Structural Steel Grades Research Articles

Comparison of non-traditional technologies for material cutting from the point of view of surface roughness

The contribution deals with comparing non-traditional cutting technologies from the point of view of generated surface roughness. The comparison is carried out for technologies of abrasive waterjet cutting, oxygen cutting, laser and plasma cutting. As an experimental material, EN S355J0 structural steel and titanium CP-Ti Grade 2 was used. Surface topography measurement was done using a Mitutoyo Surftest SJ-401 instrument, and an optical profilometer MicroProf FRT was used for comparison and verification of acquired surface data. The aim of the contribution is to clarify, on the basis of experimental measurements, the behaviour of a topographic function after various ways of cutting; the knowledge of the function is necessary for solving both theoretical and practical technological tasks. The topographic function, which is a basis for the prediction of quality and control of the cutting processes, was derived in an original way. The use of individual technologies depends on technical and economical possibilities and on environmental influences. The results of measurement of cut surface roughness are in good accordance with the results of theoretical analysis.

Results of Strain Rate and Temperature on Mechanical Properties of Selected Structural Steels

The article presents results of application of Rusinek-Klepaczko (RK) constitutive equation for the purposes of modelling of mechanical behaviour of four grades of structural steels. In order to calibrate the RK model a series of compression tests at wide range of strain rates were carried out using two testing stands: servo-hydraulic machine and split Hopkinson bar. The results were analysed to determine influence of temperature and strain rate on visco-plastic response of tested steels. It was concluded that at low temperatures the thermally activated mechanisms of plastic deformation results in the strong strain rate hardening effects, whereas at high temperatures they are limited.

Analysis of the Mechanical Properties of N-Added CMn Structural Steel by the Impulse Internal Friction Technique

The presence of substitutional solutes has a strong influence on the Snoek effect of interstitial atoms in body-centered cubic (bcc) Fe alloys, such as the structural CMn steel grades produced in hot strip mills. In the current study, bcc Fe-Mn-N alloys were analyzed using the impulse technique and the results were correlated to their mechanical properties and the AlN precipitation characteristics. The broadened Snoek peak related to the octahedral interstitial N could be resolved into three distinct Debye peaks related to the arrangement of Mn atoms surrounding the N atoms. The simulation results suggest that precipitation of AlN occurred mainly during coiling and that the precipitation kinetics was enhanced at higher coiling temperatures. Alloys isothermally held at high temperatures had a yield strength and tensile strength linearly proportional to the difference between the nominal N content and the interstitial N content. The observations point to the pronounced precipitation strengthening effect of AlN after high-temperature coiling simulations. The result also reveals that interstitial N increases both the yield strength and the tensile strength in steels coiled at low temperatures.

An engineering assessment methodology for non-sharp defects in steel structures – Part II: Procedure validation and constraint analysis

This Part II paper validates a new engineering methodology for assessing non-sharp defects in ferritic steel structures. The new approach, presented in the companion Part I paper, is based on a modification of the Failure Assessment Diagram for notches. A series of worked examples is presented based on a large dataset of U-notched SE(B) specimens machined from a heat-treated structural steel grade S690. Failure predictions of notched specimens using the modified approach result in significantly reduced conservatism compared to the standard Failure Assessment Diagram assessment method. The new methodology is also combined with the existing constraint-modified approach in the R6 defect assessment method to predict cleavage fracture in shallow, blunt-notched SE(B) specimens with a small degree of conservatism.

Application of laser peening without coating on steel welded joints

PurposeLaser peening without coating (LPwC) is an innovative surface enhancement technology for introducing compressive residual stress in metallic materials. The purpose of this study is to examine the characteristic at the laser‐peened welded zone and the fatigue lives of the welding joints.Design/methodology/approachLPwC conditions for 490 MPa grades of structural steels were selected. By using the conditions, the characteristic at the laser‐peened welded zone, residual stresses, hardness and roughness of welding toes were examined. Moreover, the fatigue lives of the toes of box‐welded joints and butt welded joints pre‐treated by LPwC were compared to the fatigue lives of those that were not pre‐treated by LPwC.FindingsThe main results are: LPwC conditions for 490 MPa grade steels were established; residual stresses, Vickers hardness and roughness at the laser‐peened welded zone were revealed; and LPwC can dramatically extend the fatigue life of welded joint.Originality/valueThe effects of LPwC on structural steels, which are widely used in bridge members, have not been well clarified; the effect of LPwC on welded zones in these structures is particularly unclear. If LPwC can be carried out such that compressive residual stress is imparted on structural steels and the welded zones in the bridge members, the fatigue lives of bridge members will be greatly increased. The paper fills some of these gaps.

Controlled Cooling Process and Mechanical Property of 590MPa Grade Structural Steel with Low Yield Ratio

To develop 590MPa grade low yield ratio steel for high-rise buildings, the new generation TMCP based on ultra fast cooling (UFC) technology was proposed. Then effects of UFC final temperature on microstructure and mechanical properties were investigated. The results show that the control of composite phases is important to obtain high strength, low yield ratio and high work hardening exponent. When UFC final temperature is 521°C, 22.5% (volume fraction) M-A phases are distributed in bainite ferrite matrix, and the excellent overall properties can be obtained, i.e., the yield strength is 570MPa, tensile strength 760MPa, yield ratio 0.75 and percentage elongation 22% with the Charpy impact energy 284J at -40°C. All these indexes can meet the requirements of relevant standards.

Structural steel for the application in offshore, wind and hydro energy production: comparison of application and welding properties of frequently used materials

Energy production by wind and hydropower sets demanding requirements on the steel grades used for structural applications. The question of steel grade selection must be answered by finding an optimum between sufficient toughness properties, good strength properties but also easy fabrication, in particular welding. Sufficient toughness is of importance in order to avoid brusque failure phenomena; good strength properties are necessary to minimise the dead weight of these structures in order to facilitate the transport and erection process. The significance of good fabrication properties consists of two facets: for instance, a good weldability can result in easy procedures and therefore high efficiency. Moreover, material with high weldability may show a higher resistance against cracking phenomena in the heat affected zone. Therefore, this article explains the different production methods which are used today for structural steel grades as well as the resulting mechanical and chemical properties and the welding behaviour.

Application of 60K (570N/mm2) Grade Structural Steel for a Super High Rise Building

Application of 60K (570N/mm2) Grade Structural Steel for a Super High Rise Building

Use of the Holloman-Jaffe Tempering Parameter in the Development of High Strength Steel Plate

Manufacturers of heavy mobile equipment are demanding higher strength steel plates with comparable flatness, formability and weldability to conventional HSLA steels. In addition to increasing load capacities, considerable weight and consequently energy savings can be achieved by using smaller components of higher strength steel. IPSCO has commissioned a plate heat treatment facility in Mobile, Alabama capable of producing steel plate with superior flatness and surface quality. Its quench and temper line is capable of producing high strength products by heating the steel into the austenite regime, water quenching to martensite, then tempering to obtain desired properties. The effect of tempering has been shown by Holloman and Jaffe to be dependent on both time and temperature. Using this relation, IPSCO has developed a laboratory procedure to determine final properties for any combination of time and temperature during tempering. For example, it was determined that a 0.15% C to 1.45% Mn steel can be tempered to produce different products from IPSCO 400F to structural steel grades with yield strengths of 620 to 965 MPa. Each grade demands a specific tensile strength or hardness as well as toughness, formability and weldability. An example is provided to show how the laboratory procedure has been applied in the development of a steel product with a minimum yield strength of 900 MPa.

Use of the Holloman-Jaffe Tempering Parameter in the Development of High Strength Steel Plate

Manufacturers of heavy mobile equipment are demanding higher strength steel plates with comparable flatness, formability and weldability to conventional HSLA steels. In addition to increasing load capacities, considerable weight and consequently energy savings can be achieved by using smaller components of higher strength steel. IPSCO has commissioned a plate heat treatment facility in Mobile, Alabama capable of producing steel plate with superior flatness and surface quality. Its quench and temper line is capable of producing high strength products by heating the steel into the austenite regime, water quenching to martensite, then tempering to obtain desired properties. The effect of tempering has been shown by Holloman and Jaffe to be dependent on both time and temperature. Using this relation, IPSCO has developed a laboratory procedure to determine final properties for any combination of time and temperature during tempering. For example, it was determined that a 0.15% C to 1.45% Mn steel can be tempered to produce different products from IPSCO 400F to structural steel grades with yield strengths of 620 to 965 MPa. Each grade demands a specific tensile strength or hardness as well as toughness, formability and weldability. An example is provided to show how the laboratory procedure has been applied in the development of a steel product with a minimum yield strength of 900 MPa.

Tribological behaviour of thin film coatings against high strength steels

The non-coated ball (SKD11; hardness 60 ± 2 HRC), balls coated with TiC-CVD, TiAlN-PVD, TiCN-CVD, TiCN-PVD and ball treated by VC-TD (thermal diffusion) have been evaluated in sliding contact against the disk which was made from automobile structural steel grade SAPH 440 and high strength steel grade SPFH 590. It was found that non-coated ball showed maximum specific wear rate and TiCN-CVD coated ball exhibited minimum specific wear rate. The effectiveness of hard thin film coated tool in metal stamping process is also investigated by performing U-bending experiment. In the case of non-coated tool, the result showed that adhesion of workpiece material on a die face was detected after 49 strokes for SPFH 590 steel. Whereas no adhesion was found on the tool coated with TiCN-CVD after 500 strokes. In order to understand the phenomenon, scratch tests were done on each type of coated tool to characterise the adhesion strength.

Effect of friction-induced hardening on the features of magnetic and eddy-current behavior of an annealed structural steel under cyclic loading conditions

The effect of friction processing on the mechanical properties in uniaxial tension, the magnetic properties, and the electromagnetic characteristics of an annealed Steel 3 (St3) grade structural steel has been studied. It is established that the coercive force, residual magnetic induction, initial magnetic permeability, and eddy-current characteristics can serve as parameters for monitoring the quality of steel hardened by friction processing. Features of friction-induced changes in the strength, magnetic properties, and electromagnetic characteristics of St3 grade steel loaded in the region of low-cycle fatigue are revealed. It is shown that magnetic and eddy-current techniques can be used for monitoring the state of a friction-hardened surface layer of steel samples in the course of their cyclic loading.

DOMEX 240 YP

Abstract Domex 240 YP is a structural steel grade designed to have good forming characteristic, including cutting. This datasheet provides information on composition, physical properties, and tensile properties as well as fracture toughness. It also includes information on forming, heat treating, and joining. Filing Code: CS-150. Producer or source: SSAB Swedish Steel Inc.

Neutron Strain Investigations of Laser Bent Samples

Bending of metal plates with high-energy laser beams presents a flexible materials forming technique where bending results from the establishment of a steep temperature gradient through the material thickness. This inevitably leads to non-uniform thermal expansion/contraction and subsequently residual stresses. Non destructive residual strain mapping with neutron diffraction through the 8mm thickness of a series WA 300 grade structural steel plate samples, focused on the region straddling the centerline of the heating bead location, shows the presence of large residual stress fields. Directly below the laser track the longitudinal strains are tensile and dominant, normal strains compressive and transverse strains slightly tensile. The magnitudes of the strains decrease outside the width of the laser beam footprint. The first laser pass induces throughthickness strains close to yield, whereafter their magnitudes decrease with increased number of laser beam passes. A comprehensive mapping of the longitudinal stresses as function of the number of laser passes is given.

Design Optimization of Composite Steel Box Girder in Flexure

Composite girders consisting of concrete deck on built-up girders are frequently used in bridge construction for their economic advantages. The use of composite girders results in a very economical design. Additional savings can be obtained in design and material costs for some members by automating design approaches based on optimization techniques. This paper describes the use of EXCEL Solver to find the minimum weight for a composite trapezoidal box cross section for a two lane bridge. Design aid tables were generated for structural steel Grades 250, 345, 485, and 690 MPa , and different spans varying from 3.0–100 m . The search for the minimum cross section used in this research satisfies the 17th Edition of the American Association of State Highway and Transportation Officials Specifications—Load Factor Design method.

Prediction and validation of through coil final mechanical properties of high strength hot rolled coil using artificial neural networks

In the manufacture of rolled steel from a hot strip mill, the final mechanical properties, such as yield strength, ultimate tensile strength and elongation to fracture, are important requirements specified by the customer. With the advent of ever more powerful computational hardware and software, non-linear modelling techniques such as artificial neural networks can result in the creation of acceptably accurate predictive models. In the present paper, the application of known metallurgical knowledge on the selection of model input data, along with the excellent non-linear mapping capabilities of neural networks, combines to create a solution for the prediction of final mechanical properties throughout the length of rolled coils from the Corus Port Talbot hot strip mill. Predictive models are trained on two data sets (one from 2003 and the other from 2005) of a structural steel grade S275 from the high strength steel family. Actual through coil tensile test results from a validation coil (rolled in 2005) were used to certify the models. The model results clearly show that when an optimised neural network architecture is trained on coil samples taken from the specific grade of steel and within a reasonable timeframe relative to the unseen validation data, an acceptably accurate model is created for the prediction of final mechanical properties.

Structural design of high-strength austenitic stainless steel

Efficient use of material is an important factor in achieving economical and sustainable structures. Typically, annealed austenitic stainless steel has a material strength of around 220 N/mm 2, somewhat lower than that of common structural carbon steel grades. This lower strength, coupled with the higher material cost, puts stainless steel at a significant disadvantage when considering material selection, despite its other desirable properties. However, the strength of stainless steel may, at relatively low expense, be considerably enhanced through modification of the chemical composition and through the process of cold working due to the strain hardening nature of the material. This strength enhancement has not generally been utilised in practice due to a lack of knowledge on the structural behaviour of this high-strength material. Given the high material cost of stainless steel, the need to optimise the efficiency of design methods and to develop the performance, availability and diversity of the current product range is clear. To this end, this paper describes tests, numerical modelling and the development of design guidance for high-strength stainless-steel members in a range of structural configurations. Material tensile tests, member tests in compression and member tests in bending have been described. The results of the tests have been successfully replicated numerically, and subsequent sensitivity studies and parametric studies have been performed. Test and numerical results have been compared against two design methods developed for standard-strength material (Eurocode 3 Part 1.4 and the deformation capacity based design method). The comparisons have revealed that both design methods provide a similar level of reliability to that offered for standard-strength material, and thus, extension of both design methods to the high-strength grades has been recommended.

Prediction of the fatigue life on the basis of damage progress rate curves

The new concept of a damage progress rate curve (DPRC) is introduced in this paper. These curves were determined experimentally for three grades of structural steels used for high pressure installations working in extreme service conditions. Stress controlled fatigue tests were performed for the steels under investigation and the changes in the inelastic strain were used as the measure of the fatigue damage progress. The results of the investigations are presented in the form of plots showing the rate of the fatigue damage process, d D/d n,as a function of the applied stress amplitude. The applicability of the Palmgren–Miner linear damage rule is restricted to the range of stress amplitudes for which damage is indeed a linear function of the number of the applied load cycles. For higher stress amplitudes damage the progress is not linear — the linear damage rule cannot be applied to predict fatigue life of the construction components. On the basis of experimentally determined DPRCs, the fatigue life was predicted for variable amplitude experiments performed on the tree structural steels investigated. The results were found to be in very good agreement with the prediction in the range of stress amplitudes, for which the linear damage rule is applicable. One exception was HL loading sequence for 15HM steel for which a big discrepancy between the average observed behaviour and the predicted behaviour was observed due to the early activation of Lüders bands.

Fatigue Properties Of High Performance Steel

A low carbon content, the addition of alloying elements, and improved mill practices have imparted high performance steel (HPS) with superior toughness, strength, and weldability. Its performance in fatigue, however, is not well understood. A research program presently being conducted at the University of Alberta has obtained the necessary material input parameters for fatigue life predictions. The fatigue performance of two different heats of HPS 485W steel is compared to two other grades of structural steel: A7 steel commonly found in older structures, and G40.21 350WT steel, commonly used in modern bridge structures. Stress or strain-controlled smooth specimen fatigue tests were conducted to obtain cyclic stress vs, strain curves, strain and stress amplitude vs. fatigue life curves, and energy per cycle vs. fatigue life curves, and to obtain the fatigue limit. Crack growth rate data were also obtained. The collected material data are used as a basis of comparison of high performance steel with more common grades of structural steel. HPS 485W steel shows high strength, good ductility, high fatigue limit level, and high fracture toughness. The fatigue test results indicate that HPS 485W steel has a fatigue resistance comparable to that of lower strength structural steels in the stable crack growth range. Its higher fatigue endurance limit, however, provides a distinct advantage.

Chemistry effects on the crack susceptibility of structural steels during continuous casting

This work is a review of research results, which have been determined in recent years in order to reveal the effects of the chemical compositions on the high temperature properties of structural steels. Special emphasis has been laid on the solidification structure, phase reactions and precipitates. For this comparison exemplary different structural steel grades have been chosen. The effect of the chemical composition on the solidification structure is shown by increasing Ni mass contents up to 10 %, the influence on the phase transformation is illustrated on the basis of a steel with a Mn mass content of 1.6 % and varying carbon contents. The influence of precipitates has been investigated both on the basis of the Mn/S‐ratio and by microalloyed structural steels with different Nb, V and Ti additions. For all these steel grades the laboratory testing conditions were the same. The high temperature properties of steels can be investigated by high temperature tensile tests; the range of good ductility is determined by the measurement of the reduction of area, e.g. RoA > 50 % or >70 %. The upper limit of the ductility range is the temperature of zero ductility, TZD%. The lower limit of the good ductility range is marked by the transition to the ductility minimum II. The experiments for a series of different structural steels show that the hot ductility properties are affected by the metallurgical phenomena mentioned before.