Designation
Name |
The value |
Designation GOST Cyrillic |
250Х25Т |
Designation GOST Latin |
250X25T |
Transliteration |
250H25T |
By chemical elements |
250Cr25Ti |
Description
Cast iron 250Х25Т used: for the production of castings of parts operating under conditions of abrasive wear (sand and gravel pumps, hydrocyclones, classifiers, flotation machines, linings of mills, etc.), as well as in aggressive environments or at high temperatures (up to 1000°C).
Alloy 250Х25Т should be used for castings with wall thickness up to 30 mm simple configuration. Details a larger cross-section or complex shape, it is recommended to cast from alloy 250Х25Т in cases where they have a large amount of machining, including drilling, threading, milling.
When the parts in aggressive environments or at high temperatures should be preferred alloys 250Х25Т and 250Х25НТ with carbon on the bottom and chrome on the upper level.
Castings must allow for their application in macroclimatic regions with moderate and cold climate indoors (climatic version Y, CL, a resolution category 4 according to GOST 15150).
Note
Wear-resistant alloy (cast iron).
Standards
Name |
Code |
Standards |
Castings with special properties (iron and steel) |
В83 |
TU 48-0114-57-90 |
Chemical composition
Standard |
C |
S |
P |
Mn |
Cr |
Si |
Ni |
Fe |
Ti |
TU 48-0114-57-90 |
2.3-2.8 |
≤0.05 |
≤0.05 |
0.4-0.8 |
23-28 |
0.3-1 |
≤0.5 |
Rest |
0.1-0.2 |
Fe is the basis.
Technological properties
Name |
The value |
Particularities of production of goods |
Smelting can be done in induction and electrical arc furnaces with acid or basic lining. It is recommended that castings be annealed prior to mechanical processing and normalization (hardening in the air) before operating under conditions of abrasive wear. The recommended heat treatment regime: Annealing at 800 °C; the normalization with 1050-1100 °C. the hardness of castings in as-cast is 35 to 50 HRC after annealing HRC 28-33, after normalization 53-60 HRC. Profit casting should be done in private legkodelimae, with a supply of metal in the profit and calculate their normals for steel casting. |
Features of heat treatment |
The heating of the parts under heat treatment is conducted with an initial temperature not more than 200 °C at a speed of 60-70 °C per hour to 600 °C. At this temperature the cage is aged for 1-2 hours, then the heating rate can be increased to 100-150 °C per hour. At the maximum temperature of the heat treatment is aging at the rate of 1 hour for every 25 mm biggest casting thickness. Heating and holding furnace of the casting can be carried out by the regime of heat treatment of steel 110G13L (or with parts made of this steel) but with air cooling. With the normalization, it is recommended to remove items from the cart immediately after rolling it out of the oven, which allows to obtain the highest wear resistance. When annealing is the cooling of the casting with the furnace to 200 to 400 °C. |
Welding defects |
Corrections of defects by welding. Technology and welding conditions should guarantee the usefulness of fixed casting in their operating conditions. For the welding of working surfaces of parts the following are recommended types of electrodes (GOST 10051): EN-У30Х28С4Н4-50, AL-80Х4СГ, EN-У30Х25РС2Г-60, EN-У30Х23Р2с2ТГ-55. Wear parts castings can be brewed type electrodes EA-2 according to GOST 10052 or close to them in composition. |
Machinability |
Machining of castings may be made with any cutting tool. The coefficient of machinability after annealing to 4.0. |