scholarly journals Properties of UFG HSLA Steel Profiles Produced by Linear Flow Splitting

2008 ◽  
Vol 584-586 ◽  
pp. 661-666 ◽  
Author(s):  
Enrico Bruder ◽  
Tilman Bohn ◽  
Clemens Müller
Keyword(s):  
Mechanical Properties ◽  
Hsla Steel ◽  
Recrystallization Temperature ◽  
Forming Process ◽  
Cold Forming ◽  
Linear Flow ◽  
Metal Structures ◽  
Local Strength ◽  
Flow Splitting ◽  
Processing Zone

Linear flow splitting is a new cold forming process for the production of branched sheet metal structures. It induces severe plastic strain in the processing zone which results in the formation of an UFG microstructure and an increase in hardness and strength in the flanges. Inbuilt deformation gradients in the processing zone lead to steep gradients in the microstructure and mechanical properties. In the present paper the gradients in the UFG microstructure and the mechanical properties of a HSLA steel (ZStE 500) processed by linear flow splitting are presented, as well as a calculation of local strength from hardness measurements on the basis of the Ludwikequation. In order to investigate the thermal stability of the UFG microstructure heat treatments below the recrystallization temperature were chosen. The coarsening process and the development of the low angle to high angle grain boundary ratio in the gradient UFG microstructure were monitored by EBSD measurements. It is shown that heat treatment can lead to a grain refinement due to a strong fragmentation of elongated grains while only little coarsening in the transverse direction occurs. A smoothing of the gradients in the UFG microstructure as well as in the mechanical properties is observed.

scholarly journals UFG-Microstructures by Linear Flow Splitting

2008 ◽  
Vol 584-586 ◽  
pp. 68-73 ◽  
Author(s):  
Clemens Müller ◽  
Tilman Bohn ◽  
Enrico Bruder ◽  
Peter Groche
Keyword(s):  
Mechanical Properties ◽  
Sheet Metal ◽  
Process Zone ◽  
Roll Forming ◽  
Microstructural Development ◽  
Cold Forming ◽  
Linear Flow ◽  
Flow Splitting ◽  
Processing Zone ◽  
Splitting Process

Linear flow splitting is a new continuous cold forming process where the edge of a sheet metal is formed into two flanges by splitting and supporting rolls. Thus the production of bifurcated profiles from sheet metal without lamination of material becomes feasible. The production of such structures takes place incrementally in a modified roll forming machine. Experimental investigateons on a HSLA steel show, that even at a surface increase of the sheet edge of about 1800% no cracks were nucleated in the profiles. EBSD measurements in the splitting centre reveal that similar to other SPD processes UFG microstructures develop in the processing zone. Thus a steady state is reached in the processing zone where increasing strain has no more (or little) influence on the materials properties i.e. its deformability, as it is typical for SPD-processes. The formation of UFG microstructures is considered to be a mandatory condition for the linear flow splitting process, as it improves the formability of the material to the extremely high level required for this process. The mechanical properties of profiles produced by linear flow splitting are characterised by large gradients, depending on the local deformation and the resulting microstructure. Very high hardness is measured at the former processing zone, i.e. the splitting centre and the flange surface, where severe plastic deformation takes place and UFG microstructures are present. In direction to lower deformation i.e. with increasing distance to the splitting ground or flange surface the hardness decreases close to the level of the undeformed material. In the present paper the linear flow splitting process is introduced and the microstructural development in the process zone is discussed on the base of EBSD measurements on profiles of the steel ZStE 500. The repartition of mechanical properties in a bifurcated profile is demonstrated by detailed hardness measurements.

scholarly journals Effect of deformation and annealing temperature on the mechanical properties and microstructure of Al-4.5Zn-1.5Mg-0.9Cr (wt. %) alloy fabricated by squeeze casting

2018 ◽  
Vol 153 ◽  
pp. 01001
Author(s):  
Maya Putri Agustianingrum ◽  
Nuzulian Akbar Arandana ◽  
Risly Wijanarko ◽  
Bondan Tiara Sofyan
Keyword(s):  
Mechanical Properties ◽  
Squeeze Casting ◽  
Deformation Behaviour ◽  
Optical Microscope ◽  
Dislocation Motion ◽  
Hot Tearing ◽  
Mg Alloys ◽  
Recrystallization Temperature ◽  
Forming Process ◽  
Mechanical Properties And Corrosion

In order to produce structural products, Al-Zn-Mg alloys undergo various forming processes. Problems that are usually found in the forming process include peripheral coarse grain (PCG) and hot tearing which decrease mechanical properties and corrosion resistance of the alloys. Addition of microalloying element such as chromium (Cr) is an alternative to overcome these problems. The presence of Cr in Al-Zn-Mg alloys supresses the grain growth by preventing excess recrystallization. In this research 0.9 wt. % Cr was added to Al-4.5Zn-1.5Mg alloy and the deformation behaviour as well as subsequent recrystallization was observed. The alloy was fabricated by squeeze casting followed by homogenization at 400 °C for 4 h. The samples were cold rolled for 5, 10, and 20 %. The 20 % deformed samples were then annealed at 300, 400, and 500 °C for 2 h. Material characterization consisted of microstructure analysis using optical microscope and Scanning Electron Microscope (SEM) – Energy Dispersive Spectroscopy (EDS), hardness testing using Micro Vicker methods. The results showed that the deformed grain ratio was 1.6, 2.84, and 2.99 in the 5, 10, and 20 % deformed samples, respectively. The elongated dendrites were effective to increase the hardness of the alloy. Recrystallization was not detected during annealing at 300 and 400 °C, but was observed at 500 °C. Whereas, for the samples without Cr addition, recrystallization occurred at 400 °C. It means that the addition of Cr increased the recrystallization temperature of the alloy. It occured because (Al, Zn)7Cr dispersoids with size less than 1 μm impeded the dislocation motion during annealing, so that recrystallization was retarded. On the other hand (Al, Zn)7Cr dispersoids with size more than 1 μm promoted the formation of new grains around them by Particle Stimulated Nucleation (PSN) mechanism. In this case, the fine (Al, Zn)7Cr dominated so that recrystallization was slower.

Effects of thread rolling processing parameters on mechanical properties and microstructures of high-strength bolts

2020 ◽  
Vol 62 (10) ◽  
pp. 1017-1024
Author(s):  
Serkan Aktas ◽  
Yasin Kisioglu
Keyword(s):  
Mechanical Properties ◽  
Low Carbon Steel ◽  
High Strength ◽  
Rolling Process ◽  
Processing Parameters ◽  
Industrial Applications ◽  
Low Carbon ◽  
Forming Process ◽  
Cold Forming ◽  
Thread Rolling

Abstract Bolt production with a grade of 10.9 class quality made from AISI4140 material with a low thread rolling index is usually implemented in accordance with the thread rolling method (cold forming) in industrial applications. In this method, the effects of die revolutions and multiple passes are unknown in the thread forming process as the devices are usually operated with respect to geometrical dimensions but not the mechanical properties and microstructures of the material. In the literature there are few studies on microstructures of low-carbon steel having a higher thread rolling index in bolt production. This study experimentally examined the effects of the processing parameters on the mechanical properties and microstructures. Parameters such as forming speed and single or multi-pass influences were considered in the production of M12 × 1.75 and M20 × 2.5 fasteners widely used in industrial applications. The experiments identified the behavior of the mechanical properties, microstructures and micro-hardness of the AISI4140 material at two forming speeds (rpm) and three passes in the thread rolling process. Thus, significantly sensible outcomes as a function of processing parameters were obtained considering the thread strength viewpoints.

scholarly journals Investigating of Mechanical Behavior of AA5083 in the Pressing Process Using Finite Element Analysis

2017 ◽  
Vol 11 (9) ◽  
pp. 51
Author(s):  
Babak Beglarzadeh ◽  
Behnam Davoodi
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Aluminum Alloy ◽  
Friction Stress ◽  
Forming Process ◽  
Element Analysis ◽  
Cold Forming ◽  
Aluminum Alloy 5083 ◽  
And Control

The process of cold forming is considered of the most different industries and the use of such process in the manufacture of components and small parts has expanded. Therefore, analyzing the behavior of metals in this process to identify and control durability that is the main factor of limiting process has particular importance in industrial forming processes. In this study, cold forming process of aluminum metal has been studied and its effect on its mechanical properties has been evaluated. For this purpose, first modeling piece of aluminum alloy 5083 for cold forming process is carried out and using finite element analysis, mechanical properties of considered piece during cold forming processes are investigated. The results show that by reducing friction, stress and strain during the process will reduce, thereby durability of the piece increases, or in other words, ductile fracture occurs in longer life and higher stresses. The results show that by proper forming operations, it can be improved the strength and durability of aluminum alloy. Finally, validation of results, by comparing simulation results with experimental results is carried out.

Effect of Pre-Strain on Mechanical Properties of Pressure Vessel Grades: Assessment of Stress Relieving/Post Weld Heat Treatments Efficiency at Regenerating Properties

2012 ◽  
Author(s):  
Deborah Heritier ◽  
Sylvain Pillot ◽  
Stéphanie Corre ◽  
Cédric Chauvy ◽  
Patrick Toussaint
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Material Properties ◽  
Pressure Vessels ◽  
Forming Process ◽  
Cold Forming ◽  
Thick Plates ◽  
Maximum Deformation ◽  
Stress Relieving ◽  
Weld Heat

During fabrication of large pressure vessels, thick plates are submitted to numerous process phases that may affect the initial (i.e. as delivered) properties of the material. Regarding the advantages (both technical and economical) of cold forming process, this technique is largely preferred and widely spread. Modern forming presses and rollers are now sufficiently powerful to roll very thick plates (typically up to 250mm thick) devoted to ultra-heavy pressure equipments. As force does not really constitute a limitation anymore, current limitations are now focusing on maximum admissible strain in materials. This particular limit is linked to: - Intrinsic maximum deformation admissible by the material (given by tensile tests), - Regulation rules coming from construction codes. From a practical point of view, the actual limitation comes from the construction codes that are very severe. Main codes (ASME Boilers and Pressure Vessels Construction Code from American side and EN 13445 Unfired Pressure Vessels Construction Code from European side) both give a limit equal to 5% strain for using material in “as-strained” condition without any heat treatment. Above this limit, the philosophy differs from one code to another. While European Code requires a full quality treatment of the strained material (Normalisation or Austenitization / Tempering), American code only requires Tempering, allowing fabricators the possibility of using the mandatory Post Weld Heat Treatment (PWHT) (needed by welded zones) as a tempering treatment to improve welded zone toughness and to regenerate material properties. The purpose of this contribution is to review the effect of pre-strain on mechanical properties (Hardness, Tensile and Toughness transition curves) for different strain levels and to evaluate the ability of typical PWHT to regenerate material properties. Results presented in this paper are based on both recent studies on the most common up-to-date materials as well as on historical data collected in the last decades. This study clearly demonstrates that the required PWHT is efficient enough to regenerate all material properties and that there is no need to apply a full quality heat treatment, even for the highest level of strain. This benefits both the fabricator and the end user as it implies reducing costs and risks of components deformation while maintaining the necessary level of service properties.

Fatigue Life Calculation Concepts for Structures with Inhomogenous Strength Properties

2007 ◽  
Vol 22 ◽  
pp. 91-99 ◽  
Author(s):  
Alfons Esderts ◽  
Rainer Masendorf ◽  
Tim Medhurst
Keyword(s):  
Fatigue Life ◽  
Collaborative Research ◽  
High Strength ◽  
Fatigue Behaviour ◽  
Strength Properties ◽  
Research Project ◽  
Cold Forming ◽  
Metal Structures ◽  
Local Strength ◽  
Actual Design

A fast transfer of new manufacturing- and material technologies to actual design use is only to be expected if calculation concepts exist, which allow an easy estimation of the parts’ strength properties. This Collaborative Research Project (CRP) will develop new manufacturing and joining techniques to create high strength structures by adjusting the local strength properties of parts. These types of structures are usually loaded dynamically. To specifically optimise the fatigue behaviour, stiffness and weight of a structure, the influences of locally strengthening manufacturing processes must be considered in the fatigue life calculation concept. It is the goal of this project to include a simulation of the fatigue behaviour in the process simulation of manufacturing. Recently research on the influence of local strengthening by cold forming on fatigue life was undertaken in cooperation within another research project. The fatigue life calculation of sheet metal structures can be based on a calculation concept developed in CRP 362, subproject C5, which takes into account the influence of forming, [1,2,3,4]. This concept shall be extended to incorporate the effects of local martensite forming in the cold formed areas.

Optimization of UOE Pipe Manufacturing Process for Improved Collapse Performance Under External Pressure

2006 ◽  
Author(s):  
Stelios Kyriakides ◽  
Mark D. Herynk ◽  
Heedo Yun
Keyword(s):  
Mechanical Properties ◽  
Parametric Study ◽  
Large Diameter ◽  
External Pressure ◽  
Material Degradation ◽  
Forming Process ◽  
Cold Forming ◽  
Collapse Pressure ◽  
Large Diameter Pipes ◽  
Pipe Manufacturing

Large-diameter pipes used in offshore applications are commonly manufactured by cold-forming plates through the UOE process. Collapse experiments have demonstrated that these steps, especially the final expansion, degrade the mechanical properties of the pipe and result in a reduction in its collapse pressure, upwards of 30%. In this study, the UOE forming process has been modeled numerically so that the effects of press parameters of each forming step on the final geometry and mechanical properties of the pipe can be established. The final step involves simulation of pipe collapse under external pressure. An extensive parametric study of the problem has been conducted, through which ways of optimizing the process for improved collapse performance have been established. For example, it was found that optimum collapse pressure requires a tradeoff between pipe shape (ovality) and material degradation. Generally, increase in the O-strain and decrease in the expansion strain improve the collapse pressure. Substituting the expansion by compression can not only alleviate the UOE collapse pressure degradation but can result in a significant increase in collapse performance.

scholarly journals Strength of self-piercing riveted Joints with conventional Rivets and Rivets made of High Nitrogen Steel

2021 ◽  
Author(s):  
Benedikt Uhe ◽  
Clara-Maria Kuball ◽  
Marion Merklein ◽  
Gerson Meschut
Keyword(s):  
Stainless Steel ◽  
Joint Strength ◽  
Lightweight Design ◽  
High Strength ◽  
High Nitrogen Steel ◽  
High Nitrogen ◽  
Forming Process ◽  
Cold Forming ◽  
Local Strength ◽  
Nitrogen Steel

The use of high-strength steel and aluminium is rising due to the intensified efforts being made in lightweight design, and self-piercing riveting is becoming increasingly important. Conventional rivets for self-piercing riveting differ in their geometry, the material used, the condition of the material and the coating. To shorten the manufacturing process, the use of stainless steel with high strain hardening as the rivet material represents a promising approach. This allows the coating of the rivets to be omitted due to the corrosion resistance of the material and, since the strength of the stainless steel is achieved by cold forming, heat treatment is no longer required. In addition, it is possible to adjust the local strength within the rivet. Because of that, the authors have elaborated a concept for using high nitrogen steel 1.3815 as the rivet material. The present investigation focusses on the joint strength in order to evaluate the capability of rivets in high nitrogen steel by comparison to conventional rivets made of treatable steel. Due to certain challenges in the forming process of the high nitrogen steel rivets, deviations result from the targeted rivet geometry. Mainly these deviations cause a lower joint strength with these rivets, which is, however, adequate. All in all, the capability of the new rivet is proven by the results of this investigation.

Numerical Fatigue Strength Evaluation of Inhomogeneous, Linear Flow Split Profiles

2008 ◽  
Author(s):  
Volker Landersheim ◽  
Chalid el Dsoki ◽  
Holger Hanselka ◽  
Thomas Bruder ◽  
Desislava Veleva ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Plastic Material ◽  
Material Behavior ◽  
Fatigue Properties ◽  
Forming Process ◽  
Linear Flow ◽  
Local Material ◽  
Durability Analysis ◽  
Flow Splitting ◽  
Local Material Properties

The innovative sheet metal forming technology “Linear Flow Splitting” offers various new options for designing profile-like components. The forming process leads to severe changes in local material properties, inhomogeneities and residual stresses within the manufactured component. These effects influence the mechanical properties of the manufactured components. If the components are designed to endure cyclic mechanical loads, it is especially important to know the components fatigue properties. This paper focuses on a method to derive the fatigue properties of Linear Flow Split Profiles by nonlinear numerical FE analysis, including durability analysis and forming simulations. This numerical approach offers the possibility to estimate the fatigue properties of components before manufacturing physical prototypes, only based on material parameters derived from tests on smooth samples. The Finite-Element analysis of the Linear Flow Splitting Process provides distributions of local material deformation and residual stresses. These results are mapped by an appropriate interface on FE models, which allow simulating the component behavior under external loads. Thus, the inhomogeneous elastic-plastic material behavior and residual stresses are considered in the computed stresses and strains. Further on, a post-processing tool was implemented to interpret the FE results considering the inhomogeneous distribution of materials fatigue properties, the mean stress distribution and the statistical size effect.

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