SU883188A1 - Steel - Google Patents

Description

one

The invention relates to metallurgy and foundry, in particular to the development of high-strength steels for castings for various purposes.

Foundry and forged structural steels of grades 15L, 20L, 25L, 20G1FL, ZOHNML, used for the manufacture of machine castings and mechanisms are known. Therefore, continuously increasing demands are made on them for mechanical and operational properties, especially, n9 ductility

J, PO 1

PC and Shock Viscosity

Closest to the proposed technical essence and the achieved result is steel 2}, containing in weight,%:

0.26-0.4

Carbon

0.8-1.6

Manganese

0.2-0.6

Silicon

0.2-0.45

Chromium

0.02-0.08

Aluminum

0.01-0.025

Nitrogen

0.1-0.45

Nickel

0.04-0.2

Vanadium

0.015-0.04

Titanium

0.005-0.08

Calcium

Rest

Iron

This steel has the following mechanical properties:

Strength, kg / mm 70

Yield strength, kg / mm 55

Relative

elongation,% 15

Relative

ten

narrowing,% 29

Shock in the- “

bone, kgm / cm 4,5.

The significant disadvantages of this steel are the coarse-grained structure, the relatively low hardenability and mechanical properties, especially ductility and toughness.

The purpose of the invention is to increase the hardenability, mechanical properties, 20 especially ductility and impact, viscosity.

The goal is achieved by the fact that steel containing carbon, margarine, silicon, chromium, aluminum, nitrogen, nickel, vanadium, titanium, calcium and iron, additionally contains niobium and rare earth metals (REM) in the following ratio of components, in wt.% :

0,26-OI

Carbon

0.8-1.6 Manganese Silicon

0.2-0.6

0.2-0.5 Chromium Aluminum

0.01-0.05 Nitrogen

0.01-0.025 Nickel

0.1-0.5

0.05-0.12 Vanadium Titan

0.01-0.05

0,005-0,05 Calcium

0.01-0.15 Niobium

Rare-earth0, 005-0,08 metals Else Iron

The additional introduction of niobium into the composition of the steel is associated with its additional effect on strength due to the hardening of the steel as a result of dispersed hardening. At the same time, niobium prevents the development of columnar dendritic and primary (. Austenitic structure of steel. REMs have a more effective influence on the structure of steel. As modifiers of the 2nd kind, REM inhibits the growth of dendrites and contributes to a fine-grained structure. Particularly important is the simultaneous introduction in steel of rare-earth metals, calcium, and aluminum, since in this case multiphase nonmetallic inclusions of globular, almost round shape with lower specific weight are formed. This contributes to their more complete removal from the melt, while the remaining uniform background is redistributed in the metal, which is accompanied by the purification of the grain boundary from harmful impurities.

All of these factors increase the hardenability of steel and its mechanical properties, especially ductility and toughness.

-Metal, melted at 300 kg induction arms, by remelting. The deacidification in the furnace was carried out with ferromanganese and ferrosilicon by calculation. During fractional casting, the steel was treated with ligature additives. Chemical properties of melted experimental are given in table. one.

All the smelted compounds began to be poured into experimental molds, made on melted models, with blanks. After blanking and quenching in water from 650s, samples were made from blanks for breaking and impact toughness, the results are shown in Table. 2

As can be seen from the table. 2, the mechanical properties of the proposed steel are superior to those of the known steel. If the strength properties are not improved so much, then the elongation and contraction increase accordingly from 15 to 18.3 -21.4% and from 29 to 35.9-38.7%, which is an increase of an average of 33 and 40% . The impact viscosity increases from 4.5 to 5.4 kgm / cm, i.e. by 24%.

Improving the mechanical properties of steel is explained by grinding its structure. For example, the density and dispersion of the dendritic structure of the proposed steel increases by almost 2 and 1.5 times, respectively, at the same time the length and width of the dendrites decrease.

In tab. 3 shows the characteristics of the dendritic structure.

 From tab. 3 it also follows that the proposed steel is characterized by a higher hardenability, which is determined by the end test. For example, the depth of hardenability of steel is 12.3-12.7 mm, while this characteristic in known steel is 9.5 mm

Thus, the proposed steel is superior to that known for all investigated properties and characteristics.

This allows recommending it for wide industrial use in the manufacture of castings for various purposes.

The expected economic effect from the introduction of steel will be about 4 thousand rubles. per year due to an increase in the quality and durability of castings by 1.3-1.4 times, ductility and toughness of steel by 38–24% and hardenability by 25%.

T a b l i

C a

Known

70

55

Offer

0.62

0.20

Known

Dredlagable

29

4.5

Table 3

9.5

4.3

25

Claims (2)

Claim Steel containing carbon, manganese, silicon, chromium, aluminum, nitrogen, nickel, vanadium, titanium, calcium and iron, characterized in that, in order to increase calcination and mechanical properties, it additionally contains niobium and rare earth metals in the following ratio components Carbon Manganese Silicon Chrome Aluminum Nitrogen Nickel Vanadium Titan Calcium Niobium Rare Earth ’Metals Iron Sources 0.01-0.025 0.1-0.5 0.05-0.12 0.01-0.05 0.005-0.05 0.01-0.15 0.005-0.08 The rest of the information, in wt.% :. 0.26-0.4 0.8-1.6 0.2-0.6 0.2-0.5. 0.01-0.05 taken into account during the examination 1. GOST 977-75 Castings from structural alloyed steel. General requirements. · 2. Copyright certificate SS.SR No. 469765, cl. C 22 C 38/50, 1975. VIYIPI Order 10127/38 Circulation 684 Subscription Branch of PPP Patent, Uzhgorod, st. Project, 4