Effect of structure and phase content on wear resistance of the economical alloyed metastable and secondary hardening steels of Cr-Mn-Ti system

Despite a large number of studies in the field of assessing the causes of the formation of hot and cold cracks during surfacing of wear-resistant alloys, today the issues of working out the use of economically alloyed wear-resistant materials and the technique of their surfacing remain relevant. Goal: The purpose of this work is to study the effect of the structure and phase composition on the wear resistance of economically alloyed metastable and secondary hardening steels of the Cr-Mn-Ti system, as well as with additional alloying with Mo, B, V. Mechanized surfacing was carried out with flux cored wires AN-22 and AN-20 with the supply of a de-energized additive to the head of the weld pool, which reduces the content of sulfur and phosphorus, the specific consumption of electricity and increases the assimilation of alloying elements and the relative mass of the flux. Cladding by manual arc welding was carried out with coated electrodes with the addition of a depleted CaF2-coated flux-cored wire filler. When surfacing with a de-energized additive, the ratio of the filler to the main electrode, the relative mass was determined by β = m1 / m2 (m1, m2 are the mass of the filler and the electrode rod, respectively). Submerged arc surfacing was carried out in the following modes: IN = 300 ... 350 A, UD = 26 ... 30 V, q = 6 ... 10 kJ / cm, with manual surfacing - IN = 180 ... 220 A, UD = 25 ... Results: The studies carried out confirm the possibility of the formation of a “white band” both in alloys with a high concentration of austenitizing elements (Mn, C, Ni) and when alloying carbide-forming elements with a relatively low affinity for carbon (V, Mo). The indicators of resistance to cracking (КС, j-integral, δС), and, consequently, resistance to wear of secondary hardening steels are higher than those of metastable and tool steels.

The The Development of E-Module Based on Learning Models of Self Directed Learning in Welding Subject

This study aimed to produce an e-module based on a self-directed learning model that was valid, practical and effective and was able to help students learn independently and understand SMAW manual arc welding theory. This study is a Reset and Development (R&D) study which refers to the ADDIE instructional development model. ADDIE development procedures namely Analysis, Design, Develop, Implementation and Evaluation. The results of this Research and Development produced a valid learning e-module based on the evaluation of material expert validators who declared valid and the material expert validators who declared valid. The practicality of using e-module was known from the use of e-module that going well and the results of students and teachers responses from questionnaire statements were high practicality. The results of the effectiveness were known from the increase in the students' understanding of subject and the test results of the difference between pre-test and post-test results of the application of this e-module were quite effective category. Based on this study, a learning e-module for SMAW Manual Arc Welding based on the Self Directed Learning model had produced. this was valid, practical and effective for use in learning and can improve the theoretical understanding of SMAW Manual Arc Welding subject.

IMPORTANCE OF PIPELINE TRANSPORTATION, USE OF CONCRETE WEIGHTING AND INSULATION MEASURES, USED DURING PIPELINE CONSTRUCTION

It was determined that the advantages and importance of pipeline transportation are related to the priority of environmental measures, the fact that costs are within the norm, and the possibility of uninterrupted transportation regardless of the season. Of the transportation methods, special attention was paid to pipe transportation, which is considered to be the most efficient. At the design stage of the pipeline, the organization of repair work during the operation of the pipeline and the capital investment allocated for construction are referred to the criteria of optimality. Although there are many technologies for pipeline aggravation, the most common of these is aggregation with a concrete coating layer. It is known that pipes with a diameter of 530 mm and a wall thickness of 14 mm are used during pipe laying in offshore areas. For concrete treatment of these pipes, it is recommended to use 400-500 grade slag portland or putty cement, especially in the marine environment. Waterproofing is considered suitable for protecting submarine pipes from wear. For the implementation of the waterproofing layer, it is recommended to use either brizol or insulation in construction. An important factor is the provision of special insulation measures in the open part of the pipe after welding, which is explained in the article. Welding must be performed in accordance with the standard and welding materials must be licensed. There are many technologies for welding. Manual arc welding has the widest field of application. Prior to welding, there are important works that can affect the quality of work, including heating the pipe and sawing the pipe ring. The differences between the post-heated welding process of the pipe and the unheated welding process are known from production experience. During operation, the pipeline is affected by climate change and loads (various shock effects; seismic; as well as ripples if submerged; underwater currents, etc.). If the weld is as strong as the base metal, it will continue to do so. This strength can also be achieved by the absence of temperature differences during welding. Keywords: pipe, pump, concrete coating, insulation, welding.

Innovation of Biomass Crusher by Application of Hardfacing Layers

This paper presents the innovation possibilities of the crushers functional parts and the results of layers’ renovation analyses of the surfaces worn by biomass crusher hammers. The worn functional surfaces of hammers made of Hardox 400 material were renovated by manual arc welding method (welded with a filled wire electrode with its own protection). As an additive material, Lincore 60-O tubular wire from Lincoln Electric was used. The quality of weld layers was assessed on the metallographic sections, where the presence of internal defects was monitored, and the microstructures of welds were identified. In addition to the metallographic analysis, the microhardness in terms of EN ISO 9015-2 was assessed. Based on the performed experiments, it is suitable for the crusher innovation to recommend the chain replacement with a shaped weldment made of Hardox 400 material, the weldability of which is very good, and to make at least one hardfacing layer on its functional surfaces. With this innovation, the service life of the crushing segment could be extended by more than ten-fold.

Welding Operation Technique of Welding Electrode Arc Welding Overhead Welding Test Board

Welding electrode arc welding, upside welding, single side welding, double side forming welding operation technology is the most difficult welding process in manual arc welding operation. It is an operation technology that senior welding operators must master, and it reflects the technical level of the welding welder. . In this paper, the welding operation essentials and operation skills of backing welding, filling welding and cover welding are studied for the welding operation of the back welding test board, which creates a theoretical basis for the improvement of the welding operator's operation skills.

The Study on the Weldability of 1MnCrMoNi Alloy Steel and Q235 Carbon Steel

In this paper, the weldability of 1mncrmoni alloy steel and Q235 carbon steel is studied. The microhardness, tensile strength, impact and other mechanical properties of the welded joint are tested by manual arc welding. The variation trend of microhardness, tensile strength and impact toughness of the welded joint under different welding methods is studied, which provides theoretical support for practical engineering application.

RISK ASSESSMENT OF CARBONATE GAS FORMATION IN MANUAL ARC WELDING

The risk analysis is performed of carbon monoxide formation during manual arc welding of metal products using electrodes. The system of protection is considered of the person against carbon monoxide in the room of manufacturing which consists of means of collective and individual protection. The reasons are analysed for failures of the workplace safety system. A failure tree was constructed of the welder's protection system against carbon monoxide using a protective mask, which is not equipped with a gas detector, and when working in a mask which is equipped with a gas detector. The mathematical models of welding processes are obtained as a result of research and analysis of the results. Mathematical expressions are given for calculating the reliability of the protection system. The risk assessment take the place for carbon monoxide poisoning during welding works with the system of ensuring the safety of the employee, i.e. the notification system for the presence of carbon monoxide in the work area (individual alarm) and without it.

Development of Technology for Welding Repair of Steel Housings Using a Combination of Ultrasonic Vibrations and Forced Cooling

Now, one of the most pressing issues in the development of petroleum engineering is increasing the efficiency of apparatus and machines, as well as reducing material, energy and labor resources. During operation, oil-refining equipment over time destroyed by welded joints due to the impact of power and temperature loads, corrosion, and other factors. The cause of damage in welded joints of oil and gas equipment can be justified by the occurrence in them of structural heterogeneity and residual stresses during and after welding. Today manual arc welding is almost the only applicable in the repair of equipment for oil and gas processing, which require welding operations. The high temperature source of energy and the difference in deformation properties of parts are the cause of the occurrence of substantial residual stresses, which cause a change in shape, a significant decrease in strength, a decrease in the corrosion resistance of the metal, which adversely affects the durability and reliability of the structure. At present, the technology of repair with due to manual arc welding with the concomitant heating of the defective area and subsequent heat treatment is used. A complex of simultaneously proceeding processes accompanies the welding process: thermal effects on the metal in the heat-affected zone, metallurgical processes in the weld pool and crystallization of the metal in the weld pool. The repair technology presented by us, which consists in a combination of ultrasonic shock vibrations and forced cooling during the welding process, allows to improve the mechanical properties of the welded joint, as well as to refuse to carry out heating during welding and subsequent heat treatment.