SU834220A1 - Steel - Google Patents

Description

one

The invention relates to metallurgy, and more specifically to corrosion resistant steels for welded structures operating at 500-550 ° C.

Known steel containing, in weight,%

Carbon 0.15

Manganese 0.50

Chrome 4.5-6.0

Molybdenum Of 45-0,60

Iron Else 1.

However, this steel has poor weldability and is characterized by a considerable tendency to form cold cracks during welding. In addition, it also has an increased tendency to general corrosion and insufficient heat resistance at temperatures up to

Closest to the proposed technical essence and the achieved effect is steel containing, wt.%:

Carbon 0.01-0.09

Chromium 2.0-4.9

Manganese 1.8-3.0

Molybdenum 0.001 -0.5

Iron Else 2.

However, steel is known - has insufficient corrosion resistance: corrosion rate in IN solution

H2SQ4 + 15 g / l CuS04 at boiling point is 600. The values of impact toughness (ac) in the base metal, the weld zone and the heat-affected zone are respectively at 15.0, 16.0 and 11.5 kgm / cm, and at 8, 0, 5.0 and 3, 5 kgm / cm. When welding without preheating, cold cracks appear. The heat resistance of the known steel is also insufficient: the values of the temporal resistance at 20, 500, 550 and (after the preliminary tempering at

5 650 ° C 2 h) are respectively 55, 43, 35 and 20 kg / mm% and the values of the yield strength are 44, 36, 31 and 17 kg / mm, respectively.

0

The purpose of the invention is to increase the corrosion resistance and heat resistance with a sufficient level of weldability and resistance to brittle fracture.

five

To achieve this goal, steel containing carbon, manganese, chromium, molybdenum and iron additionally contains aluminum, cerium and. calcium with respect to the components

0 wt.%: 0.04-0.09 Carbon 1.8-3.0 Manganese 7.0-9.0 0.4-0.6 Molybdenum 0.1-0.3 Calcium 0.01-0, 06 0,01-0,06 Aluminum Rest Iron. Melting is carried out at 50 kg in an induction furnace. The ingots weighing 25 k are forged at a section of 40x150 mm, the forging is heated at IIOO-IISO C. Then a hot-rolling section of 10x200 is made with cooling in the air. Procave.t release at 650 ° C for 2 h, followed by cooling in air. In tab. 1 shows the chemical with tav steel laboratory heats. In tab. 2 shows the corrosion resistance data. As can be seen from Table 2, the corrosion rate for a total weight loss is 2.3 less for the proposed steel compared to the known one. The resistance to hydrogen sulfide cracking under a load of 0.8 of the yield strength for the proposed steel is 1.7 times higher than that of the known steel. The mechanical properties and results of long-term tests are given in Table. 3 Therefore, the proposed steel after tempering at 650 s for 2 h and cooling in air has the above strength properties Strength at 31, 21, 14 and above at test temperatures of 2 500, 550 and, accordingly, preserving the plastic properties at the level of values of known steel. Long-term tests are carried out firmly on the metal of melting of the optimum composition. Durability

Ta, blitz 1 of the proposed steel at operating temperatures of 500, 550, 600 ° C is 50, 30 and 20%, respectively, higher than the long-term strength of the known steel. The weldability tests of the proposed steel are carried out using process X-ray tests. Such a test makes it possible to judge the tendency to form cold cracks during welding. Welding is carried out semi-automatically in a protective environment (CO) at A, Up 20-218 at a speed of 11 m / h. Welding is carried out without preheating. There are no microcracks in the metal of the heat affected zone. In tab. Figure 4 shows the values of the impact toughness of a metal that is not subject to heat during welding and the metal of the heat affected zone. As can be seen from the table. 4, the impact strength of the metal outside the temperature range of the proposed and known steel is at the same level. However, when exposed to welding heat (in the thermal zone), the toughness of the known steel noticeably decreases, especially at negative temperatures, while the impact strength of the proposed steel in the thermal zone is neither at room temperature and, most importantly, at a lower temperature to maintain It is at a high level: 7.0 vs. 3.5 kgm / cm, respectively. High toughness values in the thermal zone provide high resistance to brittle failure of welded structures, which is of great importance in their manufacture.

Table. 2

Table 4

We offer:

bone and heat resistance while maintaining weldability and resistance to brittle fracture, it additionally jj contains aluminum, cerium and calcium in the following ratio of components, weight,%:

Carbon 0.04-0.09

Manganese 1.8-3.0

Sources of information taken into account in the examination

1. Steel is high alloyed and corrosion-resistant, heat-resistant and heat-resistant alloys. GOST-5632-72. Steel grade 15x5M.

2. Authors certificate of the USSR 536250, cl. C 22 C 38/38, 1977.

Claims (2)

Claim Steel containing carbon, manganese, chromium, molybdenum and iron, jq characterized in that, in order to increase corrosion resistance and heat resistance while maintaining weldability and resistance to brittle fracture, it additionally contains 35 aluminum, cerium and calcium in the following ratio of components, weight,%! Carbon 0.04-0.09 Manganese 1.8-3.0 Chrome Molybdenum Aluminum Cerium Calcium Iron Sources 7.0-9.0 0.4-0.6 0.01-0.06 0.01-0.06 0.1-0.3 The rest of the information taken into account during the examination 1. High alloy steels and corrosion-resistant, heat-resistant and heat-resistant alloys. GOST-5632-72. Steel grade 15x5M. 2. Copyright certificate of the USSR ”536250, cl. C 22 C 38/38, 1977.