The influence of thickness blanks for car drives on the structure and properties of steel 10ХФТБч

Abstract

Purpose. For the wheeled production the high-strength brand of low-alloy steel is worked out, a carbon, manganese, silicon, titan, phosphorus, vanadium, niobium, chrome, is used in basis of that. It is necessary to set conformities to law o f influence of thickness of purveyances and alloying degree on a structure and mechanical properties of an experience steel of 10ХФТБч on the top and lower limit of maintenance of alloying elements and to specify 10ХФТБч became to the way of further increase of indexes of durability and plasticity. Methodology. Tests conducted on sheet purveyances in from 3,0 to 11,0 mm. thick Heat treatment consisted in heating to 900 оС, by subsequent self-control 1,5 mines/of mm and cooling on air. Mechanical properties determined on standard break standards for ГОСТ 1497-84 on the break machine of МУП- 20 at loading of 5 ton and rates of movement of active capture a
2,5 mm/min Research of structure became and correlation o f structural constituents the ferrit-pearlite of standards was determined by means of complex in the complement of that the light inverted microscope of "AXIOVERT 200 enters MAT" with the automatic system of analysis of images "Video-test-metal". Photography of structure of standards was conducted on SEM of "SUPRA 40 WDS". Findings. It is set that steel of 10ХФТБч has a ferritic structure with the negligible quantity of pearlite and saves high enough plasticity at different thicknesses. However, at maintenance of alloying elements on a top limit that the size of grain and, accordingly, plasticity are saved at large self-controls in the process of the recrystallization annealing. As a result o f researches microstructures are set that the increase of maintenance of alloying elements in steel assists growing of grain shallow after the recrystallization annealing, accordingly, from 4...5 points a to 6...7 point. Increase of thickness of sheet with a 3,0 mm a to 5,0 mm is accompanied by the decline of tensile strength 10ХФТБч became both in longitudinal and in transversal direction. At the increase of thickness of sheet a to 11,0 mm looked after the monotonous increase of tensile strength. Plastic descriptions have an obvious extremum at a thickness 9,0 mm. The study of fractograph surfaces of destruction longitudinal and transversal standards showed that standards in a 3,0 mm thick had had a different structure characteristic for the uncompleted process of recrystallization. Along with a fine-grained structure large grains are present testifying to the display of collective recrystallization. More equiaxed structure was had standards became a 10ХФТБч thickness 5,0 mm. The most equiaxed structure corresponded to the standards in 7,0 thick and a 9,0 mm. Originality. New scientific data are got about influence of thickness of purveyances and alloying degree 10ХФТБч became on a structure and mechanical properties. Practical value. The parameters of the recrystallization annealing of an experience steel of 10ХФТБч are set for the increase of indexes of plasticity.