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1.
摘要:铁素体作为酸性环境用管线钢的主要组织类型之一,探究其晶界结构与管线钢氢致开裂(HIC)敏感性之间关系,可为进一步优化管线钢的抗HIC性能提供指导。对热轧态管线钢进行不同工艺热处理,采用扫描电子显微镜(SEM)、电子背散射衍射(EBSD)、透射电子显微镜(TEM)观察了试样的晶界、位错结构及氢鼓泡、氢致裂纹形貌,用电化学充氢及动态充氢方法对试样的HIC敏感性及氢致塑性损失进行了测试,用电化学氢渗透及氢微印实验对试样的氢捕获效率及氢原子分布进行了观察与分析,探索了铁素体晶界结构与HIC敏感性之间内在关联。其结果表明:当材料中以小角度晶界占主导或大小角度晶界比例约为1∶1时,对氢原子的捕获效率较高,HIC敏感性也相对较大;大小角度晶界均能捕获氢原子,但与氢的作用机制不同,大角度晶界主要促进氢致裂纹萌生,而小角度晶界主要促进氢致裂纹扩展。 相似文献
2.
3.
S. M. Bruemmer R. H. Jones M. T. Thomas D. R. Baer 《Metallurgical and Materials Transactions A》1983,14(1):223-232
The effectiveness of sulfur, phosphorus, and antimony in promoting the intergranular embrittlement of nickel was investigated
using straining electrode tests in IN H2SO4 at cathodic potentials. Sulfur was found to be the critical grain boundary segregant due to its large enrichment at grain
boundaries (104 to 105 times the bulk content) and the direct relationship between sulfur coverage and hydrogen-induced intergranular failure. Phosphorus
was shown to be significantly less effective than sulfur or antimony in inducing the intergranular hydrogen embrittlement
of nickel. The addition of phosphorus to nickel reduced the tendency for intergranular fracture and improved ductility because
phosphorus segregated strongly to grain interfaces and limited sulfur enrichment. The hydrogen embrittling potency of antimony
was also less than that of sulfur while its segregation propensity was considerably less. It was found that the effectiveness
of segregated phosphorus and antimony in prompting intergranular embrittlementvs that of sulfur could be expressed in terms of an equivalent grain boundary sulfur coverage. The relative hydrogen embrittling
potencies of sulfur, phosphorus, and antimony are discussed in reference to general mechanisms for the effect of impurity
segregation on hydrogen-induced intergranular fracture. 相似文献
4.
N. Bandyopadhyay Jun Kameda C. J. Mcmahon 《Metallurgical and Materials Transactions A》1983,14(4):881-888
Measurements of the threshold stress intensity for hydrogen-induced crack extension,Kth at room temperature were made on bolt-loaded WOL specimens of a commercial 4340 steel and of laboratory heats in which the
bulk concentrations of manganese, silicon, phosphorus, and sulfur were varied. The hydrogen pressure was varied from 200 to
1600 torr (~0.03 to 0.22 MPa), and the yield strengths were varied from ~170 to 270 ksi (~1200 to 1900 MPa). Measurements
ofKIc in air were also made as a function of composition and yield strength. Significant differences betweenKIc in air andKth in H2 were found only in steels containing added Mn or Si; these elements are believed to promote segregation of phosphorus and
sulfur to austenite grain boundaries. TheKth values were uniquely related to the percentage of intergranular fracture and also to a parameter containing the calculated
maximum hydrogen concentration and the bulk concentrations of manganese, silicon, phosphorus, and sulfur. In a high purity
steel free of manganese and silicon theKth was lower thanKIc only at yield strengths greater than 200 ksi (1400 MPa). The results are consistent with an additive reduction in cohesive
strength by hydrogen and metalloid impurities. It is shown that theKth depends on hydrogen fugacity, yield strength, and grain boundary purity(i.e., cohesive strength).
Formerly with the Department of Materials Science and Engineering, University of Pennsylvania 相似文献
5.
The role of grain and grain-boundary orientation on the susceptibility of a boundary to intergranular cracking was studied
in purified iron. Cracks were introduced by cathodic charging with hydrogen at room temperature, in the absence of an externally
applied stress. In order to analyze the data, a new graphical method was devised which successfully represented the degrees
of freedom necessary to describe the boundary orientation. The results showed that boundaries with angular misorientation
of up to about 20 deg never exhibited cracking, independent of the boundary type or the common rotation axis. At higher angles,
large regions of cracked, uncracked, and mixed behavior were observed. The results were rationalized on the basis that boundary
porosity,i.e. the degree of atomic misfit, controls the cracking susceptibility of a grain boundary. The effects of interstitial solute
content and distribution on the frequency of grain-boundary cracking were also studied. 相似文献
6.
7.
Bruce D. Craig 《Metallurgical and Materials Transactions A》1982,13(5):907-912
A series of four 4130 base steels with various phosphorus concentrations was subjected to cathodic charging to determine the
effect of P on hydrogen stress cracking resistance. Static fatigue curves for several different yield strengths were obtained
for each alloy. At high yield strengths under applied loads of 60 to 80 pct of the yield, 50 ppm P (bulk concentration) was
enough to provide sufficient grain boundary P for an impurity-hydrogen interaction which produced intergranular fracture along
prior austenite grain boundaries. Decreasing yield strength and applied stress caused a transition in fracture mode to transgranular
while the resistance to hydrogen stress cracking increased with decreasing P. Microhardness measurements of prior austenite
grain boundaries were made to establish the role of P. The role of P is not apparently related to its capacity as a strengthening
element but more probably as a hydrogen recombination poison. Grain boundary hardness measurements for low temperature tempers
(200 °C) appear to be valid while those at 500 °C were not. 相似文献
8.
J. Sojka V. Vodárek P. Váňová I. Schindler L. Kander A. Wenglorzová F. Filuš 《国际钢铁研究》2011,82(7):766-771
We have evaluated the resistance of two samples of TRIP 800 steel prepared under laboratory conditions at the Faculty of Metallurgy and Materials Engineering (FMME) V?B (Technical University of Ostrava, Czech Republic) in a sour environment containing H2S. The first steel investigated had a C–Mn–Si composition, and the second steel had a C–Mn–Si–Al composition. Both TRIP steels were characterized using the yield strength in the range 420 to 450 MPa and tensile strength in the range 880 to 900 MPa. The TRIP steel samples were in the form of sheets with a thickness of 1.5 mm. The residual austenite content was 11% and 13%, respectively, in the two steels studied. The resistance to hydrogen embrittlement was evaluated in a sour environment that contained hydrogen sulphide using hydrogen‐induced cracking (HIC) and sulphide stress cracking (SSC) tests performed in accordance with NACE standards. Both TRIP 800 steels showed a high resistance to hydrogen embrittlement, and no SSC cracks were observed. Some cracking arising from HIC was observed in both steels. The measured parameters showed some variation; in some cases they were lower than recommended limits, but in other cases the measured parameters were higher (e.g., the crack length ratio was up to 70%). The cracks initiated preferentially at non‐metallic inclusions, either at elongated manganese sulphide particles, or at oxide stringers that were rich in Al. 相似文献
9.
《钢铁冶炼》2013,40(5):381-386
AbstractHydrogen in steels causes various types of cracking, which occur when the amount of hydrogen in a steel reaches a critical level. This phenomenon results from excessive internal hydrogen pressure, and is associated with the formation of cracks at material imperfections, for example non-metallic inclusions. Consequently, cracking can be prevented either by avoiding an excessive amount of hydrogen or by increasing the critical level for cracking. These two cases are demonstrated from the points of view of steelmaking and plate production. In certain applications, the hydrogen content in a steel may be increased by the absorption and diffusion of atomic hydrogen produced on the metal surface by a corrosion reaction, for example in a wet H2 S environment. This phenomenon can lead to hydrogen induced cracking (HIC). The damage mechanism as well as the main strategy to prevent hydrogen induced cracking is described in detail. 相似文献
10.
The effects of variations in the bulk concentrations of Mn, Si, and Al on the fracture behavior of HY 130 steel were studied
by means of Charpy tests, measurements of brittle fracture stress at 77 K, fracture toughness tests, and measurements of the
threshold stress intensity for crack extension (KTH) in H2. The main focus was on temper embrittlement and hydrogen-induced cracking (HIC). The susceptibility to intergranular HIC
was characterized by the KTH and was directly related to the susceptibility to temper embrittlement. Both phenomena can be eliminated by limiting the
Mn and Si contents of the steel and by avoiding contamination of the steel by Sn. The effect of Al is to cause a small age-hardening
reaction, which can noticeably affect the tendency toward cleavage fracture, and to block part of the temper embrittlement
reaction.
Formerly Research Fellow, Department of Materials Science and Engineering, University of Pennsylvania. 相似文献
11.
Stress corrosion cracking (SCC) of high-strength steel in aqueous environment and hydrogen induced cracking (HIC) during dynamic
charging under Mode III loading were investigated. The threshold stress intensities for SCC and HIC under Modes III and I
were measured and compared. It was found that both SCC and HIC under Mode III loading initiated and propagated on the planes
inclined at 45 deg to the notch plane, differing from that under Mode I loading. The fracture surfaces, however, revealed
intergranular facets, similar to that under Mode I loading. The addition of thiourea decreased the threshold value for SCC
under Mode III and Mode I loading, which was still higher than that for dynamic charging. The threshold values of both SCC
and HIC under Mode III were larger than that under Mode I,i.e., KIIIH> KIH, KIIISCC > KISCC. Based upon the fracture mechanics analysis, this difference is attributed to the different equilibrium hydrogen concentration
between Modes III and I loading. These results give strong evidence that the SCC mechanism in high strength steel under Mode
III loading is also related to hydrogen induced cracking.
Formerly Student at Beijing University of Iron and Steel 相似文献
12.
Hydrogen blistering, hydrogen‐induced plasticity loss (HIPL) under slow strain rate test and hydrogen‐induced cracking or fracture (HIC) under constant load for rail steel were evaluated. The threshold diffusible hydrogen concentrations for blistering, HIPL and HIC were 2.03 ppm, 0.26 ppm and 0.24 ppm, respectively. During charging, blistering formed first and fissure initiated at the wall of the blistering. HIPL (lδ) was found to decrease linearly with the reciprocal of the diffusible hydrogen concentration (C0), i.e. lδ = 105 ‐ 27/C0. The threshold stress for HIC (σc) in MPa decreases linearly with In C0 in ppm i.e., σc = 642 ‐ 284 In C0. 相似文献
13.
This paper reports a study of grain boundary segregation, intergranular corrosion, and intergranular stress corrosion cracking
in austenitic stainless steels. The results show that phosphorus, nitrogen, and sulfur all segregate to grain boundaries in
these materials and that they can affect one another's segregation through site compctition. In particular, the results demonstrate
that phosphorus segregation can be lowered by the presence of nitrogen and sulfur in the steel. Also, if manganese is present
in the steel, sulfur segregation will be greatly decreased as a result of formation of manganese sulfides. Phosphorus, sulfur,
and nitrogen will not initiate intergranular corrosion in the modified Strauss test, although if corrosion is initiated by
chromium depletion, these elements might enhance the corrosion process. Phosphorus segregation does enhance corrosion in the
Huey test, even in steels that have not undergone grain boundary chromium depletion, although there does not appear to be
a precise correlation between the depth of corrosion penetration and phosphorus segregation. Intergranular stress corrosion
cracking in 288 °C water at a pH of 2.5 and electrochemical potential of OVSHE can occur in these steels even in the absence of chromium depletion if sulfur is present on the grain boundaries. Phosphorus
segregation appears to have very little effect. 相似文献
14.
《Acta Metallurgica Materialia》1992,40(1):57-68
The grain boundary B content of high-purity Ni-24 at.% Al alloys containing 0.048, 0.144, 0.240 and 0.480 at.% B (100, 300, 500, 1000 ppm mass) has been determined for samples aged from 1323 to 873 K for sufficient times to attain equilibrium. The B content was derived from Auger electron spectra of the intergranular fracture facets. Many facets were exposed during fracture at ≈ 300 K, and additional facets were formed upon fracturing following hydrogen charging after heat treatment. For each alloy sample, about 25 facets were analyzed. The grain boundary B contents were in the range of 0.5–2.5 at.%. The grain boundary B content increased with decreasing temperature and with increasing bulk B content in the alloys. The energy of binding of a B atom to the grain boundary was calculated using McLean's segregation theory and assuming a unique binding energy for each alloy. The values were in the range of 0.15–0.45 eV/atom, and increased with increasing temperature and with decreasing bulk B content. These results have been rationalized in terms of a spectrum of binding energies for a given alloy. However, when the entropy of adsorption was taken into account, an enthalpy of adsorption of B to the grain boundary of 0.13 eV/atom was obtained, independent of temperatire and bulk B content. This is interpreted to mean that the spectrum of binding energies is quite restricted. The grain boundary B content of these alloys has also been measured as a function of annealing time at 773, 873, 973 and 1173 K. The diffusion coefficient of B in Ni3Al at 773 K is about 5 × 10−21 m2/s, and the equilibrium grain boundary B content is attained at about 3000 s. The diffusion coefficient at 973 K is between 10−16 and 10−17 m2/s. The activation energy for diffusion of B in Ni3Al is between 200,000 and 300,000 J/mol. 相似文献
15.
Scrap-based electric arc furnace (EAF) steelmaking is limited by a surface cracking problem in the recycled steel products,
which is known as surface hot shortness. This problem originates from the excessive amount of copper (Cu) in the steel scrap, which enriches during the oxidation
of iron (Fe) and consequently melts and penetrates into the austenite grain boundaries. In this article, the effects of arsenic
(As), antimony (Sb), and tin (Sn) on surface hot shortness were investigated. A series of Fe-0.3 wt pct Cu-x wt pct (As, Sb, or Sn) alloys with x content ranging from 0.06 to 0.10 wt pct was oxidized in air at 1423 K (1150 °C) for 60, 300, and 600 seconds inside the
chamber of a thermogravimety analyzer (TGA) where heat is supplied through infrared radiation. Scanning electron microscopy
(SEM) investigations show that (1) the presence of Sb and Sn results in severe grain boundary cracking, whereas the presence
of As does not, (2) open cracks with Fe oxides were found beneath the oxide/metal interface in the Sb and Sn alloys, and (3)
the oxide/metal interfaces for all As, Sb, and Sn alloys are planar. Penetration experiments of pure Cu and Cu-30 wt pct Sn
liquid were also conducted in the chamber of a hot-stage confocal laser scanning microscopy (CLSM) in nonoxidizing atmosphere:
(1) on the Fe-35 wt pct manganese (Mn) alloys to study the correlation between cracking and grain boundary characters, and
(2) on the pure Fe substrates to exclude the bulk segregation effects of Sn on grain boundary cracking. It was found that
grain boundary cracking rarely took place on low-energy grain boundaries. The results also suggest that the bulk segregation
of Sn in the substrate is not necessary to promote significant grain boundary cracking, and as long as the liquid phase contains
Sn, it will be highly embrittling. 相似文献
16.
Susceptibility of steel to cracking ‐either by contact with gas in wet H2S environments or near neutral solutions‐ is a dominant factor for residual life of gas‐line pipes. Three different phenomena are concerned with cracking, namely hydrogen induced cracking (HIC), sulphide stress cracking (SSC) and stress orientated hydrogen induced cracking (SOHIC). Whereas laboratory test methods for HIC are established the situation is different in combination with stress. If the coating is damaged and a near neutral liquid medium is penetrating the pipe surface a strain induced crack might occur. This type of corrosion is named near neutral SCC (NNSCC). A qualified test method with simulated cyclic loading conditions was not available. A test stand including pulsating tension on a high level qualified for high strength steels, wet environments with pH‐values between 2.7 (sour gas) and 8,3 (synthetic seawater) and bubbling several gases such as H2S, CO2 or N2 through the test solution with controlled room temperature was developed. The test‐method enables to qualify steels and pipes for line pipes in tests of short duration compared to lifecycles of line pipes. 相似文献
17.
The effects of shielding gas and post weld heat treatment on the pitting resistance, stress corrosion cracking and hydrogen embrittlement of supermartensitic stainless steel deposits were studied. Two all-weld-metal test coupons were prepared using a metal-cored wire under Ar+5% He and Ar+18%CO2 gas shielding mixtures. Solubilizing and solubilizing plus double tempering heat treatments were done with the objective of achieving different microstructural results. The samples welded under Ar+5% He showed higher pitting corrosion resistance, for all post weld heat treatments, than those welded under Ar+18%CO2. The different post weld heat treatments generated higher susceptibility to this corrosion mechanism. None of the samples presented signs of stress corrosion cracking, but in those subjected to the heat treatment, grain boundary selective attack was observed, on the surfaces of all the samples studied. The samples with highest hardness were more susceptible to hydrogen damage, thereby leading to reduced tensile strength on this condition. 相似文献
18.
Tong-Yi Zhang Wu-Yang Chu Ying Li Chi-Mei Hsiao 《Metallurgical and Materials Transactions A》1986,17(4):717-725
Hydrogen induced cracking (HIC) and stress corrosion cracking (SCC) of a high-strength steel 34CrNi3Mo (T.S = 1700 MPa) under Mode II loading were investigated using notched specimens. The stress field around the notch tip
was analyzed by means of finite element method. The result shows HIC and SCC under Mode II loading initiated at the back of
the notch tip,i.e., θ = -110 deg, where hydrostatic stress has maximum value. However, cracking is oriented along the shear stress direction
at the site, not normal to the direction of maximum principal stress component. On the contrary, if the specimens are loaded
to fracture in air under Mode II loading, cracking at the maximum shear stress site around the notch tip and the cracking
direction coincide with the direction of the maximum shear stress. The above facts indicate that hydrogen induced delayed
plastic deformation is a necessary condition for HIC, and the nature of SCC for high-strength steel in 3.5 pct NaCl solution
is HIC. The results show that HIC and SCC under Mode II loading can occur during dynamic charging with hydrogen and in 3.5
pct NaCl solution, respectively. The normalized threshold stress intensity factors under Mode II loading during dynamic charging
in 1 N H2SO4 + 0.25 g As2O3/L solution and in 3.5 pct NaCl solution are KIIH/KIIX = 0.1 and KIISCC/KIIX = 0.45, respectively. The corresponding values under Mode I loading are KIH/KIX = 0.02 and KISCC/KIX = 0.37, where KIIX and K,IX are critical values loaded to failure in air under Mode II and Mode I loading, respectively. Thus, (KIIH/KIIX)/ KIH/KIX) = 5 and (KIISCC/KIIX)/K,(ISCC/KIX) = 1.2. A typical intergranular fracture was observed during HIC and SCC under Modes II and I loading. But the fracture surfaces
of specimens failed in air are composed of dimples for both kinds of loading.
Formerly Student at Beijing University of Iron and Steel Technology 相似文献
19.
Hans Jürgen Grabke 《国际钢铁研究》1987,58(10):477-482
In steels produced and utilized in the Fed. Rep. of Germany the elements P and Sn may occur as impurities. Both these elements tend to enrich (segregate) at grain boundaries. The equilibria of grain boundary segregation in iron and the effects of alloying elements have been studied for P and Sn by Auger-electron-spectroscopy and were thermodynamically described. For a 3.5% NiCrMoV-turbine steel the grain boundary segregation of P and its effect on ductility have been studied in detail, with the results that the long-term embrittlement of this steel during application at temperatures around 400°C can be predicted and the maximum bulk concentration of P can be given. The effect of Sn on the creep of a 1% CrMoNiV steel at 550°C has been investigated, Sn favours cavity nucleation and growth, therefore tertiary creep starts earlier and premature failure occurs with increasing Sn content. Therefore, the Sn content should be kept as low as possible in heat resistant steels. Since carbon also segregates to grain boundaries and can displace P and Sn if there is enough free C in a steel, plain carbon steels are not subjected to embrittlement by P and Sn. The susceptibility to intergranular stress corrosion cracking in nitrates and other electrolytes is somewhat enhanced by P, however, only in a restricted range of potentials. In the range of maximum susceptibility the impurities have no effect, all carbon steels are susceptible to IGSCC, independently of their purity. So stress corrosion cracking cannot be suppressed by diminishing the content of phosphorus – only by avoiding the critical corrosion conditions concerning electrolyte and potential. 相似文献
20.
J. K. Sung J. Koch T. Angeliu G. S. Was 《Metallurgical and Materials Transactions A》1992,23(10):2887-2904
The role of chromium, carbon, chromium carbides, and phosphorus on the intergranular stress corrosion cracking (IGSCC) resistance
of Ni-Cr-Fe alloys in 50 pct NaOH at 140 °C is studied using controlled-purity alloys. The effect of carbon is studied using
heats in which the carbon level is varied between 0.002 and 0.063 wt pct while the Cr level is fixed at 16.8 wt pct. The effect
of Cr is studied using alloys with Cr concentrations between 5 and 30 wt pct. The effect of grain boundary Cr and C together
is studied by heat-treating the nominal alloy composition of Ni-16Cr-9Fe-0.035C, and the effect of P is studied using a high-purity,
P-doped alloy and a carbon-containing, P-doped alloy. Constant extension rate tensile (CERT) results show that the crack depth
increases with decreasing alloy Cr content and increasing alloy C content. Crack- ing severity also correlates inversely with
thermal treatment time at 700 °C, during which the grain boundary Cr content rises and the grain boundary C content falls.
Phosphorus is found to have a slightly beneficial effect on IG cracking susceptibility. Potentiodynamic polarization and potentiostatic
current decay experiments confirm that Cr depletion or grain boundary C enhances the dissolution at the grain boundary. Results
support a film rupture-anodic dissolution model in which Cr depletion or grain boundary C (independently or additively) enhances
dissolution of nickel from the grain boundary region and leads to increased IG cracking. 相似文献