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Alloy CrN78T

X27YU5T CRN70VMTUF CHN78T CRN70VMYUT CHN80TBU CRN35VT CHN70U CRN35VTU CHN77TUR 20X23H18 31Х19Н9МВБТ 40Х13 20Х13 20X25H20C2 40Х15Н7Г7Ф2МС 10X23H18 12Х25Н16Г7АР 15X12VNMF 20Х20Н14С2 37X12H8G8MFB 40X9C2 20X23H13 30Х13 40CR10CR2M 45Х14Н14В2М 13Х11Н2В2МФ

Alloy CrN78T

Alloy CrN78T: Handbook of steels and alloys. Below is systematized information on the purpose, chemical composition, types of supply, substitutes, critical point temperature, physical, mechanical, technological and foundry properties for the grade — Alloy CrN78T.

General information on CrN78T alloy

The substitute for the following grades
of steel grades: 12Х25Н16Г7АР, 20Х23Н18.
Delivery type
CrN78t pipe, CrN78t wire, CrN78t thin sheet: GOST 24982−81. Forgings and forged blanks: GOST 25054−81.
Application
Bar parts, tubes operating to a temperature of 1100 ° C.

Chemical composition of the alloy CrN78T

Chemical element %
Aluminum (Al), not more 0.15
Iron (Fe), not more than 1.0
Silicon (Si), not more than 0.8
Manganese (Mn), not more than 0.7
Copper (Cu), not more than 0.07
Sulfur (S), not more than 0.1
Titanium (Ti) 0.15−0.35
Carbon ©, not more than 0.12
Phosphorus (P), not more 0.015
Chrome (Cr) 19.0−22.0

Mechanical properties of CrN78T alloy

Heat treatment, delivery condition Section, mm t test,°C σ0, 2, MPa σB, MPa δ5, % ψ, % HB
Forgings. 980−1020°C hardening, water or air. 1000 20 196 588 25 35 200
Sheet. Tempering 980−1020°C, water, water shower or air <3,9 20   860 35    
Sheet. Tempering 980−1020°C, water, water shower or air <3,9 800   175 45    

Mechanical properties at elevated temperatures

t test,°C σ0, 2, MPa σB, MPa δ5, % ψ, %
Sheet. Hardening 980−1020°C, air
20 270 760 40  
400 245 670 40  
500 245 610 40  
600 205 590 40  
700 185 390 35  
800 93 180 70  
900   110 90  
1000   64 100  
1100   44 112  
1200   24 130  
Sample dmameter 10 mm, length 50 mm, rolled and tempered. Deformation rate 20 mm/minute. The strain rate is 0.007 1/s.
800 315 380 72 47
900 195 215 45 84
1000 100 110 64 93
1100 76 88 70 97
1200 42 54 92 100

Mechanical properties depending on heat treatment

Heat treatment, delivery condition σ0, 2, MPa σB, MPa δ10, %
Sheet thickness 1.3−1.5 mm. Tempering at 1200 °C, air.
Without tempering 170 600 38
Heat soaking 3000 h, 700°C 170 550 35
Heat soaking 3000 h, 800°C 150 590 38
Heat soaking 3000 h, 900°C 140 550 33
Heat soaking 3000 h, 1000°C 170 510 34
Sheet thickness 1.3−1.5 mm. Tempering at 1200 °C, air (cross-sectional samples)
Without holding time 170 520 40
Heat soaking 3000 h, 700°C 180 600 39
Heat soaking 3000 h, 800°C 160 550 37
Heat soaking 3000 h, 900°C 150 550 31
Heat soaking 3000 h, 1000°C 180 475 38

Mechanical properties in the long term strength test

Creep limit, MPa Creep rate, %/h t test,°C Ultimate long-term strength, MPa Test duration, h t test, h
      103 1/100 700
      27−44 1/100 800
      15−18 1/100 900
      154 1/1000 550

Technological properties of CrN78T alloy

Forging temperature
Beginning 1220, ending 850. Sections up to 300 mm are cooled in stacks in the air.
Weldability
Hardly weldable. Welding method — RTD electrodes TsT-22.
Machinability by cutting
In the heat-treated condition at HB 156 and σB = 710 MPa Kυ dv.spl. = 0,5, Kυ b.st. = 0,3.

Endurance limit of alloy CrN78T

σ-1, MPa n
216 1Е+7

Heat resistance of CrN78T alloy

Medium Temperature,°C Depth, mm/year Resistance group or grade
Air 1000 0,332 6
Air 1100 0,618 Reduced-resistant
Air 1200 1,082 Low resistant

Physical properties of CrN78T alloy

Test temperature,°C 20 100 200 300 400 500 600 700 800 900
Modulus of normal elasticity, E, GPa 224 219 213 206 200 193 184      
Alloy density, pn, kg/m3 8400 8380 8340 8310 8260 8220 8180 8130 8090 8040
Thermal conductivity coefficient W/(m — °C) 14 15 17 19 20 21 23 24 25  
Electrical resistivity (p, nominal value — m) 1090 1099 1108 1117 1127 1153 1135 1126 1123  
Test temperature,°C 20−100 20−200 20−300 20−400 20−500 20−600 20−700 20−800 20−900 20−1000
Coefficient of linear expansion (a, 10−6 1/°C) 11.8 12.8 12.8 14.4 14.8 15.8 16.1 16.5