CN106609345A - Stainless steel good in heat resistance and production method of stainless steel - Google Patents

Abstract

The invention relates to stainless steel good in heat resistance and a production method of the stainless steel. The stainless steel is improved on the basis of SUS316L, the contents of elements C, Si, Mn, Mo and Cr capable of improving the strength of the stainless steel are controlled and adjusted to the upper limit of the standard required content, and a little quantity of elements Ti capable of improving the strength of the stainless steel is added. The stainless steel mainly comprises, by weight percent, 0.02%-0.03% of C, 0.75%-1.0% of Si, 1.5%-2.0% of Mn, not larger than 0.020% of P, not larger than 0.010% 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 0.05%-0.15% of W. The strength of the stainless steel can be effectively improved through the forging process of combining hot forging, warm forging and solid solution heat treatment.

Description

A kind of preferable rustless steel of heat resistance and its production method

Technical field

The present invention relates to stainless steel forgings technical field, the particularly a kind of preferable rustless steel of heat resistance and its life Product method.

Background technology

Austenitic stainless steel is due to all having good plasticity and toughness, cold and hot working performance under high temperature and extremely low temperature 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 are the main materials 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, It is those skilled in the art that after how solving the problems, such as Austenitic stainless steel forging processing, tensile strength is close to lower limit The technical issues that need to address.

The content of the invention

It is an object of the invention to provide a kind of rustless steel and its production method, the stainless steel forgings manufacturing cost Low, mechanical performance is 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 the Ti elements of stainless hardness of steel, a kind of heat resistance preferably stainless Ingredients Weight on a small quantity Percentage ratio 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%；

W：0.05-0.15%；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 high nickel content is unfavorable for material in addition 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, in causing austenite, ferrite content increases, therefore the content of chromium is preferred Control, in the upper limit, is 17.00～19.00%.

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

Nitrogen：On the one hand nitrogen can significantly improve austenite not by solution strengthening as strong austenite former The elevated temperature strength of rust steel, another aspect nitrogen are interacted 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：Increase the intensity that manganese content can improve steel, increase the solid solubility of nitrogen in austenitic stainless steel, But manganese content is too high, martensite is produced during austenitic stainless steel can be caused, 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 During temperature, titanium is separated out in austenite to before ferritic transformation with nitrogen, carbon compound, 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.

Tungsten：The red hardness and heat resistance of steel can be improved, and the wearability of steel can be improved.

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

B. by the strand Heating Steel Ingots smelted to 1250-1280 DEG C, many fire time rough forges is carried out, 1.5-2.5 is incubated 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 stainless steel production method operation of the present invention is simple, it is easy to controls, combines through multiple forge hot and warm forging, Can effective crystal grain thinning, significantly improve workpiece performance.

Specific embodiment

Embodiment

The present embodiment produces the rustless steel of 3 batches, and each element composition is added vacuum smelting furnace according to proportioning, And 50kg vacuum drying oven meltings are passed through by corresponding proportioning suitably with addition of graphite according to decarburization situation in smelting process Obtain sample steel ingot；By the strand smelted, rising head is cut, be heated to 1250 DEG C, insulation went out after 2 hours Stove is forged, and final forging temperature is not less than 1100 DEG C and is repeatedly forged, total forging ratio >=4, per fire time deflection >=30 %；After the completion of rough forge, workpiece is annealed in time, temperature 1100-1150 DEG C；Workpiece after annealing is entered Row finish forge, is processed using warm forging, obtains finish-forging finished product；Finish-forging finished product is carried out into solution heat treatment, is heated to 1150-1190 DEG C, Forced water cooling after insulation.

The formula body stainless steel forgings difficult to understand of SUS316L are prepared for same processing technique, for being contrasted.

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

2 embodiment of table and comparative example mechanical property

Project	Tensile strength/MPa	Yield strength/MPa	Percentage elongation/%	Hardness/HRW
					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 to sample referring to table 1 Measuring mechanical property, by the content for improving the element such as C, Si, Mn, Mo, Cr in 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 to all of embodiment It is exhaustive.And these belong to the present invention spirit it is extended obvious change or variation still in the present invention Protection domain in.

Claims (4)

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%；

W：0.05-0.15%；

Balance of ferrum.

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

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

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 being incubated 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；

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.

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.