DIWA 373: High-Temperature Weldable Steel (EN 1.6368)

DIWA 373 is a weldable fine grained steel which is characterized by high yield strength at elevated tem- peratures. DIWA 373 is produced using basic oxygen steelmaking process. Its properties are achieved by normalizing and tempering or, for thicknesses exceeding 100 mm by normalizing and tempering or water quenching and tempering.

DIWA 373 is used as plate or formed part for boilers, pressure vessels, piping and other fabricated parts operating at temperatures up to 500 °C.

DIWA 373 / 15NiCuMoNb5-6-4, Material No. 1.6368, is standardized in EN 10028, part 2, for thicknesses up to 200 mm and qualified in accordance with VdTÜV material data sheet 377/1 for the application range of the AD 2000-Merkblätter in thicknesses up to 180 mm. This data sheet applies to heavy plates with thicknesses from 6 to 250 mm.

Properties

Mechanical

Property	Temperature	Value	Testing Standard	Comment
Charpy impact energy, V-notch	-20 °C	27 J		*The specified values are minimum values for the average of 3 tests. No individual value is to be less than 70 % of the specified minimum. For plate thickness below 11 mm the test can be carried out on Charpy-V specimens or Charpy-V-type specimens with reduced width. The minimum impact value will be reduced proportionally to the reduction of the specimen’s cross section
	0 °C	34 J		*
Creep strength 10^4 cycles	400 °C	324 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^4 cycles
	400 °C	402 MPa		rupture strength \| average of the scatter band known to date., 10^4 cycles
	410 °C	315 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^4 cycles
	410 °C	385 MPa		rupture strength \| average of the scatter band known to date., 10^4 cycles
	420 °C	306 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^4 cycles
	420 °C	368 MPa		rupture strength \| average of the scatter band known to date., 10^4 cycles
	430 °C	295 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^4 cycles
	430 °C	348 MPa		rupture strength \| average of the scatter band known to date., 10^4 cycles
	440 °C	281 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^4 cycles
	440 °C	328 MPa		rupture strength \| average of the scatter band known to date., 10^4 cycles
	450 °C	265 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^4 cycles
	450 °C	304 MPa		rupture strength \| average of the scatter band known to date., 10^4 cycles
	460 °C	239 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^4 cycles
	460 °C	274 MPa		rupture strength \| average of the scatter band known to date., 10^4 cycles
	470 °C	212 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^4 cycles
	470 °C	242 MPa		rupture strength \| average of the scatter band known to date., 10^4 cycles
	480 °C	180 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^4 cycles
	480 °C	212 MPa		rupture strength \| average of the scatter band known to date., 10^4 cycles
	490 °C	145 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^4 cycles
	490 °C	179 MPa		rupture strength \| average of the scatter band known to date., 10^4 cycles
	500 °C	108 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^4 cycles
	500 °C	147 MPa		rupture strength \| average of the scatter band known to date., 10^4 cycles
Creep strength 10^5 cycles	400 °C	294 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^5 cycles
	400 °C	373 MPa		rupture strength \| average of the scatter band known to date., 10^5 cycles
	410 °C	279 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^5 cycles
	410 °C	349 MPa		rupture strength \| average of the scatter band known to date., 10^5 cycles
	420 °C	263 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^5 cycles
	420 °C	325 MPa		rupture strength \| average of the scatter band known to date., 10^5 cycles
	430 °C	245 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^5 cycles
	430 °C	300 MPa		rupture strength \| average of the scatter band known to date., 10^5 cycles
	440 °C	227 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^5 cycles
	440 °C	273 MPa		rupture strength \| average of the scatter band known to date., 10^5 cycles
	450 °C	206 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^5 cycles
	450 °C	245 MPa		rupture strength \| average of the scatter band known to date., 10^5 cycles
	460 °C	180 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^5 cycles
	460 °C	210 MPa		rupture strength \| average of the scatter band known to date., 10^5 cycles
	470 °C	151 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^5 cycles
	470 °C	175 MPa		rupture strength \| average of the scatter band known to date., 10^5 cycles
	480 °C	120 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^5 cycles
	480 °C	139 MPa		rupture strength \| average of the scatter band known to date., 10^5 cycles
	490 °C	84 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^5 cycles
	490 °C	104 MPa		rupture strength \| average of the scatter band known to date., 10^5 cycles
	500 °C	49 MPa		Strength for 1% (plastic) creep strain \| average of the scatter band known to date., 10^5 cycles
	500 °C	69 MPa		rupture strength \| average of the scatter band known to date., 10^5 cycles
Elongation		16 %		min. for plate thickenss t ≤ 250 mm \| transverse specimens (ambient temp.), A5
Tensile strength		580 - 740 MPa		for plate thickness 150 < t ≤ 250 mm \| transverse specimens (ambient temp.)
		590 - 740 MPa		for plate thickness 100 < t ≤ 150 mm \| transverse specimens (ambient temp.)
		600 - 760 MPa		for plate thickness 60 < t ≤ 100 mm \| transverse specimens (ambient temp.)
		610 - 780 MPa		for plate thickness t ≤ 60 mm \| transverse specimens (ambient temp.)
Yield strength		400 MPa		min. ReH for plate thickness 200 < t ≤ 250 mm \| transverse specimens (ambient temp.)
		410 MPa		min. ReH for plate thickness 150 < t ≤ 200 mm \| transverse specimens (ambient temp.)
		420 MPa		min. ReH for plate thickness 100 < t ≤ 150 mm \| transverse specimens (ambient temp.)
		430 MPa		min. ReH for plate thickness 60 < t ≤ 100 mm \| transverse specimens (ambient temp.)
		440 MPa		min. ReH for plate thickness 40 < t ≤ 60 mm \| transverse specimens (ambient temp.)
		460 MPa		min. ReH for plate thickness t ≤ 40 mm \| transverse specimens (ambient temp.)
	100 °C	373 MPa	EN 10028-2	min. Rp0.2 for plate thickness 200 < t ≤ 250 mm \| transverse specimens
	100 °C	382 MPa	EN 10028-2	min. Rp0.2 for plate thickness 150 < t ≤ 200 mm \| transverse specimens
	100 °C	392 MPa	EN 10028-2	min. Rp0.2 for plate thickness 100 < t ≤ 150 mm \| transverse specimens
	100 °C	401 MPa	EN 10028-2	min. Rp0.2 for plate thickness 60 < t ≤ 100 mm \| transverse specimens
	100 °C	410 MPa	EN 10028-2	min. Rp0.2 for plate thickness 40 < t ≤ 60 mm \| transverse specimens
	100 °C	429 MPa	EN 10028-2	min. Rp0.2 for plate thickness t ≤ 40 mm \| transverse specimens
	150 °C	361 MPa	EN 10028-2	min. Rp0.2 for plate thickness 200 < t ≤ 250 mm \| transverse specimens
	150 °C	370 MPa	EN 10028-2	min. Rp0.2 for plate thickness 150 < t ≤ 200 mm \| transverse specimens
	150 °C	379 MPa	EN 10028-2	min. Rp0.2 for plate thickness 100 < t ≤ 150 mm \| transverse specimens
	150 °C	388 MPa	EN 10028-2	min. Rp0.2 for plate thickness 60 < t ≤ 100 mm \| transverse specimens
	150 °C	397 MPa	EN 10028-2	min. Rp0.2 for plate thickness 40 < t ≤ 60 mm \| transverse specimens
	150 °C	415 MPa	EN 10028-2	min. Rp0.2 for plate thickness t ≤ 40 mm \| transverse specimens
	200 °C	350 MPa	EN 10028-2	min. Rp0.2 for plate thickness 200 < t ≤ 250 mm \| transverse specimens
	200 °C	359 MPa	EN 10028-2	min. Rp0.2 for plate thickness 150 < t ≤ 200 mm \| transverse specimens
	200 °C	368 MPa	EN 10028-2	min. Rp0.2 for plate thickness 100 < t ≤ 150 mm \| transverse specimens
	200 °C	377 MPa	EN 10028-2	min. Rp0.2 for plate thickness 60 < t ≤ 100 mm \| transverse specimens
	200 °C	385 MPa	EN 10028-2	min. Rp0.2 for plate thickness 40 < t ≤ 60 mm \| transverse specimens
	200 °C	403 MPa	EN 10028-2	min. Rp0.2 for plate thickness t ≤ 40 mm \| transverse specimens
	250 °C	340 MPa	EN 10028-2	min. Rp0.2 for plate thickness 150 < t ≤ 200 mm \| transverse specimens
	250 °C	349 MPa	EN 10028-2	min. Rp0.2 for plate thickness 150 < t ≤ 200 mm \| transverse specimens
	250 °C	357 MPa	EN 10028-2	min. Rp0.2 for plate thickness 100 < t ≤ 150 mm \| transverse specimens
	250 °C	366 MPa	EN 10028-2	min. Rp0.2 for plate thickness 60 < t ≤ 100 mm \| transverse specimens
	250 °C	374 MPa	EN 10028-2	min. Rp0.2 for plate thickness 40 < t ≤ 60 mm \| transverse specimens
	250 °C	391 MPa	EN 10028-2	min. Rp0.2 for plate thickness t ≤ 40 mm \| transverse specimens
	300 °C	330 MPa	EN 10028-2	min. Rp0.2 for plate thickness 200 < t ≤ 250 mm \| transverse specimens
	300 °C	338 MPa	EN 10028-2	min. Rp0.2 for plate thickness 150 < t ≤ 200 mm \| transverse specimens
	300 °C	347 MPa	EN 10028-2	min. Rp0.2 for plate thickness 100 < t ≤ 150 mm \| transverse specimens
	300 °C	355 MPa	EN 10028-2	min. Rp0.2 for plate thickness 60 < t ≤ 100 mm \| transverse specimens
	300 °C	363 MPa	EN 10028-2	min. Rp0.2 for plate thickness 40 < t ≤ 60 mm \| transverse specimens
	300 °C	380 MPa	EN 10028-2	min. Rp0.2 for plate thickness t ≤ 40 mm \| transverse specimens
	350 °C	318 MPa	EN 10028-2	min. Rp0.2 for plate thickness 200 < t ≤ 250 mm \| transverse specimens
	350 °C	327 MPa	EN 10028-2	min. Rp0.2 for plate thickness 150 < t ≤ 200 mm \| transverse specimens
	350 °C	335 MPa	EN 10028-2	min. Rp0.2 for plate thickness 100 < t ≤ 150 mm \| transverse specimens
	350 °C	342 MPa	EN 10028-2	min. Rp0.2 for plate thickness 60 < t ≤ 100 mm \| transverse specimens
	350 °C	350 MPa	EN 10028-2	min. Rp0.2 for plate thickness 40 < t ≤ 60 mm \| transverse specimens
	350 °C	366 MPa	EN 10028-2	min. Rp0.2 for plate thickness t ≤ 40 mm \| transverse specimens
	400 °C	305 MPa	EN 10028-2	min. Rp0.2 for plate thickness 200 < t ≤ 250 mm \| transverse specimens
	400 °C	313 MPa	EN 10028-2	min. Rp0.2 for plate thickness 150 < t ≤ 200 mm \| transverse specimens
	400 °C	320 MPa	EN 10028-2	min. Rp0.2 for plate thickness 100 < t ≤ 150 mm \| transverse specimens
	400 °C	328 MPa	EN 10028-2	min. Rp0.2 for plate thickness 60 < t ≤ 100 mm \| transverse specimens
	400 °C	335 MPa	EN 10028-2	min. Rp0.2 for plate thickness 40 < t ≤ 60 mm \| transverse specimens
	400 °C	351 MPa	EN 10028-2	min. Rp0.2 for plate thickness t ≤ 40 mm \| transverse specimens
	450 °C	288 MPa	EN 10028-2	min. Rp0.2 for plate thickness 150 < t ≤ 250 mm \| transverse specimens
	450 °C	295 MPa	EN 10028-2	min. Rp0.2 for plate thickness 150 < t ≤ 200 mm \| transverse specimens
	450 °C	302 MPa	EN 10028-2	min. Rp0.2 for plate thickness 100 < t ≤ 150 mm \| transverse specimens
	450 °C	309 MPa	EN 10028-2	min. Rp0.2 for plate thickness 60 < t ≤ 100 mm \| transverse specimens
	450 °C	317 MPa	EN 10028-2	min. Rp0.2 for plate thickness 40 < t ≤ 60 mm \| transverse specimens
	450 °C	331 MPa	EN 10028-2	min. Rp0.2 for plate thickness t ≤ 40 mm \| transverse specimens

Chemical properties

Property	Value	Comment
Aluminium	0.01 %	min. tot. product
	0.015 %	min. tot. heat
Carbon	0.17 %	max. heat
	0.19 %	max. product
Chromium	0.3 %	max. heat
	0.35 %	max. product
Copper	0.4 - 0.9 %	product
	0.5 - 0.8 %	heat
Iron	Balance
Manganese	0.75 - 1.3 %	product
	0.8 - 1.2 %	heat
Molybdenum	0.22 - 0.54 %	product
	0.25 - 0.5 %	heat
Nickel	0.9 - 1.4 %	product
	1 - 1.3 %	heat
Niobium	0.005 - 0.055 %	product
	0.015 - 0.045 %	heat
Nitrogen	0.02 %	max. heat
	0.022 %	max. product
Phosphorus	0.025 %	max. heat
	0.03 %	max. product
Silicon	0.2 - 0.56 %	product
	0.25 - 0.5 %	heat
Sulfur	0.01 %	max. heat
	0.013 %	max. product

Technological properties

Property

Application areas

Boilers in accordance with EN 12952/ EN12953 (TRD 101) for temperatures up to 500 °C.

Pressure vessels in accordance with AD 2000-Merkblatt W1, HP 8/1, EN 13445 and CODAP 2005 for temperatures from -20 °C up to 500 °C.

Cold Forming

DIWA 373 can be cold formed according to the general procedures. CEN/TR 10347 (Guidance for forming of structural steels in processing) as well as the provisions of VdTÜV-material data sheet 377/1 shall be observed.

Delivery condtion

Delivery condition:

thicknesses ≤ 100 mm normalized and tempered

thicknesses > 100 mm normalized and tempered or water quenched and tempered

In accordance with EN 10028-2 a water quenching and tempering treatment is already possible for thick- nesses equal or superior to 100 mm.

If the heat treatment is to be performed during processing, the plates can be delivered in the normalized condition, and in exceptional cases in the as rolled condition by special agreement before the order. In this case testing of the mechanical properties is provided on the basis of simulated heat treated specimens.

General technical delivery requirements: Unless otherwise agreed, the general technical delivery requirements in accordance with EN 10021 apply.

Flame cutting and welding

DIWA 373 can be welded and flame cut according to the general procedures. The guidelines given in EN 1011 (Welding), as well as the provisions of VdTÜV-material data sheet 377/1 shall be observed.

General note

If special requirements, which are not listed in this material specification, are to be met by the steel due to its intended use or processing, these requirements are to be agreed before the order.

The indications in this data sheet are product descriptions. This data sheet is updated if necessary. The current version is available from the mill or as download at www.dillinger.de.

Heat Treatment

Austenitizing/Cooling/Tempering¹	Stress relieving
Austenitizing: 880-940 °C	580 - 620 °C²
- Cooling: After temperature equalization (880-940 °C) over the whole section cooling in air or water according to plate thickness. - Tempering: 640-680 °C After equalization over the whole section holding time at least 30 min.	≤ 15 > 15 ≤ 60 > 60	≥ 30 ≥ 2 x t 120
Cooling in still air
1) Temperatures and times concern the product. Temperatures and holding times are determined by the steel manufacturer as a function of the plate thickness and the chemical composition. In order to preserve the mechanical properties the fabricator should ensure that the subsequent heat treatments correspond to those applied by the manufacturer (indicated in the plate inspection document). 2) Higher temperatures and holding times exceeding 180 minutes are possible upon agreement.

If stress relieving and tempering are joined together in one process, the tempering conditions apply.

Hot forming

DIWA 373 can be hot formed according to the general procedures. CEN/TR 10347 (Guidance for forming of structural steels in processing) as well as the provisions of VdTÜV-material data sheet 377/1 shall be observed.

Processing history

Fully killed, fine grained steel with metallurgical treatment in the ladle.

Processing methods

The entire processing and application techniques are of fundamental importance to the reliability of the products made from this steel. The user should ensure that his design, construction and processing meth- ods are aligned with the material, correspond to the state-of-the-art that the fabricator has to comply with and are suitable for the intended use. The customer is responsible for the selection of the material. The recommendations in accordance with EN 1011-2 should be observed.

Surface condition

Surface condition: Unless otherwise agreed, the provisions in accordance with class B2 of EN 10163-2 are applicable.

Testings

Sampling, testing method and tests are in accordance with the provisions in EN 10028. For orders in accor- dance with VdTÜV material data sheet 377/1, the conditions indicated there are respected. Additional tests can be agreed upon. The plates are delivered with inspection certificate 3.1 or 3.2 in accordance with EN 10204. The document type and, in case of inspection certificate 3.2, the inspection representative are to be stated on the order.

Tensile test at ambient temperature (transverse test specimens), Tensile test at elevated temperature (transverse specimens in accordance with 10028-2)

For plate thicknesses ≥ 15 mm, the fulfilment of one of the three quality classes Z15, Z25 or Z35 in accordance with EN 10164 or similar standards can be stipulated on the order.

Tolerances

Tolerances: Unless otherwise agreed, tolerances are in accordance with EN 10029, with class B for the thickness and class N for the flatness.

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