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WELDABLE FINE-GRAINED STRUCTURAL STEEL, THERMOMECHANICALLY ROLLED DI-MC 420 is a thermomechanically rolled, fine-grained structural steel. Due to its chemical composition, this material hasa low carbon equivalent and hence excellent weldability. It is preferentially used by the customers in constructionalsteelwork, hydraulic steelwork and mechanical engineering, where exacting demands are placed on weldability.
Product description
Designation and range of application
DI-MC 420 can be delivered in two qualities as follows:
• Basic quality (B) with minimum impact values at -20 °C:
DI-MC 420 B
Material No. 1.8825 - S420M in accordance with EN 10025-4 • Low-temperature quality (T) with minimum impact values at -50 °C: DI-MC 420 T
Material No. 1.8836 - S420ML in accordance with EN 10025-4.
DI-MC 420 can be delivered in thickness from 8 to 120 mm according to the dimensional program.
Chemical composition
For the ladle analysis the following limiting values are applicable:
Product analysis, permissible variations from the ladle analysis: CEV = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15 Pcm = C + Si/30 + (Mn + Cu + Cr)/20 + Ni/60 + Mo/15 + V/10 + 5B Delivery condition
Thermomechanically rolled and, if necessary, accelerated cooled (short designation TM or M).
Mechanical and technological properties in the delivery condition
Tensile test at ambient temperature – transverse test specimens
1) For thickness > 16 mm higher minimum values can be arranged upon request.
For plate thickness of more than 15 mm, the adherence to grades Z15, Z25 or Z35 in accordance with EN 10164 orcomparable regulations, which are characterized by a minimum reduction of area on tensile specimens perpendicular tothe plate surface, can be agreed when placing the order.
Impact test on Charpy-V-specimens
Impact Energy Av [J] at test temperature of The specified minimum value is the average of 3 tests. Not more than one individual value is permitted to be below thisminimum value; it has to be at least 70 % of this minimum average value. Subsized specimens are admitted for platethickness = 12 mm, the minimum specimen width is 5 mm. The minimum impact energy will be decreased proportionally.
Tensile test and impact tests are carried out once per heat, 40 t and thickness range as specified for the yield strengthaccording to table 5 of EN 10025-4. Tests on every plate may be possible on request.
The specimens for the tensile test are prepared according to EN 10025-4. Testing is carried out in accordance withEN 10002-1 on specimens of gauge length L = 5.65 √S or L Unless otherwise agreed, the impact test will be performed according to EN 10045-1 at a temperature of –20 °C for basicquality B and at –50 °C for low-temperature quality T on Charpy-V- longitudinal test specimens taken as follows:• Unless otherwise agreed, the test results are documented in a certificate 3.1 in accordance with EN 10204.
Identification of plates
Unless otherwise agreed, the marking is carried out via steel stamps with at least the following information:• number of mother plate and individual plate Processing
The entire processing and application techniques are of fundamental importance to the reliability of the products madefrom this steel. The user should ensure that his design, construction and processing methods are aligned with thematerial, 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 to EN 1011 andSEW 088 should be observed. You find detailed information on processing in the brochure “DI-MC TechnicalInformation” of Dillinger Hütte GTS.
Cold forming
DI-MC 420 can generally be well cold formed with regard to its high toughness, i.e. formed at temperatures below 580 °C.
Cold forming is always related to a hardening of the steel and to a decrease in toughness. This change in the mechanical
properties can, as a rule, be partially recovered through a subsequent stress relief heat treatment. Flame cut or sheared
edges in the bending area should be ground before cold forming. For larger cold forming amounts we recommend you to
consult us prior to ordering.
Hot forming
Hot forming, i.e. forming at temperatures above 580 °C, leads to changes in the original material condition. It is
impossible to re-establish the same material properties that had been achieved during the original manufacture through a
further treatment. Therefore hot forming is not permitted.
Flame cutting and welding
DI-MC 420 can be flame cut in all thickness ranges without preheating due to its small tendency for hardness increase.
Plasma and laser cutting can also be carried out without preheating for typical thickness’.
DI-MC 420 has an excellent weldability if the general technical rules are observed (EN 1011 has to be appliedanalogously). The risk of cold cracking is low. The choice of the appropriate preheating temperature depends on theconstruction, plate thickness, welding heat input, chosen welding process, welding filler materials and base materials(basic quality B and low-temperature quality T). From experience, an appropriate choice of these parameters allowsdispensing with preheating up to a plate thickness of 50 mm. To avoid hydrogen-induced cold cracking, only fillermaterials which add very little hydrogen to the base metal, may be used (up to 5 ml/100 g DM according to ISO 6390). Ifthe filler material is chosen, the raised yield strength of the base material has to be taken into account.
The low content of carbon and other alloy elements leads to favorable toughness properties in the heat-affected-zone,even with high heat inputs . Depending on the chosen welding process, welding filler material as well as toughnessrequirements in the heat affected zone, it permits cooling temperatures above the limiting values of 25 s as stated inEN 1011-2 and SEW 088.
DI-MC 420 T distinguishes itself from DI-MC 420 B by an even improved weldability, especially in the thickness rangeabove 50 mm.
Heat treatment
Welded joints of DI-MC 420 are usually used in welded condition. If a stress relief heat treatment is necessary, it is
carried out in the temperature range between 530 and 580 °C with cooling in still air. The holding time should not exceed
150 minutes (even if multiple operations are carried out). For a holding time of more than 90 minutes the lower limit of the
temperature range should be aimed at.
For flame straightening, special working recommendations have to be observed (see DI-MC Technical Information ofDillinger Hütte GTS).
Tolerance
Unless otherwise agreed, tolerances are in accordance with EN 10029, with class A for the thickness.
Surface quality
Unless otherwise agreed, the specifications will be in accordance with EN 10163, class A2.
General note
If special requirements, which are not covered in this material data sheet, are to be met by the steel due to its intendeduse or processing, these requirements are to be agreed before placing the order.
The information in this data sheet is a product description. This data sheet is updated at irregular intervals. The currentversion is relevant. The latest version is available from the mill or as download at www.dillinger.de.
Sales organisations:
For your local representative pleasecontact our coordination office inDillingen: AG der Dillinger HüttenwerkePostfach 1580

Source: http://www.dillinger.biz/imperia/md/content/dillinger/publikationen/stahlbau/werkstoffblaetter/dimc_420__08_05__e.pdf