General Structural Steels Research Articles

The Effect of Periodic Inspection and Safety Criteria on the Service Life of Steel Construction Conveyors

Steel construction structures are seen in many different applications in our country and in the world. However, the periodic maintenance of these steel construction products is explained by national and international laws and regulations. According to the relevant regulation in our country, it is obligatory to carry out periodic inspections of these constructive structures, which are referred to as machinery and equipment, once a year. As in many facilities, it is obvious that these structures are the main elements of the facility and will be used throughout the life of the facility. It is not clear under which conditions these structures, which are generally produced using structural steels and which are connected by welding or bolts, will be examined in the periodic inspections. As a result of the research on the lifetime of general structural steels, it has been proved by many researchers that these structures have an infinite life if they reach the number of million repetitions. However, the life of welding or bolts, which are the connecting elements of the structure, remains uncertain. In this study, accident breaking studies were carried out by detailing the damage due to a tragic accident in a steel construction that has served for about 36 years. By keeping company and personal information confidential, the steel structure and bolt connections of the construction were examined in terms of strength, hardness and microstructure, and the results were detailed.

Determination of CCT Diagram by Dilatometry Analysis of High-Strength Low-Alloy S960MC Steel.

High-strength steels are used more than general structural steel due to their combination of properties such as high strength, good toughness and weldability. They are mainly used in the manufacture of heavy vehicles for the mining industry, cranes, transportation, etc. However, welding these grades of steel brings new challenges. Also, a simulation for welding high-strength steel is required more often. To insert a material database into the simulation program, it is necessary to conduct investigations using CCT (Continuous Cooling Transformation) diagrams, welded joints research, and more. To investigate the behavior of S960MC steel during heating and cooling, we used dilatometry analysis supported by EBSD (Electron Backscatter Diffraction) analysis. A CCT diagram was constructed. The transformation temperatures of Ac1 and Ac3 increase with increasing heating rate. The Ac1 temperature increased by 54 °C and the Ac3 temperatures by 24 °C as the heating rate increased from 0.1 °C/s to 250 °C/s. The austenite decomposition temperatures have a decreasing trend in the cooling phase with increasing cooling rate. As the cooling rate changes from 0.03 °C/s to 100 °C/s, the initial transformation temperature drops from 813 °C to 465 °C. An increase in the cooling rate means a higher proportion of bainite and martensite. At the same time, the hardness increases from 119 HV10 to 362 HV10.

Structural Design and Analysis of Electric Car Engine Mount

In this paper, the analysis of engine mounting structures that will be applied to electric vehicles is conducted. The engine mounting structure will be subjected to static loading from the mounted components assembly, including the assembly of the gearbox, electric motor, and corresponding brackets. In the structure arrangement, HSLA material is mostly used and general structural steel such as AISI 4130 is also used. This study aims to evaluate the existing design so that further optimization steps can be carried out. Simulations and analysis with a static approach were performed using SOLIDWORKS. The stress and displacement contours are then created, and the location of the critical points of maximum stress and maximum deflection can be obtained so that the safety factor of the design can be evaluated. Based on the simulation results, the current safety factor value is very high when compared to using materials with lower physical properties. In addition, it is necessary to develop further studies involving dynamic loading so that it can also be considered to reduce production costs and increase production efficiency.

Measurement of welding fume production in welding with high-alloy electrodes

Due to their good structural properties, stainless Cr-Ni steels have a very wide application in various branches of technology. During the welding of stainless Cr-Ni steels with high-alloy coated electrodes, welding fumes of complex chemical composition are generated, which is very harmful for welders and the environment. For the purposes of this experiment, two variants of one rutile Cr-Ni commercial electrode, designated E 23 12 2 LR 12, were designed and fabricated. Higher production of welding fume particles also means greater danger to humans and the environment. In order to show the influence of the base material on the production of welding fume particles, an experiment for measuring the production of welding fume particles was performed in which two different steels were used as the base material, general structural steel S235JRG2 and stainless steel X6CrNiTi18.10.

Cyclic softening behavior of structural steel with strain range dependence

In seismic analysis, the cyclic performance of structural steel members is closely related to the strain range dependence effect. The strain range dependence effect has been extensively investigated from the perspective of hardening during the range expansion. However, the research on the cyclic softening behavior induced by the shrinkage of the loading range is insufficient, which corresponds to the scenario of the descending-magnitude long tail after the peak value in seismic analysis. In this study, eight cyclic coupon tests of Q345B structural steel are conducted to comprehensively investigate the strain range dependence effect experimentally at first. The test results indicate that the stress amplitudes experience loop-wise softening when the strain range drops to a lower level and gradually converge to a stabilized magnitude higher than the reference value obtained from constant-amplitude cases. Moreover, the cyclic softening is only influenced by the historical maximal loading range regardless of the intermediate loading history. For describing the experimental observations, a sophisticated constitutive model for general structural steel is proposed wherein a novel concept of incomplete collapse effect, which possesses a clear geometric interpretation, is specially designed to characterize the cyclic softening phenomena. Considering the future demand in multi-scale analysis, the constitutive model is implemented by inverse-P norm algorithm applicable to all spatial dimensions. A semi-automatic and efficient calibration method is developed to elude manually calibrating numerous entangled material parameters. Finally, the accuracy of the proposed constitutive model is validated by two batches of material-level coupon tests and a member-level experiment of two shear damper specimens, which demonstrates the capabilities of the proposed constitutive model in reasonably predicting the cyclic softening behavior with the strain range dependence as well as other hysteretic properties.

Statistical Analysis of Corrosion Process Flow

This paper presents the results of testing two different materials in aggresive atmosphere rich in sodium chloride (NaCl) depending on different time intervals (48, 96, 168, 240 hours), in order to determine the corrosion process flow. One of the materials is general structural steel SA516 Gr.70 and the other is austenitic stainless steel X6CrNiTi18-10. The test results were statistically analyzed with the aim of obtaining statistical regression models, as well as to investigate the effect of alloying elements on the corrosion process flow. Models for predicting the corrosion process flow (mass loss) of both materials were obtained by statistical analysis and it was determined that the proportion of alloying elements influences the change in the flow. Accordingly, general structural steel is characterized by linear, while austenitic stainless steel is marked by slow corrosion process flow. This indicates that the proportion of alloying elements which improve the corrosion resistance of the material strongly affects the durability of the material in an aggressive environment.

Experimental study on ultimate strength of steel-welded ring-stiffened conical shell under external hydrostatic pressure

This paper reports experimental and numerical investigations on the ultimate strength responses of steel-welded, ring-stiffened conical shells when subjected to external hydrostatic pressure. Four small-scale shell models were fabricated from general structural steel by cold bending and arc welding. First, hydrostatic pressure tests were performed to investigate the collapse behaviour of the models. The influences of different parameters were also studied experimentally. Before the experiments, quasi-static tensile tests were performed to obtain detailed characterisation of the test model material. In addition, the initial imperfection of the shell and other as-built geometry parameters were carefully measured. The test was conducted using compressed water in a small-sized chamber and loaded to collapse. Three models with heavy stiffeners were failed by local buckling at the shell between the ring frames. Another model failed by the overall buckling of the adjacent frames together with the shell. The numerical computations were performed on the finite element code of ABAQUS FEA. The imperfection due to fabrication, such as initial out-of-circularity, and residual stresses due to welding are simulated. The quasi-static response was compared with the experimental load and plastic deformation curves. The numerical results revealed a close agreement between the collapse pressure prediction and failure modes of the simulation and the experiment.

Experimental investigations on the failure modes of ring-stiffened cylinders under external hydrostatic pressure

This paper reports on the experimental investigations on the failure modes of ring-stiffened cylinder models subjected to external hydrostatic pressure. Nine models were welded from general structural steel. The shells were initially formed by cold-rolling, and flat-bar ring frames were welded to the shell. The hydrostatic pressure tests were conducted by using water as the medium in pressure chambers. The details of the preparation and main test were briefly explained. The investigation identified the consequence of the structural failure modes, including: shell yielding, local shell buckling between ring stiffeners, overall buckling of the shell together with the stiffeners, and interactive buckling mode combining local and overall buckling. In addition, the ultimate strengths were predicted by using existing design codes. Non-linear numerical computations were also conducted by employing the actual imperfection coordinates. Finally, accuracy and reliability of the predictions of design formulae and numerical were substantiated with the test results.

Verification of possibility for controlling welding distortion generated by laser-arc hybrid welding

For predicting welding distortion and residual stress generated by laser-arc hybrid welding (HYBW) with high accuracy by the 3D thermal elastic-plastic analysis based on FEM, a heat input model considering the dual heat source of HYBW was proposed. By using the proposed model, welding distortion and residual stress generated by HYBW on the general structural steel under several welding conditions, in which the heat input ratio of laser and arc were variously changed, were obtained. Comparing with the results obtained by experiments and analyses, the validity and generality of the proposed heat input model could be verified. The tendency and magnitude of welding distortion varied with the heat input ratio of laser and arc. The results indicated the possibility for controlling welding distortion generated by HYBW with the optimum heat input ratio of laser and arc.

The Suitability of Analytical and Numerical Methods for Developing Clinching Processes with Thick Sheet Metal

At present, the use of clinching is mainly restricted to thin sheet metal. Here the joining technology is used for assemblies in mass production due to its great coast efficiency. However, the branches of industry working with thick sheet metal (utility and rail vehicle engineering, shipbuilding and general structural steel engineering) represent a major potential for using clinching technology. Unfortunately, the suitability of clinching for connecting jobs with substantially greater sheet metal thicknesses has neither been sufficiently investigated, nor are there suitable toolsets among system manufacturers that are adapted to the larger overall sheet metal thicknesses. Instead, the state-of-the-art for ascertaining tools for larger sheet metal thicknesses and point dimensions is trial and error accepting the high costs caused by producing a large number of tools and experiments. This paper demonstrates some analytical approaches to this problem and how suitable they are to describing the process of clinching in comparison to the potential of calculation with FEA.

Comparison Study of Fire Resistance According to Differences of Length of H-Section Made of Submarine Structural Steels

Submarine structural steels, such as SM 400, SM 490, and SM 520, have the same structural properties and same grades as general structural steels, but those have better weldability than general structural steels. For that reason, their usage is increasing. However, their fire resistance is not well defined, except for individual fire resistance, such as column and beam. The fire resistance of H-section made of submarine structural steels can be applied with various column lengths. The fire resistance of them is not clear to engineers and residents. To determine the fire resistance, in this paper an analysis was conducted using their mechanical properties at high temperature and related theories with a standard fire curve. As the strength of submarine structural steels is increased, the structural stability showed a rapid decrease while the longer the length of column, the less structural stability of the column represented.

Analytic Study of Structural Stability for H-Section Column Made of Submarine Structural Steels Based on Boundary Conditions and Column Lengths at High Temperature

Structural steels require performance, such as structural performance, constructional one, and fire performance as an efficient constructional material. However, structural steels have a fundamental weakness in a fire and need to improve constructional performance of welding which resulted in the development submarine structural steels, such as SM 400, SM 490, and SM 520. Their yield strengths are the same as general structural steels, but the weldability was better. Therefore, the application of submarine structural steels increases in steel building market annually. However, the fire resistance performance isnt determined when these are used as main materials in H-section columns in the case of different boundary conditions and different column lengths. In this paper, to confirm and suggest a new guideline for fire protective materials, an advanced engineering design was used with mechanical properties at high temperature and a heat stress analysis. The findings showed that fire resistance of H-section columns with longer lengths and other boundary conditions are determined to satisfy the fire resistance performance if the fire protective materials derived from 3500mm in length and hinge to hinge boundary condition apply to longer column lengths and other boundary conditions.

Performance Characteristics of the Steels for High-Rise Buildings

With the development of high-rise buildings, the requirement to the performance of steels for high-rise buildings keeps on increasing. Besides high strength and high toughness possessed by general structural steels, the steels for high-rise buildings should possess low yield ratio, excellent welding performance, fire-resistant performance and Z-direction performance. These performance characteristics of the steels for high-rise building were introduced and its development trend was pointed out.

Soundness Diagnosis Of A Steel Bridge Pier Repaired By Heating/Pressing

In order to diagnose the soundness of a steel bridge pier, repaired by heating/pressing, a series of experiments and analyses were conducted. A virgin specimen was first locally buckled by cyclic bending loads and subsequently corrected by heating/pressing. The corrected specimen was again subjected to the same loading experiment as the virgin specimen. In addition, loading experiments were simulated by elastic-plastic large deformation analysis. It was confirmed that heating temperatures should be kept below the A1 transformation temperature (around 700 °C within the general structural steel) to prevent changes to its mechanical properties. It was ideal for the imperfection, which was the residual deformation in the panel, to be controlled within the acceptance of the initial deflection. Further, it was found that correcting the residual deformation opposite the mode of local buckling of the panel was an effective method for maintaining the maximum strength of the repaired pier, equivalent to that of the virgin specimen.

WELDOX 1300

Abstract Weldox 1300 is a general structural steel with a minimum yield strength of 1300 MPa (189 ksi). This datasheet provides information on composition and tensile properties as well as fracture toughness. It also includes information on forming, heat treating, and joining. Filing Code: SA-575. Producer or source: SSAB Weldox.

WELDOX 1100

Abstract Weldox 1100 is a general structural steel with a minimum yield strength of 1100 MPa (160 ksi). This datasheet provides information on composition and tensile properties as well as fracture toughness. It also includes information on forming, heat treating, and joining. Filing Code: SA-572. Producer or source: SSAB Weldox.

WELDOX 1030

Abstract Weldox 1030 is a general structural steel with a minimum yield strength of 1030 MPa (149 ksi). This datasheet provides information on composition and tensile properties as well as fracture toughness. It also includes information on forming and joining. Filing Code: SA-571. Producer or source: SSAB Weldox.

WELDOX 900

Abstract Weldox 900 is a general structural steel with a minimum yield strength of 900 MPa (131 ksi). This datasheet provides information on composition, tensile properties, and bend strength as well as fracture toughness. It also includes information on forming, heat treating, and joining. Filing Code: SA-568. Producer or source: SSAB Weldox.

WELDOX 700

Abstract Weldox 700 is a general structural steel with a minimum yield strength of 700 MPa (102 ksi). This datasheet provides information on composition, tensile properties, and bend strength as well as fracture toughness. It also includes information on forming, heat treating, and joining. Filing Code: SA-567. Producer or source: SSAB Weldox.

WELDOX 500

Abstract Weldox 500 is a general structural steel with a minimum yield strength of 500 MPa (73 ksi). This datasheet provides information on composition and tensile properties as well as fracture toughness. It also includes information on forming, heat treating, and joining. Filing Code: SA-565. Producer or source: SSAB Weldox.