wires is 25mm, the T8 / 3 of the weld zone increases to 71.6 s, and the cooling rate decreases, and the cooling rate decreases when the other welding conditions are the same. The weld penetration depth of the two power modes is 4.7 mm, but the weld width is 16.0mm and the residual height is 3.5mm in the pulsed power mode, which is larger than the weld width and the residual height under the constant voltage mode, and with the increase of welding speed, the weld penetration depth of the weld is 4.7mm, but the weld width is 16.0mm and the residual height is 3.5mm. The weld penetration of double wire pulse MAG increases first and then decreases. When the welding speed is 9.2mm/s, the weld penetration is the largest, 5.9 mm; for the robot double wire MAG welding process of low alloy high strength steel Q690E, when the welding power source is pulse mode, When the welding heat input is controlled at about 1.57KJ / mm and the protective gas is 20CO2 80%Ar, the welded joints which meet the standard requirements and have excellent comprehensive mechanical properties can be obtained. The joint strength is greater than 770MPa- 40 鈩

本文編號：2000146