Structural steel

 

The invention relates to structural alloyed steels for the manufacture of machine parts and mechanisms and can be used in engineering, transport, automotive, road machinery and other fields, as well as in defense technique for the manufacture of ammunition. The technical result of the invention is to improve performance characteristics are: strength, through-hardenability and hardness after quenching and high temperature tempering, the temperature increase operation details to 500oC. Structural steel contains, by weight. % vanadium - 0,4-0,6; carbon is 0.37 to 0.44; chrome - 0,8-1,1; silicon - 0,17-0,37; manganese - 0,50-0,80; copper is less than 0.3; Nickel - less than 0.3; phosphorus - less than 0.025, sulfur is less than 0.025; iron - rest. table 1. , 1 Il.

The invention relates to the field of constructional alloy steels for the manufacture of machine parts and mechanisms and can be used in most branches of engineering, for example, in the transportation, automotive, road machinery, defense equipment (ammunition and other).

The famous brand of structural steels used in mechanical engineering, containing vanadium as an alloying agent. This steel HF the content of the art, 1979, 58 S.] and steel, grade 50 CR V 4 with the content of vanadium V=0,10% (standard Germany DYN 17200 [international translator of modern steels and alloys (Russia, USA, Europe, Japan), edited by Professor C. C. of Kershenbaum, M., the international engineering encyclopedia, T. 1, 448 S.]).

Doping of these steels vanadium is accomplished by injecting molten Ferroalloy ferrovanadium. This provides fine-grained microstructure of the steel in the process of solidification of the ingot, and after heat treatment in the manufacturing process details. This ensures a significant improvement of operational properties of steels.

However, a disadvantage of the known structural steels, alloyed with vanadium, is the low content of vanadium in steel up to 0.2%. It does not provide sufficient strength, hardenability of steel and increase the hardness of steel due to secondary (discrete) hardening hardened steel after high-temperature tempering (dispersion hardening), especially for steels operating at higher temperatures.

Thus, as a prototype of the selected alloy vanadium structural steel HF with the content of vanadium V=0,10-0,18% [GOST 4543-71. Steel legirovannye is)=0,37-0,44; Cr= 0,8-1,1; Si= 0,17-0,37; Mn= 0,50-0,80. Alloying the steel with vanadium at the expense of the additive in steel ferrovanadium. However, the drawback of this steel is low vanadium content in steel, which does not provide sufficient strength, through-hardenability of steel and increase its hardness after quenching and high temperature tempering. Therefore, this steel is only used when the temperature of parts up to 400oC.

The aim of the invention is to improve operational properties of structural steel, in particular, the provision of sufficient strength, through-hardenability and increasing the hardness of steel after quenching and high temperature tempering, which increases the operating temperature of the parts to 500oC.

This goal is achieved by the fact that the vanadium content in steel is increased to 0.40 to 0.60 percent.

It is known [Gudeman E. Special steel. M.: metallurgy, 1962, so 2, 1153 S. ; Goldstein, M. I., Grachev S. C., Y. Wexler, Special steel, M.: metallurgy, 1985, 116 S.], which already 0,4-0,6% of vanadium in steel is a palpable effect precipitation hardening.

The drawing shows the dependence of hardness of steel Rockwell R temperature t at ve different content the content of vanadium in steel from 0.25 to 0.45% increases the hardness of steel by 10% or more in the whole range of investigated temperatures. After tempering hardened steel at tOTP=600oC steel with 0.25% V has a hardness R= 40-42, and steel with 0.45% V - R=46-48. Thus, if V=0,25% is no reduction in hardness at tOTP=600oWith, in steel with 0.45% V is provided by the increase of the hardness due to precipitation hardening. Hence the emergence of a new quality steel - operated parts in high temperatures up to 500o(While steel HF guaranteed to work only up to 400o[Marochnik steels and alloys. Edited by C. G. Sorokin, M.: Mashinostroenie, 1989, 190 S.]).

The table shows the results of comparative tests of steels - known - HF and offer FA,5A.

The table shows the following parameters:in- ultimate tensile strength;t- yield strength;- elongation;- relative narrowing; KCU - toughness; tZack- temperature quenching, tfrom- temperature tempering.

Table data indicative of the increase in mechanical properties, particularly tensile strength steel HF,5A, about 10%, compared with the prototype.

the s, manufactured according to GOST 4543-71, required a corresponding increase of ferrovanadium in the charge in the smelting of steel. However, this dramatically increases the energy consumption and the cost of steel, which makes the process of obtaining become economically impractical [Lisienko Century, The, Boys, A. E. , O. Druzhinina,, Morozova Century A. Comparative energy intensity alternative Baskakova processing technologies vanadium ore raw materials. Physics and computer science in metallurgy: achievements and challenges: proceedings of the International conference, dedicated to the 300th anniversary of metallurgy of the Ural, the 80th anniversary of the metallurgical faculty of the Department of physics and computer science in metallurgy. Ekaterinburg: Ural state technical University, 2000, S. 12-17].

Recently, the issue of economic viability improve the use of structural steel with a content of V>0.4 percent is solved in the case of melting their way [the Decision to grant patent for invention dated 09.02.2000, on the application 98115858/02 (01196). Authors: Lisienko Century, Romanes C. A., Lads A. E. and others; Lisienko Century BC, Lads A. E., Romanes C. A. and other Smelting vanadium alloy steel in the process of PL (alloying direct). At the frontiers of science and engineering creativity. Second international scientific-technical confederado of ore direct alloying steel with vanadium The PL-process (doping direct). Due to a sharp reduction in losses of vanadium and organization of non-waste technology, the increase in the content of vanadium in steel up to 0,4-0,6% occurs at a much lower energy intensity and cost of steel, than the doping vanadium steel.

Thus, it is proposed structural steel, dissimilar steel HF increased content of vanadium - to 0.4-0.6% and have in General the following chemical composition, wt.%: Vanadium - 0,40-0,60 Carbon Is 0.37 To 0.44 Chrome - 0,8-1,1 Silicon - 0,17-0,37 Manganese - 0,50-0,80 Phosphorus - <0.025 In offer are more than 2 times in comparison with the prototype increases the content of vanadium, providing increased tensile strength by more than 10% and at the same time - the possibility of operating at higher (up to 500oWith against 400oC) temperature. Thus, there are no additional costs ligature, provided that the specificity of the PL-process. The proposed grade of steel can be classified as HF,5A; border-contents of all the others, except vanadium, elements in the steel composition, determined by the requirements of GOST 4543-71.

The lower limit of the content of vanadium - 0,4% - is sufficient to guarantee the effect of dispersion the La content of vanadium (for example, in steel HF tolerance - 0,10-0,18% V).

We offer steel is recommended for the manufacture of parts of type spline shafts, rods, bushings, shafts excavators, operating at temperatures up to 500o(Steel in superior condition, i.e., after quenching from high temperature tempering), and worm shafts, torsion and other parts of high elasticity and wear resistance (after quenching with medium or low release) [GOST 4543-71. Steel alloy construction. Grades and specifications. M: Gosstandart, 1979, 58 S.].

This provides increased durability and service life of mechanical parts, working in high temperatures.

Claims

Structural steel containing vanadium, carbon, chromium, silicon, manganese, copper, Nickel, phosphorus, sulfur and iron, characterized in that it contains components in the following ratio, wt.%:

Vanadium 0,4-0,6

Carbon from 0.37 to 0.44

Chrome 0,8-1,1

Silicon 0,17-0,37

Manganese 0,50-0,80

Copper is Less than 0.3

Nickel Less than 0.3

Phosphorus Less than 0.025

Sulfur Less than 0.025

Iron Rest

 

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FIELD: ferrous metallurgy; production of rail steel.

SUBSTANCE: the invention is pertaining to the field of ferrous metallurgy, in particular, to production of steel for manufacture of railway rails. The offered rail steel contains its components in the following ratio (in mass %): Carbon - 0.83-0.5; manganese - 0.6-1.1; silicon - 0.3-0.7; vanadium - 0.08-0.15; aluminum - no more than 0.005; nitrogen - 0.012-0.02; calcium -0.0005-0.005; chromium - 0.05-0.5; one of the devices sampled from a group including zirconium and REM, namely, zirconium -0.0005-0.005; REM - 0.0005-0.005; molybdenum - 0.11-0.3; nickel - 0.05-0.3, iron and impurities - the rest. The technical result of the invention is an increased complex of mechanical properties, firmness of steel and its resistance to brittle fracture, which improves operational stability of the rails. Out of the steel of a stated composition it is possible to manufacture the rails hardened both in oil and in a compressed air with a troostite structure.

EFFECT: the invention ensures an increased complex of the rail steel mechanical properties, firmness of the steel, its resistance to brittle fracture and production of rails with a troostite structure.

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