Die materials, hardening methods and surface coatings for forming of high, extra high and ultra high strength steel sheets (HSS/EHSS/UHSS)

• During the past years, large efforts have been made at Volvo Cars to establish a scientific and systematic approach to selection of die materials, hardening methods and surface treatments/coatings. These efforts were initiated, since both new higher strength sheet materials and new die materials with better performance were introduced. Both these higher strength sheet materials and higher performance die materials needed to be industrialized. Volvo cars transferred to a so-called Dry Presshop several years ago. This means that only the rust protection oil applied by the material supplier to the sheet prior to delivery is allowed as the stamping lubricant. No additional lubricant can be accepted. This transfer is done with regard to environmental improvement and a lean production philosophy. "Trouble-shooting" (reduction of abrasive and adhesive die wear) by using additional lubrication is therefore not possible anymore.In this investigation 1.20 and 1.95 mm thick uncoated and hot-dip galvanized sheets of DP600, DP800 and DP1000 were tested. The wear behaviour of the die materials Sverker 21 (D2), Calmax, Sleipner, Weartec, Vanadis 6 and Vancron 40 were studied. Uncoated, plasma-nitrided, PVD-coated (CrN and TiAlN) versions of dies made in the above-mentioned materials were tested.The tests were carried out both in laboratory in a U-bend test equipment and in real stamping production. Based on the results obtained in laboratory and production tests, guidelines were established for selection of die materials and surface treatments in stamping of DP600, DP800 and DP1000. These guidelines are described in the present paper.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering (hsv//eng)

Nyckelord

Stamping

Tool

Die

Wear

DP600

DP800

DP1000

D2

Calmax

Sleipner

Weartec

Vanadis 6

Vancron 40

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