Steel for Fasteners Containing Vanadium 10.9 Grade Rail Transit Mobile Equipment and Its Heat Treatment Process

Abstract

The invention provides vanadium-contained 10.9-level steel for a fastener for rail transit mobile equipment. The steel mainly comprises following chemical elements including, by mass percentage, 0.33% to 0.38% of C, 0.05% to 0.10% of Si, 0.70% to 0.90% of Mn, 0.70% to 0.90% of Cr, 0.30% to 0.60% of Ni, 0.20% to 0.30% of Mo, 0.015% to 0.045% of Als, 0.06% to 0.10% of V, 0.006% to 0.010% of [N], not larger than 0.010% of P, not larger than 0.005% of S and not larger than 0.0015% of T[O]. The autstenitic grain size of steel obtained after heat treatment is larger than 10.0 level, and according to the structure of the steel obtained after heat treatment, a small amount of small pro-eutectoid ferrite is dispersed and distributed on a tempered sorbite base body, wherein, the amount of the pro-eutectoid ferrite is smaller than or equal to 5%, and the size of the pro-eutectoid ferrite is smaller than or equal to 5 micrometers.

Description

Technical field [0001] The invention belongs to the field of alloy steel, in particular the steel used for fasteners for 10.9 grade rail transportation mobile equipment and its heat treatment process. Background technique [0002] Fasteners are also called standard parts in the market, which is a general term for a type of mechanical parts used when two or more parts (or components) are fastened and connected into a whole. It is characterized by a wide variety of specifications, different performance and uses, and a high degree of standardization, serialization, and generalization. Fasteners are the most widely used mechanical basic parts and are in great demand. The strength level of high-strength fasteners such as high-strength bolts is generally divided into four levels, 8.8, 9.8, 10.9 and 12.9, and is usually quenched and tempered medium carbon steel or medium carbon alloy steel. [0003] With the rapid and heavy load of rail transit, the impact and vibration of key component...

AI Technical Summary

Problems solved by technology

In order to ensure the low-temperature impact resistance and fatigue resistance of fasteners, at present, high-alloy structural steels such as 4340, 40CrNiMo and 18Cr2Ni4WE are mostly used for fasteners of grade 10.9 and grade 12.9 for high-speed and heavy-duty rail transit mobile equipment in my country. Difficulty, high consumption of precious alloys such as Ni and Mo, high production cost, and most of them are imported

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