High Strength Steel Materials Research Articles

Determination of Johnson–Cook Material and Failure Model Constants for High-Tensile-Strength Tendon Steel in Post-Tensioned Concrete Members

The estimation of damage in steel tendons is important for evaluating the remaining capacity of existing tensioned members. This research focuses on calculating Johnson–Cook (LC) model and damage parameters of high-strength steel material through quasi-static and dynamic uniaxial tests. Finite element analysis is used to replicate the experimental procedure, and through dynamic image correlation analysis, the numerical results accuracy is verified. In this investigation, it is found that the JC model can accurately replicate deformation and stress concentration under different strain rates and triaxiality conditions and, thus, can be used for fracture analysis of prestressed concrete members.

An Approach for an Innovative 3D Steel Strip Straightening Machine for Curvature and Saber Compensation

Due to increasing globalization and rising quality requirements, the steel and metal processing industry is facing growing cost and innovation pressure. Not least because of their high lightweight potential, high-strength steel materials are meeting the growing material requirements of steel and metal processing in areas such as aerospace and medical technology. In particular, the tight tolerance limits of applicable shape and dimensional accuracies pose a challenge in the processing of high-strength steel strip materials. Improving the processability of high-strength steel materials through the use of straighteners with set-up assistance systems significantly increases the potential for competing with other materials such as aluminum or magnesium alloys.

Investigation of block shear strength of high strength steel bolted connections

This study presents an experimental and numerical investigation of block shear strength of high strength steel (HSS) bolted connections under double shear. A total of 16 HSS (grades Q690 and Q960) and eight mild steel (MS) (grade Q345) bolted connection specimens with various geometric configurations were tested and failed in block shear failure mode. The test and finite element (FE) analysis results confirmed that the block shear failure is a combination of fracture of the net tension plane and yielding of the effective shear plane, which is located between the net and gross shear planes. The effects of material properties (such as ductility and tensile-to-yield strengths ratio (fu/fy)) of steel materials on the block shear strength were comprehensively investigated based on the validated FE models. It was found that the tensile stress across the net tension plane could be fully developed irrespective of the steel grade due to effective stress redistribution along the net tension plane and the beneficial effect of the biaxial tensile stress state. However, the shear stress magnitude along the shear plane is influenced by the ductility and fu/fy ratio of steel materials and the length of the shear plane. The low ductility and fu/fy ratio of HSS materials did not allow for effective stress redistribution along the long shear plane and the shear yielding could only partially develop along the shear plane at the ultimate state. For the HSS specimens with short shear planes, the shear stress could develop up to the shear yield strength in general. Finally, the accuracy of the existing design equations in various design codes (i.e., prEN 1993–1–8: 2021, ANSI/AISC 360–16, and CSA S16–19) and relevant literature for predicting the block shear strength of bolted connections was evaluated and design recommendations were provided.

Design and Fabrication of Injection Molds to Manufacture Double Channel Laryngoscope for Effective Airway Management: Taguchi Method for Surface Roughness Optimization

The present work focuses on the mold design and production of the multifunctional device laryngoscope with surface quality through the injection molding process. A laryngoscope is a device used by anesthesiologists to lift the tongue that facilitates to fix the air pipe in the larynx. Demand still exists in the laryngoscope part to assist anesthesiologists to take care of the airway without causing chest compression and ensure visualization of vocal cords. Therefore, the present work aims at developing a laryngoscope with a double channeled device, wherein one for aligning the camera and another for the air pipe. The paper outlines the design parameters required for manufacturing a single cavity mold to produce a laryngoscope viz. injection molding machine. The mold has multiple plates with complex fluid channels which ensures effective thermal management in-mold system. The mold is manufactured using high-strength tool steel materials and the product laryngoscope (ABS: Acrylonitrile butadiene styrene) is fabricated from the designed mold. Taguchi L9 experimental array was used to determine the optimal conditions (injection pressure, injection velocity, mold and melt temperature) for desired surface finish in the laryngoscope parts. The designed mold and optimized injection molding conditions resulted in a lower surface roughness value equal to 0.214 µm. Thereby, injection-molded laryngoscope parts can be used for large-scale productions for the benefit of medical applications.

Wear resistance performance of sheet metal die materials: a review

The high and ultra-high strength steel materials are widely used in sheet metal forming processes such as stamping, bending, piercing, etc. in the automotive industry. Because of a strong adhesive propensity between the tool and the surface, the wear of the tool is created. The wear of the tool affects the dimensional property of the products, problems of surface quality and consequently interruptions of production. The wear behaviour and wear mechanisms of sheet metal dies were studied in this paper. This paper focuses on recent developments in tribological tool wear and provides adequate data on tool wear features.

Design for local buckling behaviour of welded high strength steel I-sections under bending

Local buckling behaviour of welded high strength steel (HSS) I-sections subjected to bending is crucial for structural designs, and has been found to be affected by the interactive effect between flanges and web. To realize accurate designs considering the local buckling behaviour, the continuous strength method (CSM), direct strength method (DSM) and the method from Kato, all of which incorporate the element interaction, have been developed for hot-rolled or cold-formed structures fabricated with conventional strength steel, aluminium or stainless steel. This paper aims to extend these methods for the design of welded HSS I-sections subject to bending. The results of 593 HSS material tensile tests and 40 tests on HSS I-beams are collated. 526 numerical models are generated to expand the data pool for this study using the validated finite element method. Underpinned by the collection of test data and numerical data generated from an extensive parametric study, the design expressions based on the CSM, DSM and the method from Kato, applicable to HSS I-sections under bending, are proposed. The statistical and reliability analysis indicate that the proposed CSM, DSM and Kato’s method provide more satisfactory strength predictions than the codified design rules in Eurocode 3 and AISC specification. In comparison with the proposed CSM and DSM, the predictions based on the modified Kato’s method show higher accuracy, which may be attributed to the separate consideration for the effect of flange and web slenderness in Kato’s expression.

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.

Experimental and numerical study on net section resistance of high strength steel staggered bolted connections

This paper investigates the structural behaviour and ultimate strength of high strength steel (HSS) staggered bolted connections under tension. A total of 33 HSS (Q690 and Q960) and 15 Q345 staggered bolted connection specimens were tested. All specimens failed in net section fracture through the staggered path. The predicted net section resistance based on the s2/4g rule was achieved by most of the HSS specimens. For the specimens with a small bolt pitch to gauge (s/g) ratio, the connection efficiency (i.e., the ratio between the test ultimate load and the calculated net section resistance) exceeded 1.0 and decreased gradually with an increasing s/g ratio. Compared with the mild steel (MS) specimens, in general the HSS specimens have lower connection efficiency and overall deformation capability. Subsequently, the structural behaviour of the test specimens was investigated using finite element (FE) analysis to further interpret the test observations. The results of the test and the FE analysis indicated that for the HSS specimens, effective stress redistribution along the staggered net section was observed although the ductility and the ratio of tensile strength to yield strength (fu/fy) of HSS material are relatively lower than those of the MS material. In addition, it was also observed that the biaxial state of stress that existed in the plate area between the staggered bolt holes was influenced by the s/g ratio, which would affect the ultimate strength of the test specimens. A reliability analysis of the HSS specimens test results was carried out to re-evaluate the partial factor adopted in the design equation of the net section resistance of HSS (up to S700) in EN 1993-1-12. The analysis results of the limited test data showed that the net section resistance of HSS staggered bolted connections was predicted conservatively by the current design equation with a partial factor of 1.25.

Application of critical distance approach for fatigue assessment of welded and HFMI-treated steel joints

High Frequency Mechanical Impact (HFMI) treatment offers a great opportunity to enhance the lightweight potential of welded structures using high strength steel materials. Focusing on the IIW Recommendations for the HFMI Treatment, a fatigue assessment based on the nominal, structural as well as notch stress approach is considered. Due to its sound applicability and proper assessment of the fatigue strength, the critical distance approach acts as a valuable concept in fatigue design, which has not been broadly studied in terms of HFMI-treated weld joints. Therefore, this paper deals with the application of the critical distance approach for welded mild and high-strength steel joints in both as-welded and HFMI-treated condition. Critical distance values were determined as a = 0.1 mm for as-welded specimens and a = 0.2 mm for HFMI treated specimens but for the sake of reliability, a = 0.15 mm have been proposed for HFMI treated welded joints.

Editorial: Composite Use of High Strength Steel and Concrete Materials for Sustainable Civil Engineering

The need for sustainable construction has been hastened world-widely aiming to reduce the use of construction materials and labor costs. To do so, high strength materials will be one option.The higher the strength, the smaller the member size is required. This will free up more usable floor area and require fewer materials and construction work. The composite use of them makes the aim easier to be achieved. To bridge the gap between theoretical development and practical application, a special issue with the research topic of "Composite Use of High Strength Steel and Concrete Materials for Sustainable Civil Engineering" has been organized by the Guest Surely the high temperature and cooling deteriorated the bond strength, and this would have an adverse influence on the ultimate load-carrying capacity of the composite members.The diverse nature of contributions in this collection is a testament to the cross-disciplinary research activities about the composite use of high strength materials. Nevertheless, there is a common thread running through all contributions where high strength, when properly achieved, can be the source of great creativity in achieving more sustainable construction.

Blast Resilience Enhancement of Cable-Supported Façade Utilizing Super-Elastic Shape Memory Alloy

Due to an increased level of threat, the design of buildings to resist blast loads has gained importance. The most vulnerable component of the building is typically the cladding system, generally being lightweight and directly facing the hazard with large, exposed surface areas. A large number of cladding materials are available, with architectural intent constantly driving the development of new products and systems. Glazed facades are aesthetically appealing and are popular among architects. In this paper, the use of super-elastic shape memory alloy (SMA) to improve the blast resilience of a cable-supported system is explored. The critical component of these systems is the high strength steel material cable. In the present study it is rendered hybrid (Steel-SMA), by attaching SMA cable(s) to the steel cable at one or both ends, and the dynamic performance under blast is studied. It is shown that the introduction of SMA in the cable has the potential to improve the resilience of the facade system.

Fire performance of composite columns made of high strength steel and concrete

The use of high strength steel and concrete materials for composite column construction is partly impeded by the lack of research on their fire performance. In EN1994-1-1, the highest concrete grade allowed for designing composite columns is capped at C50. This paper investigates the behaviour of concrete encased steel (CES) composite columns made of C120 concrete and S500/690 steel section under ISO834 standard fire through a series of experimental and numerical analyses. Fire tests were carried out on five high strength CES column specimens subject to varying eccentricity of loading to study their behaviours in fire. Polypropylene fibres were added into the high strength concrete mix to prevent the explosive spalling so that explicit modelling of cover spalling phenomenon can be omitted in the numerical analysis. A unified method is proposed to determine the transient strain of high strength concrete at elevated temperatures, allowing the stress-strain curves in EN1992-1-2 to be extended to high strength concrete up to C120. A numerical model, which can capture the strain reversal of concrete caused by the flexural deformation of columns at elevated temperatures, is proposed to enable a good prediction of axial displacement responses of CES columns in comparison with the test results. Finally, based on the validated numerical model and parametric studies, a new tabulated data method is proposed for the fire resistance design of CES columns with concrete class up to C90 concrete and steel section grade up to S550.

Numerical and Experimental Investigation of the Bending Zone in Free U-Bending

Abstract With the increasing application of the advanced high strength steel material in the automobile industry, the thickness reduction of the bending area has attracted more and more attention since the product strength is highly influenced by the quality of the bending region. In this paper, three major factors, the thickness reduction, the variation of the local bending radius within the bending zone, and the tooling mark on the product’s surface, are investigated through three different loading patterns for a free U-bending profile numerically and experimentally. The results demonstrate a thinning pattern consists of three peaks over the bending region for large bending ratio (R/t = 2.14) and only one peak for small bending ratio (R/t = 0.5). Corresponding valleys for the local radius are found to match the thinning pattern. Further, the use of finite element simulation can successfully predict the location and the severity of the wear on the product. From the experiment results, even if the metal blank only experienced one stroke, the tooling mark contains both adhesive and abrasive wear. A better understanding of the characteristics of the bending zone is achieved, and the findings can help in improving the design process for forming strategies.

Innovative Measurement Of Stress Superposed Steel Strip For Straightening Machines

Higher quality requirements by customers demand higher precision and accuracy from manufacturing processes. Application oriented preparation of semi-finished materials is key for subsequent forming operations, therefore, straightening machines are employed. Straightening strengthens the material by increasing plastic deformation by means of strain hardening, resulting in undesirable reduction in formability when processing high strength materials, in particular. Conventional roll-type straightening machines process either bars or strips. This is achieved upon passing material between rolls arranged in two staggered rows. However, conventional straightening processes do not adapt to the local varying distortion of coiled strips. Innovative, self-correcting process control techniques, which adapt to the initial geometric characteristics of the strip, present a promising approach to fix this issue through optimization of the leveling process. Here, an innovative strategy to improve straightening of high strength steel materials (1.4310) is presented. This implements optimized leveling, adding minimal plastic deformation and, thus, strain hardening. To operate an intelligent straightening machine, a reliable online measurement of the surface defects is fundamentally essential. The MagnaTest, which is developed for material testing, is made feasible for such purposes after calibrating for curvature measurement. Preliminary results are promising in regards to measuring the curvature online, so that the following straightening process can be close loop controlled. The bending measurement is linked to open/closed loop control, therefore providing an optimal straightening result in regards to formability, leveling, and reduced strain hardening.

A Method for Simultaneous Optimization of Blank Shape and Forming Tool Geometry in Sheet Metal Forming Simulations

This paper presents a numerical method for simultaneous optimization of blank shape and forming tool geometry in three-dimensional sheet metal forming operations. The proposed iterative procedure enables the manufacturing of sheet metal products with geometry fitting within specific tolerances (surface and edge deviations less than 0.5 or 1.0 mm, respectively) that prescribe the maximum allowable deviation between the simulated and desired geometry. Moreover, the edge geometry of the product is affected by the shape of the blank and by an additional trimming phase after the forming process. The influences of sheet metal thinning, edge geometry, and springback after forming and trimming are considered throughout the blank and tool optimization process. It is demonstrated that the procedure effectively optimizes the tool and blank shape within seven iterations without unexpected convergence oscillations. Finally, the procedure thus developed is experimentally validated on an automobile product with elaborated design and geometry which prone to large springback amounts owning to complex-phase advanced high strength steel material selection.

NUMERICAL STUDY OF FLANGE BUCKLING BEHAVIOR OF HIGH-STRENGTH STEEL CORRUGATED WEB I-GIRDERS

Steel plate girders with trapezoidal corrugated webs (TCWPGs) have been used over the last years around the world in many roadway and railway steel bridges as they can introduce several important advantages compared to flat web plate girders. The proper design of corrugated web girders depends mainly on the flexural and shear capacity of them. However, the flexural capacity is more important. Also, not many researchers studied the flexural capacity of such girders especially, when flange local buckling failure type (FLB) occurs in these corrugated web girders. In this paper, the flange local buckling behavior of steel trapezoidal corrugated web girders built up from high-strength steel (HSS) plates has been investigated to get the advantages of both the technique of corrugated web plates (CWPs) and the high-strength steel material (HSSs) together. A new numerical parametric study on four important parameters has been carried out to explain and investigate the flange local buckling behavior of high-strength steel corrugated web girders, considering mainly the influences of the flange to web thickness ratio, unsupported length of the compression flange, the corrugation angle and the initial imperfection magnitude of the compression flange on the behavior of girders with corrugated webs built up from HSSs. Using the commonly used finite element software ABAQUS, the results of the FE models have been obtained to be analyzed and discussed. Finally, some important advices have been introduced to aid the structural engineers to design such girders under flexural loading in economical manner.

Circular hollow compression members of grade 1200 steel: experiments and design

ABSTRACT Recent developments in technology and manufacturing of steel has led to a significant increase in the strength of this material while keeping the weight constant. This has resulted in an increase in the application of high strength steel material in structural practice and consequently a rising demand in updated design guidelines. The present research covers compression experiments and design of ultra-high strength steel hollow circular members with a nominal yield strength of 1250 MPa. The performance is compared against two other grades of steel: Mild Steel grade 300 and high strength steel grade 750. Different section geometries are modelled using finite element software and validated against the experimental compression tests. A parametric analysis is conducted on a range of section geometries and lengths and the result are compared against current design guidelines of AS4100, and AISC360. The compressive performance is studied considering both the section slenderness and the member slenderness ratios. The results show that as the member slenderness and yield strength of the sections increase, the standard predictions give a more conservative prediction of the compression capacity. Using proposed modifications for member slenderness limits and compression capacity factors, design recommendations are suggested for grade 1200 steel

A study of net-section resistance of high strength steel bolted connections

This article presents an experimental and numerical investigation on the net section resistance of high strength steel (HSS) bolted connections subject to double shear. A total of 22 HSS and 11 mild steel (MS) bolted connection specimens were tested to net section fracture. HSS grades of Q690 and Q960, and MS grade of Q345 were studied. Although the HSS material has relatively lower ductility and a lower ratio of tensile strength to yield strength (fu/fy) than those of the MS material, in general, the HSS connection specimens were able to reach the connection efficiency (i.e. the ratio of the ultimate load of the connection specimens to the calculated net section resistance) of above 1.0. Subsequently, the structural behaviour of the connections was studied by finite element (FE) analysis. The effects of material ductility and fu/fy ratio on the stress development across the net section of the specimens were examined. It was found that HSS materials possess sufficient ductility to allow an efficient stress redistribution across the net section. Besides, the beneficial influence of the ‘reinforcement’ or the biaxial stress effect due to the presence of holes in the connection increases the ultimate capacity of the perforated main plate, and hence the HSS specimens were able to reach the net section resistance. However, the overall deformation capability of the HSS specimens was significantly lower than that of the MS specimens. A reliability analysis was carried out to re-examine the partial factor used in the current design equation for predicting the net section resistance in Eurocode 3.

Crush and crash analysis of an automotive battery-pack enclosure for lightweight design

The undesirable stresses and deformations during a high-speed crash can cause a short circuit or sudden fire in the battery packs, which represents a significant safety concern for vehicles. In this paper, computer-aided simulations are conducted to provide a supplemental and economic approach to evaluate the crashworthiness of a battery-pack enclosure. First, a nonlinear dynamic finite element model of a battery-pack enclosure is established and validated using the modal test. The crush and crash simulations, based on the governing equations and explicit FE code, LS-DYNA, are performed according to the test standard. Second, three high-strength steel materials are used in the validated finite-element model to perform a crashworthiness simulation with respect to robustness and lightweight design. The results show how both materials and thickness affect the crashworthiness of an automotive battery-pack enclosure. Finally, the weight of the battery-pack enclosure is reduced, while the crashworthiness is improved as well.

Applying Baydur Composite Material in Designing Automotive Door Beams

This work studied the application of Baydur pultrusion composite material to the side door anti-collision beams of cars. The beams are currently made of high-strength steel materials and arranged inside the door to meet the requirements of road safety laws and regulations. The Baydur pultrusion composite material has many advantages that metal steel does not have. Based on the characteristics of the composite materials and safety standards for vehicle side collisions, we proposed a design to use Daybur composite material instead of steel as the anti-collision beam material in automobile side doors. The structural design of the beam with the composite material is optimized so that it can effectively improve the safety performance during side collisions and reduce the body weight to save fuel consumption. The feasibility of the design has been investigated from three aspects of technical manufacturing, safety performance and market application. The application of the composite material in the anti-collision beams will provide new options for the safety and energy efficiency of civil vehicles.