WO2021258584A1 - 一种800MPa工程机械用中锰中厚钢及其制造方法 - Google Patents

一种800MPa工程机械用中锰中厚钢及其制造方法 Download PDF

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WO2021258584A1
WO2021258584A1 PCT/CN2020/122967 CN2020122967W WO2021258584A1 WO 2021258584 A1 WO2021258584 A1 WO 2021258584A1 CN 2020122967 W CN2020122967 W CN 2020122967W WO 2021258584 A1 WO2021258584 A1 WO 2021258584A1
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medium
steel
rolling
manganese
800mpa
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French (fr)
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段东明
孙超
陈颜堂
王从道
周玉伟
徐志祥
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南京钢铁股份有限公司
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Priority to AU2020455074A priority Critical patent/AU2020455074B2/en
Publication of WO2021258584A1 publication Critical patent/WO2021258584A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium

Definitions

  • the invention relates to the technical field of steel smelting, in particular to a medium-manganese medium-thick steel for 800MPa engineering machinery and a manufacturing method thereof.
  • 800MPa grade construction machinery steel is mainly used in large-scale electric shovels, drilling rigs, buckets of bulldozers, crane booms and turntables, coal machine structural parts, etc.
  • the composition system of this grade of high-strength construction machinery steel is mostly added with high content of Cr,
  • the more precious metal elements such as Ni and Mo are reduced by LF and RH vacuum treatment to reduce the content of P, S and inclusions in the steel to purify the molten steel; the use of controlled rolling and cooling, the principle of relaxation control precipitation, and microalloy precipitation strengthening and other process methods are refined
  • the grain size can increase the strength of the steel plate, and the thick steel plate needs to be quenched and tempered, which has the problem of very high raw material cost and process cost.
  • medium-manganese steel has been a research hotspot in the field of steel materials.
  • Increasing the Mn content in the material and reducing the content of precious alloying elements such as Ni, Cr, Mo in the steel can greatly reduce the overall cost of the material.
  • the characteristics of medium manganese materials can solve the problems of poor low-temperature impact toughness and high yield ratio of high-strength structural steel in the construction machinery industry, and can meet the safety performance and construction cost of high-strength construction machinery steel in the complex and harsh environment of the construction machinery industry. need.
  • the present invention provides a medium-manganese medium-thick steel for 800MPa engineering machinery and a manufacturing method thereof.
  • the manufactured steel plate has excellent comprehensive mechanical properties and can meet the requirements of complex and harsh environments in the field of engineering machinery.
  • the demand for the safety performance and low manufacturing cost of ultra-high-strength steel is not limited.
  • the present invention provides a medium-manganese medium-thick steel for 800MPa engineering machinery. Its chemical composition and mass percentage are as follows: C: 0.05% ⁇ 0.08%, Mn: 4.8% ⁇ 5.8%, Si: 0.10% ⁇ 0.35%, P ⁇ 0.010%, S ⁇ 0.003%, Ti: 0.01% ⁇ 0.05%, Ni+Cr+Mo: 0.7% ⁇ 1.2%, the balance is Fe and unavoidable impurities.
  • the steel produced by the present invention uses manganese as an important alloying element, uses cheap Mn element to replace the expensive Ni-Cr-Mo alloy, and improves the hardenability of the steel plate through Mn element so that the steel plate can be cooled in a wide range of cooling speed. Martensite structure is obtained within, and then a small amount of reverse-transformed austenite is formed in the two-phase zone tempering process.
  • the tempered martensite structure improves the strength of the steel, and the reverse-transformed austenite improves the toughness and plasticity of the steel, so that the steel has High strength and low yield ratio, and good uniformity in the thickness direction, can obtain excellent core mechanical properties that ordinary 800MPa grade high-strength structural steel does not have, and meet the safety performance of ultra-high-strength steel in the complex and harsh environment of the construction machinery industry And the demand for low manufacturing cost.
  • the aforementioned medium-manganese medium-thick steel for 800MPa engineering machinery has a product thickness of 12-50mm.
  • the aforementioned medium-manganese medium-thick steel for 800MPa engineering machinery has a product yield ratio ⁇ 0.88.
  • the aforementioned medium-manganese medium-thick steel for 800MPa engineering machinery has the following chemical composition and mass percentage: C: 0.055% ⁇ 0.080%, Mn: 4.85% ⁇ 5.80%, Si: 0.11% ⁇ 0.35%, P ⁇ 0.009%, S ⁇ 0.002%, Ti: 0.015% ⁇ 0.045%, Ni+Cr+Mo: 0.75% ⁇ 1.20%, the balance is Fe and unavoidable impurities.
  • the aforementioned medium-manganese medium-thick steel for 800MPa engineering machinery has the following chemical composition and mass percentage: C: 0.055% ⁇ 0.080%, Mn: 4.85% ⁇ 5.80%, Si: 0.11% ⁇ 0.35%, P ⁇ 0.009%, S ⁇ 0.002%, Ti: 0.015% ⁇ 0.045%, Ni+Cr+Mo: 0.75% ⁇ 1.20%, the balance is Fe and unavoidable impurities.
  • Another object of the present invention is to provide a method for manufacturing medium-manganese medium-thick steel for 800MPa engineering machinery
  • Hot metal desulfurization treatment and converter smelting P ⁇ 0.010%, S ⁇ 0.003% in molten steel;
  • Slab rolling Two-stage rolling, one-stage opening temperature ⁇ 1030°C, final rolling temperature ⁇ 930°C, two-stage opening temperature ⁇ 890°C, and final rolling temperature ⁇ 800°C;
  • Heat treatment after rolling tempering temperature 600 ⁇ 650°C, after tempering, the steel plate is air-cooled to room temperature.
  • the soaking time is calculated as thickness ⁇ (1.2-2.5min/cm).
  • the soaking time is calculated as plate thickness ⁇ (1.5-3min/mm).
  • the steel plate with a thickness of less than 40mm is sent to the heat treatment furnace for tempering within 72 hours after rolling, and the steel plate with a thickness of more than 40mm is within 48 hours after rolling Send to heat treatment furnace for tempering.
  • C is the main strengthening element, which can significantly increase the strength of the structure through interstitial solid solution strengthening, and is also an important element to improve the stability of austenite.
  • C is the main strengthening element, which can significantly increase the strength of the structure through interstitial solid solution strengthening, and is also an important element to improve the stability of austenite.
  • its content is required Control at a reasonable level;
  • Mn improves the strength of the structure through solid solution strengthening.
  • a reasonable Mn content can also greatly improve the stability of austenite.
  • Increasing the Mn content can increase the hardenability of the steel, so that the steel can obtain martensite in a wide range of cooling rates. Even full martensite, and then a small amount of reverse-transformed austenite is formed during tempering in the two-phase zone.
  • the tempered martensite structure can increase the strength of the steel, and the reverse-transformed austenite structure can improve the toughness and plasticity of the steel, thereby making Steel has excellent comprehensive mechanical properties;
  • Si is a deoxidizing element in the steelmaking process.
  • a proper amount of Si can inhibit the segregation of Mn and P and improve toughness.
  • Si can inhibit the formation of cementite, but the content should not be too high, otherwise it will significantly reduce the toughness of the material.
  • Si is controlled at 0.10% ⁇ 0.35%;
  • Mn Under the condition of adding a certain Mn content, Mn easily forms MnS with S and reduces the plasticity of the steel. P is easy to segregate at the grain boundary, which reduces the resistance to crack growth of the grain boundary, thereby reducing the toughness. Therefore, the content of P and S must be strictly controlled.
  • the present invention requires P ⁇ 0.010%, S ⁇ 0.003%;
  • Ti can hinder the migration of grain boundaries at high temperature through the precipitation of the fine and dispersed second phase, thereby refining the grains and improving the comprehensive mechanical properties of the steel.
  • the addition amount is controlled within the range of 0.01% to 0.05%;
  • a certain amount of Cr can produce obvious solid solution strengthening effect, which is beneficial to increase the strength of steel; an appropriate amount of Ni can stabilize the austenite phase, improve hardenability, reduce the brittle transition temperature, and help improve welding performance; Mo can improve The martensite tempered strength can also weaken the grain boundary segregation of Mn within a certain content range to improve toughness.
  • the present invention controls the content of Ni+Cr+Mo to 0.7% to 1.2%, which can play their role at the same time. Does not significantly increase costs;
  • the designed composition of the present invention can eliminate or add less precious alloy elements, and the cost per ton of steel has a great cost advantage over traditional high-strength steels of the same level;
  • the microstructure of the product of the present invention is composed of tempered martensite and a small part of reverse-transformed austenite.
  • the tempered martensite can ensure that the steel has high strength, and a small part of reverse-transformed austenite can ensure the high strength of the material. It has good plastic toughness, good hardenability, tempered martensite and a small amount of reverse-transformed austenite along the entire thickness direction;
  • the thickness of the steel plate produced by the present invention is 12-50mm, and its comprehensive mechanical properties meet the technical requirements of Q800F steel in the GB/T16270-2009 high-strength quenched and tempered steel plate for high-strength structure, while meeting the yield ratio of not more than 0.88.
  • Figure 1 is a metallographic structure diagram of the product of Example 1 at the thickness 1/2;
  • Figure 2 is a metallographic structure diagram of the product of Example 1 at a thickness of 1/4.
  • This embodiment provides a medium-manganese medium-thick steel for 800MPa engineering machinery with a thickness of 16mm. Its chemical composition and mass percentage are as follows: C: 0.06%, Mn: 5.1%, Si: 0.26%, P: 0.007%, S : 0.001%, Ti: 0.035%, Ni+Cr+Mo: 0.92%, the balance is Fe and unavoidable impurities.
  • the manufacturing method is as follows: the molten iron enters the converter for smelting after desulfurization treatment to reduce the content of P and S in the molten steel, P: 0.007%, S: 0.001%; LF refining completes the alloying of the mass fraction of each element, and the continuous casting speed is 1.2m/ min to obtain a slab with a thickness of 320mm.
  • the surface defects must be cleaned up; the slab is heated to a temperature of 1160°C, and the soaking time is 48min; the heated slab is controlled rolling, and the first-stage rolling temperature is 1030°C, and the final rolling The temperature is 945°C, the second-stage rolling temperature is 882°C, and the final rolling temperature is 811°C; the rolled steel plate is water-cooled, the average cooling rate is 5.1°C/s, and the redness temperature of the cooled steel plate surface is lower than 200°C; within 48 hours after rolling Send to heat treatment furnace for tempering heat treatment immediately, tempering temperature 630°C, soaking time 35min, after tempering, the steel plate is air cooled to room temperature.
  • This embodiment provides a medium-manganese medium-thick steel for 800MPa engineering machinery with a thickness of 35mm. Its chemical composition and mass percentage are as follows: C: 0.065%, Mn: 5.3%, Si: 0.26%, P: 0.007%, S : 0.001%, Ti: 0.021%, Ni+Cr+Mo: 1.13%, the balance is Fe and unavoidable impurities.
  • the manufacturing method is as follows: the molten iron enters the converter for smelting after desulfurization treatment to reduce the content of P and S in the molten steel, P: 0.007%, S: 0.001%; LF refining completes the alloying of the mass fraction of each element, and the continuous casting speed is 1.2m/ min, get a slab with a thickness of 320mm, and clean up the surface defects; the slab is heated to a temperature of 1150°C, and the soaking time is 48min; the heated slab is controlled rolling, the first-stage rolling temperature is 1030°C, and the final rolling The temperature is 940°C, the second-stage rolling temperature is 865°C, and the final rolling temperature is 825°C; the rolled steel plate is water-cooled, the average cooling rate is 6.3°C/s, and the redness temperature of the cooled steel plate surface is lower than 200°C; Fire heat treatment, tempering temperature 630°C, soaking time 77min, after tempering, the steel plate is air-cooled to room
  • This embodiment provides a medium-manganese medium-thick steel for 800MPa engineering machinery with a thickness of 50mm. Its chemical composition and mass percentage are as follows: C: 0.075%, Mn: 5.5%, Si: 0.23%, P: 0.007%, S : 0.001%, Ti: 0.021%, Ni+Cr+Mo: 1.15%, the balance is Fe and unavoidable impurities.
  • the manufacturing method is as follows: the molten iron enters the converter for smelting after desulfurization treatment to reduce the content of P and S in the molten steel, P: 0.007%, S: 0.001%; LF refining completes the alloying of the mass fraction of each element, and the continuous casting speed is 1.2m/ min, get a slab with a thickness of 320mm, and clean up the surface defects; the slab is heated to a temperature of 1125°C, and the soaking time is 55min; the heated slab is subjected to controlled rolling, the first stage of rolling temperature is 1025°C, and the final rolling The temperature is 945°C, the second-stage rolling temperature is 870°C, and the final rolling temperature is 845°C; the rolled steel plate is water-cooled, the average cooling rate is 10.3°C/s, and the surface redness temperature of the cooled steel plate is lower than 200°C; within 72 hours after rolling Send to the heat treatment furnace for tempering heat treatment immediately, tempering temperature 620°C, soaking
  • the microstructure of the product of Example 1 is composed of tempered martensite and a small amount of reverse transformed austenite, and the entire thickness direction is tempered martensite and a small amount of reverse transformed austenite.
  • Tempered martensite can ensure that the steel has high strength, and a small part of reverse-transformed austenite can make it have good plasticity and toughness under the condition of ensuring the high strength of the material.
  • the comprehensive mechanical properties of the products prepared by the present invention all meet the technical requirements of Q800F steel in the GB/T16270-2009 high-strength quenched and tempered steel plate for high-strength structures, while meeting the yield ratio of not more than 0.88.
  • composition design of the present invention can not add or add less precious alloy elements under the premise of maintaining a higher manganese content.
  • the cost per ton of steel has a great cost advantage than traditional high-strength steels of the same level, with excellent comprehensive performance and great cost. The advantages make the present invention have broad application prospects.

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Abstract

一种800MPa工程机械用中锰中厚钢及其制造方法，涉及钢铁冶炼技术领域，其化学成分及质量百分比如下：C：0.05％～0.08％，Mn：4.8％～5.8％，Si：0.10％～0.35％，P≤0.010％，S≤0.003％，Ti：0.01％～0.05％，Ni+Cr+Mo：0.7％～1.2％，余量为Fe和不可避免的杂质。所述中厚钢能获得普通800MPa级高强度结构用钢不具有的优异心部力学性能，满足工程机械行业在复杂恶劣环境中对超高强钢安全性能和低制造成本的需求。

Description

一种800MPa工程机械用中锰中厚钢及其制造方法 技术领域
本发明涉及钢铁冶炼技术领域，特别是涉及一种800MPa工程机械用中锰中厚钢及其制造方法。
背景技术
800MPa级工程机械用钢主要应用于大型电铲、钻机、推土机的铲斗、起重机吊臂和转台、煤机结构件等，此级别高强度工程机械用钢的成分体系多添加高含量的Cr、Ni、Mo等较贵重金属元素，通过LF和RH真空处理降低钢中P、S含量及夹杂物，净化钢水；采用控轧控冷、弛豫控制析出原理以及微合金析出强化等工艺手段细化晶粒，提高钢板强度，厚规格钢板还需调质处理，存在原料成本和工序成本非常高的问题。特别是厚规格的材料淬透性较差，厚度方向的组织均匀性差，钢心部低温冲击韧性差，屈强比过高(一般达到0.95左右)，过高的屈强比使材料的变形容量减小，结构件在使用过程中的安全性得不到保证，所以在提高强度的同时，需要降低屈强比，合理的强韧度、塑性匹配是工程机械用高强度结构用钢设计的首要条件。
近几年来，中锰钢是钢铁材料领域的研究热点，提高材料中的Mn含量，降低钢中Ni、Cr、Mo等贵重合金元素的含量，可以极大降低材料的综合成本。中锰材料的特性可解决工程机械行业高强度结构用钢的低温冲击韧性差、屈强比过高等问题，能够满足工程机械行业复杂恶劣环境下对高强度工程机械用钢安全性能和建造成本的需求。
发明内容
本发明针对上述技术问题，克服现有技术的缺点，提供一种800MPa工程机械用中锰中厚钢及其制造方法，制造的钢板具有优异的综合力学性能，能够满足工程机械领域在复杂恶劣环境下对超高强钢安全性能和低制造成本的需求。
为了解决以上技术问题，本发明提供一种800MPa工程机械用中锰中厚钢，其化学成分及质量百分比如下：C：0.05％～0.08％，Mn：4.8％～5.8％，Si：0.10％～0.35％，P≤0.010％，S≤0.003％，Ti：0.01％～0.05％，Ni+Cr+Mo：0.7％～1.2％，余量为Fe和不可避免的杂质。
技术效果：本发明制造的钢将锰作为重要合金化元素，利用价格低廉的Mn元素替代昂贵的Ni-Cr-Mo合金，通过Mn元素提高钢板淬透性从而使钢板在很宽的冷却速度范围内获得马氏体组织，然后在两相区回火过程中形成少量的逆转变奥氏体，回火马氏体组织提高钢的强度，逆转变奥氏体提高钢的韧塑性，使钢具有高强度低屈强比，同时沿厚度方向组织均匀性 好，能获得普通800MPa级高强度结构用钢不具有的优异心部力学性能，满足工程机械行业在复杂恶劣环境中对超高强钢安全性能和低制造成本的需求。
本发明进一步限定的技术方案是：
前所述的一种800MPa工程机械用中锰中厚钢，产品厚度为12～50mm。
前所述的一种800MPa工程机械用中锰中厚钢，产品屈强比≤0.88。
前所述的一种800MPa工程机械用中锰中厚钢，其化学成分及质量百分比如下：C：0.055％～0.080％，Mn：4.85％～5.80％，Si：0.11％～0.35％，P≤0.009％，S≤0.002％，Ti：0.015％～0.045％，Ni+Cr+Mo：0.75％～1.20％，余量为Fe和不可避免的杂质。
前所述的一种800MPa工程机械用中锰中厚钢，其化学成分及质量百分比如下：C：0.055％～0.080％，Mn：4.85％～5.80％，Si：0.11％～0.35％，P≤0.009％，S≤0.002％，Ti：0.015％～0.045％，Ni+Cr+Mo：0.75％～1.20％，余量为Fe和不可避免的杂质。
本发明的另一目的在于提供一种800MPa工程机械用中锰中厚钢的制造方法，
铁水脱硫处理及转炉冶炼：钢水中P≤0.010％、S≤0.003％；
LF精炼：达到成分体系的合金化要求；
连铸：拉速≤1.5m/min，表面缺陷清理干净；
板坯加热：温度1080～1200℃；
板坯轧制：进行两阶段轧制，一阶段开轧温度≤1030℃，终轧温度≥930℃，二阶段开轧温度≤890℃，终轧温度≥800℃；
轧后ACC：冷却速率≥1℃/s，终止冷却后钢板表面返红温度≤200℃；
轧后热处理：回火温度600～650℃，回火后钢板空冷至常温。
前所述的一种800MPa工程机械用中锰中厚钢的制造方法，板坯加热步骤，均热时间以厚度×(1.2～2.5min/cm)计算。
前所述的一种800MPa工程机械用中锰中厚钢的制造方法，轧后热处理步骤，均热时间以板厚×(1.5～3min/mm)计算。
前所述的一种800MPa工程机械用中锰中厚钢的制造方法，轧后热处理步骤，厚度40mm以内的钢板轧后72小时内送热处理炉回火，厚度大于40mm的钢板轧后48小时内送热处理炉 回火。
本发明的有益效果是：
(1)本发明中C是主要强化元素，可通过间隙固溶强化显著提升组织的强度，也是提高奥氏体稳定性的重要元素，但为了获得良好的低温冲击韧性及焊接性，其含量需要控制在合理范围水平；
Mn通过固溶强化提高组织的强度，合理的Mn含量也能大幅提升奥氏体稳定性，提高Mn含量能增加钢的淬透性，从而使得钢在很宽的冷速范围内获得马氏体甚至全马氏体，进而在两相区回火中形成少量逆转变奥氏体，回火马氏体组织能增加钢的强度，逆转变奥氏体组织能提高钢的韧塑性能，从而使钢具有优异的综合力学性能；
Si在炼钢过程中为脱氧元素，适量的Si能抑制Mn和P的偏聚并改善韧性，Si能抑制渗碳体的形成，但含量不能太高否则会明显降低材料的韧性，本发明将Si控制在0.10％～0.35％；
在添加一定Mn含量的条件下，Mn易与S形成MnS而降低钢的塑性，P易在晶界偏聚，降低晶界抗裂纹扩展能力，从而降低韧性，因此需严格控制P、S含量，本发明要求P≤0.010％、S≤0.003％；
Ti能通过细小弥散的第二相析出阻碍高温下的晶界迁移，从而细化晶粒并改善钢的综合力学性能，加入量控制在0.01％～0.05％的范围内；
一定量的Cr能够产生明显的固溶强化作用，有利于提高钢的强度；适量的Ni能够稳定奥氏体相、提高淬透性、降低脆性转变温度，并有利于提高焊接性能；Mo能够提高马氏体回火后的强度，在一定含量范围内还能够减弱Mn的晶界偏聚从而改善韧性，本发明将Ni+Cr+Mo含量控制在0.7％～1.2％，在发挥它们的作用同时不显著增加成本；
(2)本发明设计的成份在保持较高锰含量的前提下，可以不添加或少添加贵重合金元素，吨钢成本比传统同级别高强钢有极大的成本优势；
(3)本发明产品微观组织由回火马氏体和少部分逆转变奥氏体组织构成，回火马氏体能够保证钢材具有高强度，少部分逆转变奥氏体能在保证材料高强度的条件下使其具有良好的塑韧性，具有良好的淬透性，沿整个厚度方向均为回火马氏体和少量逆转变奥氏体；
(4)本发明生产出的钢板厚度12～50mm，综合力学性能达到GB/T16270-2009高强度结 构用调质钢板中Q800F钢的技术要求，同时满足屈强比不大于0.88。
附图说明
图1为实施例1产品在厚度1/2处金相组织图；
图2为实施例1产品在厚度1/4处金相组织图。
具体实施方式
实施例1
本实施例提供的一种800MPa工程机械用中锰中厚钢，厚度为16mm，其化学成分及质量百分比如下：C：0.06％，Mn：5.1％，Si：0.26％，P：0.007％，S：0.001％，Ti：0.035％，Ni+Cr+Mo：0.92％，余量为Fe和不可避免的杂质。
制造方法如下：铁水通过脱硫处理后进入转炉进行冶炼，以降低钢水中P、S含量，P：0.007％、S：0.001％；LF精炼完成各元素质量分数合金化，连铸拉速1.2m/min，得到厚度为320mm的板坯，表面缺陷要清理干净；板坯加热到温度1160℃，均热时间48min；对加热后的板坯进行控制轧制，一阶段开轧温度1030℃，终轧温度945℃，二阶段开轧温度882℃，终轧温度811℃；对轧后钢板水冷，平均冷却速率5.1℃/s，冷却后的钢板表面返红温度低于200℃；轧后48小时内送往热处理炉立即进行回火热处理，回火温度630℃，均热时间35min，回火后钢板空冷至常温。
实施例2
本实施例提供的一种800MPa工程机械用中锰中厚钢，厚度为35mm，其化学成分及质量百分比如下：C：0.065％，Mn：5.3％，Si：0.26％，P：0.007％，S：0.001％，Ti：0.021％，Ni+Cr+Mo：1.13％，余量为Fe和不可避免的杂质。
制造方法如下：铁水通过脱硫处理后进入转炉进行冶炼，以降低钢水中P、S含量，P：0.007％、S：0.001％；LF精炼完成各元素质量分数合金化，连铸拉速1.2m/min，得到厚度为320mm的板坯，表面缺陷要清理干净；板坯加热到温度1150℃，均热时间48min；对加热后的板坯进行控制轧制，一阶段开轧温度1030℃，终轧温度940℃，二阶段开轧温度865℃，终轧温度825℃；对轧后钢板水冷，平均冷却速率6.3℃/s，冷却后的钢板表面返红温度低于200℃；轧后立即进行回火热处理，回火温度630℃，均热时间77min，回火后钢板空冷至常温。
实施例3
本实施例提供的一种800MPa工程机械用中锰中厚钢，厚度为50mm，其化学成分及质量百分比如下：C：0.075％，Mn：5.5％，Si：0.23％，P：0.007％，S：0.001％，Ti：0.021％，Ni+Cr+Mo：1.15％，余量为Fe和不可避免的杂质。
制造方法如下：铁水通过脱硫处理后进入转炉进行冶炼，以降低钢水中P、S含量，P：0.007％、S：0.001％；LF精炼完成各元素质量分数合金化，连铸拉速1.2m/min，得到厚度为320mm的板坯，表面缺陷要清理干净；板坯加热到温度1125℃，均热时间55min；对加热后的板坯进行控制轧制，一阶段开轧温度1025℃，终轧温度945℃，二阶段开轧温度870℃，终轧温度845℃；对轧后钢板水冷，平均冷却速率10.3℃/s，冷却后的钢板表面返红温度低于200℃；轧后72小时内送往热处理炉立即进行回火热处理，回火温度620℃，均热时间110min，回火后钢板空冷至常温。
实施例1、实施例2、实施例3产品进行力学性能测试，结果如下表：
Figure PCTCN2020122967-appb-000001
由图1、图2可知，实施例1产品微观组织由回火马氏体和少部分逆转变奥氏体组织构成，沿整个厚度方向均为回火马氏体和少量逆转变奥氏体，回火马氏体能够保证钢材具有高强度，少部分逆转变奥氏体能在保证材料高强度的条件下使其具有良好的塑韧性。由上表可知，由本发明制备获得的产品综合力学性能均达到GB/T16270-2009高强度结构用调质钢板中Q800F钢的技术要求，同时满足屈强比不大于0.88。本发明的成份设计在保持较高锰含量的前提下，可以不添加或少添加贵重合金元素，吨钢成本比传统同级别高强钢有极大的成本优 势，优异的综合性能和极大的成本优势，使本发明具有广阔的应用前景。
除上述实施例外，本发明还可以有其他实施方式。凡采用等同替换或等效变换形成的技术方案，均落在本发明要求的保护范围。

Claims (9)

  1. 一种800MPa工程机械用中锰中厚钢，其特征在于：其化学成分及质量百分比如下：C：0.05％～0.08％，Mn：4.8％～5.8％，Si：0.10％～0.35％，P≤0.010％，S≤0.003％，Ti：0.01％～0.05％，Ni+Cr+Mo：0.7％～1.2％，余量为Fe和不可避免的杂质。
  2. 根据权利要求1所述的一种800MPa工程机械用中锰中厚钢，其特征在于：产品厚度为12～50mm。
  3. 根据权利要求1所述的一种800MPa工程机械用中锰中厚钢，其特征在于：产品屈强比≤0.88。
  4. 根据权利要求1所述的一种800MPa工程机械用中锰中厚钢，其特征在于：其化学成分及质量百分比如下：C：0.055％～0.080％，Mn：4.85％～5.80％，Si：0.11％～0.35％，P≤0.009％，S≤0.002％，Ti：0.015％～0.045％，Ni+Cr+Mo：0.75％～1.20％，余量为Fe和不可避免的杂质。
  5. 根据权利要求1所述的一种800MPa工程机械用中锰中厚钢，其特征在于：其化学成分及质量百分比如下：C：0.055％～0.080％，Mn：4.85％～5.80％，Si：0.11％～0.35％，P≤0.009％，S≤0.002％，Ti：0.015％～0.045％，Ni+Cr+Mo：0.75％～1.20％，余量为Fe和不可避免的杂质。
  6. 一种如权利要求1-5任意一项所述的800MPa工程机械用中锰中厚钢的制造方法，其特征在于：
    铁水脱硫处理及转炉冶炼：钢水中P≤0.010％、S≤0.003％；
    LF精炼：达到成分体系的合金化要求；
    连铸：拉速≤1.5m/min，表面缺陷清理干净；
    板坯加热：温度1080～1200℃；
    板坯轧制：进行两阶段轧制，一阶段开轧温度≤1030℃，终轧温度≥930℃，二阶段开轧温度≤890℃，终轧温度≥800℃；
    轧后ACC：冷却速率≥1℃/s，终止冷却后钢板表面返红温度≤200℃；
    轧后热处理：回火温度600～650℃，回火后钢板空冷至常温。
  7. 根据权利要求6所述的一种800MPa工程机械用中锰中厚钢的制造方法，其特征在于：板坯加热步骤，均热时间以厚度×(1.2～2.5min/cm)计算。
  8. 根据权利要求6所述的一种800MPa工程机械用中锰中厚钢的制造方法，其特征在于：轧后热处理步骤，均热时间以板厚×(1.5～3min/mm)计算。
  9. 根据权利要求6所述的一种800MPa工程机械用中锰中厚钢的制造方法，其特征在于：轧后热处理步骤，厚度40mm以内的钢板轧后72小时内送热处理炉回火，厚度大于40mm的钢板轧后48小时内送热处理炉回火。
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