SU1382869A1 - Steel for welding structures - Google Patents

Abstract

The invention relates to metallurgy, and more specifically to low-alloy structural steels of increased strength. The purpose of the invention is to viscosity impact. Steel predominantly for welded structures with a thickness of up to 80 mm contains, in May.%: Carbon 0.05-0.12; silicon 0.17-0.60; manganese 0.46-2.40; chromium 0.1-2.3; cerium 0.003-0.08; aluminum 0.04-0.08; calcium. 0.003-0.05; iron - the rest. The amount of one of the two elements, manganese or chromium, is at least 1.8 wt.%, And the content of the other is determined by the dependence of Mp 2.2-0.7 Cg (2,3-Cg) + + C For welded structures with a thickness of more than 80 mm, steel with a manganese content of 1.8-2.4% by weight contains 1 - 1.5% by weight of chromium. 2 hp f-ly., 2 tablets. from 9 (L

Description

The invention relates to metallurgical steels of enhanced strength with high resistance to overheating during welding, intended for the manufacture of vessels and apparatus used in the chemical, petroleum refining, petrochemical, petroleum, and other industries at negative operating temperatures.

The aim of the invention is to increase the toughness.

As impurities, the steel may contain nickel and copper in an amount of not more than 0.3 wt.%, As well as sulfur and phosphorus in an amount of not more than 0.03 wt.% Of each element.

When the content in the steel is manganese in the amount of 0.46-2.4 wt.% And chromium 0.1-2.3 wt.% For welded structures with a thickness of 80 mm, the amount of one of the two elements must be at least 1.8 wt. .%.

thinned sections, in a 5% solution of nitric acid, and in electronic growth

another is determined by the dependence of My of 2.2 - 0.7 Cg -0.7 Cg (2.3-Cg) + CS.

thirty

40

At the same time, the impact strength of ferrite increases simultaneously in the steel, the secondary structure of the superheating section is crushed, the formation of the shape-manstettite structure and ferrite edges along the grain boundaries is suppressed, which ensures an increase in the impact strength of the metal in the heat-affected zone. electroslag welding.

The steel of experimental formulations is melted into electric furnaces with a volume of Vol. T. Ingots are rolled onto a sheet 10-80 and 81-140 mm thick and welded by an electroslag method with an EV - 10G2S wire in standard modes. The welded joints are subjected to tempering at 560 C. They test the base metal (after normalization of 920 ° C and tempering of 650 ° C) for stretching and impact bending (on: samples with a Menaget cut) at temperatures of (+20) - (- 90) ° C, part 50 overheating current - on impact bending at temperatures of (-20) - (- 70) C. For the critical temperature of brittleness, take the temperature at which the KCU of one or several samples composes fS to 20 J / cm. The structure of the metal of the superheated section of the research site is ejected with an optical microscope on

Osprey Inclination of steel

, grains are estimated by the size of the former austenitic grains in the overheating area.

The chemical composition of the steel is given in table. one; The test results of the mechanical properties and impact toughness of steel rolled to a thickness of 60 and 85 mm, as well as the impact toughness of the metal of the heat affected zone of the welded joints of these steel made by electroslag welding without subsequent normalization are in tab. 2, The proposed steel has high toughness when tested down to -90 ° C, and its welded joints made by electroslag welding without subsequent normalization have the toughness higher than required by standards (& 30 J / / cm), at test temperature

Claims (3)

1. Steel for welded structures containing carbon, silicon, manganese, chromium and iron, characterized in that, in order to increase the impact and viscosity, it also contains cerium, aluminum and calcium in the following ratio, wt.% : Carbon Silicon Manganese Chromium Cerium Aluminum Calcium Iron 0.05-0.12 0.17-0.60 0.46-2.40 0.10-2.30 0.003-0.08 0.04-0.08 0,003-0,05 Rest 2. Steel according to Claim 1, preferably for welded structures with a thickness of up to 80 mm, characterized in that when the content of manganese or chromium is not less than 1.8 wt.%, The content of the second component is determined according to MP 2.2-0.7Sg-0.7 Cg (2.3-Cg) + CS. 3. Steel according to claim 1, preferably for welded structures with a thickness of more than 80 mm, characterized in that when the content of manganese is 1.8-2, 4 wt.%, The chromium content is 1 ... 1.5% by mass. . thinned sections, in a 5% solution of nitric acid, and in electronic growth Osprey Inclination of steel 0 five 0 s Carbon Silicon Manganese Chromium Cerium Aluminum Calcium Iron 0.05-0.12 0.17-0.60 0.46-2.40 0.10-2.30 0.003-0.08 0.04-0.08 0,003-0,05 Rest 2. Steel according to Claim 1, preferably for welded structures with a thickness of up to 80 mm, characterized in that when the content of manganese or chromium is not less than 1.8 wt.%, The content of the second component is determined according to MP 2.2-0.7Sg-0.7 Cg (2.3-Cg) + CS. 3. Steel according to claim 1, preferably for welded structures with a thickness of more than 80 mm, characterized in that when the content of manganese is 1.8-2, 4 wt.%, The chromium content is 1 ... 1.5% by mass. . Table 1 Continuation of table 2