CS215897B1 - Steel for nuclear reactor housings - Google Patents

Description

The present invention relates to radiation-resistant steels for the use of nuclear reactor housings used in the manufacture of water-conducting reactor housings and usable for the manufacture of other equipment whose material is exposed to neutron irradiation during operation.

Most preferably, the invention can be used to fabricate a large single power water reactor body.

Steels formerly used to manufacture atomic reactor bodies that have been worked for pressure vessels such as boiler shells, steam generator bodies and other similar devices that are not exposed to radiation during operation are known. However, the practice of operating these steels has shown that due to irradiation with a dose that exceeds the neutron area density of 2.0. IO ¹ · ^ N / cm, the temperature of irradiation is 290 ° C, the material becomes brittle reactor body while significantly decreasing impact resistance and increasing the transition temperature brittleness and toughness. These changes noticeably reduce the reliability and lifetime of nuclear reactor operation.

The known steel used for this purpose consists of: 0.06 to 0.15 wt. % carbon, 0.15 to 0.4 wt. % manganese, 0.1 to 1.0 wt. % silicon, 2.5 to 8 wt. % nickel, 0.25 to 1.25 wt. % molybdenum, 0.5 to 0.9 wt. %, up to 0.015 wt. % phosphorus, up to 0.015 wt. sulfur, up to 0.08 wt.%, aluminum, up to 0.006 wt. % nitrogen, up to 0.004 wt. oxygen and the rest is iron.

215 897

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However, this steel is only applicable at radiation doses up to 4. 10 ¹³ n / cm (E i 0.5

MeV).

The highest indicators show steel, which contains 0.13 to 0.18% by weight. % carbon, 0.3 to 0.6 wt. 0.15 to 0.3 wt. % of silicon, 1.0 to 1.6 wt.%, nickel, 1.6 to 2.5 wt.%, chromium, 0.5 to 0.7 wt. % molybdenum, 0.01 to 0.12 wt. % vanadium, 0.002 to 0.04 wt. % copper, 0.0005 to 0.009 wt. % antimony, 0.0005 to 0.009 wt. tin, 0.002 to 0.01 wt. % phosphorus, 0.001 to 0.01 wt. sulfur and the rest is iron.

This steel, as admixture, contains arsenic in an amount of from 0.004 to 0.02% by weight. The steel can be used with radiation dose 1. ΙΟ ^ θ n / cm ² (E ^ 0,5 MeV) at 300 to 350 ° C,

The drawback of this steel is its tendency to embrace by irradiation.

The main object of the invention is to provide a steel with increased radiation resistance, the use of which would ensure reliable operation of high-power nuclear water reactors of power plants whose bodies can be used at a temperature of 250 ° C to 350 ° C and radiation dose up to 2. 10 ² θ n / cm ² (E α, 0.5 MeV).

The problem was solved by forming steel on the atomic reactor bodies, consisting of 0.13 to 0.18% by weight. % carbon, 0.15 to 3 wt. % silicon, 0.3 to 0.6 wt. % manganese, 1.6 to 2.5 wt. 0.5 to 0.7 wt. % molybdenum, 0.01 to 0.12 wt. % vanadium, 0.0005 to 0.009 wt. % antimony, 0.0005 to 0.009 wt. The tin and the remainder are iron according to the invention, further comprising 1.0 to 2.0 wt. % nickel, 0.01 to 0.05 wt. % copper, 0.001 to 0.005 wt. % phosphorus and 0.0005 to 0.002 wt. arsenic, the total content of one part of phosphorus and five parts of arsenic being up to 0.01% by weight.

Chromium content from 1.6 to 2.5% by weight. in the steel according to the invention, it improves its hardenability, makes it possible to achieve uniformity of strength and ductility properties, increases impact toughness and decreases the temperature of brittleness and toughness transition.

Reduction of the astonishment content below 1.6% by weight. it does not make it possible to obtain the necessary complex mechanical properties of the steel, in particular the strength characteristics and the low critical embrittlement temperature. An increase in chromium contents above < 2.5 wt. is ineffective because complex carbides can be formed, which reduces the impact toughness value.

Chromium in fertilization with nickel and molybdenum allows to significantly increase the strength of steel. Accordingly, nickel in the range of 1.0 to 2.0 wt. and molybdenum from 0.5 to 0.7 wt.

The carbon content is from 0.13 to 0.18% by weight. can obtain steel with increased strength without lowering the critical embrittlement temperature and deteriorating the technological properties of forgings up to 650 m in thickness.

The silicon content of the steel in this range ensures both the complete deoxygenation of the steel and the production of a dense casting. An increase in the silicon content above 0.3 wt. in steel it can cause steel to become non-metallic inclusions and reduce its impact strength.

Vanadium content from 0.01 to 0.12 wt. it provides a fine-grained steel structure, which increases the impact strength of the steel and reduces the temperature of brittleness - toughness.

Arsenic content from 0.0005 to 0.002% by weight. % and phosphorus from 0.001 to 0.005 wt. % at a copper content of from 0.01 to 0.05 wt. it ensures high resistance of steel to radiation and at the same time high technological and operational properties of steel are obtained. The steel according to the invention has a given content of phosphorus and arsenic in this ratio. P + 5 As = 1. 10 wt. %.

The basic component of steel is iron. In addition to the aforementioned elements, the steel contains up to 0.010 wt. % sulfur, up to 0.009 wt. % antimony and up to 0.009 wt. tin,

The steel of the invention is melted in electric arc and Martin furnaces by known melting processes using increased purity batch materials. Deoxygenation of steel is usually carried out by the materials used in metallurgy.

In order to explain and confirm the invention, the table below gives examples of possible chemical composition of steel, the first three numbered examples being steel according to the invention and the fourth example comparing the known steel composition, also indicating the change in steel properties changing its chemical composition according to the invention.

Claims (1)

SUBJECT OF THE INVENTION Atomic reactor body steel, consisting of 0.13 to 0.18 wt. % carbon, 0.15 to 0.3 wt.%, silicon, 0.3 to 0.6 wt. % manganese, 1.6 to 2.5 wt. 0.5 to 0.7 wt. % molybdenum, 0.01 to 0.12 wt. % vanadium, 0.0005 to 0.009 wt. % antimony, 0.0005 to 0.009 wt. tin and the remainder being iron, further comprising 1.0 to 2.0 wt. % nickel, 0.01 to 0.05 wt. % copper, 0.001 to 0.005 wt. % phosphorus and 0.0005 to 0.002 wt. arsenic, the total content of one part of phosphorus and five parts of arsenic being not more than 0,01% by weight. h ⁷ 397 Chemical composition and radiation resistance of steels irradiated at a temperature of 250 to 290 ° C by a dose of radiation with a neutron area density of 2 n / cm ² (E = 0,5 MeV) -P O rM Pi <0 -P (0 P > Φ and t> 3 1 • P 09 / O ϋ eP Φ > R P rd O rP O Φ > R P toughness ° C O O H O (AND O CA Ή • P P O la O O 09 / Φ WHAT ř- fA CM O > R P 'Φ 1 1 1 + « N P P O > O Φ O rCj > N P O P O ia O O Φ O and? what <0 t * - rP m 1 1 1 1 P 1 O R PCO Φ WHAT 09 / > R P O 'what O ± 4 N CM CM H O ca 1 1 P Φ O O CM Φ >? · ' O O r · i rH 1 EH Ό ro H • • O «4 • r ~ c4 + LA 4k PM O TO CA σ \ ί- O O ο rH CM O O O O & O O O O it •to "to •to •to O O O O CM H H H O O O O R O O O O w r> * * * O O O O CM CM CM CM P O O O H O »» * » •to •to O O O O C*- <a H CQ O O H «1 O O O O O O O O O O O O rP CA ca ca O O O O H M fM O O O C P •to · » •to *to • P 03 / O O O O O P WHAT • P CM pH M · H O H O rH •O O 0 «4 •to "to Λ O O O O Φ r — 1 rH O O ř> O O H H • P Jd Κ » O O O O R CM b- P t- C*- k £> IA O *to •to •to "to rP írt & O O O O here 09 / & 00 CM M · LA O M * r-i CA έ? ·> AND "to rH rH H H L · - * d · R σ \ O σ> t- O •to * · * ·> H CM rH r4 r4 t- LA P M · Okay * O O O O CM LA LA <0 CM H CA CM • H ·, *. 4 » · * it O O O O what WHAT LA C- rH H H •to 9i •to O O O O O • • • • • KO CM <a