Regularities of Stress-Corrosion Cracking of Pipe Steel 09G2S at Cathodic Polarization in a Model Soil Environment

Peculiarities of corrosion-mechanical fracture of 09G2S pipe steel samples in the conditions of cathodic protection were investigated. It was established that depending on the level of protective potential, stress-corrosion cracking of pipe steel of a ferrite-pearlite class 09G2S can occur by different mechanisms. The range of protective potentials was determined, at which the anodic dissolution and hydrogen embrittlement occur simultaneously during the fracture of steel, namely from -0.85 V to -1.0 V. The existence of the above mechanisms is confirmed by the change in the strength and viscosity properties of the steel and the morphology of the fractures. For steels of other manufacturing technology and grades, these potential areas may differ.

Evaluation of the quality of three-layer steel bimetallic strips obtained on a unit of continuous casting and deformation

Today there is an urgency of creating high-performance continuous processes for the production of bimetals. The article describes the main tasks of improving the quality of the materials under consideration. Two stages of the technology for producing steel three-layer bimetallic strips on the unit of a combined continuous casting and deformation process are considered. The authors give recommendations on the conduct of the technological process in order to obtain high-quality bimetallic strips on such unit. The problem statement is presented. The material considers initial data for determining the temperature of the steel base strip and the stress-strain state of the metals of the cladding layers and the strip in deformation center of a three-layer bimetallic ingot. A model for calculating and a method for solving problems of thermal conductivity and elastoplasticity are shown. Regularities of the temperature change of the main steel strip are given during its passage through the molten metal of the cladding layer. Stress-strain state of the metals of the main strip and cladding layers in the deformation center was determined when three-layer bimetallic steel strips were obtained on the unit of combined continuous casting and deformation process. The authors describe the values of compression of the main steel strip and mutual displacement of the layers during compression of the bimetallic ingot by the strikers. Regularities of the distribution of axial and tangential stresses are shown along the contact line of the cladding layer with the striker. The evaluation of the process of obtaining bimetal steel 09G2S - steel 13KhFA - steel 09G2S was made on a pilot unit for continuous casting and deformation. Microstructure of the main strip and cladding layers of a three-layer bimetallic steel strip is shown when a combined continuous casting and deformation process is obtained in one unit.

Structure and hardness of wear-resistant coatings with low-frequency current modulation deposited on low carbon steel

Influence of the modes of manual electric arc surfacing of coatings with T-590 electrodes on low-alloy steel 09G2S on their structure and hardness was investigated. It is shown that the pulsed arc surfacing of coatings by electrodes forms a fine-dendritic structure of the deposited metal. Microstructure of the heat-affected zone after surfacing consists of several sections: the overheating zone with a widmanstett structure and the normalization zone with a characteristic fine-grained ferrite-perlite structure. In the initial state, the base metal (steel 09G2S) has a hardness of ~2500 MPa. The hardness of the deposited coating material due to strong mixing with the steel metal is ~ 2700 – 3000 MPa, and of thermal impact zone: 2100 – 2300 MPa. When applying the coating on DC mode, heating temperature of the surfacing bath is higher; this, as a consequence, causes grain growth. When coating on pulse modes, a structure with smaller component sizes is formed by directed low-frequency high-energy impact of the electric arc on the formed metal and due to the constant reciprocating motion of the melt with the frequency of current modulation. It was established that the application of the pulse-arc surfacing method allows preserving the previously formed hardening phases in the deposited coatings.

Impact of thermal treatment modes upon steel 09G2S durability in environment with increased CO2 values

The impact of thermal treatment modes upon durability of steel 09G2S to carbonic acid corrosion under laboratory and industrial conditions is considered. The results of the works carried out witness of the necessity in the development of new special systems of alloying ensuring the increase metal durability in environment containing CO2 high concentrations.

STRUCTURE AND PROPERTIES OF COATINGS ON PRODUCTS MADE OF STEEL 09G2S, STEEL 3 AND STEEL 12H18N10T

The investigation of the mode impact of electric arc surfacing with electrode EN-60M upon coating properties of non-alloy, low-alloy and alloy steels (steel 3, steel 09G2S, steel 12H18N10T) is carried out. As a result of this there is studied the electric arc impact upon structure, physical stress-strain and operation properties of coatings built up with electrode EN-60M. It is defined that the modification in progress with electric arc impact allows milling the structure formed of built up coatings and increasing its uniformity.

Continuous casting and deformation plant for the production of steel three-layer bimetallic strips

The technology of obtaining steel three-layer bimetallic strips on the installation of a combined process of continuous casting and deformation is described. The regularities of changes in the temperature of the main steel strip during its passage through the molten metal of the cladding layer are established. The stress-strain state of the metals of the main strip and the cladding layers in the deformation zone during the production of steel three-layer bimetallic strips is determined. The results of a study of the microstructure of the steel 09G2S – steel 13XFA – steel 09G2S bimetal obtained at a pilot installation for continuous casting and deformation are presented.

COMBINING OF MATERIAL STRAIN PROCESSING METHODS

The purpose of the work consists in the investigation of stress-strain properties and destruction mechanism of low-alloy steel 09G2S subjected to extrusion and uniformly channel angular pressing (UCAP). The combined method of Strain processing consists in the successive use of extrusion methods and UCAP. There is shown an example of low-alloy steel 09G2S strengthening with the use of extrusion and UCAP. There are presented data on stress-strain properties and destruction mechanism of steel 09G2S samples at uniaxial tension at the state of delivery and after strengthening. Strength increase and steel plasticity decrease is shown. On the basis of the results of fractal graphics analysis a viscous character of steel 09G2S destruction at the state of delivery and after extrusion and UCAP is defined.