阅读说明：本技术 一种中高温锅炉和压力容器钢板的生产方法 (Production method of medium-high temperature boiler and pressure vessel steel plate ) 是由 杨新龙 郭营利 刘国良 李金泽 董建军 姜军 陈开锋 李晓燕 于 2019-11-13 设计创作，主要内容包括：本发明涉及一种中高温锅炉和压力容器钢板的生产方法,具体包括如下步骤：化学成分设计、冶炼、加热、轧制、轧后控冷、回火、焊接后热处理；本发明是在国标GB 713-2014锅炉和压力容器用钢板基础上优化了成分设计,降低了贵重合金Mo含量和Cr含量,采取两阶段正火控轧+回火,直接在线正火控轧后回火,节省了正火工序,简化了生成工艺,而且正火轧制产生的大量变形带和位错缺陷提供了相变形核质点,细化了晶粒,提高了钢板的强韧性,有效的降低了生产成本,缩短了生产工艺流程,取得了显著的经济效益,具有广泛的推广价值。(The invention relates to a production method of a medium-high temperature boiler and pressure vessel steel plate, which comprises the following steps: designing chemical components, smelting, heating, rolling, controlling cooling after rolling, tempering, and carrying out heat treatment after welding; the invention optimizes the component design on the basis of the steel plate for the national standard GB713-2014 boiler and the pressure vessel, reduces the Mo content and the Cr content of the noble alloy, adopts two-stage normalizing controlled rolling and tempering, directly performs on-line normalizing controlled rolling and then tempering, saves the normalizing process, simplifies the generation process, provides phase change nucleation particles due to a large number of deformation zone and dislocation defects generated by the normalizing rolling, refines the crystal grains, improves the obdurability of the steel plate, effectively reduces the production cost, shortens the production process flow, obtains remarkable economic benefit and has wide popularization value.)

1. The production method of the steel plate for the medium-high temperature boiler and the pressure vessel is characterized by comprising the following steps of:

the chemical components in the step 1) are as follows by weight percent: c: 0.13-0.16%, Si: 0.5-0.8%, Mn: 0.40-0.65%, S is less than or equal to 0.010%, P is less than or equal to 0.020%, Cu is less than or equal to 0.3%, Cr: 1.15-1.25%, Ni is less than or equal to 0.3%, Mo: 0.45-0.55%, and the balance of Fe and inevitable impurities;

step 2) smelting: converter-refining-continuous casting, wherein the smelting slagging-off temperature is higher than 1560 ℃, Al is adopted for preliminary deoxidation, the refining process is alloyed, the continuous casting water distribution adopts slow cooling, and the slabs are directly stacked for 48 hours after being off-line to obtain slabs with qualified quality;

step 3), heating: the slab is heated in three sections, wherein the preheating section is less than or equal to 950 ℃, the heating section 1 is 1050-1100 ℃, the heating section 2 is 1130-1200 ℃, the soaking section is 1150-1200 ℃, and the total heating time is controlled to be less than or equal to 260 min;

step 4), rolling: after the plate blank is taken out of the heating furnace, the austenitizing temperature of 14Cr1MoR is 900 ℃, the ferrite phase transition temperature is 850 ℃, the pearlite phase transition temperature is 750 ℃, the initial rolling temperature of the first stage is not more than 1160 ℃, the high-temperature rush rolling is adopted in the stage, the final rolling temperature of the first stage is not less than 1050 ℃, the thickness to be rolled reaches 1.5-2.0 times of the thickness of a finished product, the normalizing temperature range of the second stage is adopted for rolling within 750-960 ℃, the initial rolling temperature of the second stage is not more than 960 ℃, and the final rolling temperature of the second stage is controlled to be not less than 760;

step 5), controlled cooling after rolling: after rolling, the steel plate is quickly cooled to room temperature by aerial fog;

step 6) tempering: tempering the steel plate after on-line normalizing control at the temperature of more than or equal to 650 ℃, keeping the temperature for 20-40min, and then cooling in air, wherein the detected mechanical property meets the requirement;

step 7) post-welding heat treatment: and (3) preserving the prepared sample to be detected at 620 +/-10 ℃ for 2-3h, wherein the heating speed is controlled to be 50-80 ℃/h when the temperature is increased to be higher than 400 ℃, the cooling speed is controlled to be 30-50 ℃/h when the temperature is reduced to be higher than 400 ℃, and the sample is naturally cooled to the normal temperature until the temperature is reduced to be less than or equal to 400 ℃, and then performing a mechanical property test.

2. The method for producing the steel plate for the medium-high temperature boiler and the pressure vessel as claimed in claim 1, wherein the mechanical properties detected in the step 6) are respectively as follows: tensile strength 618-.

Technical Field

The invention belongs to the technical field of engineering materials, and particularly relates to a production method of a medium-high temperature boiler and pressure vessel steel plate.

Background

The medium-high temperature boiler and pressure vessel steel 14Cr1MoR is a low alloy structural steel, is widely applied to large equipment such as boilers, ships, automobile cylinders and the like due to good plasticity and toughness, higher strength, temper brittleness resistance and excellent welding performance, has a better application prospect at home and abroad, and has the following problems in the production of the traditional pressure vessel steel 14Cr1 MoR:

1) the 14Cr1MoR steel for the pressure vessel needs higher toughness in the use process, and in the composition design, on the basis of the requirement range of the steel plate for the national standard GB713-2014 boiler and the pressure vessel, the Mo content is subject to the middle and upper limit of the standard, and the Cr content is subject to the middle and upper limit of the standard, so that the use requirement can be met, the smelting cost is high, and the weldability is poor.

2) The 14Cr1MoR is produced by adopting the controlled rolling, offline normalizing and offline tempering heat treatment processes, and the production process is complex, high in energy consumption and high in production cost.

Disclosure of Invention

The invention aims to provide a method for producing steel plates of medium-high temperature boilers and pressure vessels, which aims to solve the problems in the prior art.

In order to achieve the purpose, the invention adopts the technical scheme that: a production method of a medium-high temperature boiler and pressure vessel steel plate comprises the following steps:

the chemical components in the step 1) are as follows by weight percent: c: 0.13-0.16%, Si: 0.5-0.8%, Mn: 0.40-0.65%, S is less than or equal to 0.010%, P is less than or equal to 0.020%, Cu is less than or equal to 0.3%, Cr: 1.15-1.25%, Ni is less than or equal to 0.3%, Mo: 0.45-0.55%, and the balance of Fe and inevitable impurities;

step 2) smelting: converter-refining-continuous casting, wherein the smelting slagging-off temperature is higher than 1560 ℃, Al is adopted for preliminary deoxidation, the refining process is alloyed, the continuous casting water distribution adopts slow cooling, and the slabs are directly stacked for 48 hours after being off-line to obtain slabs with qualified quality;

step 3), heating: the slab is heated in three sections, wherein the preheating section is less than or equal to 950 ℃, the heating section 1 is 1050-1100 ℃, the heating section 2 is 1130-1200 ℃, the soaking section is 1150-1200 ℃, and the total heating time is controlled to be less than or equal to 260 min;

step 4), rolling: after the plate blank is taken out of the heating furnace, the austenitizing temperature of 14Cr1MoR is 900 ℃, the ferrite phase transition temperature is 850 ℃, the pearlite phase transition temperature is 750 ℃, the initial rolling temperature of the first stage is not more than 1160 ℃, the high-temperature rush rolling is adopted in the stage, the final rolling temperature of the first stage is not less than 1050 ℃, the thickness to be rolled reaches 1.5-2.0 times of the thickness of a finished product, the normalizing temperature range of the second stage is adopted for rolling within 750-960 ℃, the initial rolling temperature of the second stage is not more than 960 ℃, and the final rolling temperature of the second stage is controlled to be not less than 760;

step 5), controlled cooling after rolling: after rolling, the steel plate is quickly cooled to room temperature by aerial fog;

step 6) tempering: tempering the steel plate after on-line normalizing control at the temperature of more than or equal to 650 ℃, keeping the temperature for 20-40min, and then cooling in air, wherein the detected mechanical property meets the requirement;

step 7) post-welding heat treatment: and (3) preserving the prepared sample to be detected at 620 +/-10 ℃ for 2-3h, wherein the heating speed is controlled to be 50-80 ℃/h when the temperature is increased to be higher than 400 ℃, the cooling speed is controlled to be 30-50 ℃/h when the temperature is reduced to be higher than 400 ℃, and the sample is naturally cooled to the normal temperature until the temperature is reduced to be less than or equal to 400 ℃, and then performing a mechanical property test.

Further, the detection in step 6) that the mechanical properties meet the requirements respectively is: tensile strength 618-.

The invention has the beneficial effects that:

1) the steel 14Cr1MoR for medium-high temperature boilers and pressure vessels needs higher toughness in the use process, and in the composition design, the Mo content is limited under the standard, the Cr content is limited under the middle-lower limit of the standard, the smelting cost is reduced, and the weldability is improved in the range required by steel plates for national standard GB713-2014 boilers and pressure vessels.

2) The CCT curve diagram of 14Cr1MoR is simulated by using Jmatpro software to obtain the phase change temperature, two-stage normalizing, controlled rolling and tempering are adopted to replace the traditional off-line normalizing process and tempering process of the steel plate after controlled rolling, and the tempering process is directly carried out after on-line normalizing, so that the normalizing process is saved, the generation process is simplified, the deformation zone and dislocation defect generated by the normalizing, controlled rolling are fully utilized to promote the hardening of austenite, nucleation particles are provided to promote the refining and strengthening of crystal grains, the strength loss caused by the addition of alloy is reduced, the off-line normalizing process is saved, the process flow is shortened, the productivity is improved, and the production cost is reduced.

Detailed Description

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

A production method of a medium-high temperature boiler and pressure vessel steel plate comprises the following steps:

1) designing components: in the control range of steel plates for national standard GB713-2014 boilers and pressure vessels, the steel plates comprise the following chemical components in percentage by weight: c: 0.13-0.16%, Si: 0.5-0.8%, Mn: 0.40-0.65%, S is less than or equal to 0.010%, P is less than or equal to 0.020%, Cu is less than or equal to 0.3%, Cr: 1.15-1.25%, Ni is less than or equal to 0.3%, Mo: 0.45-0.55%, and the balance of Fe and inevitable impurities;

2) smelting: converter-refining-continuous casting, wherein the smelting slagging-off temperature is higher than 1560 ℃, Al is adopted for preliminary deoxidation, the refining process is alloyed, the continuous casting water distribution adopts slow cooling, and the slabs are directly stacked for 48 hours after being off-line to obtain slabs with qualified quality; and grinding the upper surface and the lower surface of the plate blank by 0-4mm, specifically according to the surface quality of the plate blank.

3) Heating: the medium-high temperature pressure container steel 14Cr1MoR has high content of chromium and molybdenum, is easy to generate burning cracks due to uneven heating, the plate blank is heated in a three-section mode, the preheating section is less than or equal to 950 ℃, the heating section 1 is 1050-1100 ℃, the heating section 2 is 1130-plus-1200 ℃, the soaking section is 1150-plus-1200 ℃, the total heating time is controlled to be less than or equal to 260min, and the steel blank is fully heated before rolling, so that the carbonitride is fully dissolved in the steel blank in a solid mode, and the coarsening of crystal grains;

4) rolling: after the plate blank is taken out of the heating furnace, the austenitizing temperature of 14Cr1MoR is 900 ℃, the ferrite phase transition temperature is 850 ℃, the pearlite phase transition temperature is 750 ℃, the initial rolling temperature of the first stage is not more than 1160 ℃, the high-temperature rush rolling is adopted in the stage, the final rolling temperature of the first stage is not less than 1050 ℃, the thickness to be rolled reaches 1.5-2.0 times of the thickness of a finished product, the normalizing temperature range of the second stage is adopted for rolling within 750-960 ℃, the initial rolling temperature of the second stage is not more than 960 ℃, and the final rolling temperature of the second stage is controlled to be not less than 760;

5) and (3) controlled cooling after rolling: after rolling, the steel plate is rapidly cooled to room temperature in an aerosol manner, and the hardened austenite is subjected to phase change strengthening;

6) tempering: tempering temperature of the steel plate after on-line normalizing control is more than or equal to 650 ℃, actually selecting 720 ℃, 680 ℃ and 650 ℃, keeping the temperature for 20-40min for air cooling, and detecting that the mechanical property meets the requirement after the tempering temperature of 650 ℃;

7) heat treatment after welding: in order to eliminate welding stress, the prepared sample to be detected is kept at 620 +/-10 ℃ for 2-3h, wherein when the temperature is increased to be higher than 400 ℃, the heating speed is controlled to be 50-80 ℃/h, when the temperature is decreased to be higher than 400 ℃, the cooling speed is controlled to be 30-50 ℃/h, when the temperature is decreased to be lower than or equal to 400 ℃, natural cooling is kept to be normal temperature, and then a mechanical property test is carried out.

The mechanical properties of the test materials are respectively as follows: tensile strength 618-.

The above example is only one process selected to be optimized, and the same effect can be obtained within the process parameters in the production step of the present invention.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.