Cyclic Material Behavior of High-Strength Steels Used in the Fatigue Assessment of Welded Crane Structures with a Special Focus on Transient Material Effects

2017 ◽  
Vol 10 (2) ◽  
pp. 331-339 ◽  
Author(s):  
Benjamin Möller ◽  
Alessio Tomasella ◽  
Rainer Wagener ◽  
Tobias Melz
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Material Behavior ◽  
Special Focus ◽  
Fatigue Assessment

scholarly journals Application of DIC Method in the Analysis of Stress Concentration and Plastic Zone Development Problems

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3460 ◽  
Author(s):  
Paweł J. Romanowicz ◽  
Bogdan Szybiński ◽  
Mateusz Wygoda
Keyword(s):  
Heat Treatment ◽  
Stress Concentration ◽  
High Strength Steels ◽  
High Strength ◽  
Experimental Tests ◽  
Theoretical Models ◽  
Material Behavior ◽  
Image Correlation ◽  
Stress Concentrations ◽  
Element Analysis

The paper presents the assessment of the possibility and reliability of the digital image correlation (DIC) system for engineering and scientific purposes. The studies were performed with the use of samples made of the three different materials—mild S235JR + N steel, microalloyed fine-grain S355MC steel, and high strength 41Cr4 steel subjected to different heat-treatment. The DIC studies were focused on determinations of dangerous zones with large stress concentrations, plastic deformation growth, and prediction of the failure zone. Experimental tests were carried out for samples with different notches (circular, square, and triangular openings). With the use of the DIC system and microstructure analyses, the influence of different factors (laser cutting, heat treatment, material type, notch shape, and manufacturing quality) on the material behavior were studied. For all studied cases, the stress concentration factors (SCF) were estimated with the use of the analytical formulation and the finite element analysis. It was observed that the theoretical models for calculations of the influence of the typical notches may result in not proper values of SCFs. Finally, the selected results of the total strain distributions were compared with FEM results, and good agreement was observed. All these allow the authors to conclude that the application of DIC with a common digital camera can be effectively applied for the analysis of the evolution of plastic zones and the damage detection for mild high-strength steels, as well as those normalized and quenched and tempered at higher temperatures.

Comparison of Material Behavior and Economic Effects of Cold and High Temperature Forming Technologies Applied to High-Strength Steels

2005 ◽  
Vol 6-8 ◽  
pp. 101-108 ◽  
Author(s):  
Reimund Neugebauer ◽  
Angela Göschel ◽  
Andreas Sterzing ◽  
Petr Kurka ◽  
Michael Seifert
Keyword(s):  
Elevated Temperatures ◽  
High Strength Steels ◽  
Dimensional Accuracy ◽  
High Strength ◽  
Economic Effects ◽  
Material Behavior ◽  
Spring Back ◽  
Forming Process ◽  
Cold Forming ◽  
Forming Tools

The focus of forming high-strength steel at elevated temperature is to improve its forming properties like elongation and to reduce the power requirements during the forming process in opposite to cold forming. Because of the undefined and large spring-back effects parts made by cold forming are not able to achieve the demanded dimensional accuracy, which is necessary for laser welding operations in car body assembly. The reduction of the spring-back behavior is another advantage of the temperature controlled forming technology. On the other side the forming at elevated temperatures requires increased costs for forming tools and tempering equipment. For a fundamental evaluation of this technology, expenditures for the complete process chain have to be considered.

Effect of Heating Parameters on the Part’s Properties in Hot Stamping Process

2012 ◽  
Vol 557-559 ◽  
pp. 2417-2422
Author(s):  
Rui Ge ◽  
An Long ◽  
Yin Chen
Keyword(s):  
Hot Stamping ◽  
High Strength Steels ◽  
Dimensional Accuracy ◽  
High Strength ◽  
Hardness Measurement ◽  
Material Behavior ◽  
Hot Forming ◽  
Accuracy Test ◽  
Stamping Process ◽  
Proper Design

In the automotive industry, the hot forming of high strength steels offers the possibility to obtain significant reduction of weight without affecting the structural performances of final products. Compared with conventional sheet metal forming, the proper design of hot stamping process chain requires the deep knowledge of both interface phenomena and material behavior at high temperatures in order to obtain the desired properties of final products in terms of microstructure and strength characteristics. The work presented in this paper aims at accurately evaluate the effect of heating parameters on the properties of final sheet components produced in hot forming operations. Different from that in the lab, all the samples and parts used for the experimental test were produced in the production line, which can objectively show the manufacturing properties and microstructure character of products in mass. Microstructure evaluation, hardness measurement and dimensional accuracy test after hot stamping were performed and considered. The best heating parameters for the researched hot stamping B-Pillar’s production were obtained through the above research.

On the Material Modeling of the Autofrettaged Pressure Vessel Steels

2008 ◽  
Author(s):  
G. H. Farrahi ◽  
E. Hosseinian ◽  
A. Assempour
Keyword(s):  
Uniaxial Tension ◽  
High Strength Steels ◽  
High Strength ◽  
Test Methods ◽  
Material Behavior ◽  
Material Modeling ◽  
Chemical Compositions ◽  
Accurate Analysis ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

Material modeling of the high strength steels plays an important role in accurate analysis of autofrettaged tubes. Although, the loading behavior of such materials is nearly elastic-perfectly plastic, their unloading behavior due to Bauschinger effect is very complicated. DIN1.6959 steel is frequently used for construction of autofrettaged tubes in some countries such as Germany and Switzerland. In spite of similarity between chemical compositions of this steel with A723 steel, due to different material processing, two steels have unlikely behavior. In this paper material behavior of DIN1.6959 has been accurately modeled by uniaxial tension-compression test results. Both 6 mm and 12.5 mm diameter specimens were used and compared. Also various functions for modeling of autofrettaged steels were investigated and new function was introduced for accurate modeling. Moreover, two test methods, i.e. uniaxial tension-compression and torsion tests, which used for modeling of autofrettage steels, were analyzed. As well, material models of three important autofrettage steels, i.e. A723, HB7 and Din1.6959 were compared.

On the Material Modeling of the Autofrettaged Pressure Vessel Steels

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
G. H. Farrahi ◽  
E. Hosseinian ◽  
A. Assempour
Keyword(s):  
Uniaxial Tension ◽  
High Strength Steels ◽  
High Strength ◽  
Test Methods ◽  
Material Behavior ◽  
Material Modeling ◽  
Chemical Compositions ◽  
Accurate Analysis ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

Material modeling of high strength steels plays an important role in the accurate analysis of autofrettaged tubes. Although, the loading behavior of such materials is nearly elastic-perfectly plastic, their unloading behavior due to Bauschinger effect is very complicated. DIN1.6959 steel is frequently used for construction of autofrettaged tubes in some countries such as Germany and Switzerland. In spite of similarity between chemical compositions of this steel with that of A723 steel, due to different material processing, these two steels have an unlikely behavior. In this paper the material behavior of DIN1.6959 was accurately modeled by uniaxial tension-compression test results. Both 6 mm and 12.5 mm diameter specimens were used and compared. Also various relations for modeling of autofrettaged steels were investigated, and a new relation was introduced for accurate modeling. Moreover, two test methods, i.e., uniaxial tension-compression and torsion tests, used for modeling of autofrettage steels, were analyzed. Also, material models of three important autofrettage steels, i.e., A723, HB7, and DIN1.6959, were compared.

Fatigue life and cyclic material behavior of butt-welded high-strength steels in the LCF regime

2015 ◽  
Vol 57 (2) ◽  
pp. 141-148 ◽  
Author(s):  
Benjamin Möller ◽  
Rainer Wagener ◽  
Heinz Kaufmann ◽  
Tobias Melz
Keyword(s):  
Fatigue Life ◽  
High Strength Steels ◽  
High Strength ◽  
Material Behavior

Study of Sheared Edge Formability of Ultra-High Strength DP980 Sheet Metal Blanks

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Saeid Nasheralahkami ◽  
Weitian Zhou ◽  
Sergey Golovashchenko
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Strength Steels ◽  
High Strength ◽  
Material Behavior ◽  
Element Analysis ◽  
Advanced High Strength Steels ◽  
Sheared Edge ◽  
Ultra High Strength Steels ◽  
Lower Tool

Advanced high strength steels (AHSS) and ultra-high strength steels (UHSS) have been increasingly implemented by the automotive industry for better crashworthiness and fuel economy. However, these steels are often sensitive to the trimmed edge cracking. The objective of the present paper is to study the sheared edge of ultra-high strength dual-phase steel, DP980, in mechanical trimming and hole punching by sheared edge quality assessment, stretchability, and hole expansion tests as well as finite element analysis. Furthermore, the mechanism of fracture propagation in trimming and hole punching processes of DP980 was discussed. Rather a unique fracture mechanism was observed for trimming of DP980 steel leading to the burr removal at the final stage of the trimming process. Finite element analysis revealed that, under very large clearances, a secondary crack initiates from the edge of the lower tool, and the primary propagated crack turns toward it simultaneously. Intersecting of these two cracks leads to the total separation and leaves the edge of the trimmed part with a broken burr. Fracture observation of trimmed specimens revealed that crack initiation sites under tension moved from the middle of the trimmed surface toward the burr tip with increasing the clearance. This study demonstrates the importance of stretchability tests for designing the stamping dies as well as a reliable finite element simulation for characterizing the material behavior during the shearing process.

Modeling and Simulation of Q&P Steels

2016 ◽  
Vol 879 ◽  
pp. 1454-1458
Author(s):  
Georg Paul ◽  
Richard G. Thiessen
Keyword(s):  
Automotive Industry ◽  
High Strength Steels ◽  
High Strength ◽  
The Body ◽  
Special Focus ◽  
High Tensile Strength ◽  
Advanced High Strength Steels ◽  
Passenger Safety ◽  
Steel Grades ◽  
Body In White

Two important objectives of the automotive industry are the decrease of the body-in-white weight and the improvement of the passenger safety. High strength steels (HSS) are widely used to achieve these objectives. Quenching and partitioning (Q&P) has recently been proposed to achieve high strength steel grades for the third generation of advanced high strength steels (AHSS), which contain a considerable amount of retained austenite. Due to their microstructure these new steel grades combine a high tensile strength with good elongation values, as long as cementite precipitation is avoided. A model describing the involved phase transformations is presented. Special focus is put on the cementite precipitation and how it is influenced by silicon and aluminum additions.

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