Structural steels for shipbuilding

The development of shipbuilding is closely connected with the creation of new advanced structural materials. First of all, they are high-strength weldable hull steels. The main requirements for them are high ductility and toughness, high brittle fracture resistance under static and dynamic loading, fatigue resistance, high general and stress corrosion resistance, good processability, including high weldability.

10ХСНД (D40, АБА) steels with yield strength of 390 MPa are the first Russian weldable hull steels. They are used in the welded hulls, including those of submarines and cruisers.

Russia’s experience in creating armored steels has shown that high strength and resistance to brittle fracture are achieved by increasing the carbon and alloying element contents. At the same time, for providing good weldability it is necessary to minimize the carbon and alloying element contents. The difficulty was to meet the contradictory requirements.

Fundamental research carried out by Russian scientists has shown that good weldability and high resistance to brittle fracture are possible only with the formation of a special structure, highly dispersed ferrite and pearlite, under special heat-treatment conditions. The best results are achieved by joint alloying low-alloy steel with chromium, nickel and molybdenum with modifying titanium, vanadium and aluminium additions.

Table 4

Characteristics	АБ2	АК25	HY80
Yield strength, Rp0.2, MPa Ultimate strength, Rm, MPa Elongation, A5, % Reduction in area, Z, % Impact energy, KV, J	590-715 637 18 55 78	590-740 640 16 50 63	562-668 — 20 20 40

The work on the subject resulted in creating АК25 steel, which is well-known nowadays. АК25 steel was successfully used in the construction of nuclear and diesel submarine hulls, nuclear-powered ice-breakers (the Lenin, the Rossia, the Sibir, etc.), hydroelectric power stations, and other structures.

In 1985–1990 they created improved АБ2 steel with higher weldability, cold resistance, plasticity. The steel shows the stability of properties and differs from its American analogue НY-80 in higher plasticity, toughness and weldability (see Table 4). Later on, they created higher-strength АБ3 steel (up to 800 MPa).

The new steels are successfully used in building ships and offshore facilities for extracting hydrocarbons, including those operating in the Arctic region. A high-priority task is to create even more economic and efficient steels on the basis of advanced achievements of physical metallurgy and use of nanotechnologies (see the diagram).

Provided by the Central Research Institute of Structural Materials “Prometey”, St. Petersburg.

Notes

stress corrosion – коррозия под напряжением

processability n – технологичность

weldability n – свариваемость

armored steel – броневая сталь

elongation n – относительное удлинение

reduction in area – относительное сужение

impact energy – работа удара

higher-strength steel – сталь повышенной прочности

offshore facilities – офшорные установки

high-priority task – первоочередная задача

physical metallurgy – металловедение

4.14. Translate the following sentences paying attention to the phrasal verbs in bold.

1. This problem was worked out by many scientists. 2. The coordinates of any point on the curve can be read off directly. 3. The experiment was carried out last year. 4. The research is being carried on. 5. This device is made up of the following parts. 6. The molten metal turned out to be contaminated with impurities. 7. At this stage we cannot go further into this rather secondary point. 8. Set out in the table are the results obtained. 9. This document has been drawn up this week. 10. Some impurities bring about detrimental effects. 11. Tsiolkovsky had not given up his idea about space travel.

4.15. One of the infinitive constructions is used with the subject and consists of three parts: the subject, the verb expressing someone’s opinion and the infinitive describing what happens with the subject. The verb may have a passive form. Such an infinitive construction is sometimes called Complex Subject.

For example:

The substance is said to be oxidized.

Говорят, что такое вещество окисляется.

Translate the sentences below in the same way.

1. The distribution of elements in nature is found to be very unequal. 2. You seem to have plenty of money. 3. You seem to have lost weight. 4. Mendeleev’s discoveries are known to have produced great changes in the field of chemistry. 5. Tom appears to be worried about. 6. He appeared to have been invited to the party. 7. This research is expected to be completed in time. 8. We are unlikely to go there this year. 9. He is heard to be singing. 10. She was said to be a good actress. 11. She was said to have been a good actress.

4.16. Test yourself. Choose the best answers from a­–d for the questions in the tests below.