SU916578A1 - Martensite-ageing steel composition - Google Patents

Description

The invention relates to metallurgy, in particular to martensitic steels used for the manufacture of molds, working under pressure during casting non-ferrous metals.

Closest to the proposed technical essence and the achieved result is maraging steel [1], containing, wt.%:

Carbon Up to 0.1

Nickel 18-30

Titanium + Aluminum 1.5 ~ 3 Cobalt 0-20

Manganese 0-1

Iron Else

The disadvantage of this steel is

its low temperature resistance.

The purpose of the invention is to increase the heat resistance of steel.

This goal is achieved by the fact that

steel containing carbon, nickel, titanium, manganese, aluminum and iron, additionally contains silicon and cerium, in the following ratio of components, wt.%:

Carbon 0.005-0.1 Nickel 16-19 Titanium 0.8-1.7 Manganese 0.2-1.0 Silicon 0.05-0.5 Aluminum 0.05-0.25

Cerium Iron 0.005-0.05 Rest Steel can contain impurities ..%: Copper up to 0.3 Chromium TO 0.2 Sulfur up to 0.015 Phosphorus up to 0,020 Calcium to 0,001 Magnesium up to 0.01

The effect of alloying elements on

the properties of the steel is as follows: nickel provides the structure of a carbon-free martensite, reduces the percentage of solubility of titanium in the <1-phase, gives the matrix

very high ductility; titanium is the most effective element that strengthens maraging steel; manganese helps to deoxidize steel; cerium increases the heat resistance of steel, increases the resistance to oxidation; silicon and aluminum contribute to the refinement of steel.

The limits of the content of alloying elements are determined by the nature of their influence on the structure and properties of steel.

The nickel content from 16 to 19% is determined by obtaining a structure of carbon-free martensite with high ductility, with a decrease in the nickel content of less than 16% in the absence of molybdenum, ductility and toughness decrease, and an increase in the nickel content of more than 19% leads to the appearance of residual austenite, which reduces strength.

Titanium is introduced into the steel as the main hardener. A decrease in the titanium content of less than 0.8%, in the absence of other hardeners, weakly hardens the steel. An increase in the titanium content of more than 1.7% leads to a decrease in ductility and viscosity.

Manganese contributes to the deoxidation of steel, increases its casting properties. Introducing it in quantities greater than 1.0. reduces ductility and toughness after aging. A decrease in the manganese content of less than 0.2% does not sufficiently deoxidize the metal.

Silicon contributes to the refining of steel, its introduction in the amount of more than 0.5% reduces the ductility and toughness after hardening. Reduction

916578

content less than 0.05% insufficiently refined steel.

Aluminum contributes to the refining of steel, its introduction in the amount of 5 more than 0.2% reduces ductility during hot working. Reducing the content of less than 0.05% insufficiently refines the metal.

Cerium is introduced into the steel as a refining additive. Its introduction in the amount of more than 0.05% reduces ductility during hot processing. Reducing the content of less than 0.005% insufficiently refines the metal.

The carbon content of 0.05% is determined by its presence in the technically pure charge materials used in smelting. An increase in carbon content of more than 0.1% leads to a decrease in ductility and viscosity after aging.

The content of impurities (copper, chromium, sulfur, phosphorus) is determined by their presence in the initial charge materials.

Example. Steel 4 compositions melted in an open induction furnace with a capacity of 60 kg.

The compositions of the steels are given in table. one.

In tab. Figures 2 and 3 show the mechanical properties of the investigated steels at room temperature and a temperature of 700 ° C, which corresponds to the temperature of the working surface of the mold when pouring liquid brass. The results of tests for heat resistance are given.

Tests show that the introduction of cerium dramatically increases the heat resistance of steel compared to that known in

₄₀ 2.5 times.

15

20

25

EO

35

Table 1

Melting Gi GN | No G ” GN AND Se | ^re Offered one 0,005. 16,0 0.4 0.3 0.25 1.7 0,005 Rest 2 0.1 19.0 1.0 0.05 0.05 0.8 0.01 Also 3 0.035 17.0 0.2 0.5 0.15 1.5 0.05 _ and _ Known four 0.05 18.5 0.3 0.3 0.2 1.51 - ~ 11 -

five

916578

6

Table 2

•Melting ^άβ ; ι about. · About ⁵ 1 X, ^α * η Number of cycles • kg / mm kg / mm * % kgm / cm before destruction

Offered

one 184 179 ten 50 4.5 11,000 2 170 165 9 45 3.5 10,500 3 180 175 ten 50 4.0 11,500 four 169 163 Known eight 48 3.0 4500

Note. The number of cycles to failure corresponds to the number of suitable parts obtained from the mold.

Table 3

Melting 0% 700 ° С, kg / mm ^nd 6 ^ 7004, kg / mm ¹ <A,% X% kgm / cm Offered one 33 zo 50 83 23 2 thirty ' 29 60 89 24 3 32 zo 50 80 22 Known four zo 28 50 80 15

Claims (1)

Claim Martensitic steel containing iron, carbon, nickel, titanium, manganese, aluminum, characterized in that, in order to improve heat resistance, it also contains silicon and cerium in the following ratio of components, wt.%: Carbon 0.005 "0.1 Nickel 16.0-19.0 · “< Compiled W. 40 "five Titanium Cerium Manganese Silicon Aluminum Iron 0.8-1.7 0.005-0.05 0.2-1.0 0.05-0.5 0.05-0.25, the rest?