Określ na podstawie tabeli, jaka powinna być wartość naprężenia gnącego σ_g w procesie gięcia stali, jeśli granica plastyczności stali wynosi 320 MPa, blacha ma grubość g=2 mm, a promień wewnętrzny krzywizny giętej blachy r_w = 3,2 mm. <br><br> <table><tr><th rowspan="3">rw/g</th><th colspan="5">Granica plastyczności Re lub R02MPa</th></tr><tr><th>190</th><th>240</th><th>290</th><th>320</th><th>350</th></tr><tr><th colspan="5">σg, MPa</th></tr><tr><td>1,0</td><td>540</td><td>670</td><td>738</td><td>790</td><td>793</td></tr><tr><td>1,25</td><td>530</td><td>660</td><td>725</td><td>775</td><td>780</td></tr><tr><td>1,6</td><td>525</td><td>642</td><td>704</td><td>764</td><td>770</td></tr><tr><td>2,0</td><td>514</td><td>627</td><td>684</td><td>752</td><td>762</td></tr><tr><td>2,5</td><td>495</td><td>608</td><td>660</td><td>735</td><td>748</td></tr><tr><td>3,2</td><td>466</td><td>580</td><td>627</td><td>706</td><td>723</td></tr><tr><td>4,0</td><td>440</td><td>555</td><td>595</td><td>680</td><td>700</td></tr><tr><td>5,0</td><td>412</td><td>528</td><td>565</td><td>654</td><td>675</td></tr><tr><td>6,3</td><td>385</td><td>497</td><td>535</td><td>625</td><td>650</td></tr></table>

• A764 MPa
• B752 MPa
• C706 MPa
• D775 MPa