Investigation of Mechanical Property of Oil Tube Steel P110S in High Temperature and High Pressure Environment Containing H2S/CO2

With the exploitation of high sour and deep oil well in china,the corrosion medium containing CO 2,H 2 S,Cl-and organic acid threaten the safety of oil equipment and tube steel severely.In this article,many experiments,including corrosion tests,tensile tests,hydrogen concentration measurement tests and SEM examinations,were performed to investigate the effect of H 2 S partial pressure and loading stress on the mechanical property of oil tube steel P110S in high temperature and high pressure environment containing H 2 S/CO 2.The tensile strength and yield strength during fracture process of P110S steel were obtained experimentally and the fracture morphology was analyzed by SEM.The results indicate that both tensile strength and yield strength decreased after corrosion.The damage of tensile strength and yield strength became serious with an increase in H 2 S partial pressure and loading stress.According to the fracture analysis,the fracture mode exhibited quasi-cleavage and dimple mixed fracture,and the area of quasi-cleavage pattern increased with H 2 S partial pressure and loading stress increasing.According to the results of tensile test and hydrogen concentration measurement test,the tensile property degradation is closely associated with diffusible hydrogen concentration of P110S steel in the H 2 S/CO 2 environment.     

新型超高强度低氢脆敏感性扭杆弹簧用钢

 通过SEM、TEM、XRD、化学相分析等方法对比研究新型扭杆弹簧用40Si2Ni2CrMoV钢（代号N1）和现有45CrNiMoVA钢微观组织及其对力学性能的影响,并利用慢应变速率拉伸方法对比研究两种不同扭杆弹簧用钢的氢脆敏感性。结果发现,N1钢由于添加硅、钼等抗回火软化元素,使得N1钢在较高的300 ℃温度回火时还能保持一定的抗拉强度,N1钢有大量细小的ε-碳化物析出,使得屈服强度增加,屈强比在0.80以上,45CrNiMoVA钢经180 ℃低温回火后屈服强度在1 550 MPa左右,屈强比只有0.72;经相同条件充氢后,N1钢的慢拉伸强度下降幅度较小,其试样断口中也没有观察到沿晶断裂特征,N1钢的氢脆敏感性明显低于45CrNiMoVA钢。     

Hydrogen partitioning in pure cast aluminum as determined by dynamic evolution rate measurements

A statistical analysis of the porosity in 99.995 wt pct pure commercially available cast aluminum has been correlated with real time hydrogen evolution data obtained in an ultrahigh vacuum furnace in order to estimate the hydrogen partitioning in the aluminum. The dynamic technique employed permitted the detection and separation of hydrogen evolved from solid solution, hydrogen released by the rupture of large pores, and gases desorbed from the aluminum surface. Results of the statistical analysis indicate average pore diameters in pure cast aluminum extend from less than 1 to over 400 μm. Interdendritic pores having diameters greater than 25 μm constitute over 98 pct of the pore volume. The overall volume fraction of pores was determined to be 0.71 pct. Compared to vacuum remelted rolled aluminum, the porosity resulted in a reduction of ultimate tensile strength of 13 pct and a reduction in yield strength of 21 pet. The evolution of hydrogen from the aluminum was observed to occur by large hydrogen pressure pulses due to the rupture of pores near the surface and by a smooth steady desorption from solid solution. The rupturing pores were observed visually and found to occur both in the solid state and after melting. A substantial change in slope of the desorption curve following the pulse train suggests the pores are the primary sources of hydrogen in the bulk. Analysis of the pore and pulse size distributions indicates more than 99 pct of the bulk hydrogen is partitioned in pores greater than 25 μm. Pressures within the larger pores (≈270 μm) were determined to be about 2.4 atm at room temperature. Hydrogen content in the large pores was found to be as high as 2 × 10¹⁶ molecules. The total hydrogen content in the pores and in solid solution was determined to be 6.3 × 10¹⁷ atoms/cm³ (0.43 cm³/100 g). Measurements on commercially available 99.9995 wt pct cast aluminum indicate the total hydrogen content to be 4.8 × 10¹⁷ atoms/cm³ (0.33 cm³/100 g).     

基于RTS-500岩石流变仪三轴强度和变形特性

采用英国GDS公司生产的RTS-500型岩石三轴流变仪试验机,进行不同围岩条件下的三轴压缩实验,并对试验结果进行分析. 确定三轴围压下的峰值应力以及其应变的变化规律,以及根据Mohr-Coulomb强度理论确定岩石的c、φ值的变化规律,研究绿泥石英片岩的强度和变形特性.结果表明:在低围压时,岩样内部非均匀化,岩石表现为脆性特性;在高围压时,岩样内部由低到高逐渐屈服,内部趋于均匀化,此时岩石出现由脆性向塑形特性转变的趋势.岩石的峰值应变与围压呈显著的线性关系,岩石残余强度对围压的敏感性明显高于峰值强度. RTS-500型岩石三轴流变仪系统实验精度较高,实验数据可靠.      

Fabrication of lotus-type porous stainless steel by continuous zone melting technique and mechanical property

Lotus-type porous stainless steel (SUS304L) rods were fabricated by the continuous zone melting technique under a pressurized mixed gas of hydrogen and inert gas such as argon or helium. Pores with cylindrical shape, whose growth direction is parallel to the solidification direction, are observed in the rods. The dependence of the porosity and averaged pore diameter on the partial pressure of hydrogen or the total pressure and on the transference velocity of rods was investigated. It was found that the porosity increases with increasing partial pressure of hydrogen under a constant total pressure and the pore diameter decreases with increasing transference velocity. The maximum porosity was about 60 pct under the experimental conditions in the present work. The observation of the microstructure and the measurement of the tensile strength were also carried out.     

不同轧制及退火处理0.1C-5Mn中锰钢的氢脆敏感性

 尽管中锰钢的强塑性等力学性能得到了较大幅度提升，但要大规模地应用于汽车部件制造，仍需解决材料在制造和服役过程中面临的氢脆等系列难题，在此背景下，利用电化学充氢、氢热分析仪、慢应变速率拉伸试验机及扫描电镜等研究了两种不同状态(热轧和温轧)0.1C 5Mn中锰钢在650 ℃保温30 min(两相区退火处理)后的氢脆敏感性。结果表明，热轧和温轧退火样的微观组织分别为板条状及等轴+板条状的铁素体与奥氏体的复相组织。尽管温轧退火样的强度比热轧退火样提高了约150 MPa，伸长率降低了约5%，但两者的强塑积均可达到约33 GPa·%。两种试验材料充氢时吸附的氢绝大部分为对应低温逸出峰的可扩散性氢，温轧退火试验材料的氢脆敏感性低于热轧退火钢。充氢热轧退火样断口起裂处的断裂机制为穿晶断裂+沿原奥氏体晶界的脆性沿晶断裂；温轧退火样的起裂处则为空心韧窝+包括奥氏体(变形后转变为马氏体)晶粒的实心韧窝，后者实际上为沿着奥氏体和铁素体界面起裂的一种脆性沿晶断裂。造成两种试验材料氢脆敏感性不同的原因主要是其微观组织及其所引起的氢致断裂方式的差异。     

Effect of threshold stress intensity on fracture mode transitions for hydrogen-assisted cracking in AISI 4340 steel

Fracture mode transition in hydrogen-assisted cracking (HAC) of AISI 4340 steel has been studied from an equilibrium aspect at room temperature with 8.6-mm-thick double cantilever beam (DCB) specimens. The threshold stress intensity,K _th , necessary for the occurrence of HAC and the corresponding fracture surface morphology have been determined as a function of hydrogen pressure and yield strength. The K _th increases with decrease in hydrogen pressure at a given yield strength and also with decrease in yield strength at a given hydrogen pressure. AsK _th increases, the corresponding HAC fracture mode changes from the intergranular (IG) and quasi-cleavage (QC) modes to the microvoid coalescence (MVC) mode. The experimental results indicate that the critical hydrogen concentration for crack extension in the IG mode is higher than that for crack extension in the MVC mode. The fracture mode transition with varying hydrogen pressure and yield strength is discussed by simultaneously considering the micromechanisms for HAC and the hydrogen pressure and yield strength dependencies ofK _th .     

高强度建筑钢屈强比的研究

通过分析生产实际的数据和应用金相、扫描电子显微镜观察,对热轧态高层建筑钢板的屈强比的影响因素进行了分析,结果表明:随着钢板厚度的增加,屈服强度下降,抗拉强度有少许的上升,屈强比有明显的下降;随着C含量的增加,抗拉强度比屈服强度的上升快,钢板的屈强比减小,随着Mn、Si含量的增加,屈服强度、抗拉强度和屈强比增加;随着开轧温度、开冷温度的提高,屈服强度和屈强比均有明显的下降,而抗拉强度下降的幅度小;晶粒细化对屈服强度的提高比对抗拉强度的明显,并能显著的提高屈强比。     

Effect of Hydrogen on Tensile Properties of Ultrafine-Grained Type 310S Austenitic Stainless Steel Processed by High-Pressure Torsion

This study addresses a hydrogen effect on the tensile properties of a type 310S austenitic stainless steel with ultrafine-grained structures produced by high-pressure torsion (HPT) and subsequent annealing. The mean grain size was reduced to ~85 nm by the HPT processing. The grain size was increased by the post-HPT annealing, but the grain size of ~265 nm was retained after annealing at 1023 K (750 °C). The tensile strength of ~1.2 GPa, which is approximately twice as much as that of the solution-treated specimen, was attained in the 1023 K (750 °C) post-HPT-annealed specimen. The elongation to failure was restored up to ~15 pct by the post-HPT annealing, although it was still insufficient in comparison with the ~55 pct elongation of the solution-treated specimen. There was no change in the tensile strength of the HPT-processed specimens and the post-HPT-annealed specimens by hydrogen charging with the hydrogen content in the range of ~20 to 40 mass ppm. The HPT-processed and the 773 K (500 °C) post-HPT-annealed specimens exhibited a ductility loss through the fully shear type fracture. The hydrogen charge into higher temperature post-HPT-annealed specimens with σ-FeCr precipitates led to a mild hydrogen embrittlement.     

Crack propagation of high strength steels in a gaseous hydrogen atmosphere

The crack propagation behavior in delayed fracture was investigated at room temperature under pressure up to 784 kPa of hydrogen gas for high strength steels with the tensile strength of 1500 or 2000 MPa. For specimens with the tensile strength of 1500 MPa, the crack propagation rateda/dt increased with C content from 0.21 to 0.42 wt pct, and then it decreased with increasing C content up to 0.53 wt pct.da/dt increased rapidly with Mn content from 0.009 to 0.84 wt pct, and it increased gradually with Mn content from 0.84 to 2.13 wt pct. The permeation flow of hydrogen from the crack tip surface could be qualitatively estimated from the dependence ofda /dt upon the hydrogen pressure based on the simple assumption. In addition to the grain boundary embrittlement caused by tempering and/or hydrogen, the permeation flow of hydrogen was used to explain qualitatively the dependence ofda/dt upon C or Mn content.     

7055铝合金恒载荷应力腐蚀性能及机理研究

采用室温拉伸、光学显微镜和扫描电镜研究了不同恒载荷条件下7055铝合金型材的应力腐蚀性能。结果表明,在腐蚀周期内,随着应力腐蚀载荷的提高,试样的强度并未出现明显的下降,而塑性下降40%。应力腐蚀载荷越接近材料的屈服强度,塑性下降就越明显,抗拉应变和延伸率均有降低。应力腐蚀试样表层部分区域有明显的点蚀、沿晶腐蚀空洞和裂纹;拉伸时,腐蚀缺口处会产生明显的应力集中而成为起裂源,拉伸断口边缘被腐蚀区域为明显的沿晶断裂。     

Hydrogen embrittlement of pseudobinary l12-type Ni3(Alo.4Mno.6) intermetallic compound

The mechanical properties of the Ll₂-type intermetallic compound Ni₂(Al_0.4,Mn_0.6), which exhibited enough deformability accompanied with the positive temperature dependence of yield stress, were examined from the point of view of its susceptibility to hydrogen embrittlement. Remarkable and moderate increases of elongation and ultimate tensile strength were observed by evacuating and with increasing strain rate, respectively, although the yield stress was almost constant independent of not only testing environment but also strain rate. On the other hand, the cathodically precharged hydrogen showed deteriorated elongations while the baking treatment resulted in restoration of elongation. Fractographic observation revealed the expected correlation between elongation and fracture mode; with increasing elongation the transgranularly fractured region increased. From this result, it is suggested that hydrogen can be removed from the specimen interior by evacuating or baking, and also that hydrogen can be injected from the sample surface by hydrogen charging; that is to say, hydrogen permeation is almost reversible for both processes. It is thus concluded that the present alloy has severe hydrogen embrittlement susceptibility, both from the residual hydrogen in the specimens as well as from that penetrated from the environment. formerly Graduate Student with Tohoku University, Sendai, Japan,     

DD407单晶高温合金760℃拉伸性能的各向异性

研究了具有[001]、[011]和[111]取向以及[001]附近取向的DD407单晶高温合金经过热处理后,在760℃温度下的拉伸性能。结果表明,该合金具有明显的拉伸性能各向异性：[001]取向上表现出了最高的屈服强度和抗拉强度;当取向逐渐偏离[001]时,强度开始降低,但在相同的偏离角度内,偏向[111]取向的试样具...     

Gaseous hydrogen embrittlement of a hydrided zirconium alloy

ZIRCALOY-4 plate specimens were gaseously hydrided up to 340 ppm H and then tested in a hydrogen gas environment of various pressures up to 2020 kPa a at 25 °C, 100 °C, and 200 °C. Notched tensile specimens were chosen to better understand the “ductile-brittle transition” associated with hydrogen content and hydrogen pressure. The purpose of the present investigation is to understand the synergistic effect of hydrogen gas and internal hydrides on the mechanical properties of ZIR-CALOY-4. The results showed that for both uncharged and hydrided specimens, the notch tensile strength decreased with increasing hydrogen pressure as well as increasing temperature. Compared with uncharged specimens, the specimens with hydrides had lower values of notch tensile strength. A ductile-brittle transition was found on specimens tested at 25 °C and at hydrogen pressures between 0 and 1010 kPa. For the specimen containing 220 ppm H, the reduction of area (RA) at 25 °C and at hydrogen pressures of 1010 kPa and above was drastically reduced, resulting in almost completely brittle behavior. This hydrogen and hydride-induced cracking was found to be an autocatalytic process. From the fractographic finding, the ductile-brittle transition was closely related to the precipitation and distribution of brittle hydrides. The ductile-brittle transition disappeared as the temperature increased to 100 °C and above. This can be attributed to the improved ductility of the zirconium matrix with increasing temperature.     

Gaseous hydrogen embrittlement of a hydrided zirconium alloy

ZIRCALOY-4 plate specimens were gaseously hydrided up to 340 ppm H and then tested in a hydrogen gas environment of various pressures up to 2020 kPa at 25 °C, 100 °C, and 200 °C. Notched tensile specimens were chosen to better understand the “ductile-brittle transition” associated with hydrogen content and hydrogen pressure. The purpose of the present investigation is to understand the synergistic effect of hydrogen gas and internal hydrides on the mechanical properties of ZIRCALOY-4. The results showed that for both uncharged and hydrided specimens, the notch tensile strength decreased with increasing hydrogen pressure as well as increasing temperature. Compared with uncharged specimens, the specimens with hydrides had lower values of notch tensile strength. A ductile-brittle transition was found on specimens tested at 25 °C and at hydrogen pressures between 0 and 1010 kPa. For the specimen containing 220 ppm H, the reduction of area (RA) at 25 °C and at hydrogen pressures of 1010 kPa and above was drastically reduced, resulting in almost completely brittle behavior. This hydrogen and hydride-induced cracking was found to be an autocatalytic process. From the fractographic finding, the ductile-brittle transition was closely related to the precipitation and distribution of brittle hydrides. The ductile-brittle transition disappeared as the temperature increased to 100 °C and above. This can be attributed to the improved ductility of the zirconium matrix with increasing temperature.     

Microstructure and Tensile Behavior of a Nano-Structured Al-Fe Based Alloy

Room temperature deformation behavior of A1-8Fe-2Mo-2V-1Zr alloy produced by spray forming and subsequent warm-extrusion at 693 K and/or rolling at 423 K was investigated in terms of tensile test and microstructural observation.In the specimen processed by spray forming and warm extrusion, the microstructure consisting of equiaxed grains with the average grain size of 500 nm in the matrix phase and uniformly dispersed fine intermetallic A13(Fe, Mo, V, Zr) and A16(Fe, Mo, V, Zr) phases less than 100 nm was characterized. It was revealed that subsequent warm rolling after warm extrusion promotes precipitation of a fine dispersoid from the supersaturated matrix phase. Warm rolling was found to be effective to increase the yield and tensile strength in the high strain rate regime. Elongation of the warm rolled specimen showed highe r value than extruded specimen over the whole strain rate region studied.     

Effect of cooling rate on the as-quenched microstructure and mechanical properties of HSLA-100 steel plates

The effect of cooling rate on the as-quenched microstructure and mechanical properties of a 14-mm-thick HSLA-100 steel using various cooling media such as brine, water, oil, air, and furnace has been studied. While quenching in brine, water, and oil resulted in lath martensite structures, the granular bainite and martensite-austenite (M-A) constituents were found in air- or furnace-cooled specimens. The average lath spacing increased slightly on decreasing the cooling rate (300 nm in brine-quenched specimen to 400 nm in oil-quenched specimen). The precipitates of Cu and Nb(C, N) were observed in all the quenching conditions except in the brine-quenched specimen. The as-quenched strength and toughness of the brine-, water-, and oil-quenched specimens were higher (yield strength: 894 to 997 MPa, ultimate tensile strength: 1119 to 1153 MPa, and Charpy V-notch energies: 65 to 70 J at −85 °C) than those of air- and furnace-cooled specimens (yield strength: 640 to 670 MPa, ultimate tensile strength: 944 to 1001 MPa, and Charpy V-notch energies: 10 to 20 J at −85 °C). For industrial production of HSLA-100 steel plates, oil or water quenching is recommended in lower thickness plates (<25 mm). For production of thicker plates, however, water quenching is more suitable.     

Estimation of the notch sensitivity of a nitrided steel by acoustic emission

The notch sensitivity of sheet corrosion-resistant 08Kh17T steel is estimated in the states before and after high-temperature (1000–1100°C) internal nitriding during tensile tests accompanied by the measurement of acoustic emission signals. A crack in the steel is shown to propagate according to a ductile mechanism is all states. As the nitrogen content increases from 0.60 to 0.85%, the ultimate tensile strength of the steel decreases by 15% in the presence of a stress concentrator and remains substantially higher than the yield strength of the sheet steel without a stress concentrator.     

Properties of cold-rolled high-strength steel sheets

For high-strength steel sheets, a new concept has become necessary,viz, the relation between strength and formability. When the relation between tensile strength and elongation is appraised for ranking in terms of the strengthening mechanism, it is found that the substitutional solid-solution hardening type is excellent and the precipitation hardening type is inferior. In batch annealing, the phosphorus-added aluminum-killed steel sheets are representative of the former type having excellent formability as indicated by a highr values despite their tensile strength of 450 N/mm². The titanium-added aluminum-killed steel sheets, which are representative of the latter type, have a tensile strength of 600 N/mm² and a relatively highr value. Continuous annealing of the highstrength steel sheets of the same chemical composition causes higher yield stresses and combinations of yield stress and elongation. Alternatively with continuous annealing the same level of strength can be achieved with smaller additions of alloying elements than with batch annealing. An additional advantage of continuous annealing is the uniformity of properties along the length of the coil. The rapid cooling possible after continuous annealing allows production of high strength steel sheets having excellent mechanical properties that are unobtainable in the batched annealed steels. For example, steel sheets of 0.4 pet Si and 1.4 pet Mn after continuous annealing, haven values and Erichsen values as higher than conventional low-carbon rimmed or capped steel sheets even while they have a tensile strengths of 550 N/mm².