CN103643012A - Enhanced heat treatment testing method for steel - Google Patents
Enhanced heat treatment testing method for steel Download PDFInfo
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- CN103643012A CN103643012A CN201310705112.2A CN201310705112A CN103643012A CN 103643012 A CN103643012 A CN 103643012A CN 201310705112 A CN201310705112 A CN 201310705112A CN 103643012 A CN103643012 A CN 103643012A
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Abstract
The invention relates to an enhanced heat treatment testing method for steel. The enhanced heat treatment testing method for the steel comprises the following steps: (1) heating and quenching stage: (1-1) heating the steel to the temperature which is higher than complete austenitizing (Ac3) temperature 30 DEG C, and performing heat preservation for a period of time to realize complete austenitizing of the material, and (1-2) rapidly cooling by utilizing water cooling; and (2) tempering and heat preservation treatment: performing secondary heat treatment after completion of quenching treatment. Through enhanced heat treatment, a gold-phase structure which is required for enhancing the performances appears in a low-carbon steel structure, so that the effect of improving and enhancing the mechanical properties of low-carbon steel can be effectively achieved, the product performances can be upgraded to a certain extent and a certain economic value is realized. Through the enhanced heat treatment process, martensite-like and other enhancement structures can appear in the structure, the strength is averagely upgraded by about 90MPa, the elongation rate is upgraded by 2-4%, and the hardness value is also slightly upgraded.
Description
Technical field
The present invention relates to metal heat treatmet, be mainly used in utilizing strengthening heat treatment mode to optimize metallographic structure in steel, to improve, to improve the mechanical property of soft steel steel, be specifically related to a kind of raising, improve the strengthening heat treatment test technique of the mechanical property of soft steel steel grade.
Background technology
Traditional strengthening property heat treatment technique is generally only directed to middle, high-carbon, because the carbon content of steel grade is for this reason conducive to strengthen in steel the appearance of metallographic structure.
To be considered to hardening capacity low always for low carbon-structural steel for a long time, during quenching, can not get martensite, or martensite content is less, thermal treatment does not have strengthening effect, although add the alloy content of raising hardening capacity, can improve its hardening capacity, on cost, promote to some extent.
Through laboratory process, research shows, soft steel can be strengthened by suitable thermal treatment process, also can obtain quenched martensite, recycle suitable subsequent heat treatment technique and impel martensitic stucture to change, utilize the tissue improvement of this part martensitic transformation, the mechanical property of raising steel grade.
Through laboratory process, research shows, soft steel is the effect that reaches its performance of strengthening by suitable thermal treatment process, also can obtain quenched martensite, thereby its comprehensive mechanical performance has also obtained corresponding raising.
A small amount of martensitic stucture that quenching stage low-carbon (LC) steel grade there will be, in the tempering stage, utilize the mode of controlling tempering temperature, soaking time to impel martensitic stucture to change to different organization types, thereby obtain the organization type that trier wants, intensity and the plasticity and toughness of steel grade can be adjusted, be controlled to reaction in mechanical property.
Summary of the invention
The object of the present invention is to provide a kind of raising, improve the strengthening heat treatment test method of the mechanical property of soft steel steel grade, by using metallographic structure in suitable strengthening optimization of Heat Treatment Process soft steel steel grade, to improve, to improve the mechanical property of soft steel steel grade, can realize the upgrading of product, the added value that improves steel grade, has certain economic worth.
Concrete technical scheme is as follows:
A strengthening heat treatment test method for steel, comprises the steps:
(1) the heating quenching stage:
(1-1) steel are heated to above to temperature insulation for some time of 30 ℃ of complete austenitizings (Ac3), make material complete austenitizing;
(1-2) utilize water-cooled to make it cooling fast;
(2) tempering insulation is processed: after completing quench treatment, it is carried out to second heat treatment.
Further, average rate of cooling >=160 ℃ in step (1-2)/S, guarantees to contain partial martensite tissue in cooling rear tissue.
Further, described steel are soft steel steel grade, utilize the structural transformation of the partial martensite producing in quenching early stage to reach the effect that improves mechanical property in step (2).
Further, further comprise step: the final mechanical property that (3) obtain is as required set different tempering stage process parameters.
Further, in step (1-1), utilize thermal imager or needed time of the complete heat penetration of thermal analogy computed in software material.
Further, after step (1-2), also comprise step: (1-3) metallography preparation carries out structure observation, observe after quenching martensite content situation in metallographic structure.
Further, after step (1-3), also comprise step: (1-4) according to generate martensitic stucture content number determine best Heating temperature T1, best temperature generates more martensitic temperature in organizing after quenching.
Further, in step (2), further comprise the steps:
(2-1) formulate different tempering temperatures;
(2-2) when temperature is heated to tempering temperature T2, be incubated respectively for some time and guarantee material heat penetration, temperature is even;
(2-3) air cooling after tempering, carries out metallography preparation;
(2-4) carry out structure observation, the transition state of quenched martensite tissue in tissues observed, makes different final tissue morphologies corresponding one by one with the tempering temperature of this structural transformation.
Further, in step (3), according to definite quenching temperature T1, the corresponding situation of tempering temperature T2 and tissue, mechanical property, determines its processing parameter according to best results of property.
Further, in step (2-2), the soaking time of tempering adopts thermal imager or thermal analogy computed in software.
Compare with currently available technology, the present invention is by strengthening thermal treatment, make to have occurred in soft steel tissue the needed metallographic structure of strengthening performance, effectively reached the effect of improvement, reinforced low-carbon steel grade mechanical property, realize to a certain extent the upgrading of product performance, had certain economic worth.By above strengthening thermal treatment process, make to have occurred the enhanced tissues such as similar martensite in tissue, intensity on average promotes about 90MPa, and unit elongation also has 2-4% lifting, and hardness value also has a little lifting.
Accompanying drawing explanation
Fig. 1 is sample thickness direction metallographic structure after thermal treatment
(a) heart portion of limit portion (b) 1/4th (c)
Fig. 2 is test technology curve
Embodiment
Describe the present invention with reference to the accompanying drawings below, it is a kind of preferred embodiment in numerous embodiments of the present invention.
It is respectively quenching, two stages of tempering that soft steel strengthening thermal treatment process is divided into, these two stages need respectively specific test to determine Heating temperature, soaking time, these three processing parameters of speed of cooling, and these three kinds of processing parameters are best effectively in conjunction with also needing a cross matching to determine.
Quench treatment: the temperature insulation for some time that steel is heated to above to 30 ℃ of complete austenitizings (Ac3), make material complete austenitizing, utilize water-cooled to make it cooling fast, average rate of cooling guarantees>=160 ℃/S, can guarantee to contain partial martensite tissue in cooling rear tissue, wherein, for different steel grade composition complete austenitizing temperature (Ac3), can use experimental formula A
cs(℃)=910-203C
1/2-15.2Ni+44.7Si+104V+31.5Mo+13.1W calculates, or simulates temperature with simulation software, higher than its temperature setting of 30 ℃, is in order to guarantee that Heating temperature is more than complete austenitizing temperature.
Soaking time scope will guarantee that each part of workpiece of thermal treatment heating all reaches its design temperature in fact exactly, heat penetration namely, also different according to the time range that varies in size of workpiece, can be with surform or MAC software simulation time of workpiece heat penetration out, as long as guarantee to surpass heat-up time this time range.
During quenching, in steelwork, need to obtain 100% martensitic position, its speed of cooling (rate of cooling) must be greater than critical cooling velocity.Its critical cooling velocity (obtaining the required minimum speed of cooling of martensitic stucture) can utilize carbon equivalent to calculate or metal simulation software surform by experimental formula, the experimental formula of calculating is numerous, but the Cooling Mode of general adopt >=160 ℃/S of water-cooled all can obtain martensite.
Be cooled to scope below the Ms temperature of metal with regard to passable to martensitic stucture, its temperature can be calculated or metal simulation software surform calculating by experimental formula, experimental formula is numerous, as follows, can be according to the different choice formula that will test the alloying constituent of steel grade.
Ms＝498.9-316.7C-33.3Mn-27.8Cr-16.7Ni-11.1(Si+Mb+W)
Ms＝496.1(1-0.620C)(1-0.092Mn)(1-0.033Si)(1-0.045Ni)(1-0.070Cr)(1-0.029Mb)(1-0.013W)(1+0.120Co)
Ms＝498.9-333.3C-33.3Mn-27.8Cr-16.7Ni-11.1(Si+Mo+W)
Ms＝537.8-361.1C-38.9(Mn+Cr)-19.4Ni-27.8Mb
Ms＝561.1-473.9C-16.7(Ni+Cr)-21.1Mb
Ms＝539-423C-30.4Mn-17.7Ni-12.1Cr-7.5Mb
Ms＝512-453C-16.Ni+15Cr-9.5Mb+217C
2-71.5MnC-67.6CrC"
Ms＝520-320C-50Mn-30Cr-20(Ni+Mb)-5(Cu+Si)
Ms＝550-240C-45Mn-35Cr-26Ni-25Mb30V-7Cu-0Si+12Co+13Al
Ms＝635-474[C+0.86(N-0.15(Nb+zr)-0.066(Ta+Hf)]-(17Cr+33Mn+2Mb+17Ni+39V+1W)
Ms＝550-350C-45Mn-30Cr-20Ni-16Mb-8W-5Si+6Co+15Al-35(V+Nb+Zr+Ti)
C＜0.05％(mass)
Ms＝525-350(C-0.05)-45Mn-30Cr-20Ni-16Mb-8W-5Si+6Co+15Al-35(V+Nb+Zr+Ti)
C＞0.05％(mass)
Ms＝41.7(14.6-Cr+5.6(8.9-Ni)+33.3(1.33-Mn)+27.8(0.47-Si)+1666.7(0.068-C-N-17.8
Temper: after completing quench treatment, it is carried out to second heat treatment, utilize the structural transformation of the partial martensite producing in quenching early stage to reach the effect that improves mechanical property.By test, the final mechanical property that can obtain is as required set different tempering stage process parameters.
Wherein, what tempering process adopted is average tempering, namely heat between Ac1 and the temperature of Ac3, the steel grade of different chemical composition can by experimental formula calculate or computer simulation out.
Experimental formula is as follows:
A
cs(℃)＝710-203C
1/2-15.2Ni+44.7Si+104V+31.5Mo+13.1W
Ac1=723-10.7Mn-16.9Ni+29.1Si+16.9Cr+290As+6.38W
Tempering temperature is generally taken between Ac1 and the temperature of Ac3, and soaking time, according to the size of heat treated part and size, guarantees that each position temperature of workpiece all reaches holding temperature.
By the temperature level of this one-phase of temper, the control of soaking time, impel a small amount of martensitic stucture that the quenching stage produces to change to different tissue morphologies, thereby rely on the different different mechanical properties of metallographic structure form reaction place.
Fig. 1 is the metallographic structure situation of test materials thickness direction after strengthening thermal treatment, and its metallographic structure is mainly by martensite, bainite, three kinds of organizational compositions of ferrite.Martensite content: limit portion: 1/20%, four place: 15%, heart portion 10%
The chemical composition of this test materials is shown in Table 1:
Table 1 test steel chemical composition
| The trade mark | C | Si | Mn | P | S | Als |
| Q345B | 0.16 | 0.25 | 1.40 | ≤0.015 | ≤0.005 | 0.030 |
Technique is divided into two stages, be respectively heating quenching stage, tempering holding stage, these two stages to need respectively specific test to determine the processing parameters such as Heating temperature, soaking time, and the best effectively combinations of these two kinds of processing parameters also need a cross matching to determine.
Concrete test technology curve as shown in Figure 2.
Quenching stage parameter is determined:
Steel are heated to above to a certain temperature insulation for some time of complete austenitizing (Ac3), guarantee material complete austenitizing (can utilize thermal imager or needed time of the complete heat penetration of thermal analogy computed in software material), utilize water-cooled to make it cooling fast, average rate of cooling guarantees >=160 ℃/S, metallography preparation carries out structure observation afterwards, mainly observe after quenching martensite content situation in metallographic structure, soft steel hardening capacity is poor, generation martensite content is less, according to generate martensitic stucture content number determine best Heating temperature T1, best temperature is for generating more martensitic temperature in tissue after quenching.
Tempering stage parameter is determined:
According to quenching test, determined best quenching temperature T1.
Set different tempering temperatures, adopt the test materials after the quenching stage, carry out backfire test.
Formulate different tempering temperatures, when temperature is heated to tempering T2, being incubated respectively for some time guarantees material heat penetration, temperature is (soaking time of tempering still can adopt thermal imager or thermal analogy computed in software) evenly, air cooling after tempering, carries out metallography preparation, carries out structure observation, in main tissues observed, the transition state of quenched martensite tissue, makes different final tissue morphologies corresponding one by one with the tempering temperature of this structural transformation.
According to different tissue morphologies, can obtain corresponding mechanical property, owing to containing martensite in tissue after quenching, so the intensity of material, hardness can be improved, mould, toughness drop, by tempering, can impel martensitic transformation, thereby when slightly falling the intensity of material, hardness, improve its plasticity and toughness, reach the effect that improves material over-all properties.
According to definite quenching temperature T1, the corresponding situation of tempering temperature T2 and tissue, mechanical property, can directly determine its processing parameter according to best results of property.
After thermal treatment, sample mechanical property is shown in Table 2.
Table 2 mechanical property
Test sample is all to adopt test technology described above.
From test-results, in intensity, all have a certain upgrade, yield strength on average promotes about 90MPa, and tensile strength on average promotes about 60MPa, and normal temperature impelling strength on average promotes 92J, and hardness value also has a small amount of raising.
By strengthening thermal treatment, make to have occurred in soft steel tissue the needed metallographic structure of strengthening performance, effectively reached the effect of improvement, reinforced low-carbon steel grade mechanical property, realized to a certain extent the upgrading of product performance, there is certain economic worth.By above strengthening thermal treatment process, make to have occurred the enhanced tissues such as similar martensite in tissue, intensity on average promotes about 90MPa, and unit elongation also has 2-4% lifting, and hardness value also has a little lifting.
By reference to the accompanying drawings the present invention is exemplarily described above; obviously specific implementation of the present invention is not subject to the restrictions described above; as long as the various improvement that adopted method design of the present invention and technical scheme to carry out; or directly apply to other occasion without improvement, all within protection scope of the present invention.
Claims (10)
1. a strengthening heat treatment test method for steel, is characterized in that, comprises the steps:
(1) the heating quenching stage:
(1-1) steel are heated to above to temperature insulation for some time of 30 ℃ of complete austenitizings (Ac3), make material complete austenitizing;
(1-2) utilize water-cooled to make it cooling fast;
(2) tempering insulation is processed: after completing quench treatment, it is carried out to second heat treatment.
2. the strengthening heat treatment test method of steel as claimed in claim 1, is characterized in that, average rate of cooling >=160 ℃ in step (1-2)/S, guarantees to contain partial martensite tissue in cooling rear tissue.
3. the strengthening heat treatment test method of steel as claimed in claim 1 or 2, is characterized in that, described steel are soft steel steel grade, utilizes the structural transformation of the partial martensite producing in quenching early stage to reach the effect that improves mechanical property in step (2).
4. the strengthening heat treatment test method of the steel as described in any one in claim 1-3, is characterized in that, further comprises step: the final mechanical property that (3) obtain is as required set different tempering stage process parameters.
5. the strengthening heat treatment test method of the steel as described in any one in claim 1-4, is characterized in that, utilizes thermal imager or needed time of the complete heat penetration of thermal analogy computed in software material in step (1-1).
6. the strengthening heat treatment test method of the steel as described in any one in claim 1-5, is characterized in that, also comprises step: (1-3) metallography preparation carries out structure observation after step (1-2), observes after quenching martensite content situation in metallographic structure.
7. the strengthening heat treatment test method of the steel as described in any one in claim 1-6, it is characterized in that, after step (1-3), also comprise step: (1-4) according to generate martensitic stucture content number determine best Heating temperature T1, best temperature generates more martensitic temperature in organizing after quenching.
8. the strengthening heat treatment test method of steel as claimed in claim 7, is characterized in that, step further comprises the steps: in (2)
(2-1) formulate different tempering temperatures;
(2-2) when temperature is heated to tempering temperature T2, be incubated respectively for some time and guarantee material heat penetration, temperature is even;
(2-3) air cooling after tempering, carries out metallography preparation;
(2-4) carry out structure observation, the transition state of quenched martensite tissue in tissues observed, makes different final tissue morphologies corresponding one by one with the tempering temperature of this structural transformation.
9. the strengthening heat treatment test method of steel as claimed in claim 8, is characterized in that, in step (3), according to definite quenching temperature T1, the corresponding situation of tempering temperature T2 and tissue, mechanical property, determines its processing parameter according to best results of property.
10. the strengthening heat treatment test method of steel as claimed in claim 8 or 9, is characterized in that, in step (2-2), the soaking time of tempering adopts thermal imager or thermal analogy computed in software.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104946858A (en) * | 2015-07-29 | 2015-09-30 | 山东伊莱特重工有限公司 | High-temperature short-time heating surface strengthening processing process |
| CN106248715A (en) * | 2016-08-26 | 2016-12-21 | 中钢集团邢台机械轧辊有限公司 | Thermal modeling test determines the test method of quenching rate of cooling |
| CN107254575A (en) * | 2017-06-01 | 2017-10-17 | 马鞍山钢铁股份有限公司 | It is a kind of to remove the heat treatment method that ferrite net metallographic structure improves steel strength |
| CN107490519A (en) * | 2017-08-07 | 2017-12-19 | 天津重型装备工程研究有限公司 | The method of testing and stress relaxation method for numerical simulation of the mechanical property of alloy forged piece |
| CN108265161A (en) * | 2018-02-11 | 2018-07-10 | 舞阳钢铁有限责任公司 | The heat treatment method of Thin Specs quenching and tempering type 12MnNiVR steel plates |
Citations (1)
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| CN102041360A (en) * | 2010-12-21 | 2011-05-04 | 南阳汉冶特钢有限公司 | Heat treatment process for improving comprehensive performance of Q345 low alloy structural steel |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102041360A (en) * | 2010-12-21 | 2011-05-04 | 南阳汉冶特钢有限公司 | Heat treatment process for improving comprehensive performance of Q345 low alloy structural steel |
Non-Patent Citations (1)
| Title |
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| 王英才: "关于低碳马氏体钢强化及其应用的探讨", 《鞍钢技术》 * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104946858A (en) * | 2015-07-29 | 2015-09-30 | 山东伊莱特重工有限公司 | High-temperature short-time heating surface strengthening processing process |
| CN106248715A (en) * | 2016-08-26 | 2016-12-21 | 中钢集团邢台机械轧辊有限公司 | Thermal modeling test determines the test method of quenching rate of cooling |
| CN107254575A (en) * | 2017-06-01 | 2017-10-17 | 马鞍山钢铁股份有限公司 | It is a kind of to remove the heat treatment method that ferrite net metallographic structure improves steel strength |
| CN107490519A (en) * | 2017-08-07 | 2017-12-19 | 天津重型装备工程研究有限公司 | The method of testing and stress relaxation method for numerical simulation of the mechanical property of alloy forged piece |
| CN107490519B (en) * | 2017-08-07 | 2019-08-13 | 天津重型装备工程研究有限公司 | The test method and stress relaxation method for numerical simulation of the mechanical property of alloy forged piece |
| CN108265161A (en) * | 2018-02-11 | 2018-07-10 | 舞阳钢铁有限责任公司 | The heat treatment method of Thin Specs quenching and tempering type 12MnNiVR steel plates |
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