CN106609339A

CN106609339A - Stainless steel with high tensile strength and production method thereof

Info

Publication number: CN106609339A
Application number: CN201510701628.9A
Authority: CN
Inventors: 王建芳
Original assignee: JIANGSU WEIER HEAVY INDUSTRY MACHINERY Co Ltd
Current assignee: JIANGSU WEIER HEAVY INDUSTRY MACHINERY Co Ltd
Priority date: 2015-10-26
Filing date: 2015-10-26
Publication date: 2017-05-03

Abstract

The invention relates to stainless steel with high tensile strength and a production method of the stainless steel with the high tensile strength. The anti-corrosion stainless steel is improved based on SUS316L, the content of C, Si, Mn, Mo and Cr elements capable of improving the strength of stainless steel is controlled and adjusted to be the upper limit of the standard request content, a small number of Ti elements capable of improving the strength of stainless steel are added, and the stainless steel mainly comprises, by weight, 0.02%-0.03% of C, 0.75%-1.0% of Si, 1.5%-2.0% of Mn, 0.020% or smaller of P, 0.010% or smaller of S, 12.00-15.10% of Ni, 17.00-19.00% of Cr, 2.50-3.00% of Mo, 0.15-0.22% of N, 0.05-0.15% of Ti and 0.5-2.5% of Nb. The strength of stainless steel can be effectively improved by the forging technology of combining hot forging, warm forging and solid solution heat treatment.

Description

A kind of higher rustless steel of tensile strength and its production method

Technical field

The present invention relates to stainless steel forgings technical field, the particularly higher rustless steel of a tensile strength and its life Product method.

Background technology

Austenitic stainless steel under high temperature and extremely low temperature due to all having good plasticity and toughness, cold and hot working performance It is widely used in the fields such as oil, chemical industry, aerospace and the energy with resistance to local corrosion performance, especially in nuclear power Field, austenitic stainless steel is the main material of critical component in all kinds of presurized water reactor nuclear islands, due to forging processing energy Ensure the seriality of metal fibrous tissue, the fibrous tissue and forging profile for making forging is consistent, metal stream Line is complete, it is ensured that part has good mechanical property and long service life, therefore all kinds of austenite stainless Steel forgings play vital effect in the construction of nuclear power station.

The material for adopting at present is mainly austenitic stainless steel (SUS304L, SUS316L etc.), such material tool The characteristics of having high intensity, good corrosion resistance.When forging process is carried out, needs are repeatedly forged such material And heat treatment, certain impact is produced on the performance of forging, often there is the machinery for not carrying out forging the front material of processing in Jing Performance fully meets standard requirement, but is forged with after heat treatment, and mechanical performance provides easy access to standard requirement Lower limit, especially tensile strength, often low even exceeded, causes forging heat treatment or even to scrap again, How to solve the problems, such as that the close lower limit of tensile strength is those skilled in the art after Austenitic stainless steel forging processing The technical issues that need to address.

The content of the invention

It is an object of the invention to provide a kind of higher rustless steel of tensile strength and its production method, the rustless steel Forging low cost of manufacture, mechanical performance are excellent, and especially tensile strength is high.

The technical scheme is that, be improved on the basis of SUS316L, control can improve stainless The content of C, Si, Mn, Mo, Cr element of hardness of steel, is adjusted to standard and is required the upper limit of content, Increase can improve on a small quantity the Ti elements of stainless hardness of steel, and a kind of stainless composition by weight percent is：

C：0.02%～0.03%；

Si：0.75%～1.0%；

Mn：1.5%～2.0%；

P≤0.020%；

S≤0.010%；

Ni：12.00～15.10%；

Cr：17.00～19.00%；

Mo：2.50～3.00%；

N：0.15～0.22%；

Ti：0.05～0.15%；

Nb：0.5-2.5%；Balance of ferrum.

The reasons why determining above-mentioned chemical composition is as follows：

Carbon：Carbon can increase the low temperature intensity of alloy by solution strengthening, play invigoration effect；Carbon content Span of control, below the dissolubility in carbon in ferrite or close to the dissolubility of carbon in ferrite, therefore Carbon content is preferably controlled in into the upper limit, is 0.02%～0.03%.

Nickel：Nickel is strong austenite former, increases the stability that nickel content is favorably improved austenite structure, The intensity of steel can be improved, and keeps good plasticity and toughness；Nickel has higher corrosion resistance to soda acid, But nickel is precious metal raw material, too high levels can cause material price high, and in addition high nickel content is unfavorable for material The raising of low temperature intensity, therefore preferably 13%～15%.

Chromium：Chromium is ferrite former, can significantly improve intensity, corrosion resistance, but while reduce plasticity and Toughness；But chromium content is too high, ferrite content in austenite can be caused to increase, therefore the content of chromium is preferred Control, in the upper limit, is 17.00～19.00%.

Molybdenum：Molybdenum is ferrite former, and molybdenum is added in austenitic stainless steel can improve austenitic stainless steel Pitting resistance, by solution strengthening its intensity can be improved, and molybdenum content is preferably controlled in into the upper limit, be 2.50%～3.00%.

Nitrogen：On the one hand nitrogen can significantly improve austenite not as strong austenite former by solution strengthening The elevated temperature strength of rust steel, another aspect nitrogen interacts with titanium, can more obviously improve material at high temperature intensity； But nitrogen content is too high, substantial amounts of nitride can be caused to separate out, the Toughness and corrosion resistance of material can be reduced again Can, therefore preferably 0.15%～0.22%.

Manganese：Increasing manganese content can improve the intensity of steel, increase the solid solubility of nitrogen in austenitic stainless steel, But manganese content is too high, can cause to produce martensite in austenitic stainless steel, therefore manganese content is preferably controlled in It is limited to 1.5%～2.0%.

Titanium：In the temperature-rise period of steel rolling, titanium and nitrogen, the little particle for combining to form disperse of carbon, to Ovshinsky Body crystal boundary plays fixation, hinders the migration of austenite grain boundary, effectively prevents AUSTENITE GRAIN COARSENING, and in drop Titanium is separated out in austenite with nitrogen, carbon compound to before ferritic transformation during temperature, becomes ferritic shape Nuclear particle, makes ferritic crystal grain refinement, significantly improves stainless intensity；And the content of titanium elements exists When between 0.05%～0.15%, the impact to γ crystallite dimensions is the most notable, therefore Ti content is preferably 0.05%～0.15%.

Silicon：Silicon can significantly improve the elastic limit of steel, yield point and tensile strength, used as the formation of chromium equivalent Element, and molybdenum, chromium etc. combines, can improve the corrosion resistance and non-oxidizability of steel, therefore by silicone content control It is 0.75～1.0% in the upper limit.

Add the effect of Nb：Improve stainless steel high temperature creep strength.

Sulfur, phosphorus：Impurity element during alloy smelting.

The rustless steel of the present invention will can improve the content of C, Si, Mn, Mo, Cr element of stainless hardness of steel, Adjusted to standard and required the upper limit of content, stainless intensity can be effectively improved, increased a small amount of Ti Element, by Ti and N, the interaction of C element, forms TiN, TiC, can effectively prevent austenite Grain coarsening, fining ferrite grains significantly improve stainless steel machinery performance.

A kind of method of above-mentioned stainless production workpiece, comprises the steps：

A. first by above-mentioned corresponding proportioning by vacuum drying oven melting acquisition sample steel ingot；

B. by the strand Heating Steel Ingots smelted to 1250-1280 DEG C, many fire time rough forges are carried out, is incubated 1.5-2.5 Come out of the stove after hour and forge, final forging temperature is not less than 1100 DEG C；Repeatedly forging can improve workpiece with crystal grain thinning Performance；

C. the workpiece that rough forge is obtained is annealed in time, temperature 1100-1150 DEG C, and protected according to thickness setting The warm time；

D. finish forge is carried out to the workpiece after annealing, is processed using warm forging, obtain finish-forging finished product；

E. finish-forging finished product is carried out into solution heat treatment, is heated to 1150-1190 DEG C, Forced water cooling after insulation.

Further, in step B, 1100～1250 DEG C of final forging temperature scope, total forging ratio >=4, per fire Secondary deflection >=30%.

Further, in step D, the temperature range of warm forging processing is 850～900 DEG C, can effectively refine crystalline substance Grain.

The corrosion-resistant stainless steel production method operation of the present invention is simple, it is easy to control, through multiple forge hot and warm forging Combine, can effective crystal grain thinning, significantly improve workpiece performance.

Specific embodiment

Embodiment

The present embodiment produces the higher rustless steel of the corrosion-resistant of 3 batches, tensile strength, and each element composition is pressed Vacuum smelting furnace is added according to proportioning, and according to decarburization situation in smelting process suitably with addition of graphite, by matching somebody with somebody accordingly Than obtaining sample steel ingot by the melting of 50kg vacuum drying ovens；By the strand smelted, rising head is cut, be heated to 1250 DEG C, insulation is come out of the stove after 2 hours and forge, and final forging temperature is not less than 1100 DEG C and is repeatedly forged, total forging Ratio >=4 are made, per fire time deflection >=30%；After the completion of rough forge, workpiece is annealed in time, temperature 1100-1150℃；Finish forge is carried out to the workpiece after annealing, is processed using warm forging, obtain finish-forging finished product；Will be eventually Forged piece carries out solution heat treatment, is heated to 1150-1190 DEG C, Forced water cooling after insulation.

With the formula body stainless steel forgings difficult to understand that same processing technique is prepared for SUS316L, for being contrasted.

The embodiment of table 1 and to comparative example standard analysis (%)

The embodiment of table 2 and comparative example mechanical property

Project	Tensile strength/MPa	Yield strength/MPa	Percentage elongation/%	Hardness/HRB
					Embodiment one	525	210	46	186
Embodiment two	515	205	44	185
					Embodiment three	520	208	45	185
SUS 316L desired values	≥480	≥177	≥40	≤187
					Comparative example	485	190	46	183

The stainless steel forgings for obtaining sampling is analyzed, the chemical composition for obtaining is carried out referring to table 1 to sample Measuring mechanical property, by the content of the elements such as C, Si, Mn, Mo, Cr in raising composition, and adds few The Ti elements of amount, can effectively prevent AUSTENITE GRAIN COARSENING, combine through multiple forge hot and warm forging, can With effective crystal grain thinning, workpiece mechanical performance is significantly improved, concrete outcome is referring to table 2.

Obviously, above-described embodiment is only intended to clearly illustrate example of the present invention, and is not to this The restriction of bright embodiment.For those of ordinary skill in the field, on the basis of the above description Can also make other changes in different forms.There is no need to give all of embodiment It is exhaustive.And these belong to the obvious change extended out of spirit or variation of the present invention still in the present invention Protection domain in.

Claims

1. a kind of rustless steel, it is characterised in that chemical composition and its mass percent are：

C： 0.02%~0.03%；

Si ： 0.75%~1.0%；

Mn：1.5%~2.0%；

P≤0.020%；

S≤0.010%；

Ni：12.00~15.10%；

Cr ：17.00~19.00%；

Mo ：2.50~3.00%；

N：0.15~0.22%；

Ti：0.05~0.15%；

Nb：0. 5~2.5%；

Balance of ferrum.

2. it is according to claim 1 it is stainless production workpiece method, it is characterised in that comprise the steps：

B. many fire time rough forges are carried out, by the strand Heating Steel Ingots to 1250-1280 DEG C smelted, is come out of the stove after insulation 1.5-2.5 hours and forge, final forging temperature is not less than 1100 DEG C；Repeatedly forging can improve workpiece performance with crystal grain thinning；

C. the workpiece that rough forge is obtained is annealed in time, temperature 1100-1150 DEG C, and temperature retention time is set according to thickness；

3. production method according to claim 2, it is characterised in that in step B, 1100～1250 DEG C of final forging temperature scope, total forging ratio >=4, per fire time deflection >=30%.

4. production method according to claim 2, it is characterised in that in step D, the temperature range of warm forging processing is 850～900 DEG C.