Surface Nanostructuring of a CuAlBe Shape Memory Alloy Produces a 10.3 ± 0.6 GPa Nanohardness Martensite Microstructure

Severe plastic deformation (SPD) has led to the discovery of ever stronger materials, either by bulk modification or by surface deformation under sliding contact. These processes increase the strength of an alloy through the transformation of the deformation substructure into submicrometric grains or twins. Here, surface SPD was induced by plastic deformation under frictional contact with a spherical tool in a hot rolled CuAlBe-shape memory alloy. This created a microstructure consisting of a few course martensite variants and ultrafine intersecting bands of secondary martensite and/or austenite, increasing the nanohardness of hot-rolled material from 2.6 to 10.3 GPa. In as-cast material the increase was from 2.4 to 5 GPa. The friction coefficient and surface damage were significantly higher in the hot rolled condition. Metallographic evidence showed that hot rolling was not followed by recrystallisation. This means that a remaining dislocation substructure can lock the martensite and impedes back-transformation to austenite. In the as-cast material, a very fine but softer austenite microstructure was found. The observed difference in properties provides an opportunity to fine-tune the process either for optimal wear resistance or for maximum surface hardness. The modified hot-rolled material possesses the highest hardness obtained to date in nanostructured non-ferrous alloys.

The Difference of Corrosion Behavior in Initial Period for the Hot-Rolled and Cold-Rolled 2205 Duplex Stainless Steel

The precipitate phases often play an important influence on the corrosion resistance of 2205 Duplex stainless steel (DSS). In the presented paper, the microstructure and corrosion resistance in the hot-rolled and cold-rolled 2205 DSS aging for different time at 850 °C was investigated by XRD, SEM and potentiodynamic polarization. It has been found that the Chi(χ) phase and Sigm(σ) phase were precipitated in turn after aging treatment of hot-rolled and cold-rolled materials, but the precipitate amount in cold-rolled material is much more than that of hot-rolled samples. The corrosion resistance of the solution-annealed cold-rolled material is similar to the hot-rolled material, but the corrosion resistance of cold-rolled material with precipitate is weaker than that of hot-rolled material after aging treatment. Pitting initiates preferentially in the Cr-depleted region from σ phase in aged hot-rolled 2205, and severe selective corrosion occurs on sigma/ferrite interfaces aged for a long aged lime. However, the initiation of pitting corrosion may take place at the phase boundary, defect and martensite in the aged cold-rolled 2205. The σ phase is further selectively dissolved by electrochemical method to investigate the difference of microstructure and corrosion behavior in hot-rolled and cold-rolled 2205 duplex stainless steel.

THE INTEGRATED LAYOUT DECISIONS FOR AUTOMATIC CONTROL OF PACKING SYSTEMS

On many industrial objects regulators of pressure are used. Following initial data are necessary for proper selection of a regulator and calculation of throughput: a working environment, entrance and target pressure, expense, temperature of a working environment, accuracy of regulation, a class of tightness, diameter of the pipeline, type of accession, constructional materials, external or internal registration of target pressure, protection against excess of pressure.The decision of this problem is closely connected with the proved choice of types of the process equipment, wide automation of technological processes, introduction of new technical decisions, use of necessary means of the control over realization of problems of complex mechanization of technological operations. In article the analysis of work of the functional module of a vertical multiline automatic packing machine on the basis of a proportional regulator of pressure «CAMOZZI» with realization of a feedback by means of an analog signal of regulator МХ-PRO [1-3] is lead. The drive of the holder for a rolled material has been tested on proportional management of position of the directing rollers used on a technological site of supply and regulation of a tension of a tape of a roll of a packing material at formation of packing.Results on use as the operating module of regulator МХ-PRO for management of a drive of the holder for a roll of a material in view of a course and pressure in a pneumatic system are received. Carried out researches provide the way to raise operational properties of a transportation system of supply of a packing material for technological processes of packing modules at the food enterprises.

Effect of Microalloying Elements on Phase Transformation, Microstructure and Mechanical Properties in Dual-Phase Steels

Dual-phase steels are the most important AHSS grades for automotive applications. Microalloying elements such as Ti, Nb or B are widely used to improve the strength of dual-phase steels. Thus, understanding the influence of these elements on the microstructure and mechanical properties of dual-phase steels along the processing route is critical for the development of new steel grades. In this work, different microalloying elements were investigated, separately or in combination. The influences of the different elements on the microstructure and mechanical properties of dual-phase steels in the hot-rolled condition and after annealing of cold-rolled material. Dilatometer measurements were performed to investigate phase transformation during a typical continuous annealing treatment of dual-phase steel after cold rolling. It was shown that, for example, Ti has a strong influence on the mechanical properties of hot-rolled material while its influence on annealed materials after cold rolling was relatively small. Conversely, B had a strong influence on cold-rolled materials but an insignificant influence on hot-rolled materials.

Modelization of the Rolling Mill with a FE Code

To reduce production costs and to improve performances of hot rolled products, it is necessary to optimize the production line. The rolling mill is one of the major factors which affect the internal quality. In fact the process tends to reduce the size of defects during the strain. The production line consisting of 24 stands has been modeled with a commercial FE-code FORGE®. First, a model has been developed and adjusted according to industrial data. Then a parametric study was carried out in order to estimate the influence of the process parameters on the internal quality of the rolled material.

An Automatic Control Strategy of Strip Width in Cold Rolling

This paper proposes an automatic control strategy of the strip width in cold rolling process. The prediction model for the exit strip width of each stand is established. In addition to the strip width variation of the incoming hot-rolled material between the measured and the pre-set values, the variations of the rolling force, tension, bending force and the roll shift amount of each stand are utilized to model and forecast the stand exit width deformation. Then, the model can be used to determine the compensation values of the different profile adjustment mechanism and the exit strip width can be controlled in high accuracy. In this way, the effect of the strip width variation of the incoming hot-rolled material and the fluctuation of the stand rolling process parameters on the exit strip width can be eliminated. Moreover, the feed-forward control of the strip width can reduce the incidence of abnormal situation, such as the strip breakage and off-tracking ,and improve the stability of the cold rolling process.

Mechanical and Electrical Properties of Carbon Nanofiber Dispersed Ti Composite Formed by Compression Shearing Method at Room Temperature

The materials used for fuel cell separators require a bending strength of more than 70 MPa. Therefore, the contact resistance is required to be 10 mΩ∙cm2, respectively. In the present study, vapor grown carbon nanofibers (VGCF) were added to Ti composite using the compression shearing method at room temperature. The mechanical properties of the compacted powder were then measured. The microstructure of the Ti/VGCF composite material was Ti with dispersed VGCF (not alloyed). In addition, the bending strength of all Ti/VGCF composites was more than 800 MPa, and the bending strength of 0-1 vol% VGCF composites was twice as much as that for Ti rolled material (ASTM grade 2). Ti/VGCF thin plates also exhibited excellent electrical property. The contact resistance of 5 vol% VGCF was found to be three times smaller than that of Ti rolled material. These properties make the Ti/VGCF composite material suitable as a separator material.

Identification and Prediction of Surface Topography with Regard to Variable Conditions of Cold Rolling Process

Contribution of the work consists in creation of a mathematical model (algorithm) for prediction of technological parameters of the two-high rolling stand DUO 210 Sva and Q110 at change of the absolute reduction Δh, for example for a deep-drawing steel and of the brand KOHAL grade 697 and low carbon steel, as well as generally speaking for any rolled material. It is possible to identify and predict on the basis of this algorithm an instant state of surface topography in respect to variable technological conditions. On this basis it is then possible to calculate and plot individual main technological parameters.

Flatness Detection and Roll Shape Adjustment of Cold Rolled Material

Cold rolling rules according to the fixed incoming crown distribution of each crown control, raw material convexity fluctuations will destroy convex degree program, light is left with the residual stress, heavy waves. This paper discusses test incoming convexity, convexity control allocation method of residual stress.