阅读说明：本技术 一种耐高温SA299GrA无铁皮钢板正火方法 (High-temperature-resistant SA299GrA sheet-iron-free steel plate normalizing method ) 是由 李建朝 刘印子 赵国昌 林明新 张萌 刘生 龙杰 李劲峰 肖雄峰 程含文 石莉 于 2019-09-30 设计创作，主要内容包括：本发明公开了一种耐高温SA299GrA无铁皮钢板正火方法,所述正火工艺：氮气保护负压氛围加热,保温900℃～950℃,总加热时间≥2.0min/mm,出炉喷雾冷却。本发明选择合适的正火热处理工艺,使钢板全厚度方向得到晶粒细化的珠光体+铁素体+贝氏体组织,晶粒度达到8.0级～9.0级,钢板具有较高的室温抗拉强度,0℃横向平均冲击功达到100J以上,400℃高温屈服强度R<Sub>p0.2</Sub>≥197MPa、高温抗拉强度≥517MPa,横向弯曲良好,钢板在高温条件下表面无铁皮,表面质量洁净且综合性能优良的耐高温性能用钢板。本方法具有正火工艺创新性强,产品质量稳定、可实现批量生产的特点。(The invention discloses a high-temperature resistant SA299GrA steel plate normalizing method without an iron sheet, which comprises the following steps: heating in nitrogen protection negative pressure atmosphere, keeping the temperature at 900-950 ℃, keeping the total heating time at more than or equal to 2.0min/mm, discharging and spraying and cooling. The invention selects proper normalizing heat treatmentThe process makes the steel plate obtain pearlite, ferrite and bainite tissues with refined grains in the full thickness direction, the grain size reaches 8.0 grade to 9.0 grade, the steel plate has higher room temperature tensile strength, the transverse average impact power at 0 ℃ reaches more than 100J, and the yield strength R at 400 ℃ and high temperature p0.2 The steel plate has the advantages of more than or equal to 197MPa, high-temperature tensile strength more than or equal to 517MPa, good transverse bending, no iron sheet on the surface of the steel plate under the high-temperature condition, clean surface quality and excellent comprehensive performance. The method has the characteristics of strong innovation of normalizing process, stable product quality and capability of realizing batch production.)

1. A normalizing method of a high-temperature resistant SA299GrA steel plate without iron skin is characterized in that a normalizing process is adopted, and the normalizing process comprises the following steps: heating in nitrogen protection negative pressure atmosphere, keeping the temperature at 900-950 ℃, keeping the total heating time at more than or equal to 2.0min/mm, and rapidly cooling by adopting two sprayers after discharging, wherein the cooling speed is more than or equal to 150 ℃/h.

2. The normalizing method of the high-temperature-resistant SA299GrA steel plate without the iron skin as claimed in claim 1, wherein the normalizing method comprises the following steps: the normalizing is heated in the atmosphere of nitrogen protection negative pressure of the furnace, the nitrogen protection negative pressure is less than or equal to minus 0.5MPa, the natural gas flow pressure is greater than or equal to 8.0MPa, the oxygen flow pressure is greater than or equal to 5.0MPa, and the air-fuel ratio is less than or equal to 1: 9.5.

3. The normalizing method of the high-temperature-resistant SA299GrA steel plate without the iron skin as claimed in claim 1, wherein the normalizing method comprises the following steps: the steel plate comprises the following chemical components in percentage by mass: c is less than or equal to 0.23%, Si: 0.20 to 0.35%, Mn: 1.38-1.50%, P is less than or equal to 0.008%, S is less than or equal to 0.005%, Ni: 0.20 to 0.25%, Cr: 0.12-0.20% of Mo: 0.05 to 0.10%, Al: 0.20-0.40%, N is less than or equal to 0.010%, H is less than or equal to 0.005%, Sn + As + Sb + Bi + Pb is less than or equal to 0.022%, and the balance of Fe and inevitable impurity elements.

4. The normalizing method of the high-temperature-resistant SA299GrA steel plate without the iron skin as claimed in claim 1, wherein the normalizing method comprises the following steps: the normalizing process steel plate obtains uniform and refined pearlite, ferrite and bainite tissues in the full thickness direction, and the grain size reaches 8.0-9.0 grade.

5. The normalizing method of the high-temperature-resistant SA299GrA steel plate without the iron skin as claimed in claim 1, wherein the normalizing method comprises the following steps: the transverse average impact energy of the steel plate at 0 ℃ reaches more than 100J, and the yield strength R at high temperature of 400 ℃ is_p0.2Not less than 197MPa and high temperature tensile strength not less than 517 MPa.

6. The normalizing method of the high-temperature-resistant SA299GrA steel plate without the iron skin as claimed in claim 1, wherein the normalizing method comprises the following steps: the maximum thickness of the steel plate is 250mm, and the width of the steel plate is 4000 mm.

Technical Field

The invention relates to the field of ferrous metallurgy, in particular to a normalizing method of a high-temperature resistant SA299GrA steel sheet without an iron sheet.

Background

Normalizing heat treatment is one of the important ways to improve the performance of mechanical equipment and the appearance quality, and because normalizing belongs to high-temperature heat treatment, the phenomena of surface oxidation, roll mark and processing cracking of a normalized workpiece are easy to generate. At present, the production method for improving the high temperature resistance and the surface non-oxidation of the normalized steel plate is still in a primary research stage, and no existing process reference and application examples exist at home and even abroad. As an important domestic wide and thick plate production base, the high temperature resistance of the steel plate is improved, the appearance quality of the steel plate without iron skin is improved, and the process research is imperative.

Disclosure of Invention

The invention aims to provide a normalizing heat treatment method for a high-temperature-resistant and iron-skin-free steel plate.

The technical scheme adopted by the invention is as follows:

a high-temperature resistant SA299GrA sheet-iron-free steel plate normalizing method adopts a normalizing process, and the normalizing process comprises the following steps: heating in nitrogen protection negative pressure atmosphere, keeping the temperature at 900-950 ℃, keeping the total heating time at more than or equal to 2.0min/mm, discharging from the furnace, carrying out spray cooling, and increasing rapid cooling by adopting two sprayers after discharging, wherein the cooling speed is more than or equal to 150 ℃/h.

Preferably, the normalizing is heated in a furnace under the nitrogen protection negative pressure atmosphere, the nitrogen protection negative pressure is less than or equal to-0.5 MPa, the natural gas flow pressure is greater than or equal to 8.0MPa, the oxygen flow pressure is greater than or equal to 5.0MPa, and the air-fuel ratio is less than or equal to 1: 9.5.

Preferably, the steel plate comprises the following chemical components in percentage by mass: c is less than or equal to 0.23%, Si: 0.20 to 0.35%, Mn: 1.38-1.50%, P is less than or equal to 0.008%, S is less than or equal to 0.005%, Ni: 0.20 to 0.25%, Cr: 0.12-0.20% of Mo: 0.05 to 0.10%, Al: 0.20-0.40%, N is less than or equal to 0.010%, H is less than or equal to 0.005%, Sn + As + Sb + Bi + Pb is less than or equal to 0.022%, and the balance of Fe and inevitable impurity elements.

Preferably, the normalizing process steel plate obtains a uniform and refined pearlite + ferrite + bainite structure in the full thickness direction, and the grain size reaches 8.0-9.0 grade.

Preferably, the transverse average impact energy of the steel plate at 0 ℃ is more than 100J, and the yield strength R at high temperature of 400 ℃ is_p0.2Not less than 197MPa and high temperature tensile strength not less than 517 MPa.

Preferably, the maximum thickness of the steel plate is 250mm, and the width of the steel plate is 4000 mm.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in:

1. in the field of ferrous metallurgy, the invention adopts the negative pressure nitrogen protective atmosphere to carry out normalizing heat treatment on the steel plate for the first time, and the steel plate with no iron sheet, no roll mark and no crack and excellent appearance quality is obtained;

2. after normalizing, the steel plate is discharged and cooled in a spray mode, so that the problem that the high-temperature resistance strength and the surface quality of the steel plate are both obtained is creatively solved;

3. the invention corrects and innovates accurate normalizing process parameters, ensures that the steel plate tissue is ferrite, pearlite and bainite, and ensures that the grain size reaches 8.0-9.0 grade, so that the steel plate has higher high temperature resistance;

4. the steel plate has higher room temperature tensile strength, the transverse average impact power at 0 ℃ reaches more than 100J, and the yield strength R at 400 ℃ and high temperature_p0.2The steel plate has the advantages that the steel plate has the tensile strength of more than or equal to 197MPa and the high-temperature tensile strength of more than or equal to 517MPa, the transverse bending is good, and the technical indexes of the comprehensive performance of the steel plate are improved innovatively;

5. the steel plate surface has no iron sheet, so that the peeling and shot blasting of the subsequent procedures are reduced, the production process flow is shortened, the production cost is reduced, the production efficiency is greatly improved, and the process optimization is realized through the innovation of the process route.

The invention adopts nitrogen protection negative pressure normalizing and spray cooling for the first time in the field of ferrous metallurgy, obtains good mechanical property, has excellent appearance quality without iron sheet, is in the leading position in product market competition, replaces product import, and reaches the international level.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments.

A high temperature resistant SA299GrA steel sheet normalizing method without iron sheet comprises the following normalizing process: (1) heating in nitrogen protection negative pressure atmosphere, keeping the temperature at 900-950 ℃, keeping the total heating time at more than or equal to 2.0min/mm, discharging from the furnace, carrying out spray cooling, and increasing rapid cooling by adopting two sprayers after discharging, wherein the cooling speed is more than or equal to 150 ℃/h. (2) The normalizing is heated in the atmosphere of nitrogen protection negative pressure of the furnace, the nitrogen protection negative pressure is less than or equal to minus 0.5MPa, the natural gas flow pressure is greater than or equal to 8.0MPa, the oxygen flow pressure is greater than or equal to 5.0MPa, and the air-fuel ratio is less than or equal to 1: 9.5.