Experimential Study on Failure Mode and Ultimate Shear Bonding Force of CFRP Plate-Steel Interface under Anchor Compression

In order to study the paste failure mode and ultimate shear bonding force of CFRP plate-steel interface anchor bonding, a single-sided shear test was carried out on a total of 15 carbon fiberboard (CFRP)-steel composite beam structure specimens in five groups. The test results show that for organic adhesives, the uniform anchoring method can improve the bearing capacity of the construction; for organic adhesives, the ultimate shearing when the specimen is peeled with inorganic glue is used. The bonding capacity is greater than that of specimens with organic adhesives.

Comparison of Microstructure and Mechanical Properties of High Strength and Toughness Ship Plate Steel

E36 ship plate steel was, respectively, produced by as rolling and normalizing process (ARNP), and EH36 and FH36 ship plate steel was produced by the thermo-mechanical control process (TMCP) with low carbon and multi-element micro-alloying. The microstructure of the three grades of ship plate steel was composed of ferrite, pearlite, and carbides at room temperature. The average grain size on 1/4 width sections (i.e., longitudinal sections) of the three grades of ship plate steel was, respectively, 5.4 μm, 10.8 μm, and 11.9 μm. EH36 and FH36 ship plate steel had the higher strength due to precipitation and grain boundary strengthening effect, while the E36 ship plate steel had the lower strength due to the recovery phenomenon in the normalizing process. EH36 and FH36 ship plate steel had higher impact toughness due to lower carbon (C) and silicon (Si) content and higher manganese (Mn) content than E36 ship plate steel. E36 ship plate steel had the best plasticity due to the two strong {110} and {111} texture components. The fracture toughness KJ0.2BL(30) values of E36 and EH36 and KJ0.2BL value of FH36 ship plate steel were, respectively, obtained at 387 MPa·m1/2, 464 MPa·m1/2 and 443 MPa·m1/2. EH36 and FH36 ship plate steel had higher KJ0.2BL(30) due to lower C and Si and higher Mn, niobium (Nb), vanadium (V), and aluminum (Al) content than the E36 ship plate steel. The fatigue crack growth rate of E36 ship plate steel was higher than that of EH36 and FH36 ship plate steel due to its higher carbon content and obviously smaller grain size. The analysis results and data may provide a necessary experimental basis for quantitatively establishing the relationship between fracture toughness, yield strength and impact toughness, as well as the relationship between fatigue crack growth rate and both strength and fracture toughness.

STRUCTURE AND PROPERTIES OF ROLLED STEEL AFTER SKIN-ROLLING ACCORDING TO DIFFERENT TECHNOLOGICAL PRODUCTION SCHEMES

Problem statement. Development of an effective technology for the skin-rolling will allow the production of hot-rolled sheet products with quality indicators that meet the requirements of standards for cold-rolled sheets. Consumers with significant economic benefits will be able to use relatively inexpensive hot-rolled sheets instead of expensive cold-rolled sheets. The purpose of the article: establishment of the effect of skin-rolling to various technological schemes for the production of hot rolled fine and thickness rolled for cold stamping on the structure and properties of the metal. Conclusion. The patterns of the formation of the structure and properties after skin-rolling of hot rolling sheet steel and plate steel for cold stamping are established. It is shown that with an increase in the degree of deformation during skin-rolling in the unit cutting unit, there is a decrease in the plasticity of hot-rolled plate steel strips of low carbon steels. As a result of heat treatment and skin-rolling on a separately located mill of hot rolled, thin-sheet low carbon steel, the plasticity of the metal rises and a homogeneous structure is formed in accordance with the requirements of ДСТУ 2834-94. Obtaining hot-rolled thin-sheet steel with quality indicators at the level of requirements for cold-rolled metal will allow the use of hot-rolled steel instead of cold-rolled one, which will ensure an increase in labor productivity and savings electricity.

Analysis of the influence of hot rolled plate steel treatment using temper and quench-temper method on vickers hardness number enhancement

This paper wants to know the effect of bending radius on the distribution of hardness, grain distribution and microstructure on the surface area of tensile stress and compressive stress after bending, quenching and tempering. Material testing helps determine and analyze material quality. The research was conducted on the bending of Hot Rolled Plate Steel material with a radius of 50 mm, 55 mm, 60 mm, 65 mm and 70 mm with a measurement distance of 1 mm, 2 mm and 3 mm, the highest value was obtained at a radius of 55 mm with a measurement distance of 1 mm. After getting the quench-temper treatment with a holding time of 30 minutes, the value of 498 HV was obtained at a radius of 70 mm with a measurement distance of 2 mm. Hardness test was performed using the austenite temperature of 900 °С, microstructure test results obtained finer grains in the compression area r=2.173 µm and in the tensile area r=2.34 µm. This observation aims to determine the microstructure of the material undergoing a heat treatment process at a temperature of 900 °С with a holding time of 30 minutes using water cooling media. The results of the observation of the microstructure of the test specimens before the quench-temper process showed that the structure of ferrite was more abundant than perlite, but after the quench-tempering process the results showed that there was more perlite than ferrite due to the presence of austenite. The treatment on the transformation of the Ar3 line causes the hardness to change the shape of the martensite microstructure into steel while the thickness of the carburizing layer increases with the increase in the carbonization temperature on the surface of the quenched specimen, resulting in the formation of martensite and residual austenite causing the coating to become hard.

Mapping Corrosivity Steel Construction at Atmospheric Conditions in Langsa Town Center and Palm Oil Mill Industry

Corrosion is one of the main causes of early failure of infrastructure both for public housing facilities and public facilities in downtown Langsa. This corrosion is caused by air pollution generated from motor vehicle and household industry exhaust fumes and exhaust smoke from the nearest palm oil mill industry from the city of Langsa. Related to air pollution, its sustainability should be a concern regarding environmental impacts that occur, one of which is atmospheric corrosion. This study aims to analyze the impact of the effects of pollution on infrastructure corrosion on construction steel which is often used on infrastructure in the city of Langsa and the palm oil mill industry. There are five types of steel model infrastructure consisting of strips of plate steel, elbow steel, cylinder steel, plate steel, and low carbon steel market have become specimens. Calculation of corrosion rate using the method of mass loss by reference to ASTM standard G50, the location selected above buildings in downtown Langsa and palm oil mill industry. The results of the study for one year showed the level of corrosion rate that occurred in 5 types of steel construction is still relatively safe or its relative corrosion resistance can be classified in the outstanding category (<1 mil per year). The conclusion is that 5 types of construction steel that have been tested, are resistant to corrosion, and are suitable for use as the main construction material in Langsa City and the palm oil mill industrial environment.

Quantitative assessment of microstructural inhomogeneity by thickness of hot-rolled plates made of cold-resistant low-alloy steel for Arctic applications

A technique to assess microstructural anisotropy assessing by the thickness of the plate steel based on the texture analysis of the image has been developed. This technique provides for the anisotropy assessment at two dimensional levels: in the short-distance and long-distance neighborhoods, which characterize the elongation along the rolling direction of fine and coarse structural constituents, respectively. The practical approval results of this technique in the study of the microstructural heterogeneity of ferritic-bainitic steels over the thickness of 25–70 mm hot-rolled plates have been presented. It has been shown that the proposed anisotropy criteria in combination with the volume fraction of coarse packet-block regions of lath bainite as well as regions of bainite without an internal developed subgrain structure adequately estimate the microstructural heterogeneity over the thickness of plate steel and can be used for a detailed interpretation of the two-stage thermomechanical processing technology with accelerated cooling including taking into account the metallurgical inheritance of the slab.