阅读说明：本技术 一种防止nd钢表面热裂的低温穿孔工艺 (Low-temperature perforation process for preventing heat cracking of surface of ND steel ) 是由 周益鑫 于 2019-09-17 设计创作，主要内容包括：本发明公开了一种防止ND钢表面热裂的低温穿孔工艺,包括以下步骤：1)坯料入厂验收；2)管坯剪断；3)剥皮；4)加热；5)穿孔；6)打头。本发明属于ND钢低温穿孔工艺技术领域,具体是提供一种耐硫酸露点腐蚀用ND钢无缝钢管的低温穿孔工艺,解决了现代机加工过程中由于温度过高导致ND钢无缝钢管在穿孔时出现表面热裂的现象,真正意义上实现了穿孔表面无损的技术效果。(The invention discloses a low-temperature perforation process for preventing heat cracking of the surface of ND steel, which comprises the following steps: 1) checking and accepting the blank in a factory; 2) cutting off the tube blank; 3) peeling; 4) heating; 5) perforating; 6) and (5) heading. The invention belongs to the technical field of ND steel low-temperature perforation processes, and particularly provides a low-temperature perforation process of an ND steel seamless steel pipe for resisting sulfuric acid dew point corrosion, which solves the problem that the surface of the ND steel seamless steel pipe is hot cracked during perforation caused by overhigh temperature in the modern machining process, and truly realizes the technical effect of nondestructive perforation surface.)

1. A low-temperature perforation process for preventing the surface of ND steel from hot cracking is characterized in that:

the process flow is as follows: the blank is accepted in a factory → the tube blank is cut off → peeled → heated → perforated → head is hit;

the invention discloses a process for preventing ND steel seamless steel pipe from low-temperature perforation, which comprises the following steps:

the method comprises the following steps: the purchased blanks are checked and accepted in the factory, and the checking components comprise chemical components, tube blank length, tube blank diameter, surface quality, tube blank straightness and the like;

step two: shearing a round bar pipe blank with phi of 60-80 mm to the length of 1500-2000 mm;

step three: peeling the round bar tube blank cut to 1500-2000 mm, wherein the peeling depth is 1-2 mm;

step four: heating the cut tube blank to 900-1100 +/-20 ℃, and selecting different heat preservation time according to the wall thickness of the steel tube, wherein the heat preservation time is 50-70 minutes;

step five: perforating on a cross rolling perforator, wherein the perforating temperature is 870-1080 ℃; the loading load current is less than or equal to 1200A, and the perforation speed is 400 r/min;

step six: performing heading treatment by using waste heat after perforation is finished;

when the peeling depth in the third step is 1mm, the heat preservation time in the fourth step is 50 minutes.

2. The low-temperature perforating process for preventing the hot cracking of the surface of the ND steel as claimed in claim 1, wherein: when the peeling depth in the third step is 1.5mm, the heat preservation time in the fourth step is 60 minutes.

3. The low-temperature perforating process for preventing the hot cracking of the surface of the ND steel as claimed in claim 1, wherein: when the peeling depth in the third step is 2mm, the heat preservation time in the fourth step is 70 minutes.

4. The low-temperature perforating process for preventing the hot cracking of the surface of the ND steel as claimed in claim 1, wherein: when the heating temperature of the tube blank in the third step is 920 ℃, the perforation temperature in the fifth step is 880 ℃.

5. The low-temperature perforating process for preventing the hot cracking of the surface of the ND steel as claimed in claim 1, wherein: in the fourth step, the heating temperature of the tube blank is 1000 ℃, and the perforation temperature in the fifth step is 920 ℃.

6. The low-temperature perforating process for preventing the hot cracking of the surface of the ND steel as claimed in claim 1, wherein: in the fourth step, the heating temperature of the tube blank is 1080 ℃, and the perforation temperature in the fifth step is 1040 ℃.

Technical Field

The invention belongs to the technical field of ND steel low-temperature perforation processes, and particularly relates to a low-temperature perforation process for preventing heat cracks on the surface of ND steel.

Background

In industrial production, because the heavy oil or coal of a fuel oil or coal-fired boiler usually contains 12-13% of sulfur, the flue gas after combustion contains sulfur dioxide, wherein part of the sulfur dioxide generates sulfur trioxide through the catalytic action of ash, metal oxide and the like, and then is combined with the combustion gas and the moisture contained in the air to generate sulfuric acid, when the environmental temperature is below 130-150 ℃, the sulfuric acid in the flue gas has dew point, namely, the sulfuric acid is condensed on the metal surface and corrodes the metal surface, namely, the so-called sulfuric acid dew point corrosion.

The ND steel, namely 09CrCuSb steel, contains chemical components such as C, Si, Mn, P, S, Cr, Cu, Sb and Fe, and the microelements form a thin and compact passive film on the surface of the ND steel, the passive film is very stable, prevents acid and water from permeating into a steel matrix, protects the matrix below a rust layer, and can effectively slow down the speed of sulfuric acid continuously developing corrosion to the depth of the steel material, thereby improving the corrosion resistance of the steel material. ND steel is the most ideal steel for resisting sulfuric acid low temperature dew point corrosion at home and abroad at present, is widely used for manufacturing devices such as coal economizers, air preheaters, heat exchangers, evaporators and the like serving in high sulfur-containing flue gas, and is used for resisting the corrosion of dew points of the sulfur-containing flue gas; because the ND steel has high Cu content and contains a certain amount of Sb, hot brittleness easily occurs in the hot processing process, and hot cracking easily occurs on the surface of the seamless steel tube in the conventional process perforation process.

Disclosure of Invention

In order to solve the existing problems, the invention provides a low-temperature perforating process of the ND steel seamless steel pipe for resisting sulfuric acid dew point corrosion, which solves the problem that the surface of the ND steel seamless steel pipe is hot cracked during perforation caused by overhigh temperature in the modern machining process, and truly realizes the technical effect of nondestructive perforation surface.

The process flow of the invention is as follows: the blank is accepted in a factory → the tube blank is cut off → peeled → heated → perforated → head is hit;

the low-temperature perforating process for the ND steel seamless steel pipe comprises the following steps of:

the method comprises the following steps: the purchased blanks are checked and accepted in the factory, and the checking components comprise chemical components, tube blank length, tube blank diameter, surface quality, tube blank straightness and the like;

step two: shearing the tube blank with phi of 60-80 mm to 1500-2000 mm in length;

step three: peeling the round bar tube blank cut to 1500-2000 mm, wherein the peeling depth is 1-2 mm;

step four: heating the cut tube blank to 900-1100 +/-20 ℃, and selecting different heat preservation time according to the wall thickness of the steel tube, wherein the heat preservation time is 50-70 minutes;

step five: perforating on a cross rolling perforator, wherein the perforating temperature is 870-1080 ℃; the loading load current is less than or equal to 1200A, and the perforation speed is 400 r/min;

step six: and (5) performing heading treatment by using waste heat after perforation is finished.

Further, when the peeling depth in the third step is 1mm, the heat preservation time in the fourth step is 50 minutes;

further, when the peeling depth in the third step is 1.5mm, the heat preservation time in the fourth step is 60 minutes;

further, when the peeling depth in the third step is 2mm, the heat preservation time in the fourth step is 70 minutes;

further, when the heating temperature of the tube blank in the third step is 920 ℃, the perforation temperature in the fifth step is 880 ℃;

further, the heating temperature of the tube blank in the fourth step is 1000 ℃, and the perforation temperature in the fifth step is 920 ℃;

further, the heating temperature of the tube blank in the fourth step is 1080 ℃ and the perforation temperature in the fifth step is 1040 ℃.

The invention has the following beneficial effects:

the invention provides a low-temperature perforation process of a ND steel seamless steel pipe for resisting sulfuric acid dew point corrosion, which overcomes the hot brittleness phenomenon of ND steel when perforating at a higher temperature, solves the surface hot cracking phenomenon of the ND steel seamless steel pipe when perforating due to overhigh temperature in the modern machining process, and truly realizes the technical effect of nondestructive perforation surface; the ND steel seamless steel pipe with excellent surface quality and sulfuric acid dew point corrosion resistance can be produced, has extremely high sulfuric acid dew point corrosion resistance, is improved by dozens of times compared with the corrosion capacity of the traditional carbon steel, is improved by 2-3 times compared with the corrosion capacity of a stainless steel pipe, can be widely applied to the industrial fields of metallurgy, electric power, petrochemical industry and the like, greatly slows down the corrosion speed when being used in devices such as coal economizers, air preheaters, heat exchangers, evaporators and the like serving in high-sulfur-containing flue gas, and avoids the problems of low service life of products generated after heat cracking and the like.

Drawings

FIG. 1 is a schematic view of a low-temperature piercing process for preventing heat cracking on the surface of ND steel according to the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by those skilled in the art without creative efforts based on the embodiments of the present invention belong to the protection scope of the present invention.

The scheme is used for the low-temperature perforation process for preventing the hot cracking of the surface of the ND steel, the heating and perforation temperature of the tube blank plays a main role, and the first step of the invention is to check and accept the purchased blank in a factory, so that the method is the basis of the hot cracking and low-temperature perforation of the surface of the ND steel; secondly, the tube blank is sheared, the length of the tube blank is controlled, so that the tube blank is easier to perforate subsequently, and the temperature of the tube blank is better controlled; the third step is that the skin peeling treatment is carried out on the sheared tube blank, so that the heating speed of the tube blank is controlled; fourthly, heating the peeled tube blank to find the temperature most suitable for perforation; and fifthly, perforating on the cross rolling perforator and controlling the perforating position to control the problem of heat cracking of the surface of the ND steel, and then performing heading treatment in the sixth step to finally obtain the ND steel seamless steel pipe with high corrosion resistance, high strength, clean surface and no heat cracking.