SU1186688A1 - Structural steel - Google Patents

Description

The invention relates to ferrous metallurgy, in particular, to the composition of the steel used: for welded structures operating at low temperatures. five

The purpose of the invention is to increase the limit of corrosion fatigue and toughness at low temperatures.

The introduction of borides of rare earth materials (RMZ) into steel crushes the grain, which contributes to an increase in toughness in welded joints. Introduction of zirconium and titanium forming with carbon 15

carbides, leads to increased cold resistance and corrosion fatigue limit.

The metal is smelted by a duplex processor: the arc furnace is an open induction, crucible furnace, using low carbon electrical steel, low carbon ferrochrome, electrolytic nickel, and 25 complex ligatures. Melt modification with borides of rare-earth metals, titanium or zirconium is carried out in

88 2

3-7 minutes before casting steel into molds.

The compositions of the steel produced are given in table. one.

Modification of the molten metal is carried out by borides RMZ for 3-7 minutes before casting steel into molds. As borides RMZ use powders of complex borated alloys containing 98.5-99.3 masD of borides of rare-earth metals of cerium group (51.7-52.0 wt.% Cerium borides, 23.1-23.3 wt.% Of lanthanum borides, 16.0-16.1 masd borides of neodymium and

7.7- 7.9 wt.% Of praseodymium borides), 0.3-0.5 wt.% Of carbon and other technological impurities. Boride powders are obtained by boronation of a complex Mishmetal type alloy. Borides absorption ranges from

83.7-97.2 wt.% And is determined by microsound probing of boride and carbide phases, extracted from steels of the experimental heats.

In tab. 2 shows data on the limit of corrosion fatigue and toughness at negative temperatures in welded joints.

Table 1

The content of components in the composition, wt.%

become WITH 5ΐ Mp A1 Si V mi Sa Borides Rare earth metal Τί Ζν N Re one 0.14 0.05 1.8 0.02 0.02 0.03 0.01 0.03 0.003 0.03 0.01 The rest a little 2 0.2 0.5 1.9 0.05 0.2 0.1 0.05 0.05 0.009 0.08 - 0.02 Also 3 0.35 0, 75 2.15 0.07 0.35 0.2 0.1 0.08 0.012 0.23 - 0.05 - ⁿ - four 0.2 0.5 1.9 0.05 0.2 0.1 0.05 0.05 0.009 - 0.1 0.02 five 0.21 0.55 2.15 0.05 0.15 0.1 0.05 0.03 0.004 0.03 '0,2 0.02 6 0.12 0.02 1.6 0.01 0.01 0.01 0.07 0.01 0.001 0.01 0.01 0,006 - "- 7 0.37 0.8 2.2 0.1 0.5 0.3 0.3 0.1 0.02 0.25 0.25 0.06 _eleven__ I know costly 0.15 0.12 1.8 0.02 0.08 0.1 0.07 0.01 - 0.02 -

3

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table 2

Composition become Limit strength MPa Conditional limit corrosion fatigue, MPa Impact strength j / cm ² at ° C The number of kinks at ⁰ С -40 -60 -20 -60 one 782 226 32 24 7 four 2 830 238 41 32 eight 6 3 ' 874 244 50 42 ten 7 four 812 230 38 thirty 9 6 five 778 236 42 31 9 6 6 714 186 18 13 four 2 7 736 206 22 14 6 3 Famous 710 180 17 12 four 2

Claims (1)

CONSTRUCTION STEEL containing carbon, silicon, manganese, aluminum, vanadium, niobium, copper ^ calcium, nitrogen and iron, characterized in that, in order to increase the limit of corrosion fatigue and toughness at negative temperatures, it additionally contains borides of rare-earth metals and extreme at least one element from the group containing titanium and zirconium, in the following ratio, wt.%: Carbon 0.14-0.35 Silicon 0.05-0.75 Manganese 1.80-2.15 Aluminum 0.02-0.07 Vanadium 0.03-0.20 Copper 0.02-0.35 Niobium 0.01-0.10 Calcium 0.03-0.08 Borides rare earth 0,003-0,012 metals At least one element from the group containing titanium and zirconium 0.03-0.23 Nitrogen 0.01-0.05 Iron Rest (61) ί 1,186