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Low-temperature punching process for preventing heat cracking of surface of ND steel

A hot cracking and low temperature technology, applied in metal rolling and other directions, can solve the problem of hot cracking on the surface of seamless pipes, and achieve excellent surface quality and sulfuric acid dew point corrosion resistance, improved sulfuric acid dew point corrosion resistance, and high resistance to Effect of sulfuric acid dew point corrosion performance

Active Publication Date: 2014-06-11
CHANGZHOU SHENGTAK SEAMLESS STEEL TUBE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

As a result, during the perforation process using the conventional process, the surface of the seamless pipe is prone to thermal cracking

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1）

[0019] A low-temperature perforation process for preventing thermal cracking on the surface of ND steel, comprising the following steps:

[0020] (1) Cut the Φ70 tube blank to a length of 1600mm;

[0021] (2) Peeling the round bar and tube blank, the peeling depth is 0.5mm~2mm;

[0022] (3) Heat the cut tube blank to 1000°C and keep it warm for 40 minutes;

[0023] (4) The piercing is carried out on a DC frequency conversion piercing machine, the piercing temperature is 970°C; the loading current is ≤1500A, and the piercing speed is 500 rpm;

[0024] (5) After the perforation is completed, use the residual heat to start the head.

[0025] The surface of the ND steel seamless pipe obtained by this process does not have thermal cracking, and at 70 °C, 50% H 2 SO 4 Soaked in the solution for 24 hours, the corrosion resistance rate of sulfuric acid is 10mg / cm 2 .h..

Embodiment 2）

[0027] (1) Cut the Φ75 tube blank to a length of 1600mm;

[0028] (2) Peeling the round bar and tube blank, the peeling depth is 0.5mm~2mm;

[0029] (3) Heat the cut tube blank to 1020°C and keep it warm for 60 minutes;

[0030] (4) The piercing is carried out on a DC frequency conversion piercer, the piercing temperature is 990°C; the load current is ≤1500A, and the piercing speed is 500 rpm;

[0031] (5) After the perforation is completed, use the residual heat to start the head.

[0032] The surface of the ND steel seamless pipe obtained by this process does not have thermal cracking, and at 70 °C, 50% H 2 SO 4 Soaked in the solution for 24 hours, the sulfuric acid corrosion resistance rate is 9.2mg / cm 2 .h..

Embodiment 3）

[0034] (1) Cut the Φ80 tube blank to a length of 1600mm;

[0035] (2) Peeling the round bar and tube blank, the peeling depth is 0.5mm~2mm;

[0036] (3) Heat the cut tube blank to 1050°C and keep it warm for 80 minutes;

[0037] (4) The piercing is carried out on a DC frequency conversion piercing machine, the piercing temperature is 1020°C; the loading current is ≤1500A, and the piercing speed is 500 rpm;

[0038] (5) After the perforation is completed, use the residual heat to start the head.

[0039] The surface of the ND steel seamless pipe obtained by this process does not have thermal cracking, and at 70 °C, 50% H 2 SO 4 Soaked in the solution for 24 hours, the sulfuric acid corrosion resistance rate is 8.9mg / cm 2 .h..

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PUM

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Abstract

The invention relates to a low-temperature punching process for preventing heat cracking of the surface of ND steel. The low-temperature punching process comprises step 1, cutting pipe blank to the required length; step 2, performing peeling treatment on the round rod pipe blank, wherein the peeling depth is 0.5 to 2 mm; step 3, heating the cut pipe blank to 1000 to 1050 DEG C plus or minus 10 DEG C and selecting the heat preservation time according to the thickness of the pipe steel wall, wherein the heat preservation time is generally 40 to 80 minutes; step 4, performing punching on a direct current frequency conversion puncher, wherein the punching temperature is 970 to 1020 DEG C, the loaded load current is not more than 1500 amperes, and the punching speed is 500 revolutions every minute; performing heading through waste heat after the punching is achieved. According to the low-temperature punching process for preventing the heat cracking of the surface of the ND steel, the heat cracking which is produced when the ND steel is punched at the high temperature is avoided and accordingly ND steel seamless steel pipes which are excellent in surface quality and sulfuric acid dew-point corrosion resistance can be produced out.

Description

technical field [0001] The invention belongs to the technical field of metal forming and processing, and in particular relates to a low-temperature perforation process for preventing thermal cracking on the surface of ND steel. Background technique [0002] In industrial production, because the heavy oil or coal of oil-fired or coal-fired boilers usually contains 2% to 3% of sulfur, the flue gas after combustion contains about 0.2% of sulfur dioxide, of which 1% to 2% of sulfur dioxide is obtained by ash and The catalysis of metal oxides, etc. produces sulfur trioxide, and then combines with the combustion gas and moisture contained in the air to form sulfuric acid. When the ambient temperature is below 130-150 ° C, the sulfuric acid in the flue gas has a dew point, that is, on the metal surface Condensation and corrosion, the so-called sulfuric acid dew point corrosion. [0003] ND steel is 09CrCuSb steel, and its chemical composition is shown in Table 1 below. ND steel i...

Claims

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Application Information

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IPC IPC(8): B23P15/00
CPCB21B19/04
Inventor 周文庆周益鑫范琪
Owner CHANGZHOU SHENGTAK SEAMLESS STEEL TUBE
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