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heat-resistant

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welded tube, not annealedRO.

Stainless steel tubes round welded special materials heat-resistant

Stainless steel tubes round welded special materials heat-resistant Product specification

welded tube, not annealed DIN 2463/17457

Pipes made of austenitic, heat-resistant steels

Heat-resistant steels were specially developed for use at high temperatures.

In the form of pipes, they are used in the construction of heat exchangers, for example.

Characteristics of heat-resistant steels

Heat-resistant steels are steels possessing good mechanical properties for short and long-term

loading due to their higher alloy content of chromium, nickel, silicon, and aluminium and with special

resistance to the effects of hot gases and combustion products as well as molten salt and metal at

temperatures above approximately 550°C. The level of their resistance depends enormously on the

reaction conditions and cannot be determined using any test method.

Scaling Resistance in the Air

Table 1

Type of Steel	Material	Temperature*
X12 CrNiTi18 9	1.4878	850°C
X15 CrNiSi 20 12	1.4828	1000°C
X 12 CrNi 25 21	1.4845	1050°C
X 15 CrNiSi 25 20	1.4841	1150°C
X 10 NiCrAlTi 32 20	1.4876	1100°C

Chemical Composition

Table 2

Material	C %	Si %	Mn max.	P max	S max	Al %	Cr %	Ni %
1.4878	≤0.12	≤1.0	2.0	0.045	0.030		17.0-19.0	9.0-12.0
1.4828	≤0.20	1.5-2.5	2.0	0.045	0.030		19.0-21.0	11.0-13.0
1.4845	≤0.15	≤0.75	2.0	0.045	0.030		24.0-26.0	19.0-22.0
1.4841	≤0.20	1.5-2.5	2.0	0.045	0.030		24.0-26.0	19.0-22.0
1.4876	≤0.12	≤1.0	2.0	0.030	0.020	0.15-0.6	19.0-23.0	30.0-34.0

The scaling resistance the high-alloyed chromium-nickel steels is achieved using a

protective top layer consisting primarily of chromium oxide.

Additional additives, especially of aluminum and silicon, provide additional protection.

.

Oxidation, sulfurization, carburization, nitrogenization, and reactions with ashes and

other solid or molten deposits are particularly important for the scaling resistance from

a technical standpoint. The reactions can occur individually or simultaneously depending

on the prevailing conditions and may have correspondingly different reaction rates.

..

The scaling limit temperatures specified in Table 1 apply to air and are an approximation for

sulfur-free combustion gases. For high water vapor contents, the actual scaling limit may be lower.

For completely combusted, sulfur-free gases, a reduction of the scaling resistance by 100 to 200°C

must be taken into account depending on the composition of the gas.

...

In combustion gases containing sulfur, there is no significant impact on the scaling resistance

when a surplus of air is available.

In complete combusted, sulfurous gases, though, the scaling limit is significantly reduced

due to the formation of sulfide. Alloys with high nickel contents can exhibit strong scaling

above the nickel-nickel sulfide eutectic point, which is approx. 640°C.

....

When exposed to incompletely combusted gases, carburization of the heat-resistant

steels can occur. In this case, bonding with chromium can result in the depletion of this

element as a mixed crystal, which is indicated by a reduced scaling resistance.

The austenitic chromium-nickel steels, especially those with a high nickel content, are less

sensitive than the corresponding ferritic chromium steels.

.....

For reductive combustion gases containing nitrogen, the behavior of the steel is similar

to that during carburization.

For deposits from the combustion gases, low-melting eutectics can form on the steel

due to reaction with the scale layer, which quickly leads to the destruction of

the material. The permissible temperature limits depend greatly in this case on the

composition of the deposits and are generally very low, for example like when

alkaline sulfates, phosphates, metals and/or heavy metal oxides are present.

Sulfidation is increased the most by hydrogen sulfide. Aluminum and silicon

improve resistance against sulfidation.

Nickel and silicon Improve the carburization resistance.

.

When starting up and shutting down systems and during downtimes, combustion products may

condense. If this condensate contains sulfurous acid or sulfuric acid, then you must

expect a stronger reaction.

..

Heat-resistant steels are generally used at temperatures at which the material creeps when

stressed. When calculating for systems, you must use the creep strength and elongation time

values provided in Table 4.

Comparison of Standards

Table 3

Material	AISI	AFNOR	UNI	GOST	SBB*
1.4878	321	Z 6 CNT 18-10	X 6 CrNiTi1811	12 Ch 48 N 10 T	A700
1.4828	309	Z15 CNS 20-12	-	20 Ch 20 N 14 S 2	H550
1.4845	310S	Z12 CN 25-20	X 22 CrNi 25 20	-	H522
1.4841	314	Z 12 CNS 25-20	X 16 CrNiSi 25 20	20 Ch 25 N 20 S 2	H525
1.4876	-	Z 8 NC 32-21	-	ChN 32 T	H500

(*)=Manufacturer's Code Schöller-Bleckmann Böhler

When using heat-resistant steels, you must expect changes in the material in certain temperature

ranges that, after cooling down to room temperature, can lead to a reduction of the ductility.

The behavior of the material at the operating temperature is generally not affected by this.

Mechanical Properties

Table 4

Type of Steel	Hardness	Elastic Limit*	Tensile Strength	Fracture Elongation**
(Material)	(HB)	(N/mm²)	(N/mm²)	(L0=5Da longitudinally)
1.4878	130-190	min. 210	500-750	min. 40%
1.4828	150-210	min. 230	500-750	min. 30%
1.4845	130-190	min. 210	500-750	min. 35%
1.4841	150-210	min. 230	550-800	min. 30%
1.4876	139-190	min. 210	500-750	min. 30%

The values apply to cold formed pipes with wall thicknesses of 0.5 to 5 mm

(*)=0.2% elastic limit

(**)=The values apply to sample thicknesses ≥ 3 mm.

In austenitic steels with higher Cr content, the Ω phase can form the temperature range from 550

to 900°C. The Ω phase is a brittle, intermetallic compound between iron and chromium and other

transition metals that do not exhibit any non-permissible changes to the ductility at operating

temperatures, but that can cause the material to become brittle after cooling down to room

temperature. Si and Cr promote these precipitation processes, while Ni and Al hinder them.

The Ω phase is only relevant in actual practice for 1.4821 and 1.4841.

The Ω phase can be dissolved again by annealing at temperatures > 900°C.

Characteristic values of the long-term behavior at high temperatures

1% Elastic Limit*

Table 5

Material	Temperature	for 1,000h	for 10,000h
1.4878	600 °C	110 N/mm²	85 N/mm²
	700 °C	45	30
	800 °C	15	10

1.4828	600 °C	120	80
	700 °C	50	25
	800 °C	20	10
	900 °C	8	4

1.4841	600 °C	150	105
	700 °C	53	37
	800 °C	23	12
	900 °C	10	5.7

1.4876	600 °C	130	90
	700 °C	70	40
	800 °C	30	15
	900 °C	13 N/mm²	5 N/mm²

(*)=The stress, based on the initial diameter, that leads to a permanent elongation of 1%

after 1,000 or 10,000 h

Creep Strength*

Table 6

Material	Temperature	for 1,000h	for 10,000h	for 100,000h
1.4878	600 °C	185 N/mm²	115 N/mm²	65 N/mm²
	700 °C	80	45	22
	800 °C	35	20	10

1.4828	600 °C	190	120	65
	700 °C	75	36	16
	800 °C	35	18	7.5
	900 °C	15	8.5	3

1.4841	600 °C	230	160	80
	700 °C	80	40	18
	800 °C	35	18	7
	900 °C	15	8.5	3

1.4876	600 °C	200	152	114
	700 °C	90	68	47
	800 °C	45	30	19
	900 °C	20 N/mm²	11 N/mm²	4 N/mm²

(*)=The stress, based on the initial diameter, that leads to breakage after 1,000, 10,000 or 100,000 h.

Physical Properties

Average linear coefficient of expansion between 20°C and ...

Table 7

Material	...400°C	...800°C	...1000°C
1.4878	18.00	19.00	-
1.4828	17.50	18.50	19.50
1.4845	17.00	18.00	19.00
1.4841	17.00	18.00	19.00
1.4876	16.00	17.50	18.50

(10⁻⁶ mm) : (m x °C)

Thermal Conductivity

Table 8

Material	20°C	500°C
1.4878	0.15	0.21
1.4828	0.15	0.21
1.4845	0.14	0.19
1.4841	0.14	0.19
1.4876	0.12	0.19

(W) : (cm x °C)

Other Characteristic Values

Table 9

Material	Density*	Specific Heat**	p***
1.4878	7.9	0.50	0.75
1.4828	7.9	0.50	0.85
1.4845	7.9	0.50	0.85
1.4841	7.9	0.50	0.90
1.4876	8.0	0.50	1.00

(*)=g/cm³

(**)=J : (g x °C)

(***)=Specific electrical resistance for (O x mm²) : m

Processing

Heat-resistant austenitic CrNi steels are characterized by a high temperature strength in addition

to their good scaling resistance. For this reason, they can generally be used for purposes in which

a high mechanical strength is required in addition to scaling resistance.

The high temperature strength of the material 1.4876 is improved through the addition of titanium

and aluminum so that the long-term values for this material at temperatures over 600°C are

comparatively high.

.

Due to the NI content, these steels are more sensitive to sulfurous gases, especially in

non-oxidizing atmospheres. On the other hand, they have better resistance to carburization

and nitrogenization in comparison to ferritic steels.

The material 1.4841 should not be used in continuous operation at temperatures below 900°C

due to its tendency to become brittle in the Ω phase.

..

It should only be necessary in a few cases for the user to hot-form the heat-resistant

austenitic steels.

The hot forming temperature is 1150 - 800°C.

...

Due to their low yield strength and high elasticity, austenitic steels have good

cold forming properties. After very strong deformation, the resulting cold hardening

effects can be undone through subsequent heat treatment with fast quenching.

....

Annealing the austenitic steels at 900°C air temperature offers advantages

In terms of cutting operations over the quenched state.

In solution annealing, the steel is cooled in water or air, and for thinner walls,

in air or inert gas.

.....

When machining austenitic steels, adequate cooling must be ensured due to their low thermal

conductivity. Its strong cold hardening behavior, which can make the use of dull tools or machining

at the cutting depth more difficult, requires the use of sharper tools and the correct specification of

the cutting depth and cutting speed.

Welding

The heat-resistant austenitic steels are, assuming the corresponding qualifications are available,

suitable for welding using all of the known methods. However, arc welding should be preferred

over gas fusion welding.

Welding slag must be removed. Its presence will lead to high removal rates, especially for

Sulfurous oven gases, due to the formation of low-melting corrosion products.

Preheating and heat treatment after welding is generally unnecessary.

Filler Metals

Table 10

Base Metal	Electrode or Welding Rod
1.4878	1.4551/1.4829
1.4828	1.4829
1.4845	1.4842
1.4841	1.4842
1.4876	2.4806/2.4807

Product Range

We supply seamless hot-rolled and cold-processed pipes made of heat-resistant steels as well as

welded pipes with dimensions and tolerances based on DIN 2462 and DIN 2463.

Acceptance

An acceptance test certificate according to DIN 50049/3.1 can be made available for the

heat-resistant pipes. Acceptance is performed according to Steel-Iron Material Data Sheet 470.

DIN 2463/17457

<p><b>Pipes made of austenitic, heat-resistant steels</b></p><br><p>Heat-resistant steels were specially developed for use at high temperatures.</p><p>In the form of pipes, they are used in the construction of heat exchangers, for example.</p><br><br><p><b>Characteristics of heat-resistant steels</b></p><br><p>Heat-resistant steels are steels possessing good mechanical properties for short and long-term</p><p>loading due to their higher alloy content of chromium, nickel, silicon, and aluminium and with special</p><p>resistance to the effects of hot gases and combustion products as well as molten salt and metal at</p><p>temperatures above approximately 550°C. The level of their resistance depends enormously on the</p><p>reaction conditions and cannot be determined using any test method.</p><br><br><p><b>Scaling Resistance in the Air</b></p><p><span class="tDescSmall">Table 1</span></p><table class="techDescTable"><thead><tr><th><b>Type of Steel</b></th><th><b>Material</b></th><th><b>Temperature*</b></th></tr> </thead><tbody><tr class="Even"><td>X12 CrNiTi18 9</td><td>1.4878</td><td>850°C</td></tr><tr class="UnEven"><td>X15 CrNiSi 20 12</td><td>1.4828</td><td>1000°C</td></tr><tr class="Even"><td>X 12 CrNi 25 21</td><td>1.4845</td><td>1050°C</td></tr><tr class="UnEven"><td>X 15 CrNiSi 25 20</td><td>1.4841</td><td>1150°C</td></tr><tr class="Even"><td>X 10 NiCrAlTi 32 20</td><td>1.4876</td><td>1100°C</td></tr></tbody></table><br><br><p><b>Chemical Composition</b></p><p><span class="tDescSmall">Table 2</span></p><table class="techDescTable"><thead><tr><th><b>Material</b></th><th><b> C %</b></th><th><b>Si %</b></th><th><b>Mn max.</b></th><th><b>P max</b></th><th><b>S max</b></th><th><b>Al %</b></th><th><b>Cr %</b></th><th><b>Ni %</b></th></tr> </thead><tbody><tr class="Even"><td>1.4878</td><td>≤0.12</td><td>≤1.0</td><td>2.0</td><td>0.045</td><td>0.030</td><td><br></td><td>17.0-19.0</td><td>9.0-12.0</td></tr><tr class="UnEven"><td>1.4828</td><td>≤0.20</td><td>1.5-2.5</td><td>2.0</td><td>0.045</td><td>0.030</td><td><br></td><td>19.0-21.0</td><td>11.0-13.0</td></tr><tr class="Even"><td>1.4845</td><td>≤0.15</td><td>≤0.75</td><td>2.0</td><td>0.045</td><td>0.030</td><td><br></td><td>24.0-26.0</td><td>19.0-22.0</td></tr><tr class="UnEven"><td>1.4841</td><td>≤0.20</td><td>1.5-2.5</td><td>2.0</td><td>0.045</td><td>0.030</td><td><br></td><td>24.0-26.0</td><td>19.0-22.0</td></tr><tr class="Even"><td>1.4876</td><td>≤0.12</td><td>≤1.0</td><td>2.0</td><td>0.030</td><td>0.020</td><td>0.15-0.6</td><td>19.0-23.0</td><td>30.0-34.0</td></tr></tbody></table><br><hr><br><br><p>The scaling resistance the high-alloyed chromium-nickel steels is achieved using a</p><p>protective top layer consisting primarily of chromium oxide.</p><p>Additional additives, especially of aluminum and silicon, provide additional protection.</p><br><table class="techDescTable"><thead><tr><th><b>.</b></th></tr> </thead><tbody></tbody></table><br><p>Oxidation, sulfurization, carburization, nitrogenization, and reactions with ashes and</p><p>other solid or molten deposits are particularly important for the scaling resistance from</p><p>a technical standpoint. The reactions can occur individually or simultaneously depending</p><p>on the prevailing conditions and may have correspondingly different reaction rates.</p><br><table class="techDescTable"><thead><tr><th><b>..</b></th></tr> </thead><tbody></tbody></table><br><p>The scaling limit temperatures specified in Table 1 apply to air and are an approximation for</p><p>sulfur-free combustion gases. For high water vapor contents, the actual scaling limit may be lower.</p><p>For completely combusted, sulfur-free gases, a reduction of the scaling resistance by 100 to 200°C</p><p>must be taken into account depending on the composition of the gas.</p><br><table class="techDescTable"><thead><tr><th><b>...</b></th></tr> </thead><tbody></tbody></table><br><p>In combustion gases containing sulfur, there is no significant impact on the scaling resistance</p><p>when a surplus of air is available.</p><p>In complete combusted, sulfurous gases, though, the scaling limit is significantly reduced</p><p>due to the formation of sulfide. Alloys with high nickel contents can exhibit strong scaling</p><p>above the nickel-nickel sulfide eutectic point, which is approx. 640°C.</p><br><table class="techDescTable"><thead><tr><th><b>....</b></th></tr> </thead><tbody></tbody></table><br><p>When exposed to incompletely combusted gases, carburization of the heat-resistant</p><p>steels can occur. In this case, bonding with chromium can result in the depletion of this</p><p>element as a mixed crystal, which is indicated by a reduced scaling resistance.</p><p>The austenitic chromium-nickel steels, especially those with a high nickel content, are less</p><p>sensitive than the corresponding ferritic chromium steels.</p><br><table class="techDescTable"><thead><tr><th><b>.....</b></th></tr> </thead><tbody></tbody></table><br><p>For reductive combustion gases containing nitrogen, the behavior of the steel is similar</p><p>to that during carburization.</p><br><hr><br><br><p>For deposits from the combustion gases, low-melting eutectics can form on the steel</p><p>due to reaction with the scale layer, which quickly leads to the destruction of</p><p>the material. The permissible temperature limits depend greatly in this case on the</p><p>composition of the deposits and are generally very low, for example like when</p><p>alkaline sulfates, phosphates, metals and/or heavy metal oxides are present.</p><p>Sulfidation is increased the most by hydrogen sulfide. Aluminum and silicon</p><p>improve resistance against sulfidation.</p><p>Nickel and silicon Improve the carburization resistance.</p><br><table class="techDescTable"><thead><tr><th><b>.</b></th></tr> </thead><tbody></tbody></table><br><p>When starting up and shutting down systems and during downtimes, combustion products may</p><p>condense. If this condensate contains sulfurous acid or sulfuric acid, then you must</p><p>expect a stronger reaction.</p><br><table class="techDescTable"><thead><tr><th><b>..</b></th></tr> </thead><tbody></tbody></table><br><p>Heat-resistant steels are generally used at temperatures at which the material creeps when</p><p>stressed. When calculating for systems, you must use the creep strength and elongation time</p><p>values provided in Table 4.</p><br><br><p><b>Comparison of Standards</b></p><p><span class="tDescSmall">Table 3</span></p><table class="techDescTable"><thead><tr><th><b>Material</b></th><th><b>AISI</b></th><th><b>AFNOR</b></th><th><b>UNI</b></th><th><b>GOST</b></th><th><b>SBB*</b></th></tr> </thead><tbody><tr class="Even"><td>1.4878</td><td>321</td><td>Z 6 CNT 18-10</td><td>X 6 CrNiTi1811</td><td>12 Ch 48 N 10 T</td><td>A700</td></tr><tr class="UnEven"><td>1.4828</td><td>309</td><td>Z15 CNS 20-12</td><td>-</td><td>20 Ch 20 N 14 S 2</td><td>H550</td></tr><tr class="Even"><td>1.4845</td><td>310S</td><td>Z12 CN 25-20</td><td>X 22 CrNi 25 20</td><td>-</td><td>H522</td></tr><tr class="UnEven"><td>1.4841</td><td>314</td><td>Z 12 CNS 25-20</td><td>X 16 CrNiSi 25 20</td><td>20 Ch 25 N 20 S 2</td><td>H525</td></tr><tr class="Even"><td>1.4876</td><td>-</td><td>Z 8 NC 32-21</td><td>-</td><td>ChN 32 T</td><td>H500</td></tr></tbody></table><p><span class="tDescSmall">(*)=Manufacturer's Code Schöller-Bleckmann Böhler</span></p><br><hr><br><br><p>When using heat-resistant steels, you must expect changes in the material in certain temperature</p><p>ranges that, after cooling down to room temperature, can lead to a reduction of the ductility.</p><p>The behavior of the material at the operating temperature is generally not affected by this.</p><br><br><p><b>Mechanical Properties</b></p><p><span class="tDescSmall">Table 4</span></p><table class="techDescTable"><thead><tr><th><b>Type of Steel</b></th><th><b>Hardness</b></th><th><b>Elastic Limit*</b></th><th><b>Tensile Strength</b></th><th><b>Fracture Elongation**</b></th></tr> </thead><tbody><tr class="Even"><td>(Material)</td><td>(HB)</td><td>(N/mm²)</td><td>(N/mm²)</td><td>(L0=5Da longitudinally)</td></tr><tr class="UnEven"><td>1.4878</td><td>130-190</td><td>min. 210</td><td>500-750</td><td>min. 40%</td></tr><tr class="Even"><td>1.4828</td><td>150-210</td><td>min. 230</td><td>500-750</td><td>min. 30%</td></tr><tr class="UnEven"><td>1.4845</td><td>130-190</td><td>min. 210</td><td>500-750</td><td>min. 35%</td></tr><tr class="Even"><td>1.4841</td><td>150-210</td><td>min. 230</td><td>550-800</td><td>min. 30%</td></tr><tr class="UnEven"><td>1.4876</td><td>139-190</td><td>min. 210</td><td>500-750</td><td>min. 30%</td></tr></tbody></table><p><span class="tDescSmall">The values apply to cold formed pipes with wall thicknesses of 0.5 to 5 mm</span></p><p><span class="tDescSmall">(*)=0.2% elastic limit</span></p><p><span class="tDescSmall">(**)=The values apply to sample thicknesses ≥ 3 mm.</span></p><br><br><p>In austenitic steels with higher Cr content, the Ω phase can form the temperature range from 550</p><p>to 900°C. The Ω phase is a brittle, intermetallic compound between iron and chromium and other</p><p>transition metals that do not exhibit any non-permissible changes to the ductility at operating</p><p>temperatures, but that can cause the material to become brittle after cooling down to room</p><p>temperature. Si and Cr promote these precipitation processes, while Ni and Al hinder them.</p><p>The Ω phase is only relevant in actual practice for 1.4821 and 1.4841.</p><p>The Ω phase can be dissolved again by annealing at temperatures > 900°C.</p><br><hr><br><br><p><b>Characteristic values of the long-term behavior at high temperatures</b></p><br><p>1% Elastic Limit*</p><p><span class="tDescSmall">Table 5</span></p><table class="techDescTable"><thead><tr><th><b>Material</b></th><th><b>Temperature</b></th><th><b>for 1,000h</b></th><th><b>for 10,000h</b></th></tr> </thead><tbody><tr class="Even"><td>1.4878</td><td>600 °C</td><td>110 N/mm²</td><td>85 N/mm²</td></tr><tr class="UnEven"><td><br></td><td>700 °C</td><td>45</td><td>30</td></tr><tr class="Even"><td><br></td><td>800 °C</td><td>15</td><td>10</td></tr><tr class="UnEven"><td><br></td><td><br></td><td><br></td><td><br></td></tr><tr class="Even"><td>1.4828</td><td>600 °C</td><td>120</td><td>80</td></tr><tr class="UnEven"><td><br></td><td>700 °C</td><td>50</td><td>25</td></tr><tr class="Even"><td><br></td><td>800 °C</td><td>20</td><td>10</td></tr><tr class="UnEven"><td><br></td><td>900 °C</td><td>8</td><td>4</td></tr><tr class="Even"><td><br></td><td><br></td><td><br></td><td><br></td></tr><tr class="UnEven"><td>1.4841</td><td>600 °C</td><td>150</td><td>105</td></tr><tr class="Even"><td><br></td><td>700 °C</td><td>53</td><td>37</td></tr><tr class="UnEven"><td><br></td><td>800 °C</td><td>23</td><td>12</td></tr><tr class="Even"><td><br></td><td>900 °C</td><td>10</td><td>5.7</td></tr><tr class="UnEven"><td><br></td><td><br></td><td><br></td><td><br></td></tr><tr class="Even"><td>1.4876</td><td>600 °C</td><td>130</td><td>90</td></tr><tr class="UnEven"><td><br></td><td>700 °C</td><td>70</td><td>40</td></tr><tr class="Even"><td><br></td><td>800 °C</td><td>30</td><td>15</td></tr><tr class="UnEven"><td><br></td><td>900 °C</td><td>13 N/mm²</td><td>5 N/mm²</td></tr></tbody></table><p><span class="tDescSmall">(*)=The stress, based on the initial diameter, that leads to a permanent elongation of 1% </span></p><p><span class="tDescSmall">after 1,000 or 10,000 h</span></p><br><br><p>Creep Strength*</p><p><span class="tDescSmall">Table 6</span></p><table class="techDescTable"><thead><tr><th><b>Material</b></th><th><b>Temperature</b></th><th><b>for 1,000h</b></th><th><b>for 10,000h</b></th><th><b>for 100,000h</b></th></tr> </thead><tbody><tr class="Even"><td>1.4878</td><td>600 °C</td><td>185 N/mm²</td><td>115 N/mm²</td><td>65 N/mm²</td></tr><tr class="UnEven"><td><br></td><td>700 °C</td><td>80</td><td>45</td><td>22</td></tr><tr class="Even"><td><br></td><td>800 °C</td><td>35</td><td>20</td><td>10</td></tr><tr class="UnEven"><td><br></td><td><br></td><td><br></td><td><br></td><td><br></td></tr><tr class="Even"><td>1.4828</td><td>600 °C</td><td>190</td><td>120</td><td>65</td></tr><tr class="UnEven"><td><br></td><td>700 °C</td><td>75</td><td>36</td><td>16</td></tr><tr class="Even"><td><br></td><td>800 °C</td><td>35</td><td>18</td><td>7.5</td></tr><tr class="UnEven"><td><br></td><td>900 °C</td><td>15</td><td>8.5</td><td>3</td></tr><tr class="Even"><td><br></td><td><br></td><td><br></td><td><br></td><td><br></td></tr><tr class="UnEven"><td>1.4841</td><td>600 °C</td><td>230</td><td>160</td><td>80</td></tr><tr class="Even"><td><br></td><td>700 °C</td><td>80</td><td>40</td><td>18</td></tr><tr class="UnEven"><td><br></td><td>800 °C</td><td>35</td><td>18</td><td>7</td></tr><tr class="Even"><td><br></td><td>900 °C</td><td>15</td><td>8.5</td><td>3</td></tr><tr class="UnEven"><td><br></td><td><br></td><td><br></td><td><br></td><td><br></td></tr><tr class="Even"><td>1.4876</td><td>600 °C</td><td>200</td><td>152</td><td>114</td></tr><tr class="UnEven"><td><br></td><td>700 °C</td><td>90</td><td>68</td><td>47</td></tr><tr class="Even"><td><br></td><td>800 °C</td><td>45</td><td>30</td><td>19</td></tr><tr class="UnEven"><td><br></td><td>900 °C</td><td>20 N/mm²</td><td>11 N/mm²</td><td>4 N/mm²</td></tr></tbody></table><p><span class="tDescSmall">(*)=The stress, based on the initial diameter, that leads to breakage after 1,000, 10,000 or 100,000 h.</span></p><br><hr><br><br><p><b>Physical Properties</b></p><br><p>Average linear coefficient of expansion between 20°C and ...</p><p><span class="tDescSmall">Table 7</span></p><table class="techDescTable"><thead><tr><th><b>Material</b></th><th><b>...400°C</b></th><th><b>...800°C</b></th><th><b>...1000°C</b></th></tr> </thead><tbody><tr class="Even"><td>1.4878</td><td>18.00</td><td>19.00</td><td>-</td></tr><tr class="UnEven"><td>1.4828</td><td>17.50</td><td>18.50</td><td>19.50</td></tr><tr class="Even"><td>1.4845</td><td>17.00</td><td>18.00</td><td>19.00</td></tr><tr class="UnEven"><td>1.4841</td><td>17.00</td><td>18.00</td><td>19.00</td></tr><tr class="Even"><td>1.4876</td><td>16.00</td><td>17.50</td><td>18.50</td></tr></tbody></table><p><span class="tDescSmall">(10⁻⁶ mm) : (m x °C)</span></p><br><br><p>Thermal Conductivity</p><p><span class="tDescSmall">Table 8</span></p><table class="techDescTable"><thead><tr><th><b>Material</b></th><th><b> 20°C</b></th><th><b>500°C</b></th></tr> </thead><tbody><tr class="Even"><td>1.4878</td><td>0.15</td><td>0.21</td></tr><tr class="UnEven"><td>1.4828</td><td>0.15</td><td>0.21</td></tr><tr class="Even"><td>1.4845</td><td>0.14</td><td>0.19</td></tr><tr class="UnEven"><td>1.4841</td><td>0.14</td><td>0.19</td></tr><tr class="Even"><td>1.4876</td><td>0.12</td><td>0.19</td></tr></tbody></table><p><span class="tDescSmall">(W) : (cm x °C)</span></p><br><br><p>Other Characteristic Values</p><p><span class="tDescSmall">Table 9</span></p><table class="techDescTable"><thead><tr><th><b>Material</b></th><th><b>Density*</b></th><th><b>Specific Heat**</b></th><th><b>p***</b></th></tr> </thead><tbody><tr class="Even"><td>1.4878</td><td>7.9</td><td>0.50</td><td>0.75</td></tr><tr class="UnEven"><td>1.4828</td><td>7.9</td><td>0.50</td><td>0.85</td></tr><tr class="Even"><td>1.4845</td><td>7.9</td><td>0.50</td><td>0.85</td></tr><tr class="UnEven"><td>1.4841</td><td>7.9</td><td>0.50</td><td>0.90</td></tr><tr class="Even"><td>1.4876</td><td>8.0</td><td>0.50</td><td>1.00</td></tr></tbody></table><p><span class="tDescSmall">(*)=g/cm³</span></p><p><span class="tDescSmall">(**)=J : (g x °C)</span></p><p><span class="tDescSmall">(***)=Specific electrical resistance for (O x mm²) : m</span></p><br><hr><br><br><p><b>Processing</b></p><br><p>Heat-resistant austenitic CrNi steels are characterized by a high temperature strength in addition</p><p>to their good scaling resistance. For this reason, they can generally be used for purposes in which</p><p>a high mechanical strength is required in addition to scaling resistance.</p><p>The high temperature strength of the material 1.4876 is improved through the addition of titanium</p><p>and aluminum so that the long-term values for this material at temperatures over 600°C are</p><p>comparatively high.</p><br><table class="techDescTable"><thead><tr><th><b>.</b></th></tr> </thead><tbody></tbody></table><br><p>Due to the NI content, these steels are more sensitive to sulfurous gases, especially in</p><p>non-oxidizing atmospheres. On the other hand, they have better resistance to carburization</p><p>and nitrogenization in comparison to ferritic steels.</p><p>The material 1.4841 should not be used in continuous operation at temperatures below 900°C</p><p>due to its tendency to become brittle in the Ω phase.</p><br><table class="techDescTable"><thead><tr><th><b>..</b></th></tr> </thead><tbody></tbody></table><br><p>It should only be necessary in a few cases for the user to hot-form the heat-resistant</p><p>austenitic steels.</p><p>The hot forming temperature is 1150 - 800°C.</p><br><table class="techDescTable"><thead><tr><th><b>...</b></th></tr> </thead><tbody></tbody></table><br><p>Due to their low yield strength and high elasticity, austenitic steels have good</p><p>cold forming properties. After very strong deformation, the resulting cold hardening</p><p>effects can be undone through subsequent heat treatment with fast quenching.</p><br><table class="techDescTable"><thead><tr><th><b>....</b></th></tr> </thead><tbody></tbody></table><br><p>Annealing the austenitic steels at 900°C air temperature offers advantages</p><p>In terms of cutting operations over the quenched state.</p><p>In solution annealing, the steel is cooled in water or air, and for thinner walls,</p><p>in air or inert gas.</p><br><table class="techDescTable"><thead><tr><th><b>.....</b></th></tr> </thead><tbody></tbody></table><br><p>When machining austenitic steels, adequate cooling must be ensured due to their low thermal</p><p>conductivity. Its strong cold hardening behavior, which can make the use of dull tools or machining</p><p>at the cutting depth more difficult, requires the use of sharper tools and the correct specification of</p><p>the cutting depth and cutting speed.</p><br><hr><br><br><p><b>Welding</b></p><br><p>The heat-resistant austenitic steels are, assuming the corresponding qualifications are available,</p><p>suitable for welding using all of the known methods. However, arc welding should be preferred</p><p>over gas fusion welding.</p><br><p>Welding slag must be removed. Its presence will lead to high removal rates, especially for</p><p>Sulfurous oven gases, due to the formation of low-melting corrosion products.</p><br><p>Preheating and heat treatment after welding is generally unnecessary.</p><br><br><p>Filler Metals</p><p><span class="tDescSmall">Table 10</span></p><table class="techDescTable"><thead><tr><th><b>Base Metal</b></th><th><b>Electrode or Welding Rod</b></th></tr> </thead><tbody><tr class="Even"><td>1.4878</td><td>1.4551/1.4829</td></tr><tr class="UnEven"><td>1.4828</td><td>1.4829</td></tr><tr class="Even"><td>1.4845</td><td>1.4842</td></tr><tr class="UnEven"><td>1.4841</td><td>1.4842</td></tr><tr class="Even"><td>1.4876</td><td>2.4806/2.4807</td></tr></tbody></table><br><br><table class="techDescTable"><thead><tr><th><b>Product Range</b></th></tr> </thead><tbody></tbody></table><p>We supply seamless hot-rolled and cold-processed pipes made of heat-resistant steels as well as</p><p>welded pipes with dimensions and tolerances based on DIN 2462 and DIN 2463.</p><br><br><table class="techDescTable"><thead><tr><th><b>Acceptance</b></th></tr> </thead><tbody></tbody></table><p>An acceptance test certificate according to DIN 50049/3.1 can be made available for the</p><p>heat-resistant pipes. Acceptance is performed according to Steel-Iron Material Data Sheet 470.</p>

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special materials

heat-resistant

Stainless steel tubes round welded special materials heat-resistant

welded tube, not annealedRO.

Product specification

welded tube, not annealed

DIN 2463/17457

Pipes made of austenitic, heat-resistant steels

Heat-resistant steels were specially developed for use at high temperatures.

In the form of pipes, they are used in the construction of heat exchangers, for example.

Characteristics of heat-resistant steels

Heat-resistant steels are steels possessing good mechanical properties for short and long-term

loading due to their higher alloy content of chromium, nickel, silicon, and aluminium and with special

resistance to the effects of hot gases and combustion products as well as molten salt and metal at

temperatures above approximately 550°C. The level of their resistance depends enormously on the

reaction conditions and cannot be determined using any test method.

Scaling Resistance in the Air

Table 1

Type of Steel	Material	Temperature*
X12 CrNiTi18 9	1.4878	850°C
X15 CrNiSi 20 12	1.4828	1000°C
X 12 CrNi 25 21	1.4845	1050°C
X 15 CrNiSi 25 20	1.4841	1150°C
X 10 NiCrAlTi 32 20	1.4876	1100°C

Chemical Composition

Table 2

Material	C %	Si %	Mn max.	P max	S max	Al %	Cr %	Ni %
1.4878	≤0.12	≤1.0	2.0	0.045	0.030		17.0-19.0	9.0-12.0
1.4828	≤0.20	1.5-2.5	2.0	0.045	0.030		19.0-21.0	11.0-13.0
1.4845	≤0.15	≤0.75	2.0	0.045	0.030		24.0-26.0	19.0-22.0
1.4841	≤0.20	1.5-2.5	2.0	0.045	0.030		24.0-26.0	19.0-22.0
1.4876	≤0.12	≤1.0	2.0	0.030	0.020	0.15-0.6	19.0-23.0	30.0-34.0

The scaling resistance the high-alloyed chromium-nickel steels is achieved using a

protective top layer consisting primarily of chromium oxide.

Additional additives, especially of aluminum and silicon, provide additional protection.

.

Oxidation, sulfurization, carburization, nitrogenization, and reactions with ashes and

other solid or molten deposits are particularly important for the scaling resistance from

a technical standpoint. The reactions can occur individually or simultaneously depending

on the prevailing conditions and may have correspondingly different reaction rates.

..

The scaling limit temperatures specified in Table 1 apply to air and are an approximation for

sulfur-free combustion gases. For high water vapor contents, the actual scaling limit may be lower.

For completely combusted, sulfur-free gases, a reduction of the scaling resistance by 100 to 200°C

must be taken into account depending on the composition of the gas.

...

In combustion gases containing sulfur, there is no significant impact on the scaling resistance

when a surplus of air is available.

In complete combusted, sulfurous gases, though, the scaling limit is significantly reduced

due to the formation of sulfide. Alloys with high nickel contents can exhibit strong scaling

above the nickel-nickel sulfide eutectic point, which is approx. 640°C.

....

When exposed to incompletely combusted gases, carburization of the heat-resistant

steels can occur. In this case, bonding with chromium can result in the depletion of this

element as a mixed crystal, which is indicated by a reduced scaling resistance.

The austenitic chromium-nickel steels, especially those with a high nickel content, are less

sensitive than the corresponding ferritic chromium steels.

.....

For reductive combustion gases containing nitrogen, the behavior of the steel is similar

to that during carburization.

For deposits from the combustion gases, low-melting eutectics can form on the steel

due to reaction with the scale layer, which quickly leads to the destruction of

the material. The permissible temperature limits depend greatly in this case on the

composition of the deposits and are generally very low, for example like when

alkaline sulfates, phosphates, metals and/or heavy metal oxides are present.

Sulfidation is increased the most by hydrogen sulfide. Aluminum and silicon

improve resistance against sulfidation.

Nickel and silicon Improve the carburization resistance.

.

When starting up and shutting down systems and during downtimes, combustion products may

condense. If this condensate contains sulfurous acid or sulfuric acid, then you must

expect a stronger reaction.

..

Heat-resistant steels are generally used at temperatures at which the material creeps when

stressed. When calculating for systems, you must use the creep strength and elongation time

values provided in Table 4.

Comparison of Standards

Table 3

Material	AISI	AFNOR	UNI	GOST	SBB*
1.4878	321	Z 6 CNT 18-10	X 6 CrNiTi1811	12 Ch 48 N 10 T	A700
1.4828	309	Z15 CNS 20-12	-	20 Ch 20 N 14 S 2	H550
1.4845	310S	Z12 CN 25-20	X 22 CrNi 25 20	-	H522
1.4841	314	Z 12 CNS 25-20	X 16 CrNiSi 25 20	20 Ch 25 N 20 S 2	H525
1.4876	-	Z 8 NC 32-21	-	ChN 32 T	H500

(*)=Manufacturer's Code Schöller-Bleckmann Böhler

When using heat-resistant steels, you must expect changes in the material in certain temperature

ranges that, after cooling down to room temperature, can lead to a reduction of the ductility.

The behavior of the material at the operating temperature is generally not affected by this.

Mechanical Properties

Table 4

Type of Steel	Hardness	Elastic Limit*	Tensile Strength	Fracture Elongation**
(Material)	(HB)	(N/mm²)	(N/mm²)	(L0=5Da longitudinally)
1.4878	130-190	min. 210	500-750	min. 40%
1.4828	150-210	min. 230	500-750	min. 30%
1.4845	130-190	min. 210	500-750	min. 35%
1.4841	150-210	min. 230	550-800	min. 30%
1.4876	139-190	min. 210	500-750	min. 30%