Review on the design of high-strength and hydrogen-embrittlement-resistant steels

Given the carbon peak and carbon neutrality era,there is an urgent need to develop high-strength steel with remarkable hydrogen embrittlement resistance.This is crucial in enhancing toughness and ensuring the utilization of hydrogen in emerging iron and steel materials.Simultaneously,the pursuit of enhanced metallic materials presents a cross-disciplinary scientific and engineering challenge.Developing high-strength,toughened steel with both enhanced strength and hydrogen embrittlement(HE)resistance holds significant theoretical and practical implications.This ensures secure hydrogen utilization and further carbon neutrality objectives within the iron and steel sector.Based on the design principles of high-strength steel HE resistance,this review provides a comprehensive overview of research on designing surface HE resistance and employing nanosized precipitates as intragranular hydrogen traps.It also proposes feasible recommendations and prospects for designing high-strength steel with enhanced HE resistance.

Mechanism of protective film formation during CO_2 corrosion of X65 pipeline steel

Electrochemical techniques, X-ray diffraction （XRD）, and scanning electron microscopy （SEM） were applied to study the corrosion behaviors of X65 steel in static solution with carbon dioxide （CO2） at 65℃. The results show that iron carbonate （FeCO3） deposits on the steel surface as a corrosion product scale. This iron carbonate scale acts as a barrier to CO2 corrosion, and can reduce the general corrosion rate. The protection ability of the scale is closely related to the scale morphological characteristics.

Enhanced Thermoelectric Transport Properties of La0.98Sr0.02CoO3-BiCuSeO Composite

We report a facile method to enhance the thermoelectric efficiency of La0.98Sr0.02CoO3-BiCuSeO by introducing BiCuSeO as a secondary phase with ultra-low thermal conductivity. Inclusion of secondary phase results in reducing the total thermal conductivity by suppressing the lattice and electronic thermal conductivities and also contributes to enhancement in the Seebeck coefficient. The wide grain size distribution of Laog^Sro02CoO3-BiCuSeO composite facilitates in breaking the interlinked transport properties through increased scattering of different wavelength phonons. The combined effect of enhanced Seebeck coefficient and ultra-low thermal conductivity, results in an improved ZT value of 0.07 at 923 K. The proposed strategy can be opted for improvement in the thermoelectric efficiency of other thermoelectric materials as well.

High level of circPTN promotes proliferation and stemness in gastric cancer

Increasing evidence proves that circular RNAs(circRNAs)play an important role in regulating the biological behaviors of tumors.The central purpose of this research was to investigate the functions of circRNA in gastric cancer.The utilization of real-time PCR was to test circPTN expression in gastric cancer cells.Cell counting colony formation assays,CCK-8 assay,and EdU assay were used to investigate proliferation.Transwell assay was applied to investigate migration.We discovered that circPTN was highly expressed in gastric cancer cells.Low expression of circPTN inhibits gastric cancer cell proliferation and migration.Elevated expression of circPTN promotes gastric cancer cell proliferation and migration.Moreover,we discovered that circPTN could accelerate self-renewal and increase the expression of stemness markers.The results of our study suggested that a high level of circPTN expression promotes the proliferation and stemness of gastric cancer cells.

Interactions between Pre-strain and Dislocation Structures and Its Effect on the Hydrogen Trapping Behaviors

This work investigated the effect of pre-strain and microstructures and their interactions on hydrogen trapping behaviors in case of 1-GPa high-strength martensitic steel Fe-0.05C-0.30Si-1.10Mn-3.50Ni-0.53Cr-0.50Mo-0.03 V(wt%).We found that the trapped reversible and trapped irreversible hydrogen contents increased significantly after applying a pre-strain of 5%,with an increase in the trapped reversible hydrogen content from 0.6 ppm in the original sample to 2.1 ppm.The hydrogen desorption activation energy also showed a slight increase.The microstructural evolution revealed that the concomitant dislocation cell-twin duplex microstructure with high-density tangled dislocations after pre-strain substantially increased the trapped reversible hydrogen contents.Additionally,the tangled dislocations pinned by the nanoprecipitates acted as deep irreversible hydrogen traps,increasing the trapped hydrogen at high temperatures after applying 5%pre-strain.These findings provide an expanded understanding of the hydrogen trapping behaviors of pre-strained microstructures.

Investigation of stress corre-sion cracking under anodic dissolution control

This review is about stress corrosion cracking (SCC) under anodic dissolution control. The section 1 is the methods distinguishing SCC controlled by anodic dissolution from those by hydrogen. The section 2 presents hydrogen-enhanced corrosion and SCC under anodic dissolution control. The section 3 demonstrates corrosion-enhanced localized plasticity and corrosion-induced deformation localization, which are the fundaments of new mechanism of SCC. The section 4 is an overview of the proposed mechanisms of SCC under anodic dissolution control. The last section proposes a new mechanism of SCC.

A strategy assisted machine learning to process multi-objective optimization for improving mechanical properties of carbon steels

Improvement in individual mechanical properties of carbon steels,such as strength or ductility,can no longer keep up with the increasingly demanding service environment.Therefore,it is of practical significance to improve two or more mechanical properties accurately and efficiently.In this work,five machine learning algorithms are first employed to establish prediction models for different mechanical properties(tensile strength,fracture strength,Charpy absorbed energy,hardness,fatigue strength,and elongation)based on the collected carbon steels data.Then,a set of mutually exclusive properties(tensile strength and elongation)and the key descriptors of the corresponding properties are identified by feature engineering,and the importance of the key materials descriptors is analyzed.The prediction models based on key descriptors for tensile strength and elongation also demonstrate good accuracy.All the key descriptors are considered as input features for the comprehensive performance(CP)calculated from the product of tensile strength and elongation.Finally,we develop a machine learning prediction model for CP and successfully apply the efficient global optimization algorithm to optimize two mutually exclusive mechanical properties.This work provides a new multi-objective optimization strategy that is expected to be used for the development of new steels with excellent comprehensive performance.

Stress corrosion cracking and its anisotropy of a PZT ferroelectric ceramics

Stress corrosion cracking (SCC) of a PZT ferroelectric ceramics in various media, such as moist at-mosphere, silicon oil, methanol, water and formamide, and its anisotropy have been investigated at constant load test using a single-edge notched tensile specimen. The results showed that SCC could occur in all media, and the threshold stress intensity factor of SCC in water and formamide, KISCC, revealed anisotropy. The KISCC for poling direction parallel to the crack plane, aISCC,Kwas greater than that perpendicular to the crack plane, bISCC,K similar to the anisotropy of fracture toughness KIC; however, the anisotropy factor of KISCC, which was abISCCISCC/KK=1.8 (in formamide) and 2.1 (in water), was larger than that of KIC, which is abICIC/KK=1.4. The stress-induced 90?domain switching causes the anisotropy of KIC and KISCC, besides, the resistance of SCC also has anisotropy.