CS199096B1 - Steel especially for reactors - Google Patents

Description

The invention relates to steel, in particular for reactors. The steels according to the invention can be used for the production of nuclear power and transport reactor bodies which operate at high pressure of the coolant.

For this purpose, it is known to use steel which contains 0.13% by weight. carbon, 0.15 to

0.30% wt. % silicon, 0.30 to 0.55 wt. % manganese, 1 to 1.5 wt. stroke, 1.0 to

1.6 wt. % nickel, 0.5 to 0.7 wt. % molybdenum, 0.01 to 0.10 wt. vanadium, 0.02 to

0.04 wt% cerium, and in equal amounts or below 0.020 wt% sulfur and phosphorus and the remainder iron. Such steel has high strength values, yield strength

However, it is prone to embrittlement due to neutron irradiation. The transition temperature 20 - 2 temperature Τ ^ of brittleness with total neutron count is about 1.10. cm increase by 120 to

160 ° C. Furthermore, it is impossible to produce components of such steel with a wall thickness of more than 400 mm due to insufficient turbidity depth.

It is also known for reactor steel containing 0.11 to 0.25% by weight carbon, 0.17 to 0.37% by weight silicon, 0.3 to 0.6% by weight manganese, 2 to 3% by weight, 6 to 0.8% by weight molybdenum, 0.25 to 0.35% by weight vanadium, at least 0.025% by weight sulfur and phosphorus and the remainder iron. Such an oeel has

199 096

199 096 high strength values with a yield point equal to or less than 539 MPa and good neutron radiation resistance. Increased brittleness transition temperature of 4? T? 60 ° C at a total neutron amount of about 1.0. 10 cm. Although it is possible to produce components with a wall thickness of not more than 400 mm from this steel, welding of these components is difficult, since it is not necessary to heat the steel up to a temperature of 300 to 350 ° C and then immediately temper it.

In addition to these steels, reactor steel is also known which contains 0.25% by weight carbon, 0.15 to 0.3% by weight silicon, 0.5 to 1.5% by weight manganese, 0.4 to 0.7% by weight % nickel, 0.45 to 0.6% molybdenum, 0.04% sulfur, 0.035% phosphorus, and the remainder being iron. This steel is characterized by good technology and weldability, but it does not have the required high strength - the yield point is equal to or below 343 MPa and embrittles under neutron irradiation when = 100 to 200 ° C with a total neutron amount of approx. IO ¹ cm @ ^-2.

Finally, a steel containing 0.20% by weight of carbon, 0.20-0.3% by weight of silicon, 0.4% by weight of manganese, 1.5-2.0% by weight of chromium, up to 4% by weight of nickel, 45 to 0.60% by weight of molybdenum, 0.03% by weight of vanadium, 0.02% by weight of sulfur and phosphorus and the remainder being iron.

This steel has great strength - the yield point is equal to or below 588 MPa, it has also high toughness and is easy to weld. However, it is susceptible to embrittlement by the action of thermal and radioactive rays, with an AT _fc = 100 to 150 ° C at a total TO -2 of neutrons of about 5. 10 .cm.

SUMMARY OF THE INVENTION It was an object of the present invention to provide a steel comprising such elements and in such a quantity as to increase the neutron irradiation resistance of the steel and increase its hardenability.

The problem has been solved and the aforementioned drawbacks of the known steels are overcome by the steel according to the invention, which is characterized in that the steel contains 0.12 to 0.20% by weight. % carbon, 0.15 to 0.37 wt. % silicon, 0.3 to 0.8 wt. % manganese, 1.6 to 2.7 wt. chromium,

0.8 to 2.0 wt. % nickel, 0.5 to 1.0 wt. % molybdenum, 0.05 to 0.15 wt. % vanadium, 0.002 to 0.08 wt. 0.01 to 0.10 wt. % copper, 0.0005 to 0.009 wt. % antimony, 0.0005 to 0.009 wt. % tin, 0.001 to 0.02 wt. %, 0.002 to 0.02 wt. phosphorus and the rest iron.

It is further preferred according to the invention that the total amount of antimony and tin in the steel is 0.001 to 0.01% by weight.

The steel according to the invention has a higher resistance to neutron radiation. At 300 ° C 20 ° -2 and total neutrons 1. 10 µm (E 0.5 MeV) the brittle transition temperature of the steel of the invention does not increase by more than 50 ° C. The steel according to the invention is intended for the production of components with a wall thickness of up to 650 mm and guarantees a breaking strength (Tg of at least 539 MPa at

199 096 at 350 ° C. The steel of the invention does not require immediate tempering after welding.

In the steels according to the invention, the iron content ranges from 92.862% by weight.

Total amounts of copper, antimony and tin achieve embrittlement resistance due to radioactive irradiation.

The carbon content of the steel is 0.12 to 0.20% by weight. At a carbon content of at least 0.12% by weight, a safe static strength of at least 607.6 MPa at 20 ° C is achieved. In order to maintain good weldability of the steel, the carbon content of the steel must not exceed 0.20% by weight. Silicon and manganese are used in a quantity that allows excellent steel soothing. The upper limit of the content of these elements is limited by the indicated values, otherwise the toughness of the steel would decrease.

Due to the chromium contained in the steel in an amount of at least 1.6% by weight, the required strength and toughness of the steel up to 650 mm in thickness was achieved. Due to the chromium content up to 2.7% by weight, good weldability of this steel is also guaranteed.

Nickel is added to the steel as an element that greatly increases the hardenability and toughness of the steel. However, the nickel content of the steel must not exceed 2.0% by weight in order to avoid the harmful effect of nickel on the resistance of the steel to radiation.

The molybdenum content of the steel according to the invention is given in a range which guarantees that the tempering brittleness does not occur in the steel and the depth of hardenability of the steel increases, which is necessary to achieve high strength and plasticity.

Vanadium is added to the steel as an element that affects the fine grain structure of the structure, the nitrogen bond and the increase in the tempering resistance of the steel. The upper limit of the content of this element in the steel is defined by 0.15% by weight in order to maintain good weldability of the steel.

The line is then used to improve the formability of the steel when forging and rolling large steel blocks. The upper limit of this element in steel is limited by 0.08% by weight due to the risk of steel being contaminated with cerium oxides, thereby deteriorating the formability of the steel and promoting the formation of caries in the steel.

The sulfur and phosphorus content within the specified limits β with respect to the content of other elements contributes to a further increase in steel toughness.

The steel according to the invention is produced in blocks of up to 160 tons and can be used as forgings or steel sheets. After quenching and tempering, steel with a thickness of up to 650 mm has the following guaranteed strength values: at 20 ° C yield strength & 539 MPa, static strength G * _B - 607.6 MPa, elongation - 15 St, relative taper of cross-section at V - 55 »; at 350 ° C, G _T - 441 MPa, & _g - 539 MPa, <T * 14%,

V - 50%.

These steels were used for automatic, manual and electro-electric welding.

This steel also did not require immediate tempering after welding and heating for anticorrosive surfacing.

The brittleness transition temperature, which was established on Charpy V-Notched specimens at 47 Pa, was not less than 40 ° C by default, with an increase in post-irradiation transition temperature at 275 to 320 ° C and neutron flux values below following:

1Ů ¹⁹ n / cm ² < 20 ' 10 ¹⁹ 30 ' 10 ²⁰ _ < 50 ’

At these transition temperature values, the steel of the present invention fully complies with the radioactive embrittlement resistance requirements set forth in the regulations on the calculation of strength of thick-walled tanks in nuclear power generating installations. According to these requirements, the use of the steel according to the invention guarantees the safe operation of pressure tanks in pressurized water reactors for at least 30 years οθ .o with a total amount of neutrons on the pressure vessel wall of at least 1. 10 cm.

Example 1

The following weight percent steel was tested: Carbon 0.12; silicon 0.27; Manganese 0.48; chrome 2.47; nickel 1.14; molybdenum 0.56; vanadium 0,12; cerium after 0.01; sulfur 0.011; phosphorus 0,009; me3 0.03; antimony 0.001; tin 0.002; the rest iron.

After heat treatment under conditions that simulated quenching and tempering to increase the hardenability of the 650 mm steel, the yield point was at room temperature (Tj = 578.18 MPa).

The brittleness transition temperature = -90 ° C was determined for samples of 5 x 5 x x 27.5 mm with a 1 mm deep V-slot.

After neutron irradiation at a total amount of neutrons 9,7 · Io ^ ^-9 cm ^"2 (E ® about 5 MeV), at a temperature of 275 to 320 ° C, the transition temperature is not increased more than about 10 ° C.

Example 2

The steel tested contained the following elements in weight percent: carbon 0.12, silicon 0.27, manganese 0.48, chromium 2.47, nickel 1.14, molybdenum 0.56, vanadium 0.12, 0.01 calculated cerium , sulfur 0.011, phosphorus 0.009, me3 0.06, antimony 0.001, tin 0.002, the rest iron.

For heat treatment under conditions simulating quenching and tempering, increasing the hardenability by a steel thickness of 650 mm, this steel had a yield point at room temperature (5 * _T = 575.26 MPa. Transition temperature, found on samples of 5 x 5 x 27, 5 mm, was = -90 [deg.] C. After irradiation at a total neutron count of 9.7 * 10 &lt; ¹⁹ &gt; ^-2 at 275-320 [deg.] C, the transition temperature increased by no more than 10 [deg.] C.

Example 3

Steel containing the following elements in weight percent was tested: carbon 0.12, silicon 0.27, manganese 0.48, chromium 2.47, nickel 1.14, molybdenum 0.56, vanadium 0.12, sulfur 0.011, phosphorus 0.009 , me3 0.08, antimony 0.001, tin 0.002, 0.01 calculated line, iron remainder. After heat treatment of the steel sample under conditions simulating quenching and tempering, increasing the hardenability of the 650 mm steel, the steel had a yield point = 584.08 MPa at room temperature. The brittle transition temperature T _fc was measured for samples of 5 x 5 x 27.5 mm with a 1 mm deep V-slot, and was -90 ° C. After irradiation at a total neutron count of 9.7 · 10 ¹ cm ^-1 (E - 0.5 MeV) at a temperature of 275 to 320 ° C, the transition temperature did not increase by more than 10 ° C.

Example 4

The following percentages of steel were tested: carbon 0.12, silicon 0.27, manganese 0.48, chromium 2.47, nickel 1.14, molybdenum 0.56, vanadium 0.12, sulfur 0.011, phosphorus 0.009, me3 0.08, antimony 0.007, oine 0.002, conversion line 0.01, the rest iron. After heat treatment of the steel sample under conditions simulating quenching and tempering, increasing the hardenability of the steel of 650 mm thickness, the steel had a yield point = 597.02 MPa at room temperature of 20 ° C. The brittle transition temperature was measured for samples of 5 x 5 x 27.5 mm with a 1 mm deep V-slot and was = -80 ° C.

After irradiation at a total neutron count of 9.7. IO ¹ cm @ ^-2 (E - 0.5 MeV), at 275 to 320 ° C, the transition temperature increased to 30 ° C.

Example 5

Steel containing the following elements in weight percent was tested: carbon 0.12, silicon 0.27, manganese 0.48, chromium 2.47, nickel 1.14, molybdenum 0.56, vanadium 0.12, sulfur 0.011, phosphorus 0.009 , me3 0.08, antimony 0.007, oine 0.009, 0.01 calculated eye, iron remainder. After heat treatment of samples of this steel under conditions simulating quenching and tempering, increasing the hardenability of this steel with a thickness of 650 mm, the steel had a yield point = 584.08 MPa at room temperature of 20 ° C. The transition temperature of brittleness, as measured on 5 x 5 x 27.5 mm specimens with a 1 mm deep V-slot, was T _to »-80 ° C. After irradiation with a total quantity of 9.7 neutrons ^«1 IO ^ cm ^<2 (E 0.5 MeV 2) at 275 to 320 ° C increased the transition temperature of 40 ° C.

Example 6

The following composition was tested in percent by weight. Carbon 0.17, silicon 0.21, manganese 0.34, chromium 1.87, nickel 1.67, molybdenum 0.82, vanadium 0.08, sulfur 0.013, phosphorus 0.008, me3 0.02, antimony 0.001, tin 0.001, the correction line 0.001, the rest iron. After heat treatment of the steel sample under conditions simulating quenching and tempering, increasing the hardenability, of a steel having a thickness of 650 mm, the steel had a yield point = 603.68 MPa at room temperature of 20 ° C. Transient brittleness temperature found in samples

190 096 with dimensions of 5 x 5 x 27.5 mm and with a 1 mm deep V-slot, ^T k ⁼ "HO ° 0". irradiation at a total neutron count of 1.2. 1Ο θ ² cm ^"2 at a temperature from 285 to 310 ° C transition temperature remained unchanged.

Example 7

Steel containing the following elements in weight percent was tested: carbon 0.17, silicon 0.21, manganese 0.34, chromium 1.87, nickel 1.67, molybdenum 0.82, vanadium 0.08, sulfur 0.013, phosphorus 0.008, MS3 0.02, antimony 0.008, tin 0.002, cerium after conversion 0.01, the rest iron.

After heat treatment of the steel sample under conditions which simulated quenching and tempering, increasing hardening, a steel of 650 mm thickness, the steel had a yield strength * 3 = = 614.46 MPa at room temperature of 20 ° C. The transient brittleness temperature, as measured on 5 x 5 x 27.5 mm samples with a 1 mm deep V-slot, was = -100 ° C. After irradiation at a total neutron count of 1.2. 10 ² θ cm ^-2 at 285 to 310 ° C, the recycle temperature was 20 ° C higher.

Example 8

Steel containing elements in weight percent was tested: carbon 0.17, silicon 0.21, manganese 0.34, chromium 1.87, nickel 1.67, molybdenum 0.82, vanadium 0.08, sulfur 0.013, phosphorus 0.008 , currency 0.02, antimony 0.008, tin 0.007, cerium for conversion 0.01, the rest iron. After heat treatment of the steel sample under conditions simulating quenching and tempering, increasing hardening, steels with a thickness of 650 mm, this steel had a yield strength of &lt; 618.38 MPa at room temperature. Brittleness transition temperature, measured on samples measuring 5x5x27,5mmee V-grooves, 1 mm deep, amounted _to T = -90 ° C. After irradiation at a total neutron count of 1.2. 10 ²⁰ cm ** ² at 285 to 310 ° C, the transition temperature increased by 20 ° C.

Example 9

Steel containing the following elements in weight percent was tested: carbon 0.17, silicon 0.21, manganese 0.34, chromium 1.87, nickel 1.67, molybdenum 0.82, vanadium 0.08, eir 0.013, phosphorus 0.008, me3 0.10, antimony 0.008, tin 0.007, cerium after conversion 0.01, the rest iron. After heat treatment of a sample of this steel under conditions simulating quenching and tempering, which increases the hardening, of a steel having a thickness of 650 mm, the steel had a yield point of 619.36 MPa at room temperature. The transition temperature of brittleness, as measured on 5 x 5 x 27.5 mm samples with a 1 mm deep V-slot, was = -90 ° C. After irradiation at a total neutron count of 1.2. 10 ²⁰ cm- ² at 285-310 ° C the transition temperature was 30 ° C higher.

Example 10

Steel containing the following elements by weight prooenteoh was tested: carbon 0.18, silicon 0.32, manganese 0.55, chromium 2.31, nickel 1.19, molybdenum 0.70, vanadium 0.06, sulfur 0.007, phosphorus 0.011, me3 0.06, antimony 0.002, tin 0.0005, era after conversion 0.02, the rest iron. After heat treatment of the steel sample under conditions simulating quenching and tempering which increases the hardening of the steel of 650 mm thickness, the steel exhibited a yield point (5 ^ = 571.72 MPa) at room temperature. 5 x 5 x 27.5 mm with a 1 mm deep V-slot was = -80 ° C. After irradiation at a total neutron count of 1.2. 10 ² ® cm ² at 285 to 310 ° C, the transition temperature increased by 10 ° C.

Example 11

A steel consisting of the following elements in weight percent was tested: carbon 0.18, silicon 0.32, manganese 0.55, chromium 2.31, nickel 1.19, molybdenum 0.70, vanadium 0.06, sulfur 0.007 , phosphorus 0.011, me5 0.06, antimony 0.002, tin 0.004, cerium after conversion 0.02, the rest iron. After heat treatment of the steel sample under conditions which simulated quenching and tempering increasing the hardening of the steel having a thickness of 650 mm, the steel had a yield point at the room temperature of Cyt = 581.53 MPa. The transition temperature of brittleness, based on 5 x 5 x 27.5 mm samples with a 1 mm deep V-slot, was _Tfc -80 ° C. After irradiation at a total neutron count of 1.2. 10 ² ® cm ² at 285 to 310 ° C, the transition temperature did not increase by more than 10 ° C.

Example 12

Steel containing the following elements in weight percent was tested: carbon 0.18, silicon 0.32, manganese 0.55, chromium 2.31, nickel 1.19, molybdenum 0.70, vanadium 0.06, cerium after conversion of 0 02, sulfur 0.007, phosphorus 0.011, mes 0.06, antimony 0.007, tin 0.004, the remainder iron. After heat treatment of the steel sample under conditions simulating quenching and tempering increasing the hardening of the steel having a thickness of 650 mm, the steel had a yield point = 567.80 MPa at room temperature. The transition temperature of brittleness, as measured on 5 x 5 x 27.5 mm samples with a 1 mm deep V-slot, was = -80 ° C. After irradiation at a total neutron count of 1.2. 10 ² ® cm ² at 285 to 310 ° C, the transition temperature increased by 30 ° C.

Example 13

Steel containing the following elements in weight percent was tested: carbon 0.18, silicon 0.32, manganese 0.55, chromium 2.31, nickel 1.19, molybdenum 0.70, vanadium 0.06, cerium after conversion of 0 02, sulfur 0.007, phosphorus 0.011, currency 0.06, antimony 0.007, tin 0.008, the rest iron. After heat treatment of this steel under conditions simulating hardening and tempering, which increased the hardening, of a steel having a thickness of 650 mm, the steel had a yield point <5 = = 570.74 MPa at room temperature of 20 ° C. The transition temperature of the brittleness found on the 5 x 5 x 27.5 mm samples with a 1 mm deep V-slot was T _k = -80 ° C. After irradiation at a total neutron count of 1.2. 10 ²⁰ OM ^"2 at a temperature from 285 to 310 ° C, the transition temperature increased to 50 ° C.

Claims (2)

OBJECT OF THE INVENTION 1. Steel, in particular for reactors, characterized by a buffer, comprises 0.12 to 0.20% by weight of carbon, 0.15 to 0.37% by weight of silicon, 0.3 to 0.8% by weight of manganese, 1.6 to 2.7 wt% chromium, 0.8 to 2.0 wt% nickel, 0.5 to 1.0 wt% molybdenum, 0.05 to 0.15 wt% vanadium, 0.002 to 0.08 wt% cerium, 0 0.01 to 0.10 weight percent, 0.0005 to 0.009 weight percent antimony, 0.0005 to 0.009 weight percent tin, 0.001 to 0.02 weight percent sulfur, 0.002 to 0.02 weight percent phosphorus, and the remainder is iron . 2. Steel according to claim 1, characterized in that the total amount of antimony and tin is 0.001 to 0.01% by weight.