Q-235钢在含U(Ⅵ)、Sr、Cs溶液中的腐蚀行为

研究了常温常压下Q-235圆柱钢切块在150 mg/L的UO_2^(2+)、Sr^(2+)、Cs^+混合溶液体系,Sr^(2+)、Cs^+混合溶液体系及去离子水体系中的浸泡腐蚀行为。结果表明:腐蚀反应主要发生在切块横切面上,短期内发生快速腐蚀的原因主要是U(Ⅵ)与Fe之间的氧化还原反应和溶解氧与Fe之间的电化学反应;腐蚀产物主要为Fe的氧化物和氢氧化物,Sr^(2+)会在其中一种腐蚀产物上发生富集;腐蚀液中存在可与Fe发生氧化还原反应的离子或溶解氧是造成Q-235钢在短期内发生快速腐蚀的主要原因。

Corrosion behavior and electrochemical property of Q235A steel in treated water containing halide ions(F^-, Cl^-) from nonferrous industry

The corrosion behaviors and electrochemical properties of Q235 A steel in the treated water containing corrosive halide anions(F-, Cl-) have been investigated with corrosion tests of static coupon and dynamic coupon testing, electrochemical measurement of open-circuit potential and linear sweep voltammetry. The results reveal that the existence of F-and Cl-ions in the simulated treated water accelerate the corrosion rate of Q235 A steel. The corrosion rate reaches maximum with F-concentration of 50 mg/L, Cl-concentration of 200 mg/L, respectively. However, Q235 A steel would passivate when an applied potential is added to the system. Meanwhile, the initiating passive potential becomes positive with F-, Cl-concentration increasing. There is a little influence of F-, Cl-concentration on the initiating passivation current density. Therefore, it is necessary to control F-, Cl-concentration in the treated water when it is recycled by the pipelines made of Q235 A steel.

Effect of Surface Nanocrystallization on Cr-Rare Earth-Boriding for Steel Q235 at Low-Temperature

A nanostructured layer was fabricated on the surface of steel Q235 by using fast multiple rotation rolling( FMRR). The Cr-Rare earth-boriding process was carried out followed at different temperatures.Experimental results showed that the thickness of the boride layer was significantly increased by surface nanocrystallization. The morphology of the boride layer was saw-toothed. An uniform,continuous and dense boride layer was obtained and adhered well to the substrate. The penetrating speed of FMRR specimens was enhanced by 1.9,1.7 and 1.5 times when the Cr-Rare earth-boriding temperature was 843,873 and 923 K.Severe plastic deformation,which grain size was approximately 100 nm,was observed on steel Q235 surface.Mechanism of Cr-Rare earth-boriding was also studied.

Prevention of Q235 Steel Corrosion using Waterborne Rust Inhibitor

Sorbitol,triethanolamine,sodium benzoate,boric acid,and sodium carbonate were mixed to prepare a waterborne rust inhibitor.A temperature and humidity accelerated corrosion test was applied to investigate the corrosion behaviour of waterborne rust inhibitor coated Q235 steel and original Q235 steel,which was carried out in a temperature and humidity test chamber(WSHW-1000)at a temperature of 80℃and humidity of 95%.Compared with the original Q235,waterborne rust inhibitor coated Q235 has better resistance to corrosion in hot and humid ambient conditions.Electrochemical impedance spectroscopy and potentiodynamic polarization were measured with a three-electrode cell in 3.5%NaCl aqueous solution on a CHI760E potentiostat/galvanostat.Molecular dynamics was simulated to verify the synergistic corrosion inhibitory mechanism of sodium carbonate and triethanolamine.The test shows that the prepared waterborne rust inhibitor can reduce the tendency of Q235 to corrosion and can also effectively reduce the corrosion rate.

Corrosion-fatigue evaluation in Q235A steel using nonlinear Rayleigh surface waves

This paper presents a non-destrcutive evaluation method for the evolution of corrosion fatigue of Q235A steel. Specimen surface degradation due to corrosion fatigue from the combined interaction of corrosion and cyclic loading leads to harmonic generation during Rayleigh wave propagation along the specimen surface,which allows for an early prediction of material fatigue life. The relative nonlinearity parameter β as an evaluation parameter,which is denoted as a ratio of fundamental and second-order harmonic amplitudes,is measured by using an experimental platform based on a pair of wedge transducers to launch and receive Rayleigh wave signal. Subjected to an immersion corrosion method with 10% NaCl solution and a 20 Hz cyclic loading,a corrosion-fatigue specimen was made,and its relative nonlinearity parameter was measured every 10 5 cycles until to 7 ×10^5 cycles. A measured curve of relative nonlinearity parameter versus fatigue load cycles,which is produced by surface degradation of specimen corrosion fatigue,showed an initial steady trend followed by a rapid increase. Experimental results demonstrate that corrosion fatigue results in the sudden destruction of a Q235A steel specimen and nonlinear Rayleigh surface waves measurement technique can be used to quantitatively characterize fatigue life of Q235A steel.

Q235钢表面电镀镍及其性能的研究

在Q 235钢表面电镀镍,以提高低碳钢表面的耐蚀性和可焊接性。对碱洗、酸洗、活化等前处理工艺进行了研究,着重研究了直流电镀和脉冲电镀的工艺参数和镀镍层的性能。结果表明:直流镀镍层和脉冲镀镍层都较为均匀、致密、无明显缺陷,且脉冲镀镍层比直流镀镍层结构更加紧密;加搅拌后所得镀层的实验结果明显优于不加搅拌时所得镀层的;脉冲镀镍层的自腐蚀电位明显高于直流镀镍层的,且加搅拌后,自腐蚀电位进一步提高。

Microstructures and mechanical properties of metal inert-gas arc welded Mg-steel dissimilar joints

The joining of Mg alloy to steel was realized by metal inert-gas arc welding, and the weld thermal cycle characteristics and Mg-steel joints were investigated. The results show that the temperature distribution in the joints is uneven. Mg alloy welds present a fine equiaxed grain structure. There exists a transition layer consisting mainly of AlFe, AlFe3 and Mg（Fe, Al）2O4 phases at Mg/steel interface, and it is the weakest link in Mg？steel joints. The welding heat input and weld Al content have the significant effect on the joint strength. The joint strength increases with increasing the heat input from 1680 J/cm to 2093 J/cm, due to promoting Mg/steel interface reaction. When weld Al content is increased to 6.20%, the joint strength reaches 192 MPa, 80% of Mg alloy base metal strength. It is favorable to select the suitable welding heat input and weld Al content for improving joint strength.

Microstructure characteristics and mechanical properties of steel stud to Al alloy by CMT welding-brazing process

Cold metal transfer （CMT） welding of nickel-coated Q235 steel studs with 606l Al alloy was carried out using ER4043 as filler metal. The welding process was stable, and appearance of weld formed well without surface defect under the parameters of welding current 121 A, welding voltage 15.4 V and welding speed 6 r/min. The microstructure of fiUer metal was analyzed by means of scanning electron microscopy. The filler metal and 6061 Al alloy were fused to form fusion welding interface, the fusion zone had a good bonding without any micro defect. The steel stud did not melt and brazing interface was formed between the filler metal and steel stud. Two different reaction layers existed in the brazing interface, the Fe2Al5 layer about 10 -12 p^m formed near the steel stud side, and the other layer was mainly composed of FeAl3. Nickel-rich zone was formed in the root toe area of the fillet weld, which was mainly composed of Al3Ni2. The tensile tests showed that the maximum shearing strength of the joints was 129 MPa. The joint was brittle fractured in the intermetallic compound layer where plenty of FeAl3 were distributed continuously.

Numerical simulation of stress distribution in Al_2O_3-TiC/Q235 diffusion bonded joints

The distributions of the axial stress and shear stress in Al2O3-TiC/Q235 diffusion bonded joints were studied using finite element method （FEM）. The effect of interlayer thickness on the axial stress and shear stress was also investigated. The results indicate that the gradients of the axial stress and shear stress are great near the joint edge. The maximal shear stress produces at the interface of the Al2O3-TIC and Ti interlayer. With the increase of Cu interlayer thickness, the magnitudes of the axial stress and shear stress first decrease and then increase. The distribution of the axial stress changes greatly with a little change in the shear stress. The shear fracture initiates at the interface of the Al2O3-TiC/ Ti interlayer with high shear stress and then propagates to the Al2O3-TIC side, which is consistent with the stress FEM calculating results.

Corrosion of Q235 steel affected by Pseudodesulfovibrio cashew differed with electron acceptors

Sulfate and nitrate reducing bacteria are important culprits for microbiologically influenced corrosion(MIC)using sulfate and nitrate as electron acceptors,respectively.Sulfate and nitrate hold different standard electrode potentials,which may lead to differences in corrosion,but their effects on corrosion by the same bacteria have not been reported.The corrosion of Q235 steel affected by Pseudodesulfovibrio cashew(P.cashew)in the sulfate and nitrate media under carbon starvation was studied.It was found that sulfate and nitrate did not lead to differences in corrosion under abiotic conditions.However,P.cashew promoted corrosion in both cases,and the consumption of H_(2)was the main mechanism for MIC.In addition,corrosion was more severe in the sulfate media.The higher corrosivity of P.cashew with sulfate as the electron acceptor is closely related to the higher number of sessile cells in the biofilm,higher bacterial motility,more hydrogen production pathways,and the increased gene expression of enzymes related to energy synthesis.

Experimental investigation on ablation characteristics of coated and uncoated steel under 30/80 μs impulse current

The ablation tests on coated and uncoated Q235 B steel sheets were conducted under 30/80 μs impulse current simulating the lightning first return stroke current, aimed at further understanding the ablation characteristics of steel and investigating the impact of anti-corrosion coating on these characteristics. Ablation characteristics were investigated through the macroscopic morphology and x-ray diffraction patterns on the surface of damaged zones, the microstructure and micro Vickers hardness on the cross-section of damaged zones, and the maximum rear-face temperature of sample sheets. It can be concluded that the ablation areas of uncoated sheet consist of the melted layer and the heat-affect layer. These ablation areas include not only the area ablated directly by the arc root, of which the depth is deeper, but also the area forming due to the splashing of molten steel, of which the depth is shallower and decreases when the area’s distance from the arc attachment point increases. For coated sheet, coating materials have decomposed and evaporated forming an ablation pit on the sheet surface, in which the steel surface is exposed, and zinc filler of coating primer has infused into the exposed surface. The ablation diameter of uncoated sheet relates to the amplitude of the 30/80 μs impulse current in quadratic function, while for coated sheet, the relation is linear. In general, under the 30/80 μs impulse current, the coating can decrease the energy injected from the arc to the steel sheet and reduce the melting and splashing of steel. As a result, the ablation severity of uncoated sheet is severer than that of coated sheet.

Atmospheric Corrosion of Q235 Carbon Steel and Q450 Weathering Steel in Turpan,China

Q235carbon steel and Q450 weathering steel were exposed to the hot and dry environment of Turpan,China for three years.The corrosion rates of both steels were calculated and compared.The morphologies of the rust layer products were observed by optical microscopy and scanning electron microscopy.Analyses of the rust layers were performed by X-ray photoelectron spectroscopy,X-ray powder diffraction,and Raman spectroscopy,and analysis results indicate that the compositions of rust are main iron rich oxide such as FeOOH,Fe_3O_4,and Fe_2O_3.The iron oxide layer content proportion was calculated through a semi-quantitative algorithm.The resistance elements（Cr,Ni,and Cu）enhanced the resistance properties of the Q450 weathering steel matrix.Moreover,the resistance elements increased the proportion of goethite crystals in the corroded rust layer.

Simulated Corrosion Test of Q235 Steel in Diatomite Soil

Through the study of the corrosion behavior of Q235 steel in actual Yingtan soil and two simulated acidic soils with different water contents, the calculation of corrosion mass losses, and the analysis of the corrosion mor- phologies and products by means of scanning electron microscope （SEM） and X-ray diffraction （XRD）, the results demonstrated that the diatomite soil could simulate the corrosion in actual soil veritably. In both actual soil and simu- lated soil with 16.4% water content, the corrosion rates of Q235 steel were approximately 0.1 mm/a, the corrosion morphologies were mainly extension and connection of corrosion spots on sample surface, and the corrosion products were composed of a-FeOOH, γ-FeOOH, Fe3 O4 and Fe2O3. When other media conditions remained unchanged, the corrosion area of Q235 steel was larger in simulated soil with 34.5 % water content, and the corrosion rate reached 0.48 mm/a after 360 h of corrosion, which was nearly 5 times as the value in actual soil. Compared with the corro- sion products in actual soil, the proportion of γ-FeOOH in simulated soil with 34.5 % water content was higher, and the wα-FeOOH/wγ-FeOOH ratio was 1. 4, which was only 1/3 of the value in actual soil.

Deformation Uniformity of Cold-Rolled Q235 Steel Rebar by FEM in Bending and Rolling Processes

An analytic model based on ANSYS/LS-DYNA has been developed on the cold rolling process for Q235 steel rebar with 12 mm in diameter. The elastic-plastic finite element method (FEM) and the cold deformation resistance model of Q235 steel were adopted in this model. Deformation uniformity of the final product has been analyzed using this model. The results indicate that the uniformity of the final product is obtained only as the centerline of the bending rolls is vertical to the centerline of the driven roll and parallel to the centerline of the drive roll in the whole rolling process. Besides, the number of the bending rolls must even realize the continuous bending and reverse bending process. Also, the number of the bending rolls must match the deformation degree of the workpiece in the cold rolling process. The validity of this finite element model was verified by the size and distribution of grains from the billet to the rebar in a practical cold rolling process.

Elasto-Plastic Test of Q235 Steel Bending Beam With Cracking Resistance

More than 30 bending beams with rectangular cross-section and different thicknesses and heights were pre- pared from Q295 steel. The specimen dimensions were about 240 mm （length） × 60 mm （height） ×70 mm （thick ness）. Flaws were cut along its middle line with a wire cutter, with lengths ranging from 6 to 35 mm. Each specimen was tested with three-point bend loading, and a process curve was obtained between load and the displacement of the loading point, in order to analyze the fracture process when opening the crack. A deformation near the prefabricated crack was observed in the testing period, and the variation of the fracture characteristic parameters was analyzed for different sizes. For a comprehensive understanding of carbon steel fracture resistance behavior, its elasticity and plas- ticity were established by determining its Young＇s modulus and Poisson＇s ratio with an optical strain gauge. This gauge was also used for the loading process test. It was found that the fracture toughness varied with the dimensions, and the toughness of the elastic limit loading was almost constant. Using the relationship of crack resistance stress intensity factor and fracture criterion, the bearing capacity of the material structure could be estimated, which shows a good agreement with the experimental test data.

Adsorption Activity and Molecular Dynamics Study on Anti-corrosion Mechanism of Q235 Steel

The correlation between inhibition efficiency and molecular structures of the inhibitor during hydrochloric acid corrosion of Q235 steel was studied by quantum chemical calculations and molecular dynamics（MD） simulation. The proton affmity（PA） calculations demonstrated that 2-（quinolin-2-yl）quinazolin4（3H）-one inhibitor has the ten- dency to be protonated in hydrochloric acid, which was in good agreement with experimental observations. Besides, quantum chemical parameters revealed that the protonated corrosion inhibitor molecules were more easily adsorbed on Q235 steel surface and improved the corrosion resistance of steel. MD simulations were implemented to search for the adsorption behavior of this molecule on Fe （110） surface, which might be used as a convenient tool for estimating the interaction mechanism between inhibitor and iron surface.

激光熔覆和电火花沉积复合涂层的组织和性能研究

研究了激光熔覆和电火花沉积处理后Q 235钢表面复合涂层的组成、硬度和耐磨性。结果表明:电火花沉积层中弥散分布着细小的硬质相颗粒,提高了涂层的显微硬度和耐磨性。复合涂层的耐磨性是Q 235钢基体的2.3倍。

Effect of Interlayers on Microstructure and Properties of 2205/Q235B Duplex Stainless Steel Clad Plate

In this research,2205/Q235 B clad plates were prepared by a vacuum hot rolling composite process.The effects of adding Fe,Ni,and Nb interlayers on the bonding interface structures and the shear strengths of the clad steel plates were studied.The results showed that 2205 duplex stainless steel and the three interlayers produced a large amount of plastic deformation and low-angle boundaries,and the main structures were the recrystallized and deformed grains.There were many recrystallized grains in the microstructure of the Q235 B low-carbon steel due to the low deformation in the rolling process.The Fe interlayer had better wettability with the two kinds of steel,but the lower strength led to the reduction of shear strength by about14 MPa compared with the original clad steel plate.The C element in the Q235 B low-carbon steel easily diffused into the Fe interlayer,and the clad steel plate attained a poor corrosion resistance because a large decarburization area was formed.The Nb interlayer reacted with the Mo element in the 2205 duplex stainless steel to form an Nb-Mo binary alloy,which generated long-banded ferrite.The decarburization area was also produced because the Nb reacted with the C element in the Q235 B to form hard and brittle NbCx.As a result,the shear strength was significantly reduced by about 282 MPa,and the corrosion resistance of the bonding surface was deteriorated.The Ni interlayer did not react with the alloy elements in both sides,and therefore effectively prevented element diffusion and improved the corrosion resistance of the bonding surface.Due to the low strength of the Ni interlayer and the increased number of bonding surfaces of the clad steel plates,the shear strength was reduced to some extent(about 40 MPa),but it still met the engineering application standards.

Microstructure and corrosion behaviors of friction stir-welded Q235 low-carbon steel joint

Friction stir welding(FSW)was used to prepare Q235 low-carbon steel joint,and the microstructure of different zones of the joint was characterized.The electrochemical corrosion behavior of different macroscopic zones of the joint was evaluated in 3.5 wt.%NaCl solution.The results showed that the retreated-side heat-affected zone(HAZRS)and the advanced-side heat-affected zone(HAZAS)did not undergo phase transformation during FSW,and their microstructures were similar to those of the base material(BM),which was mainly composed of blocky ferrite and pearlite.The retreated-side thermo-mechanical affected zone(TMAZRS),the stirring zone(SZ),and the advanced-side thermo-mechanical affected zone(TMAZAS)underwent phase transformation,and the microstructure was mainly composed of proeutectoid ferrite and pearlite.The order of the corrosion resistance of different micro-zones from high to low was:HAZRS>BM>HAZAS>TMAZRS>SZ>TMAZAS.The corrosion mechanism for BM,HAZRS,and HAZAS was mainly the dissolution of ferrite.By contrast,the corrosion mechanism for TMAZRS,SZ,and TMAZAS was mainly galvanic corrosion between proeutectoid ferrite and pearlite.

Influence of pass reduction ratio on microstructure and properties of 2205/Q235B clad steel plate

2205/Q235B clad steel plates were fabricated using a thermal simulator.The metallographic microscope,scanning electron microscope,energy-dispersive spectrometer,shear test,electrochemical corrosion test and acid immersion test were used to study the influence of the pass reduction ratio on the microstructure and properties of 2205/Q235B clad steel plate.The results show that the clad steel plates had a good bonding surface when the pass reduction ratios were between 16.3%and 36.0%.There existed the mutual diffusion effect of elements near the bonding surface,which caused the long austenite strip on the side of 2205 stainless steel and the decarburization layer on the side of Q235B low-carbon steel.The transformation ofδferrite toγaustenite and the generation of the decarburization layer were promoted because of the lower pass reduction ratio.The corrosio n resista nee of 2205 duplex-phases stainless steel worse ned by the decrease in 8 ferrite con tent.The increase in the decarburization layer thickness made the shear strength of the clad steel plates reduce from 453 to 390 MPa.The potential of the decarburization layer was lower than that of 2205 stainless steel and Q235B low-carb on steel,which was easily corroded in the corrosive medium.