HSLA Steel Research Articles

Analysis of cracks origin behaviors during sulfide stress corrosion (SSC) in HSLA steel at different temperatures by electrochemical noise

Analysis of cracks origin behaviors during sulfide stress corrosion (SSC) in HSLA steel at different temperatures by electrochemical noise

Tensile Deformation and Fracture Behavior of API-5L X70 Line Pipe Steel.

Thermo-mechanical controlled processing (TMCP) is employed to obtain the required level of mechanical properties of contemporary HSLA steel plates utilized for gas and oil pipeline production. The strength and crack resistance of pipeline steels are mainly determined by its microstructure and crystallographic texture. In this study, the influence of the structural and textural states of industrially produced API-5L X70-X80 pipeline steels on tensile mechanical properties was analyzed. TMCP routes with different hot rolling temperatures and cooling rates were employed. The texture of steel was assessed using the Taylor factor, which was calculated based on electron backscatter diffraction (EBSD). The decrease in rolling temperature resulted in the sharper texture characterized by {001} planes banding (cleavage planes in the bcc lattice) parallel to rolling direction. The tensile deformation behavior at the stage of necking was determined by the crystallographic and morphological texture of the material and demonstrated significant anisotropy. Rupture of all investigated samples was accompanied by the development of splitting on the fracture surface. The splitting was localized in the rolling plane similar to the splitting in standard Charpy tests of pipeline steels.

Investigation on the Effect of Asymmetric Cyclic Loading on Ratcheting Deformation and Bulk Texture Development in HSLA Steel

Ratcheting deformation in association with bulk texture evolution in HSLA steel is studied in this investigation. The cyclic deformation behaviors and damage modes of the specimens are obtained at room temperature, employing asymmetric stress-controlled tests under various combinations of mean stress and stress amplitudes. Bulk texture measurements of the specimens are done adopting an X-ray diffraction analysis. The results exhibit an increase in strain accumulation from 0.23 to 30.61% associated with a sharp reduction in ratcheting life from 3320 to 880 cycles by the increment in mean stress/stress amplitude. A continuous cyclic softening until the final failure is observed for all the ratcheting tests. It is noticed that variation of mean stress is more detrimental than stress amplitude in controlling strain accumulation while the effect of stress amplitude is more pronounced than mean stress for the reduction of ratcheting life. The fracture surface morphology indicates typical striation formation in the crack propagation region along with overload failure. The bulk texture studies indicate that there is a transition between ‘ϒ’ fiber and ‘ζ’ fiber during all loading conditions. The texture intensity is increased from 5.71 to 11.68 with progressive ratcheting strain accumulation. Here also, influence of stress amplitude is more significant than the mean stress.

Electron Backscattered Diffraction Characterization of S900 HSLA Steel Welded Joints and Evolution of Mechanical Properties

Electron Backscattered Diffraction Characterization of S900 HSLA Steel Welded Joints and Evolution of Mechanical Properties

The influence of final coiling temperature on the microstructure and mechanical properties of high Ti-V HSLA steels

In general, the strength-to-weight ratio is a marked property of high- strength low-alloy steel. The coiling temperature is an important process parameter in the control and improvement of final microstructure and mechanical properties. In this work, the effect of deformation and coiling temperature on microstructure and mechanical properties of high Ti- V microalloyed HSLA steels were investigated using the Gleeble 1500TM thermomechanical processing simulator. The samples were austenitised at 1150 ˚C for 300 s, then deformed in 4 passes at 1050, 1000, 950 and 900 ˚C. After final pass, the samples were cooled and isothermally held for 1800 s to simulate the coiling process at 550 and 650 ˚C. The results showed that at low coiling temperature (LCT) of 550 ˚C, the microstructures consisted of ferrite and bainite and also had higher hardness (304 HV).

Experimental Analysis of HSLA Steel Welded Joint Fracture Behaviour

In order to assess the integrity of welded pressure vessel containing a crack, the behavior of three-point bending specimens made of HSLA steel welded joint are tested at -40°C, and their fracture behaviour analyzed, as a conservative measure of crack resistance. Specimens were made of low-alloyed steel NIONIKRAL 70, welded by SAW process. Surface notches were machined by the electro-erosion method in the parent metal (PM), heat affected zone (HAZ) and weld metal (WM). The highest resistance to cracking was in PM, and the lowest one in WM, due to so-called pop-in behaviour.

The Multi-Dimensional Grain Refinement of Metastable Austenite in a HSLA Steel Developed Through Hot Rolling, Partitioning and Tempering

The Multi-Dimensional Grain Refinement of Metastable Austenite in a HSLA Steel Developed Through Hot Rolling, Partitioning and Tempering

Improvement of Ti-Ce Coordinate Addition on Pitting Corrosion Behavior of Hsla Steels Inclusions

Improvement of Ti-Ce Coordinate Addition on Pitting Corrosion Behavior of Hsla Steels Inclusions

Improvement of Strength and Toughness of 1 GPa Cu-Bearing HSLA Steel by Direct Quenching

Improvement of Strength and Toughness of 1 GPa Cu-Bearing HSLA Steel by Direct Quenching

Application of advanced NDT methods to assess structural integrity of pressure vessel welded joints

The review of non-destructive testing of pressure vessel for compressed air is given, as well as the assessment and analysis of defects on the integrity of the vessel itself. The focus here is on welded joints, as the most critical areas in pressure vessels, especially if thickness is large, like in the case considered here (50 mm), cylindrical air storage vessels made of HSLA steel. Toward this end conventional NDT methods, such as UT and Radiography are used in the first phase of this research, providing valuable data for structural integrity assessment based on detected unacceptable defects in welded joints. Anyhow, since few unacceptable defects were found by conventional UT, there was a need to use advanced NDT UT methods, such as Phased Array Ultrasonic Testing (PAUT), to evaluate defect position and size more precisely. In this way risk of failure can be assessed more reliable, which is of utmost importance for pressure vessel where probability of failure is low, but the consequence of failure is potentially catastrophic, like in the case considered here.

Effect of undercooled austenite ausforming on the role of the M–A constituents in the CGHAZ toughness of the HSLA steels with bainite structure

The brittle martensite-austenite (M-A) constituents in the coarse-grained heat-affected zone (CGHAZ) of the bainite steel are known to have negative effect on toughness. To modify the microstructure of the M–A constituents and then improve the CGHAZ toughness, this work applied ausforming to the bainite steel during its CGHAZ simulating process when the temperature of the thermal cycle decreased to 600 °C. Morphology of the M–A constituents in the CGHAZ with and without the ausforming was observed by optical microscopy (OM) and scanning electron microscopy (SEM). The microstructure of the M–A constituents was characterized by transmission electron microscopy (TEM), the toughness of the specimens was assessed through instrumented Charpy impact test, and the crack behavior beneath the fracture was revealed by SEM. Results show that the ausforming contributes to the austenite formation within the M–A constituents, which helps to improve the CGHAZ toughness from 10.50 J to 33.70 J. This work proposed a nontraditional method that enables the microstructure modification of the M–A constituents and the toughness improvement in the CGHAZ.

Microstructure and Strengthening Mechanisms in an HSLA Steel Subjected to Tempforming

An effect of tempforming on the microstructure, the carbide precipitation, and the strengthening mechanisms of high-strength low-alloyed steel has been analyzed. The quenched steel was subjected to 1 h tempering at a temperature of 873 K, 923 K, or 973 K followed by plate rolling at the same temperature. Tempforming resulted in the formation of an ultrafine grained lamellar-type microstructure with finely dispersed carbides of (Nb,V)C, Fe3C and Cr23C6. A decrease in tempforming temperature resulted in a reduction of the transverse grain size from 950 nm to 350 nm. Correspondingly, the size of Fe3C/Cr23C6 particles decreased from 90 nm to 40 nm while the size of (Nb,V)C particles decreased from 17 nm to 4 nm. Refining the tempformed microstructure with a decrease in thetempforming temperature provided an increase in the yield strength from 690 MPa to 1230 MPa.

Validation of materials-informed digital twin: Mapping residual strains in HSLA steel weldment using high energy X-rays

The shipbuilding industry has placed an emphasis on establishing digital twin prototypes to advance computational lifecycle analysis capabilities. However, material processing data is not currently included in simulations for structural performance, which could lead to inaccuracies. Integrated Computational Materials Engineering (ICME) techniques yield a path to solving this problem through linking digital information across multiple length scales in order to minimize the time and cost of physical testing needed for validation. This paper details the initial work of a larger materials-informed digital twin effort seeking to validate the need for fabrication inclusion in lifecycle analysis. First, the selection and fabrication of the “sister sample” specimens used for physical validation from a single plate of HSLA-100 steel. Second, the finite-element analysis (FEA)-based welding simulations of the reinforced dog-bone weldment. Third, comparison of predicted strain data from FEA simulations to two-dimensional (2D) strain maps using energy dispersive diffraction (EDD) techniques at the Cornell High-Energy Synchrotron Source (CHESS). The results showed high correlation between the measured EDD data and the FEA predictions, particularly for the high strain (>0.0015) fields of first principle strain vectors measured parallel to each welding pass. This computational validation is the first step towards validating the materials-informed digital twin method for increasing accuracy of structural analysis and fatigue lifecycle evaluation.

AUSTENITE – FERRITE TRANSFORMATION TEMPERATURES OF C MN AL HSLA STEEL

The article is aimed to investigate a shift of transformation temperatures of C-Mn-Al HSLA steel with different cooling rates. The transformation temperatures from austenite to ferrite have been determined by dilatometry using thermal-mechanical simulator Gleeble 1500D. To define the start and finishing temperatures of the austenite-ferrite transformation intersectional method was used. Effect of cooling rate on transformation temperature has been evaluated for 0.17, 1, 5, 10, 15, 20, 25°C.s-1. There was found out that rising the cooling rate results in moving transformation temperature range to lower temperatures. The transformation temperatures have been also compared with temperatures calculated using equations of several authors. Some of them have considered cooling rates only. Cooling rates have effect on final microstructure. The effect has been evaluated by measuring hardness (HV10) relating the cooling rates from 0.17 to 25°C.s-1. Increasing cooling rates resulted in increase of hardness. Moreover, Thermo-Calc software was used to determine the Ae3 and Ae1 equilibrium temperatures. Equilibrium transformation temperatures Ae3-Ae1 were higher than experimentally measured by dilatometric method using Gleeble 1500D.

Zinc Coatings for High-Strength Low Alloy Steels: Comparison of Microstructure and Hydrogen Embrittlement During Heat Treatment

In this paper, the effect of hydrogen embrittlement in High-strength low-alloy steel (HSLA) material was studied. HSLA steels are known for their susceptibility to hydrogen induced failure especially when subjected to hydrogen rich environment. In this research, samples from HSLAS were surface-treated using chemical vapor deposition (CVD) techniques, followed by direct Zinc coating using physical vapor deposition (PVD). Other samples were additionally post-heat treated at a temperature of 260∘C for 4[Formula: see text]h to optimize the coating process. The hydrogen embrittlement test was performed by immersing the tensile samples in a solution containing H2SO4diluted with water for 24[Formula: see text]h. Hardness, and mechanical properties were evaluated using tensile testing. XRD and SEM were used for microstructural and topographical features’ examination of the treated samples. The results indicate that the samples of combined [Formula: see text] coating that was backed at 260∘C show superior resistance to hydrogen embrittlement compared to other conditions. This could be attributed to the buildup of a strong outer layer that prevents hydrogen from diffusing towards the base HSLAS material. The greater mechanical properties are possibly due to the reduction of hydrogen amount generated by the surface reaction associated by the formation of Zn(N[Formula: see text] phase and the reduction of hydrogen amount passed through Zn and C3N4layers.

Perspectives on Maximizing Strengthening Mechanisms in Automotive HSLA Steel

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Enhanced Long-Term Reliability of Seal DeltaSpot Welded Dissimilar Joint between 6061 Aluminum Alloy and Galvannealed Steel via Excimer Laser Irradiation.

Structural-adhesive-assisted DeltaSpot welding was used to improve the weldability and mechanical properties of dissimilar joints between 6061 aluminum alloy and galvannealed HSLA steel. Evaluation of the spot-weld-bonded surfaces from lap shear tests after long-term exposure to chloride and a humid atmosphere (5% NaCl, 35 °C) indicated that the long-term mechanical reliability of the dissimilar weld in a corrosive environment depends strongly on the adhesive–Al6061 alloy bond strength. Corrosive electrolyte infiltrated the epoxy-based adhesive/Al alloy interface, disrupting the chemical interactions and decreasing the adhesion via anodic undercutting of the Al alloy. Due to localized electrochemical galvanic reactions, the surrounding nugget matrix suffered accelerated anodic dissolution, resulting in an Al6061-T6 alloy plate with degraded adhesive strength and mechanical properties. KrF excimer laser irradiation of the Al alloy before adhesive bonding removed the weakly bonded native oxidic overlayers and altered the substrate topography. This afforded a low electrolyte permeability and prevented adhesive delamination, thereby enhancing the long-term stability of the chemical interactions between the adhesive and Al alloy substrate. The results demonstrate the application of excimer laser irradiation as a simple and environmentally friendly processing technology for robust adhesion and reliable bonding between 6061 aluminum alloy and galvannealed steel.

Root formation and mechanical properties in laser keyhole welding of 15 mm thick HSLA steel

Deep penetration laser welding is promising in joining thick (> 10 mm) steel sections. Focused laser beam by drilling vapour cavity, the keyhole, generates deep and narrow welds. Full penetration single-pass joining has a persistent problem with root quality where humping is one of the most frequent imperfection. This strongly hampers the use of high-power laser for thick plate welding. A 16 kW disk laser was used for single-pass welding of 15 mm thick plates in a butt joint configuration. Root humping occurred within a wide range of welding parameters. This provides narrow processing window. By adding an arc source to the laser beam process, the tendency of root humping increases. To achieve humping-free welds and consistent root quality over length, a delicate balance of process parameters is required. High heat input (> 0.50 kJ/mm) was positive to achieve a combination of low hardness (< 325 HV) and good Charpy toughness at -50 °C (> 50 J).

Design of a novel HSLA steel with a combination of high strength (140–160 ksi) and excellent toughness

Abstract Three steels were designed based on HSLA-100 with additional levels of Mn, Ni, Cr and Cu. The steels were prepared by controlled rolling and tempered at temperatures in range of 550–700°C. The continuous cooling time curves were shifted to longer times and lower temperatures with the increased tendency for the formation of martensite at lower cooling rates. The microstructures revealed that controlled rolling results in austenite with uniform fine grain structure. The steel with the highest amount of Mn showed the greatest strength after tempering at 750 °C. The top strength was attributed to the formation of Cu-rich particles. The steel with 1.03 wt.% Mn, tempered at 650 °C exhibited the best Charpy impact toughness at –85°C. On the other hand, the steel that contained 2.11 wt.% Mn and tempered at 700 °C showed the highest yield strength of 1 097.5 MPa (∼159 ksi) and an impact toughness of 41.6 J at –85°C.

Finite Element and Finite Volume Modelling of Friction Drilling HSLA Steel under Experimental Comparison.

Friction drilling is a widely used process to produce bushings in sheet materials, which are processed further by thread forming to create a connection port. Previous studies focused on the process parameters and did not pay detailed attention to the material flow of the bushing. In order to describe the material behaviour during a friction drilling process realistically, a detailed material characterisation was carried out. Temperature, strain rate, and rolling direction dependent tensile tests were performed. The results were used to parametrise the Johnson–Cook hardening and failure model. With the material data, numerical models of the friction drilling were created using the finite element method in 3D as well as 2D, and the finite volume method in 3D. Furthermore, friction drilling tests were carried out and analysed. The experimental results were compared with the numerical findings to evaluate which modelling method could describe the friction drilling process best. Highest imaging quality to reality was shown by the finite volume method in comparison to the experiments regarding the material flow and the geometry of the bushing.