CN104294166A - Chromium-nickel microalloyed carbon steel nuclear seamless steel tube and production method thereof - Google Patents

Abstract

The invention provides a chromium-nickel microalloyed carbon steel nuclear seamless steel tube. The steel tube is prepared from the following components in percentage by weight: 0.16-0.20 percent of C, 0.17-0.25 percent of Si, 0.35-0.50 percent of Mn, 0.15-0.30 percent of Cr, 0.06-0.12 percent of Ni, and the balance of Fe, while the amount of P, S, Al, Mo and Cu serving as residual elements in steel is controlled according to standard. The invention further provides a method for producing the hot-rolled seamless steel tube. The steel tube has the effects that by means of microalloying, the flow accelerated corrosion resistance rate of the carbon steel tube can be reduced by about 45 percent, the transverse low-temperature average impact energy of steel at -20 DEG C is improved by about 250 percent and reaches about 80J on average, the service life of the steel tube can be prolonged, the changing frequency of the steel tube can be reduced, and the power generation efficiency of a nuclear power station can be improved. Therefore, brittle fracture of the steel tube due to cracking generated when the steel tube is processed at low temperature cannot happen, and the operation safety of the steel tube at low-temperature environment can be improved.

Description

The carbon steel nuclear power weldless steel tube of chromium nickel microalloying and production method thereof

Technical field

The present invention relates to for resist fluids accelerated corrosion (FAC), take into account carbon steel nuclear power weldless steel tube and the production method thereof of a kind of chromium nickel microalloying of-20 DEG C of low-temperature impact toughness simultaneously, be mainly used in nuclear power station conventional island and nuclear island non-core level part.

Background technology

Electric power is as the requisite energy of people's daily life, and be also the blood of industrial development, therefore, demand is quite large simultaneously.And nuclear power is as clean energy, obnoxious flavour zero release can be accomplished, simultaneously because its security is more and more higher, therefore obtain the support energetically of country.

Conventional island and nuclear island non-core level carbon steel pipe, because its work is in the environment that medium accelerates flowing relatively, medium is supersaturated vapor simultaneously, needs to take precautions against its Flow accelerated corrosion.But the Flow accelerated corrosion speed of plain carbon stool pipe is high, in order to ensure nuclear power pipe operating safety, steel pipe needs regularly to carry out detecting and changing, add the stop frequency of Nuclear power plants, reduce the operational efficiency of Nuclear power plants, affect the stability of electrical network, too increase the possibility of other Steel Pipe Heat fatigue failures of Nuclear power plants simultaneously.Therefore the Flow accelerated corrosion speed that carbon steel pipe is high, not only have impact on the working efficiency of Nuclear power plants, also makes the security of Nuclear power plants be affected.So the Flow accelerated corrosion speed reducing carbon steel pipe is extremely urgent.

In addition, China's Nuclear power plants and nuclear power equipment Manufacturing spread all over coastal most area, include the low temperature areas such as Liaoning, therefore conventional island and nuclear island non-core level carbon steel weldless steel tube also need to consider the impelling strength under its-20 DEG C of low temperature, to ensure the security of steel pipe processing and installation process, otherwise steel pipe carries out processing and installing at low temperatures, will crack, cause steel pipe at the course of processing or operational process Fracture.

Summary of the invention

For service condition and the working conditions of nuclear power conventional island and nuclear island non-core level carbon steel pipe, the invention provides a kind of carbon steel nuclear power weldless steel tube and production method thereof of chromium nickel microalloying, while preventing Flow accelerated corrosion, the characteristic possessing low-temperature impact toughness can be taken into account.

For achieving the above object, the invention provides a kind of carbon steel nuclear power weldless steel tube of chromium nickel microalloying, the composition of this steel pipe is by weight percentage: C 0.16 ~ 0.20%, Si 0.17 ~ 0.25%, Mn 0.35 ~ 0.50%, Cr 0.15 ~ 0.30%, Ni 0.06 ~ 0.12%, surplus is Fe, simultaneously P, S, Al, Mo, Cu be in steel residual element by standard manipulated variable

Also provide a kind of production method of producing above-mentioned hot rolled seamless steel tube, step is as follows simultaneously:

1. pipe is smelted: pipe is smelted and carried out control raw material by composition range described in claim 1;

2. tube rolling: after pipe perforation, adopt PQF high precision restraint three-roll continuous rolling unit to be rolled, carry out tension reducing afterwards, total deformation reaches more than 500%; For ensureing that steel pipe has uniform tissue, after tension reducing, the temperature requirement of steel pipe controls between 880 ~ 930 DEG C, ensures that steel pipe cooling temperature is heat-treated after less than 350 DEG C again simultaneously;

3. normalizing thermal treatment: owing to adopting microalloying, for ensureing the abundant solid solution of alloying element, adopting temperature to be 920 DEG C and carrying out normalizing thermal treatment.

Effect of the present invention is: by adding the Cr of 0.15% ~ 0.30%, the resist fluids accelerated corrosion speed of carbon steel pipe is enable to reduce about 45%, thus substantially prolongs the work-ing life of steel pipe, decrease the replacement frequency of steel pipe, and then improve the generating efficiency of Nuclear power plants.China's Nuclear power plants and nuclear power equipment Manufacturing spread all over coastal most area in addition, include the low temperature areas such as Liaoning, and as adopted plain carbon stool, the poor toughness under steel pipe low temperature, steel pipe is very easy to brittle rupture occurs in processing and installation process.For solving this problem, by great many of experiments and organize optimizing components more, the Ni of 0.06% ~ 0.12% is added in this carbon steel, the horizontal low temperature average impact merit of steel-20 DEG C is made to promote about 250%, reach average about 80J, thus make steel pipe carry out processing at low temperatures can not therefore to crack and cause brittle rupture, add steel pipe processing safety at low ambient temperatures.

Embodiment

The carbon steel nuclear power weldless steel tube of chromium nickel microalloying of the present invention and production method thereof are illustrated in conjunction with the embodiments.

The carbon steel nuclear power weldless steel tube of chromium nickel microalloying of the present invention, the composition of this steel pipe is by weight percentage: C 0.16 ~ 0.20%, Si 0.17 ~ 0.25%, Mn 0.35 ~ 0.50%, Cr 0.15 ~ 0.30%, Ni 0.06 ~ 0.12%, surplus is Fe, simultaneously P, S, Al, Mo, Cu be in steel residual element by standard manipulated variable.

The low-temperature impact toughness of-20 DEG C of the described micro-alloyed hot-rolled weldless steel tube of chromium nickel reaches 80J, and Flow accelerated corrosion speed reaches 0.11mm/.

The production method of the carbon steel nuclear power weldless steel tube of chromium nickel microalloying of the present invention, includes following steps:

1. pipe is smelted: pipe is smelted and carried out control raw material by mentioned component scope, and especially Cr, Ni control near center line; Pipe adopts the technique of die casting+forging to produce.

2. tube rolling: after pipe perforation, adopt PQF high precision restraint three-roll continuous rolling unit to be rolled, carry out tension reducing afterwards, total deformation reaches more than 500%; For ensureing that steel pipe has uniform tissue, after tension reducing, the temperature requirement of steel pipe controls between 880 ~ 930 DEG C, the too low steel pipe of temperature is in two-phase region internal strain, easy formation banded structure, temperature is too high, easy formation Wei Shi body burnt structure, these two kinds tissues are difficult to be eliminated completely by follow-up normalizing treatment, thus have impact on the impelling strength of steel.Meanwhile, ensure that steel pipe cooling temperature is heat-treated after less than 350 DEG C again;

3. normalizing thermal treatment: owing to adopting microalloying steel pipe to contain trace alloying element, for ensureing the abundant solid solution of alloying element, adopting temperature to be 920 DEG C and carrying out normalizing thermal treatment.

Embodiment 1:

The carbon steel nuclear power weldless steel tube of chromium nickel microalloying of the present invention and the chemical composition of plain carbon stool pipe are as following table:

Table 1 pipe chemical composition (wt%)

For ensureing the recovery rate of nickel and the stability of composition in steelmaking process, nickel plate being cut into area and being less than 10cm ²small pieces, simultaneously ferrochrome block weight is less than 10 kilograms/block; Molten steel keeps high vacuum time to be not less than 10 minutes after entering VD, little to ensure steel grade gas content.

In addition, in table 1, Ni and Cr of plain carbon stool pipe is the residual element in steel, unintentionally Addition ofelements.P, S, Mo, Cu, Al five kinds of elements are residual element, will be limited by standard manipulated variable.

Embodiment 2:

The rolling requirements of steel pipe of the present invention is as follows:

Adopt heavy in section pipe, be rolled, carry out tension reducing afterwards with PQF high precision restraint three-roll continuous rolling unit, altogether three road distortion, deflection is large, and concrete rolling sees the following form:

Table 2 rolling specs and deflection

Organize for guarantee simultaneously and change completely, steel pipe is cooled to just can carry out subsequent heat treatment after below 350 DEG C.

Embodiment 3:

Steel pipe all adopts 920 DEG C of normalizings, and carry out-20 DEG C after normalizing and impact and resist fluids accelerated corrosion test, result is as following table:

Table 3 performance test

Find out from above test-results, by carrying out the improvement of composition on the basis of plain carbon stool pipe, the ballistic work of steel pipe-20 DEG C adopting the present invention to produce improves more than 250% relative to plain carbon stool pipe, simultaneously Flow accelerated corrosion rate reduction about 45%.，

More than test the present invention's steel pipe result of producing and all meet the service requirements of Nuclear power plants for conventional island and nuclear island non-core level nuclear power pipe, and steel pipe processing and installation can be carried out in northern cold cold weather.

Claims (3)

1. the carbon steel nuclear power weldless steel tube of a chromium nickel microalloying, it is characterized in that: the composition of this steel pipe is by weight percentage: C 0.16 ~ 0.20%, Si 0.17 ~ 0.25%, Mn 0.35 ~ 0.50%, Cr 0.15 ~ 0.30%, Ni 0.06 ~ 0.12%, surplus is Fe, simultaneously P, S, Al, Mo, Cu be in steel residual element by standard manipulated variable.

2. the micro-alloyed hot-rolled weldless steel tube of chromium nickel according to claim 1, is characterized in that: the low-temperature impact toughness of-20 DEG C of described carbon steel nuclear power weldless steel tube reaches 80J, and Flow accelerated corrosion speed reaches 0.11mm/.

3. a production method for the carbon steel nuclear power weldless steel tube of chromium nickel microalloying as claimed in claim 1, the method includes following steps:

1. pipe is smelted: pipe is smelted and carried out control raw material by composition range described in claim 1;

2. tube rolling: after pipe perforation, adopt PQF high precision restraint three-roll continuous rolling unit to be rolled, carry out tension reducing afterwards, total deformation reaches more than 500%; For ensureing that steel pipe has uniform tissue, after tension reducing, the temperature requirement of steel pipe controls between 880 ~ 930 DEG C, ensures that steel pipe cooling temperature is heat-treated after less than 350 DEG C again simultaneously;

3. normalizing thermal treatment: owing to adopting microalloying, for ensureing the abundant solid solution of alloying element, adopting temperature to be 920 DEG C and carrying out normalizing thermal treatment.