DI-TANK 355: High-Performance Steel for Reliable Hydrocarbon Storage

DI-TANK 355 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 at a temperature below 580 °C. Irregularities at the 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.

Thermo-mechanical rolling according to EN 10028-5 (M) or thermo-mechanical control process according to A/SA841, A/SA841M (TMCP).

DI-TANK 355 can be flame cut in all thickness ranges without preheating due to its low hardenability.

Plasma and laser cutting can also be carried out without preheating for typical thickness. The family of DI-TANK has an excellent weldability if the general technical rules are observed (EN 1011 has to be applied analogously). The risk of cold cracking is low, so a preheating may not be necessary for most of the welds. When welding thicker plates preheating can still be avoided if filler materials and welding conditions are applied that lead to a very low hydrogen transfer (up to 5 ml/100 g DM according to ISO 3690).

The low contents of carbon and other alloy elements lead to favourable toughness properties in the heat-affected-zone, even with relatively high heat inputs. Depending on the chosen welding process, welding filler material as well as toughness requirements in the heat affected zone, also it permits t8/5 cooling times above of 25 s as stated in EN 1011-2. The upper limit of heat input is however dependent from the toughness requirements in particular the impact test temperature.

A stress relief heat treatment may be required above 580 °C by the API 650, API 620 and also EN 14620. The standards authorize a reduction of the PWHT temperature (below 580 °C) providing a longer holding time, with the purchaser’s agreement. Then, the parameters of the PWHT have to be specified and agreed at the time of the inquiry. Nevertheless, DI-TANK 355 is offered with a HP value (Pcrit) of 17,6.

If special requirements which are not listed in this material data sheet, are to be met by the steel due to its intended use 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 as occasion demands. The latest version is available from the mill or as download at www.dillinger.de.

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 heat treatment. Therefore hot forming is not permitted. The same limitation applies for heat treatments.

In addition to the marking required by the product specification, at least the following information will be marked, with low stress steel stamps:

BOF-converter process and metallurgical ladle treatment.

The steel is fully killed and fine grained by the addition of nitrogen fixing elements.

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

Unless otherwise agreed, the provisions in accordance with class B2 of EN 10163-2 in case of ordering the P355ML2 variant, otherwise in accordance with ASTM-A20 in case of ordering the A/SA841(M)- grade A class 1 variant, are applicable.

Tensile test and impact tests are carried out according to the relevant standards. Unless otherwise agreed, the impact test will be performed at -50 °C on transverse test pieces.

Unless otherwise agreed, the tolerances for the thickness in accordance with class B of EN 10029 in case of ordering the P355ML2 variant, otherwise in accordance with ASTM-A20 in case of ordering the A/SA841(M)-grade A class 1 variant, are applicable.