X8CrNi25-21 1.4845 BS-EN-10095-1999
Austenitic heat-resisting steels
Steel designation
Name：X8CrNi25-21
Number：1.4845
X8CrNi25-21 1.4845 Chemical composition
C：max.0.10
Si: max.1.50
Mn(max):2.00
P(max):0.045
S(max):0.015
Cr:24～26
Ni:19.00～22.00
N:. max.0.11
X8CrNi25-21 1.4845 Mechanical properties at room temperature
Form: bars
Thickness a or diameter(d:mm): a ≤160
HB max.:192
Proof strength: Rp0,2N/mm² (min):210
Rp1,0N/mm²(min):250
Tensile strength （Rm N/mm²）:500～700
A % min
Long product:35
Flat products:（1）0,5≤a<3：（1，tr）：33 （2）3 < a （1|tr）: 35
Heat treatment
Symbol: +AT (A T=solution annealed)
Temperature(℃):1050～1150
Type of cooling: water, air, cooling sufficiently rapid
Maximum application temperature Ta for air
Ta max(℃):1050
(The loss of metal caused by scaling does not exceed 1 g/m2⋅h at Ta, and does not exceed 2 g/m2 at Ta + 50 ℃ on average for a period of 120 h with four intermediate coolings.)
Creep properties
Estimated average value of the strength for 1 % elongation at elevated temperature (Strength in N/mm2)
Elongation 1 % in 1 000 h:
600℃:100
700℃:45
800℃:18
900℃:10
Elongation 1 % in 10 000 h:
600℃:90
700℃:30
800℃:10
900℃:4
Estimated average value of the strength for rupture at elevated temperature
(Strength in N/mm2)
Rupture in 1 000 h:
600℃:170
700℃:80
800℃:35
900℃:15
Rupture in 10 000 h:
600℃:130
700℃:40
800℃:18
900℃:8.5
Rupture in 100 000 h:
600℃:80
700℃:18
800℃:7
900℃:3
Physical properties for the steels and nickel alloys
Density(kg/dm2):7.9
Linear expansion coefficient (10⁻⁶K⁻¹): between 20℃ and
200℃:15.5
400℃:17.0
600℃:17.5
800℃:18.5
1000℃:19.0
Thermal conductivity
W/(m.K)
at 20℃: 15
at 500℃：19
Specific heat capacity
kJ(kg.k)
at 20℃：0.50
Electrical resistivity
Ω.mm²/m
at 20℃：0.85
Magnetizability：no (slightly magnetic when cold worked)