2. 1 August 4-9, 2013 – Waikoloa, Hawaii Recent Developments in Flat Rolling Technologies Dr. Hailiang YU hailiang@uow.edu.au 2013.08.05

3. 2 August 4-9, 2013 – Waikoloa, Hawaii Outline  Conventional rolling technologies Developments of rolling technologies ① Heated roll rolling ② Cryogenic rolling ③ Variable gauge rolling ④ Through-width vibration rolling ⑤ ARB & Asymmetric rolling Conclusions

4. 3 August 4-9, 2013 – Waikoloa, Hawaii Conventional rolling technologies Rolling temperature Rolling schedule Roll wear and lubrication Cooling speed …… Temperature of workpiece and roll Movement of roll Rolling speed control Automatic gauge control Automatic width movement Reheating F’ce Roughing MillFinishing MillROT Cooling Down Cioiler 1100~1250 o C1000~1050 o C800~900 o C100~700 o C Fig. 1 Conventional hot rolling process

5. 4 August 4-9, 2013 – Waikoloa, Hawaii Contents Conventional rolling technologies  Developments of rolling technologies ① Heated roll rolling ② Cryogenic rolling ③ Variable gauge rolling ④ Through-width vibration rolling ⑤ Multilayer material rolling Conclusions

6. 5 August 4-9, 2013 – Waikoloa, Hawaii ① Heated roll rolling Magnesium alloy strips are widely used in aerospace, automotive industry, etc. They are difficult to produce using a cold forming process due to their poor deformation ability. Hot rolling of magnesium alloy strips may be hazardous owing to the possibility of dust explosion. Can a rolling process with heated roll be used to roll cold magnesium alloy strips? Fig. 2 Friction and wear tester made by RAL

7. 6 August 4-9, 2013 – Waikoloa, Hawaii ① Heated roll rolling Influence factors Roll temperature Strip thickness Rolling velocity Reduction ratio …… Predict the mean temperature of strip at the exit of rolling deformation zone Fig.3 Thermal field in rolling deformation zone under various initial strip thicknesses *YU HL, et al. Journal of Materials Engineering and Performance, 2012, 21: 1841-1848

8. 7 August 4-9, 2013 – Waikoloa, Hawaii ② Cryogenic rolling Recent years, a lot of interest has been shown in the production of materials with nano-sized grains, especially in bulk through Severe Plastic Deformation (SPD). The SPD techniques, which include high-pressure torsion, equal- channel angular pressing, accumulative roll bonding, equal channel rolling, …… Cryorolling has potential for large-scale industrial applications of nanostructural materials. Due to the suppression of dynamic recovery during cryorolling both the tensile strength and yield strength were considerably increased. Moreover, the cryorolling process offers other advantages, such as, lower required plastic deformations, simple processing procedures and ability to produce continuously long length product. Roll mill Liquid nitrogen Samples

9. 8 August 4-9, 2013 – Waikoloa, Hawaii When the ratio of upper and down rolling velocities is 1.4, the Al 1050 is of grain lattice length with 211 nm, which is much smaller than that obtain by traditional asymmetric rolling with 500 nm. Both the strength and ductile of Al 1050 materials increase with the ratio of upper and down rolling velocities from 1.1 to 1.4. When the ratio of upper and down rolling velocities is 1.4, the tensile stress reaches 196 MPa which is larger 22.3% that with the ratio of upper and down rolling velocities of 1.1. Fig. 4 Curve of engineering stress-strain (a), tensile and yield stress (b) Al 1050 under various ratios of upper and down rolling velocites Fig. 5 TEM of Al1050 after rolling with ratio of upper and down rolling velocities 1.1 (a), 1.4 (b) *YU HL, et al. Scientific Reports, 2012, 2, 772; Mater Sci Eng A, 2013, 568: 212-218. ② Cryogenic rolling

10. 9 August 4-9, 2013 – Waikoloa, Hawaii ③ Variable gauge rolling There is a trend of energy saving and emission reduction in steel industry, and rolling with reducing resource consumption attracts lots of attentions. Variable gauge rolling process is a new technology to produce flat products with different thicknesses, such as Longitudinal Profile (LP) plates, Tailor Rolled Blanks (TRB). LP plates are market potential steels in the bridge (as shown in Figure), architecture, shipbuilding, etc. TRBs are used in automobile manufacturing to instead of the Tailor Welded Blanks (TWB). Fig. 6 Mosel bridge, Luxembourg 1100 t LP plates Designedthickness welding Weight increase Conv. method New method Opt. thickness Decrease weight Decrease the length of welding seam The position where LP plate is used Separating wall bottom

11. 10 August 4-9, 2013 – Waikoloa, Hawaii Figure shows the equivalent stress distribution of plate in the rolling deformation zone at various rolling stages. Compared the stress distribution in plate at 0.05 s and 0.45 s, 0.1 s and 0.4 s, 0.15 s and 0.35 s, 0.2 s and 0.3 s respectively, the stress in deformation zones of the former ones are larger than these of the latter ones when they have the same reduction. Fig. 8 Equivalent stress distribution of workpiece under various rolling stages (1) Fig. 7 Kinds of profiles of VGRed products ③ Variable gauge rolling YU HL et al. Steel Research International, 2013, DOI: 10.1002/srin.201300012

12. 11 August 4-9, 2013 – Waikoloa, Hawaii Fig. 9 Rolling force (a) and wave motion of rolling force (b) under various reductions Fig. 10 Illustration of thin zone in VGR process YU HL et al. Steel Research International, 2013, DOI: 10.1002/srin.201300012 ③ Variable gauge rolling

13. 12 August 4-9, 2013 – Waikoloa, Hawaii ④ Through-width vibration rolling Fig. 11 schematic illustration of through-width vibration rolling (TWVR) Chen Y. Mater Sci Eng A, 2012, 551: 296

14. 13 August 4-9, 2013 – Waikoloa, Hawaii Width vibration = 2.5 mm Width vibration = 0 mm Fig. 12 Shear strain along strip width direction Plastic strain Fig. 13 Friction force during rolling ④ Through-width vibration rolling Fig. 13 Yield strength and ultimate tensile strength of the as-TWVR sample as a function of the applied amplitudes

15. 14 August 4-9, 2013 – Waikoloa, Hawaii ⑤ Multilayer material rolling *YU HL, et al. Scientific Reports, 2013, 3, 2373; DOI: 10.1038/srep02373 Fig.14 Bonding quality of the interface Fig.15 TEM graph of the bonding zone

16. 15 August 4-9, 2013 – Waikoloa, Hawaii Conclusions Advanced rolling technologies Change heated part Deep reduction of rolling temperature Adjustment the rolling movement along thickness direction Adjustment the rolling movement along width direction Adjustment the number of workpieces Conventional rolling technologies Heated roll rolling technologies Cryogenic rolling technologies Variable gauge rolling technologies Through-width vibration rolling technologies Multilayer materials rolling

17. 16 August 4-9, 2013 – Waikoloa, Hawaii Thanks for your attention hailiang@uow.edu.au