CN105296869A - Stainless steel material and manufacturing methods thereof - Google Patents

Abstract

The invention discloses a stainless steel material and manufacturing methods thereof. The stainless steel material is Cr-Mn-N austenitic stainless steel with nickel replaced with nitrogen. The manufacturing methods comprise a smelting method, a blank punching method and a machining method. The smelting method mainly comprises the step of smelting high-nitrogen steel through two alloying nitrogen-increasing methods, namely using nitrogen-containing materials and gaseous nitrogen. The blank punching method mainly comprises the steps of conducting circulative blank punching, conducting heat treatment, conducting solid solution treatment, and controlling the heat retention temperature and heat retention time, wherein hardness values and impact toughness values serve as the main reference for die selection. The machining method mainly comprises the steps of controlling appropriate machining parameters of milling and turning. The stainless steel material and the manufacturing methods thereof have the advantages that the stainless steel material is the novel austenitic stainless steel; the smelting method is applicable to batch smelting of the high-nitrogen steel with the nitrogen content ranging from 0.4 wt% to 0.75 wt%; the blank punching method inhibits cold hardening phenomena in the high-nitrogen steel machining process, and blank punching is facilitated; through the machining method, the problem that machining difficulty is large due to high hardness of the high-nitrogen steel is solved.

Description

A kind of stainless material and manufacture method thereof

Technical field

The present invention relates to stainless steel and smelting, working method, more particularly, relate to a kind of stainless material and manufacture method thereof.

Background technology

1, the meaning of high nitrogen steel is used

Stainless steel is the steel not easily got rusty, and stainless rustless property and solidity to corrosion are due to its rich chromium oxide film (passive film) and being formed on the surface.There is due to stainless steel the number of features such as excellent solidity to corrosion, formability, consistency and the obdurability in very wide temperature range, obtain with its excellent specific property in the industries such as heavy industry, light industry, daily necessities industry and building decoration and apply widely, being not only functional material, is also modern structure material.Stainless steel has the advantage that life cycle is long, cost is low, can 100% recycling, is also the green material that can not cause environmental pollution (unleaded, without polyvinyl chloride, without Environmental Hormone).Stainless steel has been the metallic substance that output unique now and demand continue rising (world's average growth rate per annum 6%) since the invention of 20th century, and due to renewal and the progress of technology, the reduction of cost, stainless output constantly promotes.

Stainless material is widely used in the product with human contact, as wrist-watch, jewellery, medicine equipment, human organ implantation etc., these fields stainless steel trade mark used is mainly SUS304 (06Cr19Ni10) and SUS316L (022Cr17Ni12Mo2), but this two classes material nickel content is all more than 8%.Research in recent years shows, nickel may have stripping when Long Term Contact human body and work the mischief to human body, be mainly reflected in the impact that nickel may be carcinogenic on the anaphylaxis of skin and nickel, namely nickeliferous metallic substance is for the manufacture of the article of contact human body skin, anaphylaxis can be brought out, and when using nickeliferous metallic substance in human body, may induce an illness.

Nickeliferous metal products (comprising coating) and human body skin direct long term contact, some people can cause skin lesion in various degree in contact site, slight having be rubescent, scratch where it itches, and serious meeting is red and swollen, fester, and this phenomenon is referred to as nickel allergy.In daily life, people often contact nickeliferous metal products (as wrist-watch, jewellery etc.), therefore cause allergic case of common occurrence.The research of allergic mechanism is caused to show to nickel, metal can not directly and human body skin generation untoward reaction, skin is in directly contacting with nickeliferous goods for a long time, absorb the nickel ion discharged in nickel-containing material, with skin mucosa epithelium protein binding, be stranded in epidermis, cause skin surface to occur the pathological changes such as eczema, cause allergy.This process can be described as nickel-containing material with human body skin Long Term Contact process, and the effect of human sweat accelerates the corrosion process of material.

The sensitivity response that nickel produces human body and carcinogenic impact, cause the attention of world medical circle and material circle day by day.Various countries are more and more stricter to the nickel content restriction in daily and medical metal material, and the most high nickel content allowed in standard regulation is also more and more lower.Start just have standard to specify from the eighties in 20th century, alloy nickel massfraction being greater than 1% puts carcinogenic substance and allergic material category under, and requires " safety certificate " that in quality product certificate, additionally may produce detrimental consequences to human body.1994, the ISO6871-2-1994 international standard passed through was warned: the oral rectification alloy that nickel massfraction is greater than 1%, belonged to human body not tolerant " danger classes " alloy.In July, 1999, European Union has issued guiding regulation CEDirective94/27/EEC, namely nickel instruction (TheNickelDirective) is commonly called as, harsher to the regulation of daily necessities production material, point out in the material (embedded material, orthopaedic false tooth etc.) in implant into body, nickel massfraction should more than 0.05%, and the alloy of the product such as jewellery, wrist-watch, ring, bracelet for the manufacture of Long Term Contact human body skin, nickel content then should more than 0.5 μ g/cm with the amount of infiltrating weekly skin ²for the highest limitation.Foreign vendor particularly European Union member countries is very positive to nickel instruction reaction.On January 20th, 2000, English law is included in nickel instruction in.On July 21st, 2000, Germany forbid producing and the nickeliferous composition of import and long-term skin contact time money accessories.2002, China's jewellery industry is formulated and has been promulgated mandatory technological standard GB11887-2002 " regulation of jewellery precious metal and naming method ", wherein clear stipulaties: the nickel burst size of jewellery and human body skin Long Term Contact part must be less than weekly 0.5 μ g/cm ², and the bioassay standard of jewellery nickel burst size was established in 2005.Within 2007, rise, China's horological industry is formulating mandatory technological standard " directly contacting the regulation of limits of harmful substances in the wrist-watch element of human body skin ", wherein also specify the nickel burst size requirement with human body skin Long Term Contact part.Although existing better with its corrosion resistance nature of stainless steel of human contact's product, all there is the potential risk that nickel burst size exceeds standard.Therefore, in order to avoid discharging excessive problem at the nickel with human contact's stainless steel product, Study in Low-Nickel so that without the austenitic stainless steel of nickel and processing technology imperative.

In addition, from resource view analysis, China is a country lacking nickel, chromium resource, and Chinese nickel resources reserves are 6,700,000 tons, and copper nickel sulfide mineral accounts for 91% of total reserves, and all the other are oxidized ore.Countries in the world are dog-eat-dog in contention nickel chromium triangle development of resources control, therefore nickel chromium triangle resource provisioning is the important limiting factor that China's development stainless steel is produced, and nickel cost of material is surging in recent years, relatively make Nickel Chrome Stainless Steel high expensive, therefore develop low nickel and even nickelles stainless steel has important strategic importance.

2, the development of correlation technique

Low nickel or have passed through several stage without the development of the austenitic stainless steel of nickel is continuous progress along with the development of austenitic stainless steel.Austenitic stainless steel, since earlier 1920s invention, has obtained swift and violent development.At present, austenitic stainless steel has developed into most important steel class in stainless steel, and its turnout and usage quantity account for more than 60% of stainless steel ultimate production and consumption.

Along with the development of smelting technology, argon-oxygen Decarburising and refining method (AOD) and vacuum oxygen decarburization process (VOD) start as commercial large production application in stainless production technique.Can decarburization economically by refining techniques, and be easy to carbon content to be down to below 0.03wt%, greatly reduce the generation of sensitization phenomenon.Ultra-low carbon austenitic stainless steel, with the solidity to corrosion of its excellence and over-all properties, instead of gradually containing Nb, Ti class stainless steel.But the reduction of carbon, make the strength degradation of austenitic stainless steel.For making up the undercapacity that carbon drop causes, the effect of nitrogen in stainless steel starts as people are paid attention to.From nineteen twenties, it is found that and can improve intensity at stainless nitrogen in steel, find again that it has wholesome effect to the corrosion resisting property of steel afterwards successively.But nitrogen is in 1938 as the report the earliest that alloy element uses.Hinder nitrogen as the widely used principal element of alloying element be first nitrogen add problem.Under atmospheric pressure, nitrogen solubility is very low, adds very difficult.Because add-on is very little, therefore it is not obvious to the advantageous effect of steel.In addition, in some steel alloy, there is disadvantageous effect in nitrogen in impelling strength, plasticity etc., hinders the attention of people to the application of nitrogen further.

Nineteen fifties, in great shortage due to noble element nickel resources in stainless steel at that time, has impelled people to the extensive research of chromium nickel manganese nitrogen and chromium-manganese-nitrogen austenitic stainless steel.The result of this research, result in i.e. 200 births being of Cr-Mn-Ni-N stainless steel series.N content in steel concentrates in 0.10 ~ 0.25% scope.To the sixties, due to the industrial application of the outer refining techniques of AOD furnace, what make nitrogen adds the solution obtained with control problem to a certain degree.Make the beneficial effect of nitrogen in stainless steel more and more by people are familiar with to the further research of nitrogen-contained stainless steel.At that time, investigator had realized that nitrogen is while significantly improving stainless mechanical property, also improved the corrosion resistance nature of steel, and particularly resistance to local corrosion performance is as intergranular corrosion resistance, pitting attack and crevice corrosion etc.

But by the restriction of the factors such as smelting condition, the solubleness of nitrogen in stainless steel still remained at low levels at that time.Along with the development of pressurization metallurgical technology, nitrogen can be solid-solution in steel with larger content, and therefore brings larger impact to the performance of steel.The effect of nitrogen in steel is again by people institute extensive concern.Industry has expressed very large interest to high nitrogen steel.

The solubleness of nitrogen in iron alloy is closed and is:

logN＝-293/T-1.16-logf _N+0.5logP _N2

In formula, T is temperature, and fN is the activity quotient of nitrogen, and by alloying metal affect, wherein Cr, Mn, Mo, Nb reduce its activity quotient value.

At present, developed the smelting technology of multiple high nitrogen steel abroad, comprised plasma smelting, pressurization induction furnace has been smelted, pressurization electric slag refusion and smelting, powder metallurgy and utilize advanced computer alloy design method to carry out normal pressure under the smelting etc. of high nitrogen steel.The main trend of high nitrogen steel development has: (1) high-strength and high-toughness steel.This type of steel mainly utilizes N to the contribution of steel mechanical property, by suitable metallurgical technology and appropriate alloy designs, is greatly solid-solution in steel by N, thus develops the stainless steel of superstrength, superhigh tenacity.Part achievement shows, and this is the another approach of research ultrahigh-strength steel.Worked out solid solution condition lower yield strength more than 2000MPa, under cold deformation state, intensity is more than the ultrahigh-strength steel of 3600MPa.(2) stainless steel of the excellent combination property based on corrosion resisting property.This type of steel mainly utilizes N to the contribution of the corrosion resisting property of steel, and takes into account the impact of N in mechanical property, for special Service Environment, works out series of new super stainless steel.(3) to economize on resources, to reduce costs as the economical stainless steel of main purpose.This type of steel utilizes N on the impact of structure of steel, partly or entirely substitute noble metal nickel, make steel still keep austenite structure under lower raw materials cost, thus in performance, take into account the feature of austenitic steel and N to the effect of Steel Properties, expand stainless use further.

The stainless material of this patent research, mainly utilize N to the contribution of corrosion resisting property, the nickel element in stainless steel is substituted completely with N, work out on basis completely not containing the high nitrogen stainless steel of nickel element, fundamentally solve the stainless nickel allergic problem being human contact's product is applied, and save nickel metals resources.Meanwhile, adding by N, improve material hardness and wear resisting property, material hardness is greater than original ultra-low carbon austenitic stainless steel.

Nitrogen unit have solution strengthening effect, not only can improve steel strength, toughness, creep resistance, improves wear resistance, and can improve its solidity to corrosion.Matrix is that the steel being the nitrogen containing more than 0.4% in austenitic steel containing the nitrogen of more than 0.08% and matrix in ferritic steel is called high nitrogen steel.Nitrogen stainless austenite mutually in solid solution easier than carbon, and have the effect delaying Carbide Precipitation, effectively can improve intensity and the solidity to corrosion of steel simultaneously.With the development of the stainless steel of nitrogen replacement nickel, solidity to corrosion and intensity can be improved by the nitrogenize of stainless steel height, make Ovshinsky phase stabilizer and replace nickel, in quality and cost, obtain effect.The smelting of high nitrogen stainless steel mainly faces two problems, namely how to obtain high content nitrogen in melted state, and how to ensure to make nitrogen be in dissolved state in process of setting, instead of free state.For obtaining high nitrogen content, the major measure taked has: alloying constituent reasonable in design; Take suitable operational path; Select suitable nitrogen carriers.Current high nitrogen smelting steel technology mainly adopts and adds to molten liquid steel the smelting process that solid nitrogenous material makes steel alloying, adopts the alloying of gaseous nitrogen or two kinds of modes to combine.

To sum up, can see, prior art exists the nickeliferous stainless steel of human contact can produce nickel allergic problem; Meanwhile, when smelting nitrogen-contained stainless steel, difficulty is smelted in existence, the adding proportion of stainless nitrogen in steel does not reach the technical barrier of design requirements.

Simultaneously, relative to traditional stainless steel, high nitrogen steel exists more serious cold working hardening phenomenon in processing production process, and (steel produce strong viscous deformation at normal temperature or the processing below Tc, make lattice distortion, distortion, crystal grain produces shearing, slippage, and crystal grain is elongated, significantly improve hardness, reduce plasticity and impelling strength, be called cold working hardening), traditional stainless blank process for stamping and machining process are not suitable for high nitrogen steel; And high nitrogen steel exists because of the large problem of hardness die mechanical processing difficulty.

Summary of the invention

One of the technical problem to be solved in the present invention is, the stainless steel nickeliferous for the above-mentioned human contact of prior art can produce nickel allergic problem, provides a kind of stainless material.This stainless material is the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, due to not nickeliferous, can not produce nickel allergic problem with during human contact, and it also avoid the nickel using shortage of resources, be the novel austenite stainless steel of a kind of intensity, tenacity excellent simultaneously.

Two of the technical problem to be solved in the present invention is, the above-mentioned nitrogen-contained stainless steel for prior art smelts difficulty, the adding proportion of stainless nitrogen in steel does not reach the defect of design requirements, provides a kind of method of the induction furnace smelting high-nitrogen steel that pressurizes.The obvious feature of the method is that the nitrogenous material of applying solid and gaseous nitrogen two kinds of alloying nitriding methods carry out smelting high-nitrogen steel, thus makes accurate composition control, and nitrogen recovery reaches more than 99%; Adopt the smelting process repeatedly studied, test, verify simultaneously, by the Control of Nitrogen Content of high nitrogen steel in the scope of design requirements, can meet design requirement.

Three of the technical problem to be solved in the present invention is, there is more serious cold working hardening phenomenon in the above-mentioned high nitrogen steel for prior art, traditional stainless blank process for stamping is not suitable for the problem that high nitrogen steel is shaped in processing production process, provides the method for a kind of high nitrogen steel blank punching press.

Four of the technical problem to be solved in the present invention is, for prior art there is more serious cold working hardening phenomenon in above-mentioned high nitrogen steel, traditional machining process is not suitable for high nitrogen steel in processing production process and high nitrogen steel exists because of the large defect of hardness die mechanical processing difficulty, a kind of machining process of high nitrogen steel is provided.

The manufacture method of stainless material of the present invention comprises: method, the method for high nitrogen steel blank punching press, the machining process of high nitrogen steel of pressurization induction furnace smelting high-nitrogen steel.

Austenite is the high temperature variant of the iron with face-centered cubic crystal structure, generally Thermodynamically stable between 740 DEG C and 1538 DEG C, and contain from 0 to the maximum carbon of 2.1 % by weight (at 1153 DEG C) with solution, generally, all steel capital with face-centered cubic lattice are called austenitic steel.The present invention after deliberation, experiment, find that high nitrogen steel is through circulating flushing base, thermal treatment, solution treatment, in the process, heat treated holding temperature is between 1050-1100 DEG C, soaking time is greater than 0.5 hour, the holding temperature of solution treatment is increased between 1080-1120 DEG C, soaking time >=1.0 hour, and oil quenching cools fast, in the case, cold working hardening phenomenon in the high nitrogen steel course of processing is obviously suppressed, face-centered cubic lattice simultaneously in high nitrogen steel is basicly stable, composition profiles in high nitrogen steel is more even, materials microstructure performance can be recovered in time, be beneficial to high nitrogen steel pressed blanks, in the machining process of high nitrogen steel of the present invention, for the problem that hardness is large, difficulty of processing is large of high nitrogen steel, work out method and the machined parameters of suitable Milling Process and turnery processing, high nitrogen steel can be overcome because of the large problem of hardness die difficulty of processing, precision sizing is carried out to high nitrogen steel.

The temperature of the usual solution treatment of conventional wristwatch 316L appearance component is at 900 DEG C, be incubated half an hour, and high nitrogen steel is due to the singularity of smelting technology, a large amount of can separate out when 850-950 DEG C that nitride causes material composition, the performance such as corrosion-resistant is damaged, therefore its solid solution temperature must reach more than 1050 DEG C; Many experiments shows can be optimized in about 1100 DEG C insulations corrosion-resistant, the glossiness etc. that after 1 hour, high nitrogen steel occurs due to the punching press in early stage.

The present invention solves the technical scheme that one of its technical problem adopts: construct a kind of stainless material, and this stainless material is the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, and this stainless material comprises the component of following weight percent:

Cr：18-22％；

Mn：14-17％；

N：0.4-0.75％；

C: be less than 0.15%.

In stainless material of the present invention, this stainless material is used for the part with the product of direct body contact.

The present invention solves the technical scheme that its technical problem two adopts: a kind of method constructing induction furnace smelting high-nitrogen steel that pressurizes, and utilizes the melting of pressurization induction smelting furnace, comprises the steps:

S1: according to the elemental composition of target steel grade, target steel grade limit nitrogen content value is at ambient pressure calculated by following formula (1) and formula (2), this limit nitrogen content value is multiplied by modified value and obtains smelting the actual of nitrogen content in prepared furnace charge and add weight percent, and this modified value is between 0.7 ~ 0.9;

Formula (1):

$lg\[\%N\]=\frac{1}{2}lg(p_{N_2}/p^0)-188/T-1.17-{\mathrm{lgf}}_N^{Me}$

In formula for nitrogen partial pressure, p ⁰for standard atmospheric pressure;

Formula (2):

$\begin{array}{c}\lg f_N^{Me}=\{-164\mathrm{\ω}\[Cr\]+8.33\mathrm{\ω}\[Ni\]-33.2\mathrm{\ω}\[Mo\]-134\mathrm{\ω}\[Mn\]+1.68\mathrm{\ω}{\[Cr\]}^2-1.83\mathrm{\ω}{\[Ni\]}^2-2.78\mathrm{\ω}{\[Mo\]}^2+8.82{\[Mn\]}^2\\ +\left(1.6\mathrm{\ω}\[Ni\]+1.2\mathrm{\ω}\[Mo\]+2.16\mathrm{\ω}\[Mn\]\right)\mathrm{\ω}\[Cr\]+\left(-0.26\mathrm{\ω}\[Mo\]+0.09\mathrm{\ω}\[Mn\]\right)\mathrm{\ω}\[Ni\]\}/T+\{0.0415\mathrm{\ω}\[Cr\]+\\ 0.0019\mathrm{\ω}\[Ni\]+0.0064\mathrm{\ω}\[Mo\]+0.035\mathrm{\ω}\[Mn\]-0.0006\mathrm{\ω}{\[Cr\]}^2+0.001\mathrm{\ω}{\[Ni\]}^2-0.0013\mathrm{\ω}{\[Mo\]}^2-0.0056\mathrm{\ω}{\[Mn\]}^2\\ +\left(-0.009\mathrm{\ω}\[Ni\]-0.0005\mathrm{\ω}\[Mo\]-0.0005\mathrm{\ω}\[Mn\]\right)\mathrm{\ω}\[Cr\]+\left(0.0003\mathrm{\ω}\[Mo\]+0.0007\mathrm{\ω}\[Mn\]\right)\mathrm{\ω}\[Ni\]\}+0.13\mathrm{\ω}\[C\]\\ +0.06\mathrm{\ω}\[Si\]+0.046\mathrm{\ω}\[P\]+0.007\mathrm{\ω}\[S\]+0.01\mathrm{\ω}\[Al\]-0.9\mathrm{\ω}\[Ti\]-0.1\mathrm{\ω}\[V\]-0.003\mathrm{\ω}\[W\]-0.12\mathrm{\ω}\[O\]\end{array}$

In formula for the activity quotient of nitrogen in molten steel; The massfraction % that ω [m] is alloying element m;

S2: by the requirement preparation smelting material of element contained by steel grade, cleaning crucible, loads the smelting material prepared;

S3: find time to pressurization induction furnace melting room, start power transmission when vacuum tightness is less than 15Pa to heat smelting material, initial power is 40KW, progressively increasing power, after there is molten bath, maintains and controls power, avoiding splash;

S4: turn down power after furnace chargeization is clear, enter refining, refining 30-40 minute, vacuum tightness≤5Pa, depart from and comprise following element O, N, H;

S5: the GN 2 alloying: open Nitrogen plant, be filled with nitrogen, furnace pressure is at least adjusted to and fills nitrogen pressure, improves the saturation solubility of nitrogen in molten steel;

S6: alloying: add the raw materials for metallurgy of raising partial pressure by charging opening substep and calculate the nitrided ferro-chromium, nitrogenized manganese or other nitrogen pick-up alloy that obtain, to improve yield of alloy according to the actual weight percent that adds of nitrogen content in S1;

S7: add reductor, controls molten steel temperature higher than fusing point 100 ~ 150 DEG C, chargedly pours in ingot mould, cooling;

S8: venting, broken empty, open bell and take out ingot mould, make high nitrogen steel.

In the method for pressurization induction furnace smelting high-nitrogen steel of the present invention, according to composition and the requirement of nitrogen of different target steel grade, calculate the activity quotient of nitrogen in molten steel, saturation solubility according to formula (1) and formula (2), fill nitrogen pressure and nitrogen pick-up alloy addition.

In the method for pressurization induction furnace smelting high-nitrogen steel of the present invention, described step S5 adopts the GN 2 alloyage process, nitrogen gas purity >=99%, fills nitrogen pressure by formula: $\lg p_{N_2}=2\×(\lg \[\%N\]-\lg K_N+\lg f_N^{Me})$ Calculate in conjunction with formula (2).

In the method for pressurization induction furnace smelting high-nitrogen steel of the present invention, the reductor in step S7 is crucible carbon, deoxidized aluminium.

The present invention solves the technical scheme that its technical problem three adopts: the process for stamping constructing a kind of high nitrogen steel blank, for the punching press of nitrogen steel blank high in blank pressing equipment, comprises the following steps:

S1: select mould

To select after tempered process Rockwell hardness HRC between 60-70 and notched bar impact strength between 55-120J/cm ²mould, by described die assembly in blank pressing equipment;

S2: thermal treatment

S2.1: to high nitrogen steel drift base, often rushes base and once liquidates the high nitrogen steel heat treatment after base afterwards once, heat treated holding temperature between 1050-1100 DEG C, soaking time >=0.5 hour;

S2.2: circulation carry out S2.1 be operated to set point number after, carry out a solution treatment: heat treated holding temperature is increased between 1080-1120 DEG C, soaking time >=1 hour, and oil quenching cools fast;

S2.3: circulation is carried out being operated to of S2.1 and S2.2 and struck out high nitrogen steel blank.

In the process for stamping of high nitrogen steel blank of the present invention, described mould be after tempered process Rockwell hardness HRC between 62-64 and notched bar impact strength between 60-90J/cm ²mould.

In the process for stamping of high nitrogen steel blank of the present invention, the soaking time in described step S2.1 is between 0.5-0.75 hour.

In the process for stamping of high nitrogen steel blank of the present invention, in described step S2.2, the set point number of the operation of S2.1 is carried out in circulation is 4-7 time.

In the process for stamping of high nitrogen steel blank of the present invention, the soaking time in described step S2.2 is 1-2 hour, and oil quenching cools fast.

In the process for stamping of high nitrogen steel blank of the present invention, high nitrogen steel is the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, and wherein the mass percent of nitrogen content is between 0.4-0.75%.

The present invention solves the technical scheme that its technical problem four adopts: the machining process constructing a kind of high nitrogen steel, comprises the following steps:

S1: select cutter

Select Rockwell hardness HRA to be greater than 95, bending strength δ is greater than the cutter of 2GPa;

S2: processing

S2.1: milling

Mechanical means adopts following machined parameters to carry out milling to high nitrogen steel: cutting speed Vc is between 60-100m/min, rotating speed n is between 3000-5000r/min, feed engagement fz is between 0.01-0.02mm/z, and speed of feed F is between 200-300mm/min, and bite AP is between 0.03-0.2mm;

S2.2: turning

Mechanical means adopts following machined parameters to carry out turning to high nitrogen steel: rotating speed n is between 700-1000r/min, and feed of every rotation fr is between 0.02-0.04mm/r, and bite AP is between 0.05-0.3mm;

Until high nitrogen steel is processed into the part meeting design requirements;

Wherein, adopt cooling fluid when milling and turning, the emulsion of cooling fluid to be massfraction be 3-6%, the pH value of described emulsion is between 9.0-9.5.

In the machining process of high nitrogen steel of the present invention, the refraction coefficient of described emulsion between 1-3, and is rust preventing emulsion.

Implement the method for stainless material of the present invention and smelting thereof, blank punching press, mechanical workout, there is following beneficial effect:

1, stainless material

This stainless material is the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, during human contact, can not produce nickel allergic problem, and it also avoid the nickel using shortage of resources, be the novel austenite stainless steel of a kind of intensity, tenacity excellent simultaneously.

2, the method for pressurization induction furnace smelting high-nitrogen steel

The obvious feature of the method is that the nitrogenous material of applying solid and gaseous nitrogen two kinds of alloying nitriding methods carry out smelting high-nitrogen steel, thus makes accurate composition control, and nitrogen recovery reaches more than 99%; Adopt the smelting process repeatedly studied, test, verify simultaneously, by the Control of Nitrogen Content of high nitrogen steel in the scope of design requirements, can meet design requirement, reach accurate composition control, the effect that nitrogen recovery rate is high and stable; The present invention can make the recovery rate of nitrogen reach more than 99%, especially the high nitrogen steel smelted up to 0.7% becomes a reality, and be applicable to the special steel smelting nitrogen content 0.4%-0.75% in enormous quantities, make batch production for becoming possibility with the nickelles stainless steel of human contact.

3, the method for high nitrogen steel blank punching press

High nitrogen steel is through circulating flushing base, thermal treatment, solution treatment, in the process, heat treated holding temperature is between 1050-1100 DEG C, soaking time>=0.5 hour, the holding temperature of solution treatment is increased between 1080-1120 DEG C, soaking time>=1 hour, and oil quenching cools fast, in the case, cold working hardening phenomenon in the high nitrogen steel course of processing is obviously suppressed, face-centered cubic lattice simultaneously in high nitrogen steel is basicly stable, composition profiles in high nitrogen steel is more even, materials microstructure performance can be recovered in time, is beneficial to the compacting high nitrogen steel being carried out to blank; To select after tempered process Rockwell hardness HRC between 60-70 simultaneously and notched bar impact strength between 55-120J/cm ²mould carry out the compacting of blank, the problem that when general mould carries out blank punching press to high nitrogen steel, punching press effect is poor can be overcome.

4, the machining process of high nitrogen steel

In the machining process of high nitrogen steel of the present invention, for the problem that hardness is large, difficulty of processing is large of high nitrogen steel, work out method and the machined parameters of suitable Milling Process and turnery processing, high nitrogen steel can be overcome because of the large problem of hardness die difficulty of processing, be beneficial to and precision sizing is carried out to high nitrogen steel.

Embodiment

In order to there be understanding clearly to technical characteristic of the present invention, object and effect, now with embodiment, the present invention is illustrated.

Stainless material:

This stainless material is the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, and this stainless material comprises the component of following weight percent:

Cr：18-22％；

Mn：14-17％；

N：0.4-0.75％；

C: be less than 0.15%.

This stainless material is preferred for the part with the product of direct body contact, as watchband, the watchcase and bottom etc. of wrist-watch.Certainly, in other embodiments, this stainless material also may be used for mechanical means, structure material, Industrial materials etc.

A kind of method of the induction furnace smelting high-nitrogen steel that pressurizes:

(house is produced in the production of pressurization induction furnace: northern electric furnace factory to utilize the melting of pressurization induction smelting furnace; Model: ZG--0.05T), comprise the steps:

S1: according to the elemental composition of target steel grade, target steel grade limit nitrogen content value is at ambient pressure calculated by following formula (1) and formula (2), this limit nitrogen content value is multiplied by modified value and obtains smelting the actual of nitrogen content in prepared furnace charge and add weight percent, and this modified value is between 0.7 ~ 0.9;

Formula (1):

$lg\[\%N\]=\frac{1}{2}lg(p_{N_2}/p^0)-188/T-1.17-lg{f}_N^{Me}$

In formula for nitrogen partial pressure, p ⁰for standard atmospheric pressure;

Formula (2):

$\begin{array}{c}\lg f_N^{Me}=\{-164\mathrm{\ω}\[Cr\]+8.33\mathrm{\ω}\[Ni\]-33.2\mathrm{\ω}\[Mo\]-134\mathrm{\ω}\[Mn\]+1.68\mathrm{\ω}{\[Cr\]}^2-1.83\mathrm{\ω}{\[Ni\]}^2-2.78\mathrm{\ω}{\[Mo\]}^2+8.82{\[Mn\]}^2\\ +\left(1.6\mathrm{\ω}\[Ni\]+1.2\mathrm{\ω}\[Mo\]+2.16\mathrm{\ω}\[Mn\]\right)\mathrm{\ω}\[Cr\]+\left(-0.26\mathrm{\ω}\[Mo\]+0.09\mathrm{\ω}\[Mn\]\right)\mathrm{\ω}\[Ni\]\}/T+\{0.0415\mathrm{\ω}\[Cr\]+\\ 0.0019\mathrm{\ω}\[Ni\]+0.0064\mathrm{\ω}\[Mo\]+0.035\mathrm{\ω}\[Mn\]-0.0006\mathrm{\ω}{\[Cr\]}^2+0.001\mathrm{\ω}{\[Ni\]}^2-0.0013\mathrm{\ω}{\[Mo\]}^2-0.0056\mathrm{\ω}{\[Mn\]}^2\\ +\left(-0.009\mathrm{\ω}\[Ni\]-0.0005\mathrm{\ω}\[Mo\]-0.0005\mathrm{\ω}\[Mn\]\right)\mathrm{\ω}\[Cr\]+\left(0.0003\mathrm{\ω}\[Mo\]+0.0007\mathrm{\ω}\[Mn\]\right)\mathrm{\ω}\[Ni\]\}+0.13\mathrm{\ω}\[C\]\\ +0.06\mathrm{\ω}\[Si\]+0.046\mathrm{\ω}\[P\]+0.007\mathrm{\ω}\[S\]+0.01\mathrm{\ω}\[Al\]-0.9\mathrm{\ω}\[Ti\]-0.1\mathrm{\ω}\[V\]-0.003\mathrm{\ω}\[W\]-0.12\mathrm{\ω}\[O\]\end{array}$

In formula for the activity quotient of nitrogen in molten steel; The massfraction % that ω [m] is alloying element m;

S2: by the requirement preparation smelting material of element contained by steel grade, cleaning crucible, loads the smelting material prepared; It should be noted that, steel grade herein does not refer to end article height nitrogen steel, but the main body steel in high nitrogen smelting steel process, do not comprise N, such as steel grade can be, but not limited to be 13Cr21Mn16N (non-standard grade of steel);

S3: find time to pressurization induction furnace melting room, start power transmission when vacuum tightness is less than 15Pa to heat smelting material, initial power is 40KW, progressively increasing power, after there is molten bath, maintains and controls power, avoiding splash;

S4: turn down power after furnace chargeization is clear, enter refining, refining 30-40 minute, vacuum tightness≤5Pa, depart from and comprise following element O, N, H;

S5: the GN 2 alloying: open Nitrogen plant, be filled with nitrogen, furnace pressure is at least adjusted to and fills nitrogen pressure, improves the saturation solubility of nitrogen in molten steel;

S6: alloying: add the raw materials for metallurgy of raising partial pressure by charging opening substep and calculate the nitrided ferro-chromium, nitrogenized manganese or other nitrogen pick-up alloy that obtain, to improve yield of alloy according to the actual weight percent that adds of nitrogen content in S1;

S7: add reductor, controls molten steel temperature higher than fusing point 100 ~ 150 DEG C, chargedly pours in ingot mould, cooling;

S8: venting, broken empty, open bell and take out ingot mould, make high nitrogen steel.

According to composition and the requirement of nitrogen of different target steel grade, calculate the activity quotient of nitrogen in molten steel, saturation solubility according to formula (1) and formula (2), fill nitrogen pressure and nitrogen pick-up alloy addition.

Described step S5 adopts gaseous state nitriding method, and nitrogen gas purity >=99% fills nitrogen pressure by formula: $\lg p_{N_2}=2\×(\lg \[\%N\]-\lg K_N+\lg f_N^{Me})$ Calculate in conjunction with formula (2).

Reductor in step S7 is crucible carbon, deoxidized aluminium (the conventional carbon of industry and aluminium).In the method for the present embodiment, high nitrogen steel refers to the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, and its composition is with reference to above-mentioned " stainless material ".

The advantage of pressurization induction furnace is that insufflation gas is beneficial to nitrogen adsorption after pressurizeing.

The process for stamping of high nitrogen steel blank

For the punching press of nitrogen steel blank high in blank pressing equipment, this process for stamping comprises the following steps:

S1: select mould

To select after tempered process Rockwell hardness HRC between 60-70 and notched bar impact strength between 55-120J/cm ²mould, by described die assembly in blank pressing equipment;

S2: thermal treatment

S2.1: to high nitrogen steel drift base, often rushes base and once liquidates the high nitrogen steel heat treatment after base afterwards once, heat treated holding temperature between 1050-1100 DEG C, soaking time >=0.5 hour;

S2.2: circulation carry out S2.1 be operated to set point number after, carry out a solution treatment: heat treated holding temperature is increased between 1080-1120 DEG C, soaking time >=1 hour, and oil quenching cools fast;

S2.3: circulation is carried out being operated to of S2.1 and S2.2 and struck out high nitrogen steel blank.

Preferably, described mould be after tempered process Rockwell hardness HRC between 62-64 and notched bar impact strength between 60-90J/cm ²mould; Soaking time in described step S2.1 is between 0.5-0.75 hour; In described step S2.2, the set point number of the operation of S2.1 is carried out in circulation is 4-7 time; Soaking time in described step S2.2 is 1-2 hour; High nitrogen steel is the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, and wherein the mass percent of nitrogen content is between 0.4-0.75%.

A kind of machining process of high nitrogen steel

This machining process comprises the following steps:

S1: select cutter

Select Rockwell hardness HRA to be greater than 95, bending strength δ is greater than the cutter of 2GPa;

S2: processing

S2.1: milling

Mechanical means adopts following machined parameters to carry out milling to high nitrogen steel: cutting speed Vc is between 60-100m/min, rotating speed n is between 3000-5000r/min, feed engagement fz is between 0.01-0.02mm/z, and speed of feed F is between 200-300mm/min, and bite AP is between 0.03-0.2mm;

S2.2: turning

Mechanical means adopts following machined parameters to carry out turning to high nitrogen steel: rotating speed n is between 700-1000r/min, and feed of every rotation fr is between 0.02-0.04mm/r, and bite AP is between 0.05-0.3mm;

Until high nitrogen steel is processed into the part meeting design requirements;

Wherein, adopt cooling fluid when milling and turning, the emulsion of cooling fluid to be massfraction be 3-6%, the pH value of described emulsion is between 9.0-9.5.The manufacturer of emulsion: Noel Coward Science and Technology Ltd. of Shenzhen; Model: H537.

The refraction coefficient of described emulsion between 1-3, and is rust preventing emulsion.

The embodiment of stainless material:

Embodiment 1

This stainless material is the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, and this stainless material comprises the component of following weight percent:

Cr：18％；Mn：14％；N：0.4％；C：0.1％。

Embodiment 2

This stainless material is the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, and this stainless material comprises the component of following weight percent:

Cr：22％；Mn：17％；N：0.75％；C：0.12％。

Embodiment 3

This stainless material is the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, and this stainless material comprises the component of following weight percent:

Cr:18%; Mn:14%; N:0.4%; C:0.1%; S:0.02%; P:0.025%; Si:0.8%; Cu:0.2%; Al:0.01%; And Fe.

Embodiment 4

This stainless material is the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, and this stainless material comprises the component of following weight percent:

Cr:22%; Mn:17%; N:0.75%; C:0.12%; S:0.01%; P:0.015%; Si:0.1%; Cu:0.2%; Al:0.012%; And Fe.

Embodiment 5

This stainless material is the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, and this stainless material comprises the component of following weight percent:

Cr：21％；Mn：16％；N：0.6％；C：0.13％。

Embodiment 6

This stainless material is the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, and this stainless material comprises the component of following weight percent:

Cr：21％；Mn：16％；N：0.5％；C：0.13％；S：0.002％；P：0.006％。

Embodiment 6

This stainless material is the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, and this stainless material comprises the component of following weight percent:

Cr:21%; Mn:16%; N:0.5%; C:0.13%; S:0.002%; P:0.006%; Si:0.7%; Cu: nothing; Al: nothing; And Fe.

Embodiment 7

This stainless material is the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, and this stainless material comprises the component of following weight percent:

Cr:20.6%; Mn:15.79%; N:0.46%; C:0.13%; S:0.003%; P:0.007%; Si:0.72%; Cu: nothing; Al: nothing; B:0.0014%; And Fe.

The embodiment of the method for pressurization induction furnace smelting high-nitrogen steel:

Embodiment 8

Equipment adopts 50Kg pressurized Induction Melting stove, and final vacuum is 6.67 × 10 ^-2pa, power is 160KW, and frequency is 2500Hz, and batch is 43Kg.Steel grade is 13Cr21Mn16N (non-standard grade of steel), and Composition Control scope and smelting control objectives are in table 1.

Table 1:13Cr21Mn16N Composition Control scope and control objectives

By formula the saturation solubility of nitrogen to be made during by can be calculated temperature 1873K to be greater than the inflated with nitrogen force value of 0.7% needs, wherein nitrogenized manganese nitrogen content 5.95%.

Concrete steps are as follows:

(1) pure iron, chromium metal, molybdenum, crucible carbon are loaded in stove.Nitrogenized manganese, manganese, reductor load feed bin.

(2) find time to pressurization induction furnace melting room, start power transmission heating furnace charge when vacuum tightness is less than 15Pa, power 40KW, progressively increases.

(3), after furnace charge clears out existing molten bath, control power, avoid splash, vacuum tightness progressively reduces.

(4) turn down power, enter refining, refining 30Min, vacuum tightness≤5Pa, de-O, N, H etc.

(5) alloying: add part reductor, Cu by charging opening substep.

(6) the GN 2 alloying: open Nitrogen plant, be filled with nitrogen 2-3 minute, regulating stove internal pressure, to required force value, improves the saturation solubility of nitrogen in molten steel.

(7) MnN alloy is added.

(8) adding final reductor, control molten steel temperature higher than fusing point 100 ~ 150 DEG C, to decline and oxide film is mixed in beam for avoiding noting temperature, chargedly pour into ingot mould, lower the temperature 5min.

(9) exit, broken empty, open bell and take out ingot mould, in order to carrying out postorder thermal treatment.

Table 2: the chemical composition (%) of Finished Steel

C	Mn	Si	Cr	Al	N	S	P
								0.13	16.06	0.7	20.5	－	0.71	0.002	0.006

Nitrogen recovery reaches 99%

Embodiment 9

Equipment adopts 50Kg pressurized Induction Melting stove, and final vacuum is 6.67 × 10 ^-2pa, power is 160KW, and frequency is 2500Hz, and batch is 43Kg.Steel grade is 13Cr22Mn17N (non-standard grade of steel), and Composition Control scope and smelting control objectives are in table 3.

Table 3:13Cr22Mn17N Composition Control scope and control objectives

C

Mn

Si

Cr

N

S

P

Span of control

＜0.15

14-17

＜1

18-22

0.4-0.7

＜0.03

＜0.035

Target component

－

16

－

21

0.45

－

－

By formula during by can be calculated temperature 1873K, the saturation solubility of nitrogen be made to be greater than the inflated with nitrogen force value of 0.45% needs, wherein nitrogenized manganese nitrogen content 5.95%, nitrided ferro-chromium nitrogen content 4.42%.

Concrete steps are as follows:

(1) pure iron, chromium metal, ferro-niobium, vanadium iron, crucible carbon are loaded in stove.Nitrogenized manganese, silicon, carbon, deoxidized aluminium, ferro-boron, nitrided ferro-chromium, reductor load feed bin.Crucible carbon, deoxidized aluminium are reductor.

(2) find time to pressurization induction furnace melting room, start power transmission heating furnace charge when vacuum tightness is less than 15Pa, power 40KW, progressively increases.

(3), after furnace charge clears out existing molten bath, maintain and control power, avoiding splash, vacuum tightness progressively reduces.

(4) turn down power to 25KW, enter refining, refining 30 minutes, vacuum tightness≤5Pa, de-O, N, H etc.

(5) alloying: add part reductor, Si by charging opening substep.

(6) the GN 2 alloying: open Nitrogen plant, be filled with nitrogen 2-3 minute, regulating stove internal pressure fills nitrogen pressure to filling nitrogen pressure or being a bit larger tham, improves the saturation solubility of nitrogen in molten steel.

(7) FeB, FeCrN, MnN is added.The smelting material improving partial pressure refers to FeB herein.

(8) adding final reductor, control molten steel temperature higher than fusing point 100 ~ 150 DEG C, to decline and oxide film is mixed in beam for avoiding noting temperature, chargedly pour into ingot mould, lower the temperature 5 minutes.

(9) exit, broken empty, open bell and take out ingot mould, in order to carrying out postorder thermal treatment.

Table 4: the chemical composition (wt%) of Finished Steel

C	Mn	Si	Cr	B	N	S	P
								0.13	15.79	0.72	20.6	0.0014	0.46	0.003	0.007

Nitrogen recovery reaches 99.9%.

According to composition and the requirement of nitrogen of different target steel grade, calculate the activity quotient of nitrogen in molten steel, saturation solubility according to formula (1) and formula (2), fill nitrogen pressure and nitrogen pick-up alloy addition.

Say further: described step S5 adopts gaseous state nitriding method, nitrogen gas purity >=99% fills nitrogen pressure by formula: ${\mathrm{lgp}}_{N_2}=2\×(\lg \[\%N\]-{\mathrm{lgK}}_N+{\mathrm{lgf}}_N^{Me})$ Calculate in conjunction with formula (2).

The embodiment of the process for stamping of high nitrogen steel blank:

Embodiment 10

Equipment adopts 50-300t hydropress; thermal treatment band stove adopts nitrogen atmosphere protection; holding temperature 1050 DEG C; each soaking time 0.6 hour; vacuum quencher holding temperature 1120 DEG C in solution treatment; each soaking time 1.1 hours, pressed compact mould therefor material is DC53 (HRC64, impelling strength 70J/cm ²), sheet material grade of steel used is 13Cr21Mn16N (non-standard grade of steel), and measured hardness HV270, composition is in table 5.

Table 5: the chemical composition (wt%) of high nitrogen steel

C	Mn	Si	Cr	Al	N	S	P
								0.13	16.06	0.7	20.5	－	0.71	0.002	0.006

Idiographic flow:

-----> is cutting into shell base, and-----> opens ear, and---------------> slightly presses, and--every 1 time---> band stove softens, and---circulating 4 times,-------> slightly shovels, and---------------> repaiies hole to > essence shovel-----to > fine grinding to > corase grind in > pressure-sizing in > solution treatment (until size basic forming) in > punching to use spray gun thermoplastic sheet material

During thick pressure, the size cold deformation of material is larger, cold working hardening comparatively serious (often pressing a HV to increase by more than 10), must press once softening once (after softening hardness can close to initial value), every 4 take turns after carry out a solution treatment with thorough softener material, restorer structure property.

The hardness of moulding stock preferably must reach HRC62-64, and notched bar impact strength reaches 60-90J/cm ².As HRC62, notched bar impact strength 60; Or HRC64, notched bar impact strength 90; Or HRC63, notched bar impact strength 80.

Embodiment 11

S1: select mould

After selecting tempered process, Rockwell hardness HRC is 60 and notched bar impact strength is 55J/cm ²mould, by described die assembly in blank pressing device.

S2: thermal treatment

S2.1: to high nitrogen steel drift base, often rush base and once liquidate the high nitrogen steel heat treatment after base afterwards once, heat treated holding temperature is 1050 DEG C, and soaking time is 0.6 hour.

S2.2: circulation carry out S2.1 be operated to 4 times after, carry out a solution treatment: heat treated holding temperature is increased to 1080 DEG C, soaking time 1 hour, oil quenching cools fast.

S2.3: circulation carries out the operation 3 times of S2.1 and S2.2 to striking out high nitrogen steel blank, namely carries out 1 operation being operating as this step of S2.1 and S2.2 successively, repeats 3 such operations.

Other is identical with embodiment 10, repeats no more.

Embodiment 12

S1: select mould

After selecting tempered process, Rockwell hardness HRC is 70 and notched bar impact strength is 120J/cm ²mould, by described die assembly in blank pressing equipment.

S2: thermal treatment

S2.1: to high nitrogen steel drift base, often rush base and once liquidate the high nitrogen steel heat treatment after base afterwards once, heat treated holding temperature is 1100 DEG C, and soaking time is 0.75 hour.

S2.2: circulation carry out S2.1 be operated to 5 times after, carry out a solution treatment: heat treated holding temperature is increased to 1120 DEG C, soaking time 1.2 hours, oil quenching cools fast.

S2.3: circulation carries out the operation 7 times of S2.1 and S2.2 to striking out high nitrogen steel blank.

Other is identical with embodiment 10, repeats no more.

Embodiment 13

S1: select mould

After selecting tempered process, Rockwell hardness HRC is 62 and notched bar impact strength is 60J/cm ²mould, by described die assembly in blank pressing equipment.

S2: thermal treatment

S2.1: to high nitrogen steel drift base, often rush base and once liquidate the high nitrogen steel heat treatment after base afterwards once, heat treated holding temperature is 1070 DEG C, and soaking time is 0.6 hour.

S2.2: circulation carry out S2.1 be operated to 5 times after, carry out a solution treatment: heat treated holding temperature is increased to 1100 DEG C, soaking time 1 hour, oil quenching cools fast.

S2.3: circulation carries out the operation 5 times of S2.1 and S2.2 to striking out high nitrogen steel blank.

Other is identical with embodiment 10, repeats no more.

Embodiment 14

S1: select mould

After selecting tempered process, Rockwell hardness HRC is 64 and notched bar impact strength is 90J/cm ²mould, by described die assembly in blank pressing equipment.

S2: thermal treatment

S2.1: to high nitrogen steel drift base, often rush base and once liquidate the high nitrogen steel heat treatment after base afterwards once, heat treated holding temperature is 1080 DEG C, and soaking time is 0.6 hour.

S2.2: circulation carry out S2.1 be operated to 5 times after, carry out a solution treatment: heat treated holding temperature is increased to 1090 DEG C, soaking time 1.1 hours, oil quenching cools fast.

S2.3: circulation carries out the operation 2 times of S2.1 and S2.2 to striking out high nitrogen steel blank.

Other is identical with embodiment 10, repeats no more.

Embodiment 15

S1: select mould

After selecting tempered process, Rockwell hardness HRC is 63 and notched bar impact strength is 80J/cm ²mould, by described die assembly in blank pressing equipment.

S2: thermal treatment

S2.1: to high nitrogen steel drift base, often rush base and once liquidate the high nitrogen steel heat treatment after base afterwards once, heat treated holding temperature is 1090 DEG C, and soaking time is 0.7 hour.

S2.2: circulation carry out S2.1 be operated to 6 times after, carry out a solution treatment: heat treated holding temperature is increased to 1110 DEG C, soaking time 1 hour, oil quenching cools fast.

S2.3: circulation carries out the operation 6 times of S2.1 and S2.2 to striking out high nitrogen steel blank.

Other is identical with embodiment 10, repeats no more.

The embodiment of the machining process of high nitrogen steel:

Embodiment 16

Use PCV-30 machining center, maximum speed 15000r/min, cooling fluid is semi-synthetic cutting fluid H537; Milling cutter used is UKK:KEC0304 carbide-tipped milling cutter, and when Cutting Process parameter is as shown in table 6, Milling Process can normally be carried out; Lathe tool used is MBN25 (boron nitride blade), and when turning process parameter is as shown in table 7, turnery processing can normally carry out.

Table 6: milling process parameter

Table 7: turning process parameter

Embodiment 17

The machining process of high nitrogen steel.

The method comprises the following steps:

S1: select mould

Select Rockwell hardness HRA to be 96, bending strength δ to be the mould of 2.1GPa;

S2: processing

S2.1: milling

Mechanical means adopts following machined parameters to carry out milling to high nitrogen steel: cutting speed Vc is 60m/min, and rotating speed n is 3000r/min, feed engagement fz be 0.01mm/z, speed of feed F be 200mm/min, bite AP is 0.03mm;

S2.2: turning

Mechanical means adopts following machined parameters to carry out turning to high nitrogen steel: rotating speed n is 700r/min, and feed of every rotation fr is 0.02mm/r, bite AP is 0.05mm;

Until high nitrogen steel is processed into the part meeting design requirements;

Wherein, when milling and turning, adopt cooling fluid, cooling fluid to be massfraction be 5% emulsion, the pH value of described emulsion is 9.0.The refraction coefficient of described emulsion is 2, and is rust preventing emulsion.

Embodiment 18

The method comprises the following steps:

S1: select mould

Select Rockwell hardness HRA to be 95.5, bending strength δ to be the mould of 2.3GPa;

S2: processing

S2.1: milling

Mechanical means adopts following machined parameters to carry out milling to high nitrogen steel: cutting speed Vc is 100m/min, and rotating speed n is 5000r/min, feed engagement fz be 0.02mm/z, speed of feed F be 300mm/min, bite AP is 0.2mm;

S2.2: turning

Mechanical means adopts following machined parameters to carry out turning to high nitrogen steel: rotating speed n is 1000r/min, and feed of every rotation fr is 0.004mm/r, bite AP is 0.3mm;

Until high nitrogen steel is processed into the part meeting design requirements;

Wherein, when milling and turning, adopt cooling fluid, cooling fluid to be massfraction be 3% emulsion, the pH value of described emulsion is 9.5.The refraction coefficient of described emulsion is 3, and is rust preventing emulsion.

Embodiment 19

The method comprises the following steps:

S1: select mould

Select Rockwell hardness HRA to be 96, bending strength δ to be the mould of 2.5GPa;

S2: processing

S2.1: machined parameters during milling

Mechanical means adopts following machined parameters to carry out milling to high nitrogen steel: cutting speed Vc is 70m/min, and rotating speed n is 3500r/min, feed engagement fz be 0.015mm/z, speed of feed F be 211mm/min, bite AP is 0.09mm;

S2.2: machined parameters during turning

Mechanical means adopts following machined parameters to carry out turning to high nitrogen steel: rotating speed n is 800r/min, and feed of every rotation fr is 0.039mm/r, bite AP is 0.18mm;

Until high nitrogen steel is processed into the part meeting design requirements;

Wherein, when milling and turning, adopt cooling fluid, cooling fluid to be massfraction be 6% emulsion, the pH value of described emulsion is 9.2.The refraction coefficient of described emulsion is 1, and is rust preventing emulsion.

Whole implementation example:

Embodiment 20

Equipment adopts 50Kg pressurized Induction Melting stove, and final vacuum is 6.67 × 10 ^-2pa, power is 160KW, and frequency is 2500Hz, and batch is 43Kg.Steel grade is 13Cr21Mn16N (non-standard grade of steel), and Composition Control scope and smelting control objectives are in table 8.

Table 8:13Cr21Mn16N Composition Control scope and control objectives

C

Mn

Si

Cr

Al

N

S

P

Span of control

＜0.15

14-17

＜1

18-22

＜0.02

0.4-0.75

＜0.03

＜0.035

Target component

－

16

－

21

－

0.7

－

－

By formula the saturation solubility of nitrogen to be made during by can be calculated temperature 1873K to be greater than the inflated with nitrogen force value of 0.7% needs, wherein nitrogenized manganese nitrogen content 5.95%.

Concrete steps are as follows:

(1) pure iron, chromium metal, molybdenum, crucible carbon are loaded in stove.Nitrogenized manganese, manganese, reductor load feed bin.

(2) find time to pressurization induction furnace melting room, start power transmission heating furnace charge when vacuum tightness is less than 15Pa, power 40KW, progressively increases.

(3), after furnace charge clears out existing molten bath, control power, avoid splash, vacuum tightness progressively reduces.

(4) turn down power, enter refining, refining 30Min, vacuum tightness≤5Pa, de-O, N, H etc.

(5) alloying: add part reductor, Cu by charging opening substep.

(6) the GN 2 alloying: open Nitrogen plant, be filled with nitrogen 2-3 minute, regulating stove internal pressure, to required force value, improves the saturation solubility of nitrogen in molten steel.

(7) MnN alloy is added.

(8) adding final reductor, control molten steel temperature higher than fusing point 100 ~ 150 DEG C, to decline and oxide film is mixed in beam for avoiding noting temperature, chargedly pour into ingot mould, lower the temperature 5min.

(9) exit, broken empty, open bell and take out ingot mould, in order to carrying out postorder thermal treatment.

Table 9: the chemical composition (wt%) of high nitrogen steel

C	Mn	Si	Cr	Al	N	S	P
								0.13	16.06	0.7	20.5	－	0.71	0.002	0.006

Nitrogen recovery reaches 99%

By aforesaid method, obtain the high nitrogen steel of contained element mass percent as shown in table 9.

Blank punching press is carried out to this high nitrogen steel:

S1: select mould

After selecting tempered process, Rockwell hardness HRC is 63 and notched bar impact strength is 90J/cm ²mould, by described die assembly in blank pressing equipment.

S2: thermal treatment

S2.1: to high nitrogen steel drift base, often rush base and once liquidate the high nitrogen steel heat treatment after base afterwards once, heat treated holding temperature is 1080 DEG C, and soaking time is 0.6 hour.

S2.2: circulation carry out S2.1 be operated to 5 times after, carry out a solution treatment: heat treated holding temperature is increased to 1090 DEG C, soaking time 1.1 hours.Solution treatment preferably adopts oil quenching process, in other embodiments, also can adopt Water Quenching.

S2.3: circulation carries out the operation 2 times of S2.1 and S2.2 to striking out high nitrogen steel blank.

Mechanical workout is carried out to the high nitrogen steel blank made:

Mechanical workout comprises the following steps:

S1: select mould

Select Rockwell hardness HRA to be 96, bending strength δ to be the mould of 2.5GPa;

S2: processing

S2.1: machined parameters during milling

Mechanical means adopts following machined parameters to carry out milling to high nitrogen steel: cutting speed Vc is 70m/min, and rotating speed n is 3500r/min, feed engagement fz be 0.015mm/z, speed of feed F be 211mm/min, bite AP is 0.09mm;

S2.2: machined parameters during turning

Mechanical means adopts following machined parameters to carry out turning to high nitrogen steel: rotating speed n is 800r/min, and feed of every rotation fr is 0.039mm/r, bite AP is 0.18mm;

Until high nitrogen steel is processed into the part meeting design requirements;

Wherein, when milling and turning, adopt cooling fluid, cooling fluid to be massfraction be 6% emulsion, the pH value of described emulsion is 9.2.The refraction coefficient of described emulsion is 2, and is rust preventing emulsion.

Above embodiments of the invention are described; but the present invention is not limited to above-mentioned embodiment; above-mentioned embodiment is only schematic; instead of it is restrictive; those of ordinary skill in the art is under enlightenment of the present invention; do not departing under the ambit that present inventive concept and claim protect, also can make a lot of form, these all belong within protection of the present invention.

Claims (10)

1. a machining process for high nitrogen steel, is characterized in that, comprise the following steps:

S1: select cutter

Select Rockwell hardness HRA to be greater than 95, bending strength δ is greater than the cutter of 2GPa;

S2: processing

S2.1: milling

Mechanical means adopts following machined parameters to carry out milling to high nitrogen steel: cutting speed Vc is between 60-100m/min, rotating speed n is between 3000-5000r/min, feed engagement fz is between 0.01-0.02mm/z, and speed of feed F is between 200-300mm/min, and bite AP is between 0.03-0.2mm;

S2.2: turning

Mechanical means adopts following machined parameters to carry out turning to high nitrogen steel: rotating speed n is between 700-1000r/min, and feed of every rotation fr is between 0.02-0.04mm/r, and bite AP is between 0.05-0.3mm;

Until high nitrogen steel is processed into the part meeting design requirements;

Wherein, adopt cooling fluid when milling and turning, the emulsion of cooling fluid to be massfraction be 3-6%, the pH value of described emulsion is between 9.0-9.5.

2. the machining process of high nitrogen steel according to claim 1, is characterized in that, the refraction coefficient of described emulsion between 1-3, and is rust preventing emulsion.

3. a process for stamping for high nitrogen steel blank, for the punching press of nitrogen steel blank high in blank pressing equipment, is characterized in that, use the machining process of high nitrogen steel in claim 1 or 2, the process for stamping of described high nitrogen steel blank comprises the following steps:

S1: select mould

To select after tempered process Rockwell hardness HRC between 60-70 and notched bar impact strength between 55-120J/cm ²mould, by described die assembly in blank pressing equipment;

S2: thermal treatment

S2.1: to high nitrogen steel drift base, often rushes base and once liquidates the high nitrogen steel heat treatment after base afterwards once, heat treated holding temperature between 1050-1100 DEG C, soaking time >=0.5 hour;

S2.2: circulation carry out S2.1 be operated to set point number after, carry out a solution treatment: heat treated holding temperature is increased between 1080-1120 DEG C, soaking time >=1 hour, and oil quenching cools fast;

S2.3: circulation is carried out being operated to of S2.1 and S2.2 and struck out high nitrogen steel blank.

4. the process for stamping of high nitrogen steel blank according to claim 3, is characterized in that, described mould be after tempered process Rockwell hardness HRC between 62-64 and notched bar impact strength between 60-90J/cm ²mould.

5. the process for stamping of high nitrogen steel blank according to claim 3, it is characterized in that, the soaking time in described step S2.1 is between 0.5-0.75 hour.

6. the process for stamping of high nitrogen steel blank according to claim 3, is characterized in that, in described step S2.2, the set point number of the operation of S2.1 is carried out in circulation is 4-7 time.

7. the process for stamping of high nitrogen steel blank according to claim 3, it is characterized in that, the soaking time in described step S2.2 is 1-2 hour, and oil quenching cools fast.

8. the process for stamping of high nitrogen steel blank according to claim 3, is characterized in that, high nitrogen steel is the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, and wherein the mass percent of nitrogen content is between 0.4-0.75%.

9. a stainless material, is characterized in that, uses the machining process of high nitrogen steel in claim 1 or 2, and this stainless material is the Cr-Mn-N austenitic stainless steel replacing nickel with nitrogen, and this stainless material comprises the component of following weight percent:

Cr：18-22％；

Mn：14-17％；

N：0.4-0.75％；

C: be less than 0.15%;

S: be less than 0.03%;

P: be less than 0.035%;

Si: be less than 1%;

Al: be less than 0.02%;

Surplus is Fe.

10. stainless material according to claim 9, is characterized in that, this stainless material is used for the part with the product of direct body contact.