Stress corrosion cracking behavior (SCC) of typical nuclear structural materials stainless steel in high-temperature and high-pressure water was reviewed. The effect of material type, mechanical properties, water chemistry on the sensitivity, initiation and propagation of cracks were discussed. The development of the zinc injection technology in the coolant system and its inhibitory effect on the primary side stress corrosion (PWSCC) were introduced. Finally, by taking various factors and actual operating conditions into consideration, the method of reducing the sensitivity of SCC was summarized, and the problems that should be focused on in future research were proposed.

As the most important method for massive and long haul transportation of oil and gas resources, offshore pipelines undertake the significant tasks of oil and gas gathering and transportation, namely the “lifeline” of offshore oil and gas engineering. However, microbiologically influenced corrosion in the marine environment is one of the important causes of corrosion damage to offshore pipelines. Based on the service environment of marine oil and gas pipelines, this paper reviews the research progress of microbiologically influenced corrosion failure of coastal pipelines in the marine environment, focusing on the regularity and mechanism of corrosion induced by sulfate reducing bacteria and iron oxidizing bacteria, which are representative bacteria for the corrosion occurrence in the marine environment. Also, the corresponding protection methods of pipelines are summarized, which provides reference for the research on microbiologically influenced corrosion damage and the corrosion control engineering of pipelines operated in marine environment.

The corrosion mechanism and the relevant factors influencing the corrosion process of ribbed steel in service in different circumstances are analyzed and discussed in this paper. Peculiarly, and the corrosion status and its evolution process in atmospheric environments was described in terms of the influencing factors related with the following six aspects: wind sand damage, rain wash, atmosphere, fresh water, ocean and nuclear radiation. Combined with the current social market demand and existing protection technology, the main development direction of ribbed steel protection technology is pointed out.

The corrosion evolution characteristics of Q235B steel in O₃/SO₂ containing composite atmosphere was examined by means of a simulation of dry/wet cyclic corrosion test, electrochemical impedance spectroscopy (EIS) and polarization curves measurements, as well as X-ray diffractometer (XRD) and 3D laser measurement microscope. The results show that the synergistic effect of O₃ and SO₂ can obviously inhibit the corrosion of Q235B steel. When the concentration of Na₂SO₃ in the simulated environment is 0.01 mol/L, the corrosion rate of Q235B steel in the simulated O₃/SO₂ containing composite atmosphere increases rapidly and then decreases slowly. When the concentration of Na₂SO₃ in the simulated environment is 0.05 mol/L, the corrosion rate of Q235B steel increases slowly and then decreases rapidly. When the concentration of Na₂SO₃ in the simulated atmosphere is 0.10 mol/L, the corrosion rate of Q235B steel increases first and then decreases slowly. Compared with the atmosphere without O₃, when the content of SO₂ in the simulated atmosphere is lower, the synergistic effect of O₃ and SO₂ will promote the formation of α-FeOOH. When the content of SO₂ in the atmosphere is higher, the effect of O₃ on the phase composition of the corrosion products is not obvious.

Acid pickling is an essential procedure in manufacturing stainless steel products. However, inappropriate operation may result in some defects on the product surfaces. To understand the pickling effect, the morphology and corrosion behavior of 316L stainless steel were assessed by means of laser confocal microscopy (LSM), scanning electron microscopy (SEM), atomic force microscope (AFM), potentialdynamic polarization (PP), electrochemical impedance spectroscopy (EIS), Mott-Schottky (MS) and ellipsometry (ES). The results indicated that the corrosion resistance of 316L stainless steel in 3.5%NaCl solution was improved after pickling, but pitting corrosion was found on the surface of 316L stainless steel if the steel was over-pickled. The enhancement of the corrosion resistance could be due to the formation of Cr₂O₃-riched passivation film on the surface after pickling. The pitting corrosion initiated from the pores in the passive film, which was formed after extended immersion in pickling acid. A pickling solution droplet remaining on the surface led to a thicker passive film formed locally, which had different optical reflection, and was displayed as a macroscopic white spot on the surface.

The corrosion inhibition performance of 2,5-Dihydroxy-1,4-dithiane (DDD) for X70 pipeline steel in 0.5 mol/L sulfuric acid solution was studied via experimental and theoretical means. Electrochemical experimental data show that DDD can effectively inhibit the corrosion of X70 steel in sulfuric acid solution. The corrosion inhibition efficiency of DDD can reach 93.6% at 298 K. In addition, DDD can still exhibit good corrosion inhibition performance at higher temperatures. The adsorption of DDD on the surface of X70 steel is consistent with Langmuir single layer adsorption. Results of quantum chemical calculation and molecular dynamics simulation also proved the above adsorption and inhibition mechanism of DDD on steel deduced from experimental results.

The electrochemical corrosion behavior and corrosion morphology of Fe-based amorphous alloys containing sulfide inclusion were examined by means of electrochemical workstation and transmission electron microscope. The results show that both of the sulfide inclusions Al₂S₃ and precipitates Al₅₇Mn₁₂ exist in the amorphous alloy. The corrosion rate of the amorphous alloy increases with the increase of the concentration of FeCl₂ in the solution. The passivation film in the Cr-depleted zone around the inclusions is weak, which is the location of pitting initiation. Al and Mn of precipitates Al₅₇Mn₁₂ are preferentially dissolved in FeCl₂ solution, resulting in pits initiation, however, in the solutions of higher FeCl₂ concentration, secondary pores within pits could form due to the presence of autocatalytic effect.

The corrosion behavior of carbon steels in Hunan province was comparatively studied via atmospheric exposure testing and atmospheric corrosion monitoring (ACM) technique, while the effects of environmental factors and the samples' shape on the corrosivity evaluation of atmospheric environments were assessed. The results showed that the corrosion rate of carbon steels have a positive correlation with SO₂ deposit rate in the atmosphere, while the Cl^- deposit rate becomes the important influence factor when the corrosion of carbon steels exposed in sites at or nearby a chlorine chemical plant. The corrosion rate of Q345 steel is higher than that of Q235 steel, and the corrosion rate of Q235 angle steel is higher than that of the Q235 flat steel. A linear relationship between the corrosion rate and the cumulative electric quantity measured by ACM was revealed for Q235 carbon steel, thus ACM technology can be used to predict the atmospheric corrosion behavior of carbon steels and assess the corrosivity of atmospheric environments.

The corrosion behavior of four anticorrosion alloys, including 316L stainless steel, 254SMo stainless steel, C276 alloy and Inconel 740H alloy, in an artificial flue-gas condensate of pH 1.09 which aims to simulate the flue-gas condensate of ultra-supercritical boilers, is studied by means of open-circuit potential- and potentiodynamic polarization curve-measurement, as well as electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. It shows that all the four alloys exhibit passivation characteristics in the artificial flue-gas condensate. The deterioration process of the formed passive films by the aggressive ions in the flue-gas condensate is different for the four alloys with individually unique chemical composition. Among them, the passivation current density is the lowest and the polarization resistance is the highest for 254SMo stainless steel, which may be ascribed to that the formed passive film of high quality contains high Cr content, and appropriate amount of Mo and Ni on 254SMo stainless steel.

The corrosion fatigue characteristics of the Al-Mg-Si alloy and its butt welded joints in a simulated industrial atmosphere are studied by means of mechanical performance test, axial force loading fatigue test, scanning electron microscope, electrochemical test and other methods. The results show that the mechanical properties of butt-welded joints of Al-Mg-Si alloy are lower than that of the base metal, and the welded joints are more prone to corrosion in the simulated industrial atmosphere. The corrosion fatigue sensitivity of welded joints is higher, the corrosion fatigue cracks of the base metal initiate from corrosion pits at grain boundaries, while the fatigue cracks of the welded joints initiate easily at the locations rich in welding defects and inclusions of the weld seam. The existence of large number of welding defects and Al₂O₃ inclusions introduced during the welding process may be responsible to why the corrosion fatigue performance of the welded joints of Al-Mg-Si alloy is lower than that of the base metal. Besides, the presence of inclusions will induce stress concentration, and around which high-density lattice distortion areas will also emerge. These areas will act as anodes to be preferentially dissolved and thereby, where to become the priority area of corrosion fatigue crack initiation, eventually lead to fatigue fracture of the test piece. Therefore, for the actual production, the forming process and welding process should be optimized, and the number of welding defects and inclusions should be controlled, so as to improve the corrosion fatigue performance of the alloy.

The erosion-corrosion behavior of 20 steel in simulated oilfield produced fluid with different sand particle sizes and at different temperatures was studied via a rotating cylindrical electrode experimental device, as well as other methods such as corrosion mass loss measurement, morphological observation and electrochemical techniques. The results show that the increase of sand particle size can obviously promote the erosion wear of 20 steel, which is consistent with the morphology observation. With the increase of sand particle size, both the effect of corrosion promoting erosion and the effect of erosion promoting corrosion firstly increase and then decrease. When the sand particle size is in the range of 40~70 μm to 120~200 μm, the erosion-corrosion mode of the steel may mainly be ascribed to the mixed control of erosion and electrochemical corrosion. When the particle size of the sand is 200~300 μm, the erosion wear is dominant. The erosion-corrosion of 20 steel at different temperatures is mainly controlled by erosion and electrochemical corrosion. The higher the temperature, the much obvious the promotion effect of corrosion on erosion.

The effect of a hybrid corrosion inhibitor, namely mixtures of benzotriazole (BTA) and sodium formate (SFA), on the corrosion behavior of bronze in 3% (mass fraction) NaCl solution was assessed by means of CHI760E electrochemical workstation and X-ray photoelectron spectroscopy (XPS) technique. The results demonstrated a satisfied anti-corrosion enhancement effect of SFA, indicated by increased film resistance and interfacial electron-transfer resistance on bronze surface measured by electrochemical impedance spectroscopy. The XPS analysis indicated a major impact of the type of the formed oxides on bronze surface to the formation of Cu-BTA complex. And in the presence of SFA, the corrosion product on bronze surface is dominated by Cu₂O, which is more conductive to the adsorption of BTA and the formation of Cu (I)-BTA complex, thereby improving the corrosion resistance of bronze. This study not only provides a deeper insight into the theoretical basis for the anti-corrosion of bronze, but also suggests an effective approach to protect bronze cultural relics as well.

The effect of ClO₂^- amount on the metastable pitting of S2205 stainless steel in Cl^- containing medium was studied by means of slow potentiodynamic scan. The results show that the competitive adsorption of ClO₂^- and O₂ hinders the formation and repairation of the passivation film, while the strong oxidation causes the partial dissolution of the passivation film, thereby its stability is reduced. Meanwhile, ClO₂^- competes with Cl^- for adsorption, the greater the concentration, the higher the replacement rate, as a result, such competition may provide protectiveness for the passivation film to a certain extent. The competitive adsorption of ClO₂^- and Cl^- can suppress the metastable pitting nucleation, at this time, the nucleation could mainly occur on inclusions and active sites on the metal surface, of which the later might be generated on the surface grooves with a certain critical depth. Due to the decrease in the stability of the passivation film, as the concentration of ClO₂^- increases, the number of metastable pitting nucleation increases slightly, and the growth rate of metastable pitting has little relationship with the concentration of ClO₂^-. After the addition of ClO₂^-, Cl^- induced metastable pitting nucleation was inhibited, E_m increases rapidly, then its change with the concentration is not obvious, and the stability of the passivation film decreases, caused E_b decreases rapidly, it slowly decreases with the increasing concentration of ClO₂^-, then the metastable state of pitting is more likely to be transformed into the stable stage. The increase in potential could facilitate the dissolution of inclusions on the metal surface, inhibiting the metastable pitting nucleation, while increasing the Cl^- migration rate and thus promoting the growth of metastable pitting.

The effect of denitration agent (NaClO₂) concentration on the corrosion resistance of S2205 stainless steel in denitration solutions was studied by means of potentiodynamic polarization curve, electrochemical impedance and Mott-Schottky curve measurements. Meanwhile, the variation of critical pitting temperature (CPT) with the NaClO₂ concentration was measured by potentiostatic polarization method. The results show that as the NaClO₂ concentration increases, the corrosion resistance of the steel decreases first and then increases. In the potential range of 0.4~0.6 V, the insoluble Cr³⁺ oxide in the passivation film of p-type semiconducting is transformed into soluble Cr⁶⁺ oxide, as a result, which degrade the stability of the passivation film. The carrier density is the largest and the relevant corrosion resistance is the worst for the passivation film formed in the solution with 6%NaClO₂. The CPTs corresponding to the solutions containing 3%, 6%, and 9% NaClO₂ were 65.2, 57.4 and 62.5 ℃, respectively.

The corrosion behavior of 140ksi high grade steels, namely the so-called oil country tubular goods (OCTG), in the single environment and multi-consecutive environment in the full-life-cycle of high pressure and high temperature gas wells was systematically studied via high pressure and high temperature corrosion testing system. The results showed that the decreasing trend of corrosion rates of 140ksi high grade OCTG steels in both single environment tests and multi-consecutive environment tests could be ranked as follows: CR_{fresh acid}＞CR_{used acid}＞CR_{formation water}＞CR_{condensate water}, and some “genetic effects” were also observed in the multi-consecutive environment tests. The corrosion rates of 140ksi high grade OCTG steels decreased with the increase of test time in the formation water for both single environment tests and multi-consecutive environment tests, which tended to be stable after 60 d exposure. Based on the pitting rates, the service life of 140ksi high grade OCTG steels under different corrosion conditions was calculated using the finite element method.

In view of the high toxicity and high cost of the current corrosion inhibitors, a new type of surfactant corrosion inhibitor was synthesized using two green raw materials of erucic acid and oleic acid, and the performance of the two corrosion inhibitors for P110 steel in 15% (mass fraction) hydrochloric acid solution were assessed by means of mass loss measurement, electrochemical measurement, Scanning Kelvin probe (SKP) and scanning electron microscope (SEM). Results show that the two corrosion inhibitors have good corrosion inhibition effects at 90 ℃ and can be used as effective corrosion inhibitors for oil and gas field acidification. In comparison with the P110 steel tested in the blank 15%HCl solution, the surface morphology of the same steel tested in the 15%HCl solution with addition of the two corrosion inhibitors maintained a better state, indicating that the two corrosion inhibitors had a good effect. Finally, through quantum chemical calculation, the synthetic corrosion inhibitor has been proved to be effective from the perspective of molecular calculation, and the correlation between experimental and theoretical results has also been demonstrated.

The hydrogen absorption behavior of Ti70 alloy was studied by electrolytic hydrogen charging and then characterized via hydrogen analyzer and metallographic microscope. The relationship between the hydrogen content with the microstructure, diffusion direction and specific surface area of Ti70 alloy was examined. The results show that the increased continuity of β phase strongly facilitates the absorption capacity of Ti70 alloy, whereas, the β phase provides more tetrahedral interstitial sites, becoming the easier diffusion path for H. The distribution of H in the alloy is macroscopically non-uniform. The H content shows a sharp decreasing from the surface to the interior. The diffusion of H along the thickness direction is much more difficult than the rolling direction. This should be attributed to the blocking effects caused by the elongated α phase in the thickness direction and the more continuous β phase along the rolling direction. The H absorption capacity was found to increase with the specific surface area of the alloy sample, which further proved that the absorbed H is not sufficiently diffused in the alloy sample, as a result, the larger the surface area per unit volume, the higher the H absorption capacity.

The corrosion behavior of T/S-52K pipeline steel in solutions of different NaCl concentration was studied by means of EDS, SEM, EIS and other analysis methods. The results showed that with the increase of Cl^- concentration, the anodic dissolution of the activated regions was accelerated, which promoted the local corrosion of the sample surface, resulting in serious local corrosion. However, with the increasing coverage of the corrosion products scale, the effective reaction area decreased, so the uniform corrosion rate of the sample changed little. When NaCl concentration was 8 g/L, the reaction process of T/S-52K pipeline steel electrode was mainly controlled by diffusion. When NaCl concentration was 20 g/L, the reaction process of T/S-52K pipeline steel electrode was controlled by both diffusion and activation polarization. When NaCl concentration was 35 g/L, the electrode reaction process on the surface of the sample was mainly controlled by activation polarization.

The chlorine-induced corrosion behavior of Q235 steel in N₂-0.26%HCl-1.6%O₂-3.2%CO₂ mixed gas at 500 and 600 ℃ was investigated. At both temperatures, the Q235 steel presented obvious mass gain and the corrosion rate increased rapidly with the increase of temperature. The scales formed at both temperatures are very similar, with formation of an outer thicker Fe₂O₃ layer and an inner Fe₃O₄ layer. Most of the surface of scales peeled off and the case is more serious at 600 ℃. Furthermore, at this temperature a large number of holes appeared in the Fe₃O₄ layer. The corrosion mechanism of Q235 steel conforms to the “activated oxidation mechanism”, especially at 600 ℃, which means that volatile metal chlorides form at the metal/oxide interface and then diffuse outwards, turning into oxides finally in the region of higher oxygen partial pressure. Therefore, Q235 steel is not suitable to be used above 500 ℃ in an oxidizing chlorine-containing atmosphere.

The corrosion behavior of weld joints of Q345NS steel in sulfuric acid was studied via immersion test, and proper post characterization. The results show that due to the welding process, the element concentration difference between the base metal and the weld seam leads to that alloy elements such as Cr, Cu, Sb in the base metal diffuse towards and enrich in the weld seam. At the same time, the high temperature in the welding process will promote that process, resulting in the formation of a depletion zone of alloying elements on the side of the heat-affected zone near the base metal. The high temperature during the welding leads to the secondary allocation of Cu and Sb, and their content difference is further expanded. The large enrichment of Cu and Sb in the corrosion product scale can promote the densification of the corrosion product scale and improve the corrosion resistance to sulfuric acid for the weld Q345NS steel.