Complex Phase steels

Transcription

1 Automotive Worldwide steels Extract from the product catalogue -European edition Note: Information contained in this catalogue is subject to change. Please contact our sales team whenever you place an order to ensure that your requirements are fully met. Please contact us if you have a specific requirement that is not included in the range of products and services covered by this catalogue. We are also reachable by the address automotive.request@arcelormittal.com.

2 We are also reachable by the address steels Advanced high strength steels Description The family of steels supplements ArcelorMittal's VHSS (very high strength steel) product range. These steels are cold formed to make lightweight structural elements. A number of automotive parts, such as sills and door reinforcements, have simple shapes and the steel is therefore only slightly deformed. For this reason, ArcelorMittal has added the family of steels to its range. These steels offer high as-delivered yield strength and good bendability and stretch flangeability. Applications Given their high energy absorption capacity and fatigue strength, these grades are particularly well suited for automotive safety components requiring good impact strength and for suspension system components. Seat flange in 600 (thickness: 1.5 mm) Door bar in (thickness: 2 mm) Tunnel stiffener in 800 (thickness: 1.6 mm) 2

3 Fender beam in (roll-formed) Fender beam in (roll-formed) Suspension arm in 800 (thickness: 3.1 mm) Designation and standard Euronorms 600 VDA HCT600C (+ZE) HCT780C (+ZE, +Z) CR570Y780T-CP (-UNC,-EG,-GI) HCT980C (+ZE) CR780Y980T-CP (-UNC,-EG) Y800 HCT980C (+Z) CR780Y980T-CP (-GI) 750 HDT750C (+Z) 800 SF HDT780C (+Z) HDT950C (+Z) SF 3 HR660Y760T-CP (-UNC,-GI)

4 Euronorms Uncoated (EN :2015): Steel grade name Electrogalvanized (EN : EN :2017): Steel grade name +ZE Galvannealed (EN :2015): Steel grade name +ZF Extragal (EN :2015): Steel grade name +Z VDA Uncoated: Steel grade name-unc Electrogalvanized: Steel grade name-eg Galvannealed: Steel grade name-ga Extragal : Steel grade name-gi SF (Stretch Flanging): grade specially developed for improved stretch flangeability. While the ArcelorMittal grades conform perfectly well to the indicated EN standards, ArcelorMittal grades generally offer tighter mechanical properties (see table below). The above indicative table summarizes the European and VDA standards corresponding to the ArcelorMittal product range. Technical characteristics Mechanical properties Guaranteed values for ISO 20x80 specimen of uncoated sheet in the strip center at ambient temperature ST -Transverse direction (perpendicular to the rolling direction) / -Rolling direction YS (MPa) UTS (MPa) ef (%) L0 = 80 mm th < 3 mm Direction 600* SF ST * Y800 SF (Stretch Flanging): grade specially developed for improved stretch flangeability. * The guarantees for this grade are subject to change. Microstructure of hot rolled 800 4

5 Microstructure of hot rolled Chemical composition (%) C Max Mn Max Si Max 600 0,10 1,60 0,40 0,17 2,20 0,60 0,17 2,20 0,60 0,18 2,40 0,60 SF 0,18 2,40 0,60 Y800 0,20 2,70 0, ,25 1,40 0, ,10 2,00 0,25 0,14 1,70 0,25 SF (Stretch Flanging): grade specially developed for improved stretch flangeability. Available coatings and Worldwide availability Uncoated EUR NAM SAM Electrogalvanized RSA 600 SF SF / Y /MP /M 800 HY /MP CHI EUR NAM SAM RSA CHI

6 Extragal EUR NAM SAM Jetgal RSA CHI EUR NAM SAM RSA CHI 600 SF SF / Y /MP /M 800 HY /MP 1000 Available in non-visible part quality quality (Z) Undergoing customer testing Under development Available in visible and non-visible part EUR : Europe Region -NAM : North America Region -SAM : South America Region -RSA : South Africa Region -CHI : China X Product available /O Product under development SF (Stretch Flanging): grade specially developed for improved stretch flangeability. Please consult us about products under development. Recommendations for use and secondary processing Forming Although their ultimate elongation is lower than that of DP and TRIP steels, steels have good formability for their high strength level. Forming limit curves can be used to define maximum strains without necking for different deformation paths. Forming limit curves for steels: in 1.5 mm thickness 6

7 in 3 mm thickness In addition, steels exhibit good roll-forming, bending and hole expansion behavior. The graph below illustrates hole expansion behavior according to the ISO standard for a number of Dual Phase and steels with UTS=1000 MPa. The family -and especially the Stretch Flangeable (SF) product, which was specially designed for exceptional stretch flangeability -has higher hole expansion values. View of hole expansion in grades CR-CP 1000 and CR-CP 1000 SF in 1.5 mm thickness. The CP 1000 SF achieves a much higher hole expansion value. The table below shows typical minimum bending radius values for steels in 1.5 mm thickness. 7

8 The table below shows typical minimum bending radius values for steels in 1.5 mm thickness. Rolling direction Transverse direction SF 1 Rolling direction Transverse direction Bending method: 90 flanging For more information about the forming of steels in special thicknesses and with special coatings, please consult us. Welding Resistance spot welding The range of steels has very good resistance spot weldability. The welding range, determined according to the ISO standard, is quite wide. The table below shows examples (indicative) of spot welding characteristics for matching joints, determined according to the ISO standards. Coating Thickness (mm) Extragal Nugget diameter Pure tensile Weld diameter Tensile-shear (mm) (kn) (mm) (kn) Laser welding Laser welding tests have revealed no particular difficulties. ArcelorMittal can provide technical assistance in adjusting the welding parameters for all steels in the range. Fatigue 8

9 steels exhibit good fatigue properties and can be used in suspension system parts such as suspension arms. The table below gives examples of Wöhler curves for a variety of steels. They are expressed as stress amplitude versus cycles to failure and are obtained with a stress ratio of R = 0.1 and repeated tensile loading. Wöhler or SN curves for steels (R=0.1) The graph below shows the low cycle or EN curves for the same steels. These are expressed as strain amplitude versus number of reversals (one cycle equals two reversals). Other high and low cycle fatigue data are available on request. Low cycle or EN curves for steels (R=-1) ArcelorMittal can provide a full database on the fatigue performance of steels. Impact strength As a result of their very high YS and UTS values, steels are particularly well suited for anti-intrusion parts. steels have been characterized in the 3-point bending flex test using top hat cross-section specimens impacted at 30 kph. The tests showed very good behavior of these steels. Mass savings potential compared to an HA 380 steel (reference) ArcelorMittal Last update: