阅读说明：本技术 一种提高18CrNiMo7-6锻件探伤合格率的方法 (Method for improving flaw detection qualification rate of 18CrNiMo7-6 forge piece ) 是由 许亮 李姚君 丁佐军 陆秦旭 郜均虎 魏航 于 2020-06-03 设计创作，主要内容包括：本发明公开了一种提高18CrNiMo7-6锻件探伤合格率的方法,属于高温合金锻造技术领域,其技术方案要点是包括以下步骤：S1、原材料下料；S2、锻造加热：将原材料加热；S3、锻造：第一工步：取S2中加热完成的原材料,对原材料进行上平板镦粗和上平板拔长,充分破碎钢锭铸态组织,采取高温大变形的方式,压实钢锭,第二工步：对第一工步处理完成的原材料进行上平板镦粗和上砧拔长,得到锻件；S4、锻后冷却：将锻件置入炉中均匀缓冷至300℃出炉,之后锻件空冷；S5、预备热处理：锻件采取900-950℃正火,之后锻件空冷至室温,然后锻件采取600-750℃回火,最后锻件空冷至室温,本发明的优点在于改善锻件组织结构,提高锻件的探伤合格率低。(The invention discloses a method for improving the flaw detection qualification rate of 18CrNiMo7-6 forgings, which belongs to the technical field of high-temperature alloy forging and adopts the technical scheme that the method comprises the following steps: s1, blanking raw materials; s2, forging and heating: heating the raw material; s3, forging: the first process step is as follows: taking the raw material heated in the step S2, upsetting an upper flat plate and drawing out the upper flat plate on the raw material, fully crushing a steel ingot casting structure, compacting the steel ingot by adopting a high-temperature large-deformation mode, and performing a second step: carrying out upper flat plate upsetting and upper anvil drawing on the raw material processed in the first step to obtain a forge piece; s4, cooling after forging: placing the forge piece into a furnace, uniformly and slowly cooling to 300 ℃, discharging, and then air cooling the forge piece; s5, preheating: the method has the advantages that the structure of the forged piece is improved, and the flaw detection percent of pass of the forged piece is low.)

1. The method for improving the flaw detection qualification rate of the 18CrNiMo7-6 forge piece is characterized by comprising the following steps of: the method comprises the following steps:

s1, blanking raw materials;

s2, forging and heating: feeding the raw material into a forging heating furnace for heating;

s3, forging: the first process step is as follows: taking the raw material heated in the step S2, upsetting an upper flat plate and drawing out the upper flat plate on the raw material, fully crushing a steel ingot casting structure, compacting the steel ingot by adopting a high-temperature large-deformation mode, and performing a second step: carrying out upper flat plate upsetting and upper anvil drawing on the raw material processed in the first step to obtain a forge piece; the third step is as follows: upsetting and punching the forge piece; the fourth step: rolling the ring by using the forging piece;

s4, cooling after forging: placing the forge piece into a furnace, uniformly and slowly cooling to 300 ℃, discharging, and then air cooling the forge piece;

s5, preheating: normalizing the forging at 900 plus 950 ℃, then air-cooling the forging to room temperature, tempering the forging at 600 plus 750 ℃, and finally air-cooling the forging to room temperature.

2. The method for improving the flaw detection qualification rate of the 18CrNiMo7-6 forging according to claim 1, wherein the method comprises the following steps: in the first step of step S3, the upsetting speed of the upper plate upsetting is controlled within the range of 300-1000 mm/min.

3. The method for improving the flaw detection qualification rate of the 18CrNiMo7-6 forging according to claim 1, wherein the method comprises the following steps: in the first step of the step S3, after upsetting is carried out to the process requirement height, the pressure is maintained for 10-100S, so that the center of the forge piece is loose and the defects have time to be fully compacted.

4. The method for improving the flaw detection qualification rate of the 18CrNiMo7-6 forging according to claim 1, wherein the method comprises the following steps: in the second step of step S3, the feed amount is controlled to be 0.2 to 0.7 times the upper anvil width when the upper anvil is elongated.

5. The method for improving the flaw detection qualification rate of the 18CrNiMo7-6 forging according to claim 1, wherein the method comprises the following steps: in the second step of step S3, the reduction amount of the upper anvil during the drawing is in the range of 30 to 100 mm.

6. The method for improving the flaw detection qualification rate of the 18CrNiMo7-6 forging according to claim 1, wherein the method comprises the following steps: in step S2, the raw material is charged into the furnace at an initial temperature of 600 ℃ or lower, then heated to 950 ℃ at a heating rate of 120 ℃/h or lower and is kept at the temperature, and then heated to 1280 ℃ at 1230 ℃ at 200 ℃/h or lower and is kept at the temperature.

7. The method for improving the flaw detection qualification rate of the 18CrNiMo7-6 forging according to claim 6, wherein the method comprises the following steps: the heat preservation time of the raw material at 750 plus materials and 950 ℃ is T1, T1 is the maximum effective section of the raw material 0.2-0.8min/mm, the heat preservation time of the raw material at 1230 plus materials and 1280 ℃ is T2, and T2 is the maximum effective section of the raw material 0.2-0.8 min/mm.

Technical Field

The invention relates to the technical field of high-temperature alloy forging, in particular to a method for improving the flaw detection qualification rate of 18CrNiMo7-6 forgings.

Background

With the development of economy and society, China also follows the guidelines of times and people for improving sustainable development, and more novel energy sources enter the visual field of people, such as nuclear power, hydroelectric power, wind power and geothermal power generation, which occupy larger and larger proportions in the energy industry. The wind power generation is very environment-friendly, and the wind energy is huge, so that the wind power generation is increasingly paid attention to all countries in the world, and the Chinese and western regions are widely known, and the wind power generation has a Qinghai-Tibet plateau and a loess plateau and contains rich wind energy resources. In 2019, the installed capacity of the newly added wind power in the world exceeds 60GW, the installed capacity is increased by 19% on the same scale, and the accumulated installed capacity reaches 650 GW. Wherein, the land wind power is newly added with 54.2GW which is increased by 17% on the same scale, and the development related to the wind power generation industry in China is driven.

The 18CrNiMo7-6 steel is used for manufacturing wind power and industrial carburized gears, the demand of the 18CrNiMo7-6 forging of the gear box forging is increased explosively, the flaw detection requirement of the forging is improved, as the 18CrNiMo7-6 is white-point sensitive steel, the white-point defect is easy to occur by adopting common dehydrogenation annealing, the austenite is not completely transformed in the subsequent forging process, residual austenite exists in the structure, the residual austenite is gradually transformed to martensite along with time in the subsequent machining, the shear stress and the tensile stress caused by the change are changed, the structure is broken, and the flaw detection qualification rate of the forging is low.

Disclosure of Invention

The invention aims to provide a method for improving the flaw detection qualification rate of 18CrNiMo7-6 forgings, which has the advantages of improving the tissue structure of the forgings and improving the flaw detection qualification rate of the forgings.

The technical purpose of the invention is realized by the following technical scheme:

a method for improving the flaw detection qualification rate of 18CrNiMo7-6 forgings comprises the following steps:

s1, blanking raw materials;

s2, forging and heating: feeding the raw material into a forging heating furnace for heating;

s3, forging: the first process step is as follows: taking the raw material heated in the step S2, upsetting an upper flat plate and drawing out the upper flat plate on the raw material, fully crushing a steel ingot casting structure, compacting the steel ingot by adopting a high-temperature large-deformation mode, and performing a second step: carrying out upper flat plate upsetting and upper anvil drawing on the raw material processed in the first step to obtain a forge piece; the third step is as follows: upsetting and punching the forge piece; the fourth step: rolling the ring by using the forging piece;

s4, cooling after forging: placing the forge piece into a furnace, uniformly and slowly cooling to 300 ℃, discharging, and then air cooling the forge piece;

s5, preheating: normalizing the forging at 900 plus 950 ℃, then air-cooling the forging to room temperature, tempering the forging at 600 plus 750 ℃, and finally air-cooling the forging to room temperature.

Further, in the first step of step S3, the upsetting speed of the upper plate upsetting is controlled within the range of 300-1000 mm/min.

Further, in the first step of step S3, after upsetting is carried out to the process requirement height, the pressure is maintained for 10-100S, so that the center of the forge piece is loose and the defects have time to be fully compacted.

Further, in the second step of step S3, when the upper anvil is elongated, the feed amount is controlled to be 0.2 to 0.7 times the upper anvil width.

Further, in the second step of step S3, the range of the pressing amount of the upper anvil at the time of drawing is 30 to 100 mm.

Further, in step S2, the raw material is charged into the furnace at an initial temperature of 600 ℃ or lower, heated to 750-950 ℃ at a heating rate of 120 ℃/h or lower and then heat-preserved, and then heated to 1230-1280 ℃ at 200 ℃/h or lower and then heat-preserved.

Furthermore, the heat preservation time of the raw material at 750 + 950 ℃ is T1, T1 is the maximum effective section of the raw material 0.2-0.8min/mm, the heat preservation time of the raw material at 1230 + 1280 ℃ is T2, and T2 is the maximum effective section of the raw material 0.2-0.8 min/mm.

In conclusion, the invention has the following beneficial effects:

1. in the forging process, upsetting and stretching are performed twice, the center of the forging is compacted for the first time, the surface of the forging is compacted for the first time, the cast structure of the steel ingot is fully crushed, the residual austenite is eliminated in a high-temperature large deformation mode, stress change caused by the residual austenite is eliminated while the structure is crushed, and therefore the defects of the structure of the forging are reduced, and the qualification rate of flaw detection of the forging is improved.

2. In the first step, the upsetting speed is controlled within the range of 300-1000mm/min for rapid upsetting, which is beneficial to more rapidly breaking the original crystal structure.

3. The pressure maintaining time is within 10s-100s, so that the center of the forge piece is loose and the defects have sufficient time to be fully compacted, and the flaw detection qualification rate of the forge piece is further improved.

4. In the second step, the rolling reduction of drawing is reasonably controlled, and the surface compaction effect of the forge piece is improved.

Drawings

FIG. 1 is a schematic structural diagram of steps of a method for improving the flaw detection yield of an 18CrNiMo7-6 forging.

FIG. 2 is a metallographic micrograph A of a forging in a metallographic examination of the forging;

FIG. 3 is a metallographic micrograph B of the forging in a metallographic examination of the forging;

FIG. 4 is a metallographic micrograph C of the forging in a metallographic examination of the forging;

FIG. 5 is a metallographic micrograph D of the forging in a metallographic examination of the forging.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.