AISI 8630表面热丝TIG堆焊Inconel 625的组织及性能研究
发布时间：2019-01-26 08:54
【摘要】：海洋油气资源的开采是缓解能源紧张的重要手段,海洋油气的钻采及输运设备需要较高的强度以及耐腐蚀性能。双金属复合材料是满足海洋油气钻采需求的优选方案,而堆焊是制备双金属复合材料高效、可靠的方法之一,但目前针对堆焊层组织及性能影响因素的系统性研究较少。本文采用热丝TIG方法,以AISI 8630为基材进行Inconel 625合金的耐腐蚀层堆焊,研究了堆焊工艺参数、焊后热处理工艺、基材表面粗糙度以及小孔径基材对堆焊层的组织成分分布、力学性能及耐腐蚀性的影响规律,为双金属复合材料在海洋油气钻采及输运设备中的应用提供理论及试验支持,本文主要工作如下:堆焊工艺参数通过影响熔池温度梯度G和冷却速度R来改变堆焊层的组织及性能。当预热温度由140℃升高至300℃时,熔池的温度梯度G和冷却速度R降低,堆焊层的熔深、熔宽、稀释率、平面晶宽度和热影响区晶粒尺寸稍有增加,硬度由232HV10减小至197HV10,耐腐蚀性能有所下降;堆焊电流通过影响堆焊稀释率的值,从而改变堆焊层及基材的组织及性能,当堆焊电流由230A增至290A时,稀释率由0.314增加到0.371,耐腐蚀性能不断下降,堆焊层组织尺寸变大,马氏体含量减少,铁素体含量增加,进而硬度降低,当电流为290A时基材热影响区(HAZ)出现较大魏氏体组织,影响材料性能;堆焊电压对熔宽影响较大,当堆焊电压由12.5V增至15.5V时,熔宽增加2.46mm,堆焊电压的升高缓解了晶界“贫化”现象,使腐蚀速率由0.143降至0.114;堆焊速度由250mm/min增至350mm/min时,稀释率由0.326降至0.271,耐腐蚀性能提高,组织的晶粒尺寸不断减小,适当提高堆焊速度有利于控制魏氏体体积,堆焊层硬度在270mm/min时达到最大值219HV10。焊后热处理(PWHT)有利于堆焊层和基材组织及成分的均匀分布。Cr、Mo元素的存在使得基材具备较大的回火抗力;随着PWHT温度的升高,基材HAZ组织不断长大,堆焊层硬度持续下降,热影响区硬度呈现先下降后上升的趋势,堆焊层耐腐蚀性不断提升;当PWHT温度为850℃时,铁素体尺寸过大,影响使用性能;当PWHT温度为650℃时,热影响区冲击及拉伸性能最好,-60℃冲击功达42.7J,拉伸屈服强度达714MPa;综合考虑,推荐热处理温度为650℃。基体表面粗糙度通过“陷光”效应影响堆焊热输入,进而影响堆焊组织及性能。基体粗糙度值减小,陷光效应减弱,稀释率相应降低,但当粗糙度值小于0.8μm时,减小趋势不明显;当基体表面粗糙度由12.5μm减小至0.4μm时,堆焊层中铁元素含量下降约10%,耐腐蚀性能提高32%,堆焊层组织更加细小均匀。采用正交试验针对直径为35mm的小孔内壁堆焊进行工艺优化,最优工艺参数为电弧电压12.5V,堆焊电流180A,堆焊速度20cm/min,送丝速度160cm/min。结果表明,堆焊层中Fe、Ni、Cr、Mo、Nb各元素均匀分布,所对应的质量分数分别为20%、54%、15%、6%、4%;小孔堆焊层硬度相较于非小孔下降约13HV10;工件耐腐蚀性能提升约7倍,提高了油气钻采及输运设备的使用寿命。
[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，
本文编号：2415324
[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，
本文编号：2415324
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