In this work was performed a comparative analysis of the efficiency of horizontal and vertical rolls in the "rolling-pressing" process. The comparison was performed based on the study of stress-strain state of both variants with the aid of computer simulation in the program DEFORM-3D based on the finite element method. For analysis of the stress state was used the Lode-Nadai coefficient, allowing you to determine which type of deformation is realized at a specific point – tension, compression or shear. For analysis of the strain state was used equivalent strain, which allows to estimate the common level of accumulated strain. In the comparative analysis of parameters of SSS was revealed that the use of vertical rolls at the exit from the matrix during "rolling-pressing" process, allows you to achieve a more favorable distribution of deformation along the entire length of the deformable workpiece.
Ecological and economic reasons are forcing industry to improve efficiency and to save energy and resources. Especially for the automotive and transport industry – but also for all other industrial branches dealing with accelerated masses – lightweight design is a key issue for achieving this goal. Higher process stability, improved material exploitations, and general shortening of process chains are the most important aims of Fraunhofer IWU. The requirements of the future car achieve the lightweight construction concepts, in which materials, design and manufacturing process harmonize optimally. A target-oriented design helps to save weight by using optimally adapted structures. To enable the design of the structuring, the influence of structures manufactured by different forming technologies including electromagnetic forming (EMF), forming by elastomer tools, and hydro-mechanical deep drawing, was systematically analyzed through complementing numerical and experimental investigations. Knowledge about the influence of the structuring technology and the process parameters on the resulting structure and the part performance allows conclusions regarding the optimization of the part functionality via a suitable selection and design of the process.
In the present paper, by “modelling of thermal process” will be understood the thermal techniques modelling, applied to the heating of steel billets in a large scale, in view of processing by plastic deformation. These technologies are correlated with the particularities of the thermal aggregates, having as main objective the reducing of energy consumptions and the optimizing of projecting the aggregate.
When heating the steel billets in view of processing by plastic deformation, the duration and quality of heating are influenced by the way the material are receiving the heat flow. Reception of the heat flow depends on the way the heated surface is exposed to the thermal radiation in compliance with their position on the hearth of the heating aggregate. This present work intends to establish some parameters in view of optimizing the heating process.
A basic point of the work is also a theoretic calculus of proposed heating technology. The authors are having in view the complexity of technical evolutions.
There are some cases when there should be a constant rate of heating, case that represents a study objective in the present article. Starting from general calculus relations, there are proposed particular situations with practical applicability.
The effects of heat treatment and initial microstructure on tensile properties of 0.22C-1.30Mn-0.3Si-B-Ti, high-strength hot stamping steels with martensite-ferrite matrix were investigated. Hot stamping steels possessed limited elongations of about 8% in a tensile strength ranging from 1300 to 1500 MPa when quenched at temperatures above A3 temperatures. The total elongations were tried to improve by partial austenization between A1 and A3 temperature and quenching. A1 and A3 temperatures were calculated via ThermoCalc. Microstructural characterization was made by using Light Microscope and Scanning Electron Microscope. Microstructure is composed of ferrite+martensite. It was seen that annealing temperature affects the volume fraction of phases. It was concluded that initial microstructure is an important parameter for the final microstructure. This method can be used for automobile parts which require higher TE with sufficient yield and tensile strength. Also this process may be a way of using Zn coated steel sheets in hot stamping process.
At the end of 2012 a new rolling 4200mm mill at NLMK DanSteel was put into service. Since the company has focused on production of heavy plates for construction, offshore and shipbuilding purposes. The enterprise is consistently expanding assortment as regards sizes and grades of steel used for production of heavy plates. For example, at the end of 2014 the enterprise expanded the range of TMCP rolled heavy plates, namely structural steel of strength category S355ML, S420ML, S460ML up to 100 mm and received certificates. The same was done for TMCP plates for fixed offshore structures and shipbuilding.
The report presents slab quality requirements, features of production technology for specified quality and thickness categories as well as microstructure investigations, enhanced mechanical test results, including evaluation of the anisotropy of the hardness gradient, strain aging properties and toughness up to -80°C in different thickness layers, showing the actual level of cold resisting properties of produced steels. Investigations of welded joints with different heat inputs and for different chemical compositions of steel also will be presented.
In this study the material flow of a newly developed ultra-high-carbon lightweight steel (uhc-steel) with a high amount of aluminum was investigated in an extrusion process. Cylinder compression tests were performed for material characterization and frictional behavior was determined by using ring compression tests. Numerical simulations were carried to determine the optimal die geometry as well as to calculate the process loads and dominated stresses in the die occurring during the process. Based on the numerical results, an extrusion process was designed and implemented. Experiments showed that the uhc-steel can be formed by extrusion however it is associated with a high wear rate.