【摘要】：海洋油氣資源的開采是緩解能源緊張的重要手段,海洋油氣的鉆采及輸運(yùn)設(shè)備需要較高的強(qiáng)度以及耐腐蝕性能。雙金屬復(fù)合材料是滿足海洋油氣鉆采需求的優(yōu)選方案,而堆焊是制備雙金屬復(fù)合材料高效、可靠的方法之一,但目前針對堆焊層組織及性能影響因素的系統(tǒng)性研究較少。本文采用熱絲TIG方法,以AISI 8630為基材進(jìn)行Inconel 625合金的耐腐蝕層堆焊,研究了堆焊工藝參數(shù)、焊后熱處理工藝、基材表面粗糙度以及小孔徑基材對堆焊層的組織成分分布、力學(xué)性能及耐腐蝕性的影響規(guī)律,為雙金屬復(fù)合材料在海洋油氣鉆采及輸運(yùn)設(shè)備中的應(yīng)用提供理論及試驗支持,本文主要工作如下:堆焊工藝參數(shù)通過影響熔池溫度梯度G和冷卻速度R來改變堆焊層的組織及性能。當(dāng)預(yù)熱溫度由140℃升高至300℃時,熔池的溫度梯度G和冷卻速度R降低,堆焊層的熔深、熔寬、稀釋率、平面晶寬度和熱影響區(qū)晶粒尺寸稍有增加,硬度由232HV10減小至197HV10,耐腐蝕性能有所下降;堆焊電流通過影響堆焊稀釋率的值,從而改變堆焊層及基材的組織及性能,當(dāng)堆焊電流由230A增至290A時,稀釋率由0.314增加到0.371,耐腐蝕性能不斷下降,堆焊層組織尺寸變大,馬氏體含量減少,鐵素體含量增加,進(jìn)而硬度降低,當(dāng)電流為290A時基材熱影響區(qū)(HAZ)出現(xiàn)較大魏氏體組織,影響材料性能;堆焊電壓對熔寬影響較大,當(dāng)堆焊電壓由12.5V增至15.5V時,熔寬增加2.46mm,堆焊電壓的升高緩解了晶界“貧化”現(xiàn)象,使腐蝕速率由0.143降至0.114;堆焊速度由250mm/min增至350mm/min時,稀釋率由0.326降至0.271,耐腐蝕性能提高,組織的晶粒尺寸不斷減小,適當(dāng)提高堆焊速度有利于控制魏氏體體積,堆焊層硬度在270mm/min時達(dá)到最大值219HV10。焊后熱處理(PWHT)有利于堆焊層和基材組織及成分的均勻分布。Cr、Mo元素的存在使得基材具備較大的回火抗力;隨著PWHT溫度的升高,基材HAZ組織不斷長大,堆焊層硬度持續(xù)下降,熱影響區(qū)硬度呈現(xiàn)先下降后上升的趨勢,堆焊層耐腐蝕性不斷提升;當(dāng)PWHT溫度為850℃時,鐵素體尺寸過大,影響使用性能;當(dāng)PWHT溫度為650℃時,熱影響區(qū)沖擊及拉伸性能最好,-60℃沖擊功達(dá)42.7J,拉伸屈服強(qiáng)度達(dá)714MPa;綜合考慮,推薦熱處理溫度為650℃。基體表面粗糙度通過“陷光”效應(yīng)影響堆焊熱輸入,進(jìn)而影響堆焊組織及性能�；w粗糙度值減小,陷光效應(yīng)減弱,稀釋率相應(yīng)降低,但當(dāng)粗糙度值小于0.8μm時,減小趨勢不明顯;當(dāng)基體表面粗糙度由12.5μm減小至0.4μm時,堆焊層中鐵元素含量下降約10%,耐腐蝕性能提高32%,堆焊層組織更加細(xì)小均勻。采用正交試驗針對直徑為35mm的小孔內(nèi)壁堆焊進(jìn)行工藝優(yōu)化,最優(yōu)工藝參數(shù)為電弧電壓12.5V,堆焊電流180A,堆焊速度20cm/min,送絲速度160cm/min。結(jié)果表明,堆焊層中Fe、Ni、Cr、Mo、Nb各元素均勻分布,所對應(yīng)的質(zhì)量分?jǐn)?shù)分別為20%、54%、15%、6%、4%;小孔堆焊層硬度相較于非小孔下降約13HV10;工件耐腐蝕性能提升約7倍,提高了油氣鉆采及輸運(yùn)設(shè)備的使用壽命。
[Abstract]:The exploitation of marine oil and gas resources is an important means to relieve the energy shortage, and the drilling and production and transport equipment of marine oil and gas requires higher strength and corrosion resistance. Bimetal composite material is the preferred method to meet the demand of offshore oil and gas drilling, and the surfacing is one of the effective and reliable methods for preparing the double-metal composite material, but the systematic research on the influence factors on the structure and performance of the surfacing layer is less. In this paper, a hot-wire TIG (hot-wire TIG) method is used to build the corrosion-resistant layer of Inconel 625 alloy on the basis of AISI 8630, and the influence of the welding process parameters, the post-welding heat treatment process, the surface roughness of the base material and the distribution of the microstructure, the mechanical properties and the corrosion resistance of the surfacing layer are studied. In order to provide the theoretical and experimental support for the application of the bimetal composite in the offshore oil and gas drilling and transportation equipment, the main work of this paper is as follows: The parameters of the surfacing process change the structure and the property of the overlaying layer by influencing the temperature gradient G and the cooling rate R of the molten bath. when the preheating temperature is raised to 300 DEG C from 140 DEG C, the temperature gradient G and the cooling speed R of the molten pool are reduced, the welding depth, the melting width, the dilution ratio, the plane crystal width and the thermal influence area of the overlaying layer are slightly increased, the hardness is reduced from 232HV10 to 197HV10, and the corrosion resistance can be reduced; When the build-up current is increased from 230A to 290A, the dilution ratio is increased from 0.314 to 0.371, the corrosion resistance can be reduced, the microstructure of the overlaying layer is large, and the martensite content is reduced. The ferrite content is increased, and the hardness is decreased, and when the current is 290A, the heat-affected zone (HAZ) of the base material has a larger body structure, which influences the material property. The welding voltage has a large influence on the melting width, and when the overlaying voltage is increased from 125.5V to 155.5V, the melting width is increased by 2.46mm. The increase of the build-up voltage relieved the 鈥渄epletion鈥，

本文編號：2415324