Boiler steel 20CrMoVTiB4-10, 1.7729 chromium-molybdenum-vanadium temperature with titanium and boron addition for turbine parts according to PN-EN 10269 norms.

 

Standards Steel Grades
Chemical Composition %
C: Mn: Si: P: S: Cr: Mo: Ni: V: Ti: Al: Cu: As: B: Sn: W:
PN 20HMFTB
0.17 - 0.24 <0.50 <0.35 <0.03 <0.03 0.9 - 1.4 0.8 - 1.1 <0.5 0.7 - 1.0 0.05 - 0.12 - - - <0.005 - -
IS 20CrMoVTiBH
0.17 - 0.24 <0.50 <0.35 <0.03 <0.03 0.9 - 1.4 0.8 - 1.1 <0.5 0.7 - 1.0 0.05 - 0.12 - - - - - -
EN 20CrMoVTiB4-10 - 20 CrMoVTiB 4-10 - 20CrMoVTiB5.10 - 1.7729
0.17 - 0.23 0.35 - 0.75 <0.40 <0.02 <0.02 0.9 - 1.2 0.9 - 1.1 <0.2 0.6 - 0.8 0.07 - 0.15 0.015
0.08
<0.2 <0.02 0.001 - 0.01 <0.02 -
GOST 20Ch1M1F1TR - 20Kh1M1F1TR - EP182 - 20Х1М1Ф1ТР - ЭП182
0.17 - 0.24 <0.50 <0.37 <0.03 <0.03 0.9 - 1.4 0.8 - 1.1 <0.3 0.7 - 1.0 0.05 - 0.12 - <0.2 - <0.005 - <0.2
BS 681-820
0.17 - 0.23 0.35 - 0.75 0.10 - 0.35 <0.02 <0.02 0.9 - 1.2 0.9 - 1.1 <0.2 0.6 - 0.8 0.07 - 0.15 <0.08 <0.2 <0.02 0.001 - 0.01 <0.02 -

 

20CrMoVTiB4-10, 1.7729 - boiler steel

20CrMoVTiB4-10 steel belongs to the group of titanium and boron modified pearlitic boiler steels. It is characterized by high relaxation and creep resistance, and low sensitivity to notch action.

Boron addition improves relaxation properties. 20HMFTB steel products are used in a heat-treating state, where after heat treatment they exhibit a sorbitol-peroxide structure with carbides.

This grade is not recommended for use where the yield point exceeds 80 kG/mm2. 20CrMoVTiB4-10 products are used at operating temperatures of 20 ℃ to 550 ℃ for turbine couplings such as screws.


Mechanical properties of 20CrMoVTiB4-10 / 20HMFTB steel

Strength properties for dimensions < 200 mm
Tensile strength Rm > 785 MPa
Yield point Re 667 - 765 MPa
Elongation A5 > 15%
Contraction Z > 45%
Impact resistance KCU2 > 49 J
Hardness HB 241 - 269 HB

 


Yield limits of thermally improvemed 20CrMoVTiB4-10 bars at varied temperatures

Re values at particular temperatures
Temperatures 20℃ 50℃ 100℃ 150℃ 200℃ 250℃ 300℃ 350℃ 400℃ 450℃ 500℃ 550℃ 600℃
Yield point MPa 647 662 657 637 613 598 588 588 583 569 534 490 427

 


Creep limit R1 and creep strength R2 of 1.7729, 20CrMoVTiB4-10 steel in tempered condition

Properties specified in the MPa Approximate properties at temperatures
520℃ 530℃ 540℃ 550℃ 560℃ 570℃
Creep limit R1/10000 302 287 273 259 248 237
R1/100000 243 233 226 218 210 203
Creep resistance Rz/10000 329 314 298 281 267 252
Rz/100000 279 265 252 240 229 220

 


Heat treatment of 20CrMoVTiB4-10, 1.7729 steel

Heat treatment
Heat treatment type Cooling type Temperatures
Normalization - 1050 - 1100℃
Hardening in air 950 - 1000℃
in oil 980 - 1050℃
Tempering in air 660 - 730℃

 


Welding, cutting and gouging of 20CrMoVTiB4-10, 1.7729 steel

Steel 20CrMoVTiB4-10, 1.7729 should not be welded. The exceptional joining process is bonding, which, despite being limited, can be frictional or electrically resistive with proper bonding and heat treatment parameters.

Materials can be cut with propane-butane-oxygen flame, acetylene-oxygen flame, or plasma arc. Before you start cutting, you must preheat to:

<50mm

- 350 - 400℃ with dimensions >50mm

In the case of gas cutting, the temperature of the lower limits should be chosen. When performing plasma cutting, use the heating temperatures of the upper limits of the range given above. After cutting, the product should be slowly cooled to ambient temperature together with the oven, hot sand or asbestos mat.

In addition, steel can be arc-air electrode deseamed or flame gouged. Before the process, the products must be heated to the cutting temperature, and also cooled down to ambient temperature. After the process, appropriate thermal processes must be performed, however, this does not guarantee the possibility of cracking on the grooved surfaces, especially in arc-air electrode deseaming.


In the 20CrMoVTiB4-10 grade Virgamet provides:

 


List of equivalents and other determinations of 20HMFTB steel:

20CrMoVTiBH, 20CrMoVTiB4-10, 20 CrMoVTiB 4-10, 20CrMoVTiB5.10, 25CrMoVB6.11, 1.7729, 20Ch1M1F1TR, 20Kh1M1F1TR, EP182, 20Х1М1Ф1ТР, ЭП182, BS 681-820


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