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The effect of coupling of copper and phosphorus in steel on atmospheric corrosion behavior was investigated using high-throughput experimental methods. Wire beam electrodes and plates with discrete distribution of composition gradients were prepared through a selective laser melting method. By combining array electrode scanning tests and EPMA, the electrochemical properties and the relationship between different copper and phosphorus contents were rapidly determined. Plenty of data obtained were analyzed according to relevant standards and screened to identify compositional ranges corresponding with the relevant compositions of existing grades of steel. To further analyze the effect of copper and phosphorus on the corrosion behavior, dry/wet cyclic corrosion test were performed using plates. A combination of XRD, FTIR, SEM, EDS, and EPMA were used to analyze the corrosion behavior. It was observed that both copper and phosphorus promoted the formation of amorphous substances, supporting the proposed mechanism by previous researchers. Furthermore, in the absence of manganese interference, copper could accumulate at the metal/rust layer interface, rendering the rust layer cation-selective and effectively inhibiting the deep penetration of chloride ions. Moving forward, we expect to develop this high-throughput experiments to investigate the coupling effects of other elements on corrosion behavior.

The corrosion resistance of ferrous alloys is greatly influenced by the presence of alloying elements, however, predicting the coupling effects of these elements remains a challenge. In the present paper, the effects of various alloying elements on the corrosion resistance of iron matrix material were investigated using high-throughput density functional theory (DFT) calculations. This work explores the dissolution behavior of metal and alloy surfaces and established correlations between calculated parameters and experimentally measurable values to predict polarization curves and simulate corrosion behavior. The results showed that doping with Cu, P, Ni, Al, Mn, Co, Si, Ti, and Zn on the Fe (110) surface can reduce the corrosion current density of the iron matrix. For Fe-Cu and Fe-Mn steels, coupling P-Ti in Fe-Cu steel and P-Si in Fe-Mn steel can significantly improve their corrosion resistance. The developed model can quantitatively predict material properties and efficiently screen compositions to design corrosion-resistant alloys.

White Etching Layer (WEL) and Brown Etching Layer (BEL) always form on the surface of rails and bearings subjected to rolling cyclic contact stress. Because of the different properties between WEL/BEL and matrix, the cracks initiate and propagate easily, leading to failure ultimately. The WEL and BEL found on pearlite rail, have been widely investigated, but WEL and BEL on bainite rail and martensite bearing have not been further studied. Especially the BEL on martensite bearing raceways has rarely been reported. This study investigates the features of WEL and BEL found on martensite bearing raceway. The BEL locates in the middle of WEL and matrix, but its hardness values are the highest, which is different from the general results reported: WEL > BEL > matrix. The WEL is mainly consisted of austenite with coarse grains, ferrite and retained tempered martensite. The mainly composition of BEL is quenched martensite. Thermal effect is the main formation mechanism of the WEL and BEL in this study. BEL forms because the surface temperature exceeds Acm point, and then rapidly decreases. The formation of WEL may originate from two processes: (1) The austenitizing and slowly cooling process again of BEL; (2) The austenitizing and slowly cooling process of the matrix. WEL and BEL forming processes are closely related to the diffusion and redistribution of carbon. The contributory heat conduction and diffusion mechanism in the confined spaces of grease lubricated bearings have been also discussed in this study.

The effect of HCO3− and Cl− on the corrosion behavior of Q345 carbon steel in soil simulated solutions was investigated through electrochemical and surface characterizations. The results show that the sample behaves with active dissolution state in low concentration of Cl− solution while pseudo passivation of sample is observed in high concentration of Cl− solution. However, in solutions containing low concentration of HCO3−, the addition of high concentration Cl− does not result in the pseudo passivation of sample due to the formation of discontinuous film, which increases the corrosion rate. In addition, in solution containing high concentration of HCO3−, the addition of high concentration Cl− leads to much higher increase of corrosion rate. The deep corrosion pit is observed on the matrix due to the rapid rupture of FeCO3 film and the sufficient development of pitting.

The optimization of water chemistry in pressurized water reactor (PWR) primary circuit is one of the most effective ways to achieve both safety and economy for operating PWR nuclear power plants (NPPs). Special attention has been paid to fundamental research and engineering application of Zn-injection water chemistry (ZWC) in PWR primary circuit in recent years in China due to the rapid development of nuclear power. The present paper mainly reports the status of PWR NPPs in China and some fundamental understandings of ZWC on material corrosion. Effects of temperature (T), pH at T value, Zn concentration, Zn-injection sequence and lasting time on electrochemical corrosion behavior, oxide film characteristic and stress corrosion cracking (SCC) susceptibility of nuclear-grade austenitic alloys were investigated. A modified point defect model was used to discuss the effects of ZWC on the oxide films in high-temperature pressurized water. Some water chemistry parameters in PWR primary coolant system are proposed for mitigating corrosion and SCC of nuclear-grade austenitic alloys.

Corrosion fatigue crack growth (FCG) behavior of 316LN stainless steel was investigated in high-temperature pressurized water at different temperatures, load ratios (R = Kmax/Kmin) and rise times (tR). The environmental assisted effect on FCG rate was observed when both the R and tR exceeded their critical values. The FCG rate showed a linear relation with stress intensity factor range (ΔK) in double logarithmic coordinate. The environmental assisted effect on FCG rate depended on the ΔK and quantitative relations were proposed. Possible mechanisms of environmental assisted FCG rate under different testing conditions are also discussed.

Low cycle fatigue behaviors of SA508-3 low-alloy steel were investigated in room-temperature air, high-temperature air and in light water reactor (LWR) water environments. The fatigue mean curve and design curve for the low-alloy steel are developed based on the fatigue data in room-temperature and high-temperature air. The environmental fatigue model for low-alloy steel is developed by the environmental fatigue correction factor (Fen) methodology based on the fatigue data in LWR water environments with the consideration of effects of strain rate, temperature, and dissolved oxygen concentration on the fatigue life.

This study investigated stress corrosion cracking (SCC) behavior of scratched areas across various depths and stress on alloy 690TT, through precise loading (252 samples in total) and SCC tests. Resultsindicate that SCC mainly initiates at the side walls of the scratch grooves rather than the bottom (sustains the highest stress level), given the low applied load stress about 13% of that at the bottom. Scratch depth is a more significant factor to SCC initiation in scratch groove than loading stress. A probabilistic model was established to predict SCC initiation induced by scratches of varyingdepths.

During the deformation of Mg alloys, {10-12} extension twin, as one of the most active deformation mechanisms, contributed much to the formation of basal texture, yet little to dynamic recrystallization (DRX) grains, i.e., effective grain refinement. In this work, {10-12} extension twin had been creatively utilized to achieve grain refinement and property improvement in a Mg-Gd-Y alloy by multi-directional impact forging (MDIF). Firstly, flourishing {10-12} extension twins divided the parent grain into many fine independent regions (~10 μm). Meanwhile, a large number of twin boundaries were pinning mainly by interaction with neighboring dislocations in twin or matrix. Secondly, those pinned twin boundaries can effectively accumulate dislocation slips and promote the formation of extensive low angle grain boundaries (LAGBs). These high densities of LAGBs can further subdivide the independent regions provided by extension twins into micro-regions (~5 μm). Thirdly, those fine micro-regions developed to be DRX after a dynamic recovery. Finally, we obtained a yield isotropy high-strength Mg alloy with an ultimate tensile strength of 354 MPa after MDIF of 110 passes. This work proposed a brand new insight to prepare wrought Mg alloy with fine grain, yet without strong texture, which is beneficial to better formability and mechanical property isotropy.