Low carbon structural steel 15X25T alloyed with chrome and titanium (EI439, X25T)

Thermocouple covers, det. furnace arm up to 1000 deg., electrodes of spark plugs, tubes of heat exchangers, pyrolysis plants in aggressive environments up to 350 deg.

for welded structures that are not exposed to shock loads at operating temperatures from -20 ° C to 1100 ° C. Pipes for heat exchangers operating in aggressive environments. Equipment, parts, thermocouple covers, spark-ignition spark electrodes, heat exchangers .; ferritic steel

Classification

Country	Section	Category
CIS, Russia, Ukraine	Corrosion-resistant alloys and steels	Corrosion-resistant heat-resistant steel

Chemical composition

Standard	Fe, %	Si, %	Mn, %	Cr, %	P, %	C, %	S, %
GOST 5632-72	70.99–76	< 1	< 0.8	24–27	< 0.035	< 0.15	< 0.025

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Physical characteristics

Temperature, °C	$$E\cdot 10^{9}$$, $$MPa$$	$$\alpha\cdot 10^{6}$$, $$K^{-1}$$	$$\varkappa$$, $$\frac{W}{m\cdot K}$$	$$\rho$$, $$\frac{kg}{m^3}$$	$$c\cdot 10^{-3}$$, $$\frac{J}{kg\cdot K}$$	$$R\cdot 10^{-6}$$, $$\Omega\cdot m$$
20	204		17	7600		0.71
100	200				0.462
200	197	10
300	189	10.6
400	176	10.8
500	164	11.3
600	140	11.5
700	124	11.6
800	119	11.6
900	109	12.2

Mechanical properties at 20 °C

Rolling	Standard	$$\sigma _{U}$$, $$MPa$$	$$\sigma_{P}$$, $$MPa$$	$$\epsilon_L$$, %	$$\psi$$, %	$$KCU\cdot 10^{3}$$, $$\frac{J}{m^2}$$	Treatment
Pipes are coldly deformed.	GOST 9941-81	461		17
Pipes are hot deformed.	GOST 9940-81	441		17
Rod	GOST 5949-75	440	295	20	45
The plates	GOST 7350-77	440		14		200	Annealing
Sheet	GOST 5582-75	530		17			Annealing 740-780 ° C

Brinell hardness number

Rolling	Standard	Classifiers	Value, HBW
Hire	GOST 5949-75	raw, rolling, Transverse	230–270

Technological Properties

Weldability	Flake Susceptibility	Propensity to temper brittleness
Difficult to weld	insensitive	inclined

Analogues

USA	Germany
446	1.4746 (X8CrTi25)
	сталь X8CrTi25

Standards

Standard	Description
GOST 5632-72
GOST 5949-75
GOST 5582-75
GOST 7350-77
GOST 9940-81
GOST 9941-81

Description of chemical elements

Element	Units of measurement	Description
Fe	%	Iron
Si	%	Silicon
Mn	%	Manganese
Cr	%	Chrome
P	%	Phosphorus
C	%	Carbon
S	%	Sulfur

Description of physical characteristics

Parameter	Units of measurement	Description
$$E\cdot 10^{9}$$	$$MPa$$	Elastic modulus
$$\alpha\cdot 10^{6}$$	$$K^{-1}$$	Coefficient of thermal (linear) expansion (range 20°C–T)
$$\varkappa$$	$$\frac{W}{m\cdot K}$$	Coefficient of thermal conductivity (the heat capacity of the material)
$$\rho$$	$$\frac{kg}{m^3}$$	The density of the material
$$c\cdot 10^{-3}$$	$$\frac{J}{kg\cdot K}$$	The specific heat of the material (range 20°C–T)
$$R\cdot 10^{-6}$$	$$\Omega\cdot m$$	Electrical resistivity

Description of mechanical properties

Parameter	Units of measurement	Description
$$\sigma _{U}$$	$$MPa$$	Ultimate tensile strength
$$\sigma_{P}$$	$$MPa$$	Proportionality limit
$$\epsilon_L$$	%	Elongation at break (longitudinal)
$$\psi$$	%	Reduction in cross section on fracture
$$KCU\cdot 10^{3}$$	$$\frac{J}{m^2}$$	Impact toughness

Designation of types of weldability

Parameter	Units of measurement	Description
no limits		Welding is performed without heating and without subsequent heat treatment
Boundedly welded		Welding is possible with heating up to 100–120 °C and subsequent heat treatment
Difficult to weld		For obtaining quality welded joints, additional operations are required: heating up to 200–300 °C for welding, heat treatment after welding — annealing
Not applicable for welded structures