High Strength Carbon Steel Research Articles

Stainless steels as a solution for corrosion and erosion problems involving grains in agribusiness sector applications

Agricultural activities such as grain processing play a crucial role in Brazil's economy, contributing significantly to its gross domestic product (27.4% in 2021). The use of carbon steel equipment leads to considerable environmental and economic losses in agribusiness due to corrosion. This study explores the erosion-corrosion behavior of a dual-phase 11Cr and an 18Cr8Ni stainless steel (SS), compared to a mild (ASTM A36) and a high-strength carbon (AHSS) steel under conditions close to the agribusiness reality. The impact of corn particles as erosive component associated to pure water and chloride-containing environments was studied using a fog chamber, a topic until now unexplored in the literature. The methodology adopted is novel and explores the erosion-corrosion synergy in cumulative steps, aiming to shed light on the mechanisms of corrosion and wear that affect the materials in the agribusiness industry. The findings reveal that corn particles, despite their soft nature, can easily remove non-adherent corrosion products from the steel surface. In the deionized water medium, the impact of the soft particles can also shift the corrosion pattern of advanced high-strength steels from general corrosion to localized pitting damage reduzing the corrosion rates. The carbon and 11Cr steels showed the highest corrosion rates under the pure corrosion condition in both media. The erosion-corrosion process considerably reduced the corrosion rate, mainly in the deionized water medium for the carbon steels. An exception to this behavior was 18Cr8Ni steel, whose corrosion rates, however, were the lowest among the materials. Low-chromium stainless steel emerges as a cost-effective solution to erosion-corrosion challenges in the agribusiness segment.

Carbon Dioxide Corrosion Mechanisms: Historical Development and Key Parameters of CO2-H2O Systems

The recent failures in flexible pipes have motivated the exhaustive research of corrosion mechanisms on high-strength carbon steel armor wires that are the main structural compounds of those structures that mostly operate in seawater environments in the presence of carbon dioxide (CO2) and confined spaces. Recently, the literature reported discoveries about electrolyte properties (as Fe+2(aq)/HCO3-(aq.) ratio) and supersaturation, near neutral pH inside the confined space, multiphase reactions of contaminants present in CO2 gas, the formation and dissolution mechanism of FeCO3 film, and interaction of CO2 gas impurities with the corrosion scale. Therefore, this review is aimed at presenting an up-to-date narrative of the CO2 corrosion phenomenon in carbon steel, connecting background fundamentals with current data studies.

Optimizing the hydrogen embrittlement resistance by Cu addition in a low carbon high strength steel

This study used the electrochemical hydrogen permeation test and the slow strain rate tensile (SSRT) test to examine the impact of Cu addition on hydrogen embrittlement (HE) in a low carbon high strength steel. The following method explains how Cu alloying affected HE resistance. (i) Cu alloying refined the prior austenite grain size, which increased the effective area of grain/packet/block/lath boundaries and mitigated the strain localization, and thus provided additional reversible hydrogen traps, homogenized the hydrogen distribution and suppressed local accumulation of hydrogen at boundaries. (ii) Cu alloying promoted the Cu-rich precipitates, which had strong binding energy with hydrogen. Also, the “incoherent” fcc Cu-rich precipitates contrary to the “slightly coherent” Cu-rich with an energy-poor trap strongly trapped hydrogen and enhanced the HE resistance.

Effect of High-Temperature Tempering on Microstructure and Mechanical Strength of Laser-Welded Joints between Medium-Mn Stainless Steel and High-Strength Carbon Steel

The strengthening effect due to high-temperature tempering (HTT) at 700 °C on the microstructure and mechanical properties of welded joints between medium-Mn stainless steel (MMnSS) and high-strength carbon steel (CS) was studied. The microstructure of the weldments was investigated using Laser and scanning electron microscopes. An Electron probe microanalyzer (EPMA) was used to assess quantitatively the elemental distribution profiles of alloying elements within the weld zone. The strengthening precipitates induced during welding and HTT were characterized by transmission electron microscopy (TEM). Uniaxial tensile tests and microindentation hardness (HIT) measurements of the weld joints were conducted to evaluate the strengthening effect. Fully fresh-martensite and fine-tempered martensitic structures were promoted in the as-weld and HTT processes, respectively. The HTT structure exhibited a remarkable improvement in mechanical properties (a better combination of yield and tensile strength together with moderate ductility) compared to its weld counterpart. TEM investigation revealed that various types of precipitates have been promoted in the structures of the weld and HTT, e.g., nanosized vanadium and chromium carbides. It is apparent that the proposed HTT of the joints is an effective treatment for improving the mechanical properties due to inducing the formation of fine interphase precipitates, resulting in enhanced mechanical strength of the joints.

Impact of Ultra-Flash Tempering Treatment on the Microstructure and Mechanical Properties of High-Strength Carbon Steel

A novel high-frequency induction technology was successfully developed to carry out ultra-flash tempering treatment (UFTT) of high-strength carbon steel (HS-CS) with a heating rate of 1000 °C/s. The as-received HS-CS is a fully martensitic structure with low toughness. UFTT strategy at various temperatures is proposed to produce a tempered martensitic lath structure with promoting carbide precipitates in this structure. Microstructure evolution during UFTT was characterized using secondary electron imaging and electron backscatter diffraction technique in a scanning electron microscope. Micro-indentation hardness tests were measured through the cross-section of the steel to analyze the impact extent of UFTT. The mechanical properties were measured by uniaxial tensile tests. The results revealed that UFTT at various temperatures (550-650 °C) significantly affected the microstructure and the mechanical strength of the steel. A fully tempered martensitic microstructure with various types of carbide precipitates was promoted. Although, the microhardness and tensile strength of flash-tempered steel decreased owing to the breakdown of lath and dislocation structure in the achieved microstructure by UFTT. Hence, it is expected that the promoted microstructure during UFTT in the tested steel will result in a superior strength-toughness synergy. Based on the achieved results, the UFTT technique provides an alternative route for the conventional processing to tailor the microstructure of microalloyed HS-CS, consequently, optimizing the mechanical performance. Meanwhile, Economically, it is a cost-effective route to manufacture advanced high-strength steel.

Enhancement of the resistance to hydrogen embrittlement by tailoring grain boundary characteristics in a low carbon high strength steel

In this work, the feasibility of using “grain boundary engineering” to reduce the susceptibility to hydrogen embrittlement in a low carbon low alloy steel was examined. By adding Cu element, the fraction of random grain boundary (RGB) exhibited the highest value in the steel with 1%Cu, while the fraction of special grain boundary (SGB) showed a monotonical decline. The slow strain rate tensile (SSRT) test revealed that the elongation loss presented an increase with Cu addition increasing from 1 % to 3 %. This can be explained in terms of hydrogen diffusion, hydrogen trap and crack propagation. The steel with 1%Cu had a higher fraction of high angle grain boundary (HAGB), which contributed to a higher density of hydrogen traps and a lower hydrogen diffusion rate. Moreover, the steel with 1%Cu had the highest fraction of SGB (∑3, ∑5, ∑7 and ∑≥9), which was beneficial to the resistance to crack propagation. Under the combined effect of RGB and SGB, a higher resistance to hydrogen embrittlement was achieved in the steel with 1%Cu.

Life‐Cycle‐Assessment of purlin systems: the influence of the low carbon high strength steels in CO2eq. emissions

AbstractDue to the decarbonization of the energy sector, embodied carbon has been recognized as the dominant climate impact driver. In response, countries are currently accelerating their efforts to comply with climate change commitments and regulations, pressure grows for the construction sector to reduce its impact rapidly.In the present paper, the life cycle assessments (LCA) of purlin roof systems, used as secondary structural elements on single‐story industrial buildings, are compared. Three structural materials are considered: metallic‐coated structural steel, reinforced concrete, and structural timber. In addition, different steel grades are compared to highlight the environmental benefits of using high‐strength steels (HSS) allowing weight‐optimized design.The LCA focuses on the product stage (modules A1‐A3), transport (module A4), end‐of‐life (module C), and the benefits and loads beyond the system boundary (module D). The life cycle inventory (LCI) is composed of construction environmental product declarations (EPD) published according to EN 15804. All the LCA evaluations are performed using the commercial software One Click LCA following the recommendations of EN 15978.

On the fatigue behaviour and reliability assessment of high strength welded details

This research focusses on the fatigue behaviour of welded components made of high strength duplex (EN 1.4162) and carbon steel. It starts by investigating the base material alongside welded cruciform joints submitted to cyclic loading through experiments and finite element models. The obtained results are then compared with existing research on high strength (carbon and stainless) steel equivalents. This collated database of >500 reference test results is then used to assess the applicability of the current Eurocode and IIW provisions to predict the fatigue life of higher strength steels and to propose new rules that include the benefit of their higher material strength. Proposals are made to upgrade certain fatigue classes (e.g., transverse stiffeners and butt welds) when high strength steel grades are employed. The reliability of these proposals is then supported by the use Weibull models, commonly used in survival analysis.

Experimental testing of stainless steel bolt assemblies at elevated temperatures

This paper presents the results from a programme of elevated temperature tests focussing on the tensile behaviour of austenitic stainless steel bolts of grade A2–80 and A4–70. The tensile tests were carried out on bolt assemblies in the temperature range of 20 °C and 900 °C under a steady-state approach. Following the tests, a suite of tensile strength reduction factors were derived and these were compared with the existing bolt reduction factors proposed in the literature along with the codified values for equivalent stainless steel plate materials. The comparisons reveal that the manufacturing process of the stainless steel bolt, particularly the nature of thread rolling, can significantly affect their fire performance. For example, the present study reported a reduction factor of 0.098 for A4–70 at 800 °C as opposed to 0.176 (80% higher) and 0.34 (250% higher) for a bolt formed through a different manufacturing process and equivalent stainless steel plate materials, respectively. It was also concluded that while both the tensile strength and the ductility of stainless steel bolts gradually decrease with increasing temperature, stainless steel bolts retain a higher portion of their room temperature tensile strength compared with equivalent high strength carbon steel bolts beyond high temperatures of 450 °C for A2–80 bolts and 400 °C for A4–70 bolts.

The role of reverted transformation in hydrogen embrittlement of a Cu-containing low carbon high strength steel

This work presents an investigation on the role of reverted transformation in hydrogen embrittlement, aiming at revealing the influencing mechanism of austenite and grain boundary characteristics on hydrogen embrittlement (HE) susceptibility during reverted transformation. The results showed that HE susceptibility decreased with the annealing temperature increasing from 680 °C to 720 °C, which attributed to a combined effect of austenite and grain boundary distribution. Both the fractions of austenite and high angle grain boundary (HAGB) increased with the annealing temperature increasing from 680 °C to 700 °C, which resulted in a lower HE susceptibility at 700 °C due to strong H storage of austenite and HAGB. As the annealing temperature further increased to 720 °C, the fraction of austenite exhibited a decline, but the fraction of HAGB monotonously increased. As a result, a lower HE susceptibility was achieved at 720 °C. This indicated that grain boundary distribution played a determining role in the resistance to HE. We ascribed this to the variant selection and Bain/CP grouping.

Evaluation of microstructural and environmental effects on the hydrogen uptake and desorption in high-strength carbon steels: A thermal desorption spectroscopy study

The hydrogen uptake in three high-strength carbon steels is studied after exposure to three different environments: an aqueous solution with CO2 bubbling, CO2/H2S bubbling, and cathodic charging without external gassing. The hydrogen uptake is substantially higher in CO2/H2S environment compared to CO2 environment for all materials. The lamellar cementite morphology absorbs higher hydrogen than the material with spheroidite microstructure with similar carbon content. The corrosion layer formed on the steels in CO2 environment strongly affects the hydrogen effusion and the thermal desorption spectroscopy spectrum in all materials, while the corrosion layer formed in CO2/H2S environment does not show this effect.

Surface Topography Model of Ultra-High Strength Steel AF1410 Based on Dynamic Characteristics of Milling System

AF1410 is a low carbon high alloy ultra-high strength steel. It not only has high strength and high toughness, but also has a high stress corrosion resistance. However, due to the characteristics of hard quality and poor thermal conductivity, AF1410 is a difficult material to process. In the process of milling, the geometric factors of process parameters, the flexible deformation of milling cutter and the flutter of the process system all affect the surface roughness, which makes it difficult to predict the surface roughness of milling parts. In order to solve this problem, a prediction model for surface topography of ultrahigh strength steel AF1410 was studied. To solve this problem, this paper studies the formation of milling surface topography, considers the dynamic displacement of the milling system, proposes a modeling method of surface topography based on the dynamic characteristics of the milling system and forms a prediction model. On this basis, the surface topography of ultra-high strength steel is simulated and analyzed, and the accuracy of the model is verified by experiments. The study realizes the prediction of milling surface topography of AF1410 parts and reveals the formation mechanism of milling surface topography from geometric and physical perspectives.

Role of cementite morphology on corrosion layer formation of high-strength carbon steels in sweet and sour environments

The effect of cementite morphology on the corrosion layer formation of four high-strength carbon steels was studied in an aqueous solution containing CO2 and CO2/H2S. The linear polarization resistance and weight loss data reveal that as the cementite phase fraction is increased, the corrosion rate increases in CO2 environment, while no trend is observed in the CO2/H2S environment. The results indicate that a porous and, non protective corrosion layer forms in the CO2 environment, whereas a protective layer forms in the CO2/H2S environment. A mechanism that explains the role of cementite morphology on corrosion layer formation in a CO2 environment is proposed for the studied materials.

Influence of thermally grown oxides on interfacial friction during hot deformation of large-size forging ingots

High-strength steels are pre-heated in gas-fired furnaces before undergoing the open-die forging process. This process increases thermal oxidation on steel surfaces, affecting the interfacial friction between ingot and anvils during deformation. Two medium carbon high-strength steels with different nickel contents were oxidized, and the mechanical characteristics of oxide layers were investigated by micro and nano-indentation methods. It was found that the formed layers on high nickel steel had lower Young modulus and hardness compared to the steel with lower nickel. Finite element modeling and ring tests were used to assess oxide layers' effect on interfacial friction during deformation. The results demonstrated that oxide layers' formation decreased the interfacial friction and deformation load, acting as lubricants at high temperatures.

The Effects of NaCl on Hydrogen Permeation and Sulfide Stress Cracking Resistance of C110 High-strength Steel

Sulfide stress cracking (SSC) limits the application of high-strength low-alloy carbon steel C110 in the oil and gas industries. Chloride ions (Cl−) play an indispensable role in SSC. This study aims to evaluate the effects of NaCl on hydrogen permeation and SSC susceptibility by electrochemical techniques including hydrogen permeation test and electrochemical impedance spectroscopy (EIS), and the novel notched tensile slow strain rate test on carbon steel C110 under wet-H2S environments. The results show that the higher concentration of Cl− reduces hydrogen absorption and enhances SSC susceptibility. However, it is widely accepted that the reduction in hydrogen absorption results in an increase in SSC resistance. To figure out the role of Cl− in the SSC mechanism, the morphology of the side and the cross-sectional surface were observed. It was found that a higher pit density in a condition with a higher Cl− concentration leads to increased SSC susceptibility as pits act as crack initiation sites. The SSC mechanism transfers from hydrogen embrittlement to pit-induced cracking when the Cl− concentration in the solution increases.

Studying the strengthening mechanisms and mechanical properties of dissimilar laser-welded butt joints of medium-Mn stainless steel and automotive high-strength carbon steel

In this study, a post-weld heat treatment (PWHT) at a high temperature of 700 °C for 10 min was proposed to significantly improve the mechanical performance of dissimilar laser-welded butt joints between medium-manganese stainless steel (MMn-SS) and high-strength carbon steels (HS-CS) as base metals (BMs). Electron backscatter diffraction and transmission electron microscopy were employed to characterise the microstructures and study the deformation mechanisms in the paired metals of the dissimilar joints during PWHT and tensile straining. Micro-indentation hardness tests were performed to analyse the mechanical responses in the weld zones after PWHT. The results revealed that PWHT at 700 °C significantly affected the microstructure and mechanical strength of the BMs and their weldments. A fully tempered martensitic microstructure with recrystallised grain regions was formed in the fusion zones (FZs) of the weldments, which were processed at low and high specific point energies (SPEs) of 19, 25, and 30 J. BM HS-CS was significantly strengthened owing to the interphase precipitation hardening of vanadium carbide precipitates during the proposed PWHT. The strength-ductility balance of BM MMn-SS was improved by combining the martensitic transformation and mechanical twinning mechanisms. Although, the tensile strength of BM HS-CS increased from 500 to 630 MPa and that of the metal in the FZ decreased from 1100 to 800 MPa owing to PWHT. Hence, HS-CS is a weak metal for dissimilar joints, and joint failure was promoted in it.

Hydrogen embrittlement of high-strength API carbon steels in H2S and CO2 containing environments

This study aims to understand the Sulfide Stress Cracking (SSC) resistance of API carbon steels exposed to wet sour environments containing CO2. A mini-pipe specimen was cut from API grade tubulars and placed in an SSC test cell to perform the investigation. The specimen was highly strained and internally pressurized while exposed to the corrosive environment for seven days. The partial pressure ratio (PPR) of CO2 (i.e. ratio of partial pressure of CO2 to the total pressure) was varied to study the effect of CO2 content on SSC. Experiments were performed while maintaining a constant H2S concentration and temperature. The steels' variations in mechanical properties (ultimate tensile strength and plastic strain before failure) after exposure to the sour environment are used to quantify the embrittlement. In addition, the specimens were examined using optical microscopes to assess the severity of the SSC corrosion based on shear deformation patterns and crack features. The SSC resistance of the tested steels was minimized when the PPR of CO2 was approximately 20%. Results demonstrate that the materials have adequate SSC corrosion resistance to be utilized in the environment containing 280 ppm H2S. Nevertheless, their SSC resistance reduced noticeably between 10 and 30% PPR of CO2.

Refinement mechanism of nanoscale Cu-rich precipitates by Mo addition and its effect on strength-toughness of Cu-bearing low carbon high strength steel

Effect of Mo element on the precipitation behavior of nanoscale Cu-rich particles in Cu-bearing low carbon high strength steels was investigated in this work. The addition of 0.82 wt% Mo refined the size of grain interior Cu-rich particles (ICRPs) from 12 nm to 8 nm, accompanied by the structure changed from 3R-Cu to 9R-Cu. Mo also inhibited the formation of grain boundary Cu-rich particles (BCRPs) with the size of ∼30 nm. The calculation of phase field method indicated that Mo was repelled from Cu-rich particles and enriched in α-Fe matrix, which suppressed the diffusion of Cu atoms and merger of Cu-rich particles. The measured yield strength of CuMo-bearing steel increased by 87 MPa, mainly due to the refinement of ICRPs. The reduction of BCRPs suppressed the crack initiation and propagation at grain boundaries, which contributed to the increment of absorbed energy at −40 °C by 41J.

Favorable Impact Toughness of High Heat Input Coarse-Grained HAZ in an Ultra-Low Carbon High-Strength Microalloyed Steel

Favorable Impact Toughness of High Heat Input Coarse-Grained HAZ in an Ultra-Low Carbon High-Strength Microalloyed Steel

Microstructure and Impact Toughness of the Coarse-Grain HAZ Physically Simulated with Different Heat Inputs in a 690 MPa Ultra-low Carbon High-Strength Microalloyed Steel

Microstructure and Impact Toughness of the Coarse-Grain HAZ Physically Simulated with Different Heat Inputs in a 690 MPa Ultra-low Carbon High-Strength Microalloyed Steel