DILLIMAX and DILLIDUR: Innovative solutions for earth-moving and mining equipment

Land- and water-based lifting equipment is nowadays capable of handling unimaginably heavy loads. The hydraulic excavators used in mines around the globe, for example, lift takes of ore as big as a detached house in a single scoop. Modern mills grind absolute mountains of ore-containing rock every day. High-tensile and wear-resistant steel plate in increasingly great thicknesses is used everywhere for these applications. In many cases, not only high mechanical strength, but also extremely good toughness ratings are specified to provide reserves of safety for operation under these demanding conditions.

Dillinger Hütte GTS plays a special role in driving this trend. The high-tensile DILLIMAX product family, tried and proven over decades, now also includes DILLIMAX 690 in thicknesses up to 250 mm. Dillinger Hütte GTS can thus now supply solutions of between 8 mm and 250 mm plate thickness in a large range of other dimensions. Yield strengths extend up to 1100 MPa, with toughness guaranteed even down to temperatures as low as -60° C.
Yet another innovation in DILLIMAX 690: carbon equivalents (CEV) have been drastically decreased beyond the specification in the EN 10 025, Part 6, standard. The result: dependable and cost-efficient processing, thanks to reliably calculable and comparatively low preheat temperatures prior to welding.

Wear-resistant, low-temperature tough
DILLIDUR IMPACT is now available in plate thicknesses up to 150 mm. DILLIDUR IMPACT augments the wear-resistant DILLIDUR 400 V, DILLIDUR 450 V and DILLIDUR 500 V products, permitting applications involving exceptionally high toughness requirements.
In service, DILLIDUR is spared nothing. The cutting edge of a high-capacity excavator shovel, for example, is thrust time and time again, for years on end, into the rock face. The results: abrasion and wear. Wear-resistant DILLIDUR steels are therefore used to boost service-lives in such applications. They must not only be hard and wear-resistant, however, particularly in welded and thick-walled components. It must also be possible to weld such elements using the lowest possible preheat temperatures and with no cracking. In addition, repairs are frequently performed under extremely adverse conditions. But hardness and cracking-resistance (Charpy notch impact strength) are, in fact, two contrary properties. Low-temperature tough, wear-resistant DILLIDUR IMPACT can provide solutions for such demanding applications. This grade is now available in plate thicknesses of up to 150 mm and, in the near future, direct from Dillinger Hütte Group steel stockholders.

A whole series of production operations is necessary to produce such thick high-strength wear-resistant plates:

• Ultra-clean steelmaking (i.e., low percentages of embrittling elements, such as sulphur).
• Casting of extremely thick slabs or ingots (i.e., the material from which the plates are later rolled).
• Rolling under enormous rolling forces, using the so-called "high-shape process", with extremely large thickness reductions for every rolling pass; the slabs are rolled to net plate dimensions, the centre and interior of the plate being homogenised as a result of the deformations occurring during rolling.
• Special facilities for quenching and tempering of thick high-tensile wear-resistant grades.
• Machines for levelling of thick plates.

Dillinger Hütte GTS casts the world's thickest feed slabs, providing it with unique potentials for the production of thick quenched and tempered (QT) heavy plates.