CN1363691A - Refining agent for stainless steel - Google Patents

Abstract

A refining agent for stainless steel contains rear-earth (10-35 wt%), Ba (10-30), Mg (0.4-6), Si (10-30), V (5-24), Mn (4-16), Ti (4-20) and Fe (rest). Said granular refining agent can fine crystal grains, stabilize austenite, decrease or eliminate free nitrides, and remove oxygen, gas and impurities, resulting in high anticorrosion and mechanical performance and low cost.

Description

A kind of refining agent for stainless steel

Technical field

The invention belongs to the stainless steel smelting technique, specifically, it relates to a kind of refining agent for stainless steel.

Background technology

Stainless steel is used in national economy as a kind of important ferrous materials increasingly extensively.How further to improve stainless quality product and production efficiency and become the problem that steel industry receives much concern.

In stainless fusion process, add refining agent, can simplify production technique, reduce production costs significantly.That Chinese invention patent application 99120040 discloses is a kind of " refining agent for stainless steel and be used for the method for smelting stainless steel " (open November 10 1999 date).Refining agent for stainless steel wherein, its composition are Re 2.0-20.0%, Ca 2.0-16.0%, Al0.5-6.0%, Ba 3.0-18.0%, Mg 0.5-9.5%, V 3.0-30.0% by weight percentage, surplusly are Si.When using it for smelting stainless steel, cast that steps in sequence is melting-remove slag-remake new slag-intensification deoxidation---adding refining agent---.

Chinese invention patent application 01106581 disclosed " a kind of refining agent for refractory stainless steel " (open October 17 calendar year 2001 on date), combined by following each composition, the proportioning of each composition is by weight: RE10-40%, Ca5-15%, Mg5-15%, V3-8%, Ti5-30%, Si10-30%, Fe surplus.The shape of refining agent can be particulate state or bulk.

Adopt above-mentioned two kinds of refining agent for stainless steel smelting stainless steels, all need not can obtain the qualified and good steel of performance, both simplified technology, reduced production cost again again through solutionizing thermal treatment.But existing refining agent for stainless steel is used for smelting stainless steel, easily seals or dwindles the austenitic area and increase ferrite content, makes stainless steel produce magnetic or magnetic increases.Contain aluminium in the existing refining agent constituent element, though aluminium has deoxidation effect, the Al of its formation ₂O ₃Fine foreign matter is difficult to whole eliminatings in molten steel, influence the molten steel quality.

Summary of the invention

The object of the present invention is to provide a kind of novel refining agent for stainless steel, this refining agent for stainless steel has grain refining, stable austenite, reduces or eliminates multiple functions such as free carbide, deoxidation degasification and removal inclusion or change inclusion morphology when being used for smelting stainless steel, thereby the stainless steel that makes production avoids solutionizing to be handled, reduce or eliminate magnetic, improve corrosion resistance nature, improve mechanical property, reduce production costs.

For achieving the above object, the composition of refining agent for stainless steel provided by the invention and weight proportion are:

RE??10-35％????????????????????????????????????Ba?10-30％

Mg??0.4-6％????????????????????????????????????Si??10-30％

V???5-24％?????????????????????????????????????Mn??4-16％

Ti 4-20% surplus is Fe.

The refining agent for stainless steel that above-mentioned each composition is made is a particulate state.

Refining agent for stainless steel provided by the invention contains rare earth RE, barium Ba, magnesium Mg, silicon Si, vanadium V, manganese Mn, titanium Ti and iron Fe.Its middle-weight rare earths RE, barium Ba, magnesium Mg, silicon Si and vanadium V are same as the prior art to the effect that the stainless steel fusion process is produced, manganese Mn is as a kind of austenizer, can promote the austenitic formation of stainless steel, thereby make the stainless steel of production reduce or eliminate magnetic.Titanium and carbon can be combined into highly stable titanium carbide (TiC) compound, have reduced chromium carbide (Cr ₂₃C ₆) form tendency, thus the corrosion resistance of steel improved.Make a concrete analysis of as follows:

The stainless steel corrosion resistance nature is with stress corrosion influence, intergranular corrosion and pitting attack maximum.Stress corrosion can improve the ability of stress corrosion resistant by the content that increases Si, and this is the reason that the electrochemistry anodic process is prevented from because of silicon, and the composition that contains Si in this refining agent can improve the stress corrosion resistant ability.

The reason of intergranular corrosion be since in the stainless steel carbide separate out along crystal boundary and cause due to the poor chromium.Carbon in elements such as Ti in this refining agent and V and the molten steel is combined into carbide, so just can make the carbon in the steel no longer be combined into chromium carbide with chromium, add that vanadium can reduce carbon atom velocity of diffusion at high temperature, so just can not cause the poor chromium of crystal boundary district, thereby play the effect that prevents intergranular corrosion.

Stainless steel after refining agent is handled is because inclusion and free particles shape carbide decreases have reduced microcell and organized the galvanic corrosion tendency, thereby reduced intergranular corrosion.Shown in the table one be, CF-8, CF-8M be by sulfuric acid, copper sulfate and copper scale boiling test method(s), adopts to add CF-8, CF-8M that refining agent and solutionizing handle relatively, and visible spot corrodes penetration depth and reduces nearly 2/3.

Table one CF-8, CF-8M add the corrosion resistance behind the refining agent

Sequence number	????1	????2	?????????3	??????????4
					The materials chemistry composition	CF-8 Cr18％， Ni?9％	CF-8 Cr18％， Ni?9.8％	CF-8M Cr18％，Ni?10％， Mo?2.5％	CF-8M Cr18％，Ni10.9％， Mo?2.3％
Treatment process	Solutionizing is handled and is not added refining agent	0.25% refining agent, as cast condition	Not adding the refining agent solutionizing handles	0.25% refining agent as cast condition
					The maximum point pit degree of depth (mm)	2.20	0.58	2.40	0.8

The etch 24 hours in 35 ℃, 60% iron trichloride hydrochloric acid soln of the sample of this experiment.

Contain a certain amount of manganese in this refining agent, manganese addition is similar to nickel for the effect of austenitic steel, manganese can reduce the critical quenching rate of steel, when cooling, increase austenitic stability, suppress austenitic decomposition, make the austenite that forms under the high temperature be remained to normal temperature, thereby the austenitic area is enlarged, cause the magnetic of steel to reduce.

Barium is agent of a kind of deoxidization desulfuration efficiently and the grain-refining agent in cast steel and the cast iron, adds the barium sulphide that is generated in the molten steel and is spherical discrete distribution, and the inclusion that this form distributes helps improving the stainless spot corrosion ability of doing.

The avidity of rare earth element and oxygen has very strong deoxidization desulfuration ability greater than aluminium, adds shape, size and distribution that rare earth can change inclusion simultaneously, thereby improves the comprehensive mechanical property of steel.

Embodiment

Refining agent for stainless steel provided by the invention can adopt the general method uniform mixing to form; Also can adopt the using method identical with correlation technique to be used for smelting stainless steel, be applicable to casting and steel rolling, the refining agent add-on is 0.2-0.4%.Further specify with two embodiment below the present invention is used for the technique effect that the stainless steel melting is produced.

Embodiment 1: with composition is V 21% Ba 20% RE 20% Ti 19.5% Mn 7%Mg 2% Si 10%, surplus is that the refining agent of Fe is handled the stainless molten steel of 100kg with the intermediate frequency furnace melting, the refining agent add-on is 0.25%, the CF-8 stainless steel performance that obtains as shown in Table 2:

Table two CF-8 adds the performance behind the refining agent

Sequence number	Chemical ingredients					Treatment process	Mechanical property
										????C	????Si	????Mn	??Cr	??Ni		????σ b????Mp a	????σ s????Mp a	????δ ????％
	??1	Standard component					——	Standard performance
??485											??205	??35
								??2	??0.07	??0.44			??0.85	??18	??10	0.25% refining agent as cast condition	??540	??255	??55
??3	??0.06	??0.77	??0.85	??19	??11	1050 ℃ of solution treatment of 0.25% refining agent	??520				??235	??67

Embodiment 2:

With composition is V 24% Ba 20% RE 25% Ti 15% Mn 4% Mg 2% Si10%, surplus is that the refining agent of Fe is handled the stainless molten steel of 100kg with the intermediate frequency furnace melting, the refining agent add-on is 0.25%, the CF-8M stainless steel performance that obtains as shown in Table 3:

Table three CF-8M adds the performance behind the refining agent

Sequence number	Chemical ingredients						Treatment process	Mechanical property
											????C	??Si	??Mn	??Cr	?Ni	??Mo		??σ b??Mp a	??σ a??Mp a	??δ ??％
	?1	Standard component						??????????——	Standard performance
485												?205	?30
									?2	?0.07	?0.92			?1.21	??19	?10	?2.5	0.25% essence is frozen sharp as cast condition	570	?275	?40
?3	?0.065	?0.6	?0.98	?18.5	?11	?2.6	1050 ℃ of solution treatment of 0.25% refining agent	550				?270	?68

Following table four has listed more embodiment (each data is weight percentage in the table): table four:

The embodiment sequence number	????RE	????Mg	????V	????Ti	????Ba	????Si	????Mn	????Fe
									????3	????10	????6	????10	????20	????15.5	????30	????8	????0.5
????4	????20	????4.2	????24	????4	????15	????22	????10	????0.8
									????5	????27	????0.4	????5	????15	????30	????10	????12	????0.6

The small amount of impurities that each constituent Central Plains is contained does not have substantial influence to effect of the present invention.

Claims (1)

1. a refining agent for stainless steel is characterized in that, its composition and weight proportion are:

RE??10-35％?????????????????????????????????Ba??10-30％

Mg??0.4-6％?????????????????????????????????Si??10-30％

V???5-24％??????????????????????????????????Mn??4-16％

Ti 4-20% surplus is Fe;

The refining agent for stainless steel that above-mentioned each composition is made is a particulate state.