The thermophysical properties of API 5L X80 steel were experimentally measured, in order to use these in computational models to determine the temperature field in welded joints. In this work, values of thermal expans...The thermophysical properties of API 5L X80 steel were experimentally measured, in order to use these in computational models to determine the temperature field in welded joints. In this work, values of thermal expansion coefficient, specific heat, thermal diffusivity and thermal conductivity were experimentally obtained as a function of temperature. The thermal expansion coefficient was determined at temperatures of 20°C to 1200°C in a dilatometer DIL 402 PC. The specific heat was determined on a differential scanning calorimeter at temperatures between 300°C and 1200°C. The diffusivity and thermal conductivity were determined in the temperature range 100°C to 800°C in a 457 LFA diffusivimeter using laser flash technique. The thermal expansion coefficient remained approximately with constant value of 8.5 × 10-6 K-1 and suffered two falls reaching values -25 × 10-6 K-1 and -50 × 10-6 K-1 in the stages of heating and cooling respectively. It was observed for this material, minimum and maximum values of specific heat equal to 0.571 J/gK and 1.084 J/gK at temperatures of 300°C and 720°C, respectively. The behavior of thermal diffusivity and thermal conductivity in the temperature range 100°C to 800°C tends to decrease with increasing temperature. Based on the measured properties, computational modeling of the temperature field can be numerically obtained with better accuracy.展开更多
采用废钢+70%~80%铁水-100 t UHP EAF-双工位120 t LF-VD-连铸-轧制工艺流程生产石油管用钢API5L BNS。通过电弧炉全程泡沫渣操作,EBT出钢合金化,连铸全程保护浇注,大压缩比、无扭微张力轧制,获得钢的良好的低倍组织、夹杂物、表面质量...采用废钢+70%~80%铁水-100 t UHP EAF-双工位120 t LF-VD-连铸-轧制工艺流程生产石油管用钢API5L BNS。通过电弧炉全程泡沫渣操作,EBT出钢合金化,连铸全程保护浇注,大压缩比、无扭微张力轧制,获得钢的良好的低倍组织、夹杂物、表面质量,满足极为严格的微量元素的控制目标,各项指标均满足用户协议要求。展开更多
High-grade(API 5L X80)and large-diameter(OD 1422 mm)line pipes are used in the Sino-Russian eastern route gas pipeline project for high pressure(12 MPa)transmission,and this can significantly increase the transmission...High-grade(API 5L X80)and large-diameter(OD 1422 mm)line pipes are used in the Sino-Russian eastern route gas pipeline project for high pressure(12 MPa)transmission,and this can significantly increase the transmission capacity and meet China's energy strategic demand.With the increase of steel grade,transmission pressure,pipe diameter and design coefficient,however,ductile crack of line pipes becomes the dominant crack mode,so it is necessary to focus on crack arrest and control study.In this paper,therefore,an intensive study was performed on the Battelle Two-Curve(BTC)method which is the major solution to the calculation of arrest toughness,as well as the crack resistance curve and decompression curve.Based on the study,the principle and application range of the BTC method were confirmed.In addition,a series of analysis were conducted on the issues which occurred when the BTC method was applied to high-strength,high-toughness line pipe steel,and the commonly used modified approaches to BTC calculation results were also provided.After the crack control scheme of the X80 large OD 1422 mm line pipes for the Russian Bovanenkovo-Ukhta was reviewed,the BTC calculation results were corrected on the basis of the design parameters of the Sino-Russian eastern routine gas pipeline project,the Charpy V-notched(CVN)impact energy which meets the project requirement was finally worked out to be 245 J.展开更多
Oil and gas line pipes are laid underground and run through different areas in the laying process,so they will be subjected to different degrees of corrosion and even crack,leading to enormous casualties and economic ...Oil and gas line pipes are laid underground and run through different areas in the laying process,so they will be subjected to different degrees of corrosion and even crack,leading to enormous casualties and economic losses.In order to guarantee the safe operation of line pipes,therefore,it is significant to investigate the electrochemical corrosion behaviors of pipe steel in a simulated soil environment.In this paper,the electrochemical corrosion behaviors of the base metals and welding materials of API 5L X90 steel longitudinally submerged arc welding pipes in near-neutral simulated soil solution(NS4)were studied by means of the electrochemical impedance spectroscopy(EIS)and the potentiodynamic polarization testing technology.It is shown that the typical characteristic of anodic dissolution is presented but with no passivation phenomenon when X90 linepipe steel is put in NS4 solution.The base material is thermodynamically more stable than the seam weld material.The base material and seam weld samples were polarized under -850 mV polarization potential for different durations.It is demonstrated that with the proceeding of polarization,the polarization resistance and the corrosion resistance increase while the corrosion current density decreases.And the corrosion resistance of base material is better than that of seam weld material.展开更多
文摘The thermophysical properties of API 5L X80 steel were experimentally measured, in order to use these in computational models to determine the temperature field in welded joints. In this work, values of thermal expansion coefficient, specific heat, thermal diffusivity and thermal conductivity were experimentally obtained as a function of temperature. The thermal expansion coefficient was determined at temperatures of 20°C to 1200°C in a dilatometer DIL 402 PC. The specific heat was determined on a differential scanning calorimeter at temperatures between 300°C and 1200°C. The diffusivity and thermal conductivity were determined in the temperature range 100°C to 800°C in a 457 LFA diffusivimeter using laser flash technique. The thermal expansion coefficient remained approximately with constant value of 8.5 × 10-6 K-1 and suffered two falls reaching values -25 × 10-6 K-1 and -50 × 10-6 K-1 in the stages of heating and cooling respectively. It was observed for this material, minimum and maximum values of specific heat equal to 0.571 J/gK and 1.084 J/gK at temperatures of 300°C and 720°C, respectively. The behavior of thermal diffusivity and thermal conductivity in the temperature range 100°C to 800°C tends to decrease with increasing temperature. Based on the measured properties, computational modeling of the temperature field can be numerically obtained with better accuracy.
文摘采用废钢+70%~80%铁水-100 t UHP EAF-双工位120 t LF-VD-连铸-轧制工艺流程生产石油管用钢API5L BNS。通过电弧炉全程泡沫渣操作,EBT出钢合金化,连铸全程保护浇注,大压缩比、无扭微张力轧制,获得钢的良好的低倍组织、夹杂物、表面质量,满足极为严格的微量元素的控制目标,各项指标均满足用户协议要求。
文摘High-grade(API 5L X80)and large-diameter(OD 1422 mm)line pipes are used in the Sino-Russian eastern route gas pipeline project for high pressure(12 MPa)transmission,and this can significantly increase the transmission capacity and meet China's energy strategic demand.With the increase of steel grade,transmission pressure,pipe diameter and design coefficient,however,ductile crack of line pipes becomes the dominant crack mode,so it is necessary to focus on crack arrest and control study.In this paper,therefore,an intensive study was performed on the Battelle Two-Curve(BTC)method which is the major solution to the calculation of arrest toughness,as well as the crack resistance curve and decompression curve.Based on the study,the principle and application range of the BTC method were confirmed.In addition,a series of analysis were conducted on the issues which occurred when the BTC method was applied to high-strength,high-toughness line pipe steel,and the commonly used modified approaches to BTC calculation results were also provided.After the crack control scheme of the X80 large OD 1422 mm line pipes for the Russian Bovanenkovo-Ukhta was reviewed,the BTC calculation results were corrected on the basis of the design parameters of the Sino-Russian eastern routine gas pipeline project,the Charpy V-notched(CVN)impact energy which meets the project requirement was finally worked out to be 245 J.
基金Project supported by the CNPC Application Fundamentals Research Project,“Basic Research on Safe Operation of In-Service High-Strength Pipelines”(Grant No.2014B-3313).
文摘Oil and gas line pipes are laid underground and run through different areas in the laying process,so they will be subjected to different degrees of corrosion and even crack,leading to enormous casualties and economic losses.In order to guarantee the safe operation of line pipes,therefore,it is significant to investigate the electrochemical corrosion behaviors of pipe steel in a simulated soil environment.In this paper,the electrochemical corrosion behaviors of the base metals and welding materials of API 5L X90 steel longitudinally submerged arc welding pipes in near-neutral simulated soil solution(NS4)were studied by means of the electrochemical impedance spectroscopy(EIS)and the potentiodynamic polarization testing technology.It is shown that the typical characteristic of anodic dissolution is presented but with no passivation phenomenon when X90 linepipe steel is put in NS4 solution.The base material is thermodynamically more stable than the seam weld material.The base material and seam weld samples were polarized under -850 mV polarization potential for different durations.It is demonstrated that with the proceeding of polarization,the polarization resistance and the corrosion resistance increase while the corrosion current density decreases.And the corrosion resistance of base material is better than that of seam weld material.
