S690QL High Strength Steel – Dillimax 690T

S690QL high yield steel used in mobile crane

S690QL high yield steel used in mobile crane

S690QL Dillimax 690T is a fine grained quenched and tempered steel plate notable for its high strength. S690QL plates are used in a wide variety of engineering applications where strength is important – including cranes, critical structural components in building and stadia and pipes and gates in hydroelectric projects. It is a high strength steel for fixed and mobile equipment under heavy loading.

One of the advantages that S690QL has over more traditional steels is that whilst on a per ton basis the plates are more expensive the construction costs can be significantly reduced. This is because far less steel over all is required, welding costs (even though welding is more difficult) is reduced and the costs for filler are also reduced. Additionally there are the cost savings to be made in operation due to lighter machinery meaning less structural support costs, energy costs for movement or both.

Dillimax High Yield Steel Comparison Table showng the cost advantage of S690QL over conventional S355 Plates

Dillimax High Yield Steel Comparison Table showng the cost advantage of S690QL over conventional S355 Plates

Dillimax is a Dillinger Hutte’s brand name for high strength plate and is equivalent to RQT701 and Supralsim. Euivalent grades of steel include A709-100 ASTM), TStE690V (DIN)  E690T, E690TFP, S690T (AFNOR). E690 (ISO). The steel number of S690QL is 1.8928

Large Ex-stock availability S690QL

We have a large range of S690QL plates in stock as well as the tougher S690QL1 plates with are tested to -60 ºC rather than the -40 ºC of Dillimax 690T

Like all the Dillimax plates the focus has been on keeping a very low CEV value whilst maintaining the strength of the steel as the plates get thicker. Dillinger has done this really successfully with the result that we carry large stocks of S690QL from 100 mm to 250 mm.

These are the thicknesses where it becomes very difficult to roll high quality high strength steel plate and is one of the reasons why we carry such a large stock. of course we also have an equivalent stock in the thinner plates – all the way down to 6 mm

Plate dimensions are something that we focus on in order to maintain a high plate availability for our customers whilst minimizing wastage. For plates all the way up to 250 mm we maintain a maximum width of 3 metres (as well as the more normal 2055m and 2.5m). As the plate thicknesses increase the lengths obviously get shorter as some of our thicker plates weigh more than 20 MT at just 4m in length. Longer than that an they become increasingly difficult to transport as they exceed the axle weight limits of many HGVs and trucks

S690QL plates come with a 3.2 MTC to En10204. 3.1 MTCs are not possible from our stock given the safety critical use that many of our customers use these plates for.

European customers can purchase S690QL plates from AncoferWaldram or order new rolling directly from Dillinger Hutte. You can purchase a copy of EN10025-6 from BSI (EN10137 has been withdrawn).

S690QL Chemical Composition – Ladle Analysis

GradeC % max.
Si % max.
Mn % max
P % max.
S % max.
N % max.
B % max.
Cr % max.
Cu % max.
Mo % max.
Nb % max.
Ni % max.
Ti % max.
V % max.
Zr % max.
S690QL0.20.81.70.020.010.0150.0051.50.50.70.0620.050.120.15

S690QL Product Analysis

GradeC % max.
Si % max.
Mn % max
P % max.
S % max.
N % max.
B % max.
Cr % max.
Cu % max.
Mo % max.
Nb % max.
Ni % max.
Ti % max.
V % max.
Zr % max.
S690QL0.220.861.80.0250.0120.0160.0061.60.550.740.072.10.070.140.17

Maximum CEV Values for S690Ql (ladle)

  Maximum CEV in % for nominal product thickness in mm
GradeSteel Number≤ 50> 50 ≤ 100> 100 ≤ 150
S690QL1.89280.65
0.77

0.83

Carbon Equivalent Value CEV = CEV = C+Mn/6+(Cr+Mo+V)/5+(Cu+Ni)/15

Given the alloy content the weldability of high strength S690QL steel plates is lower than standard structural steel plates. As a result the better mills, such as Dillinger, work very hard to reduce alloy content by imptoved rolling and quenching and tempering techniques to deliver the yields required whilst reducing the welding difficulty

CEVWeldability
<0.35Excellent
0.36 - 0.40Very Good
0.41 - 0.45Good
0.46 - 0.50Fair
>50Poor

S690QL Mechanical Properties

Nominal Thickness (mm)3 - 5050 - 100100 - 150
Rm - Tensile strength (MPa)770 - 940760 - 930710 - 900
Rm - Tensile strength (MPa)690650630
Test Temperature-20°-40°
KV - Impact energy (J) longitudinal504030
A - Min. elongation Lo = 5,65 √ So (%)14

S690QL Processing

Working with high strength steels it is really important to ensuring that the fabricator is competent in the processing of the steel plate for the application and meets the requirements of EN 10011-2 and CEN/TR 10347 and appropriate national standards.

Cold Forming

The maximum allowable stress relieving temperature for S690QL is (560 °C/1040 °F) and cold forming takes place below this temperature. In order to reduce issues during cold forming of Dillimax 690 any flame cut or sheared edges in the bending area need to be ground before cold forming. Because cold forming can increase the hardness of the steel and reduce toughness the bending radius may often need to be increased over the minimums proscribed in manufacturer’s recommendations.

Hot Forming

Hot forming of S690QL and other high yield steels is not recommended as the hot forming will remove the benefits of the mills tempering process. This means that the hot formed plate will then need to be tempered again. Given that much of the strength of the plate comes from the optimised tempering process any ad hoc tempering is likely to lead to quote different results than those of the initial plate. Consequently the MTC will not reflect the actual properties of the steel.

Other S690QL and High Strength Steel Brands

  • Thyssen – Naxtra M700, XABO 890, XABO 960
  • Ilsenburger Grobblech – Maxil 690, MAxil 890, Maxil 960
  • Voest Alpine – Aldur 700QL, Alform 700M
  • Industeel – Supralsim 690, Superelso 690, Superelso 890, Superelso 960
  • SSAB – Weldox 700, Weldox 900, Weldox 960
  • Corus/ Tata – RQT70, RQT 901