The advantages to hot working magnesium are: When heating magnesium and its alloys, watch the  temperature carefully as the metal is easily burned.  Overheating also causes small molten pools to form within  the metal. In either case, the metal is ruined. To prevent  burning, magnesium must be protected with a sulfur dioxide  atmosphere while being heated. Proper bending around a short radius requires the removal of  sharp corners and burrs near the bend line. Layouts should  be made with a carpenter’s soft pencil because any marring  of the surface may result in fatigue cracks. Press brakes can be used for making bends with short radii.  Die and rubber methods should be used where bends are  to be made at right angles, which complicate the use of a  brake. Roll forming may be accomplished cold on equipment  designed for forming aluminum. The most common method  of forming and shallow drawing of magnesium is to use a  rubber pad as the female die. This rubber pad is held in an  inverted steel pan that is lowered by a hydraulic press ram.  The press exerts pressure on the metal and bends it to the  shape of the male die. The machining characteristics of magnesium alloys are  excellent, making possible the use of maximum speeds of  the machine tools with heavy cuts and high feed rates. Power  requirements for machining magnesium alloys are about  one-sixth of those for mild steel. Filings, shavings, and chips from machining operations  should be kept in covered metal containers because of the  danger of combustion. Do not use magnesium alloys in  liquid deicing and water injection systems or in the integral  fuel tank areas. Keep titanium particles away from sources of ignition.  Small particles of titanium burn very easily. In sufficient  concentration, these small particles can cause an explosion.  If water touches molten titanium, a steam explosion could  occur. Extinguish titanium fires with dry talc, calcium  carbonate, sand, or graphite. Apply the powder on the burning  metal to a depth of  1 ⁄ 2-inch or more. Do not use foam, water,  carbon tetrachloride, or carbon dioxide. Titanium in its mineral state, is the fourth most abundant  structural metal in the earth’s crust. It is lightweight,  nonmagnetic, strong, corrosion resistant, and ductile.  Titanium lies between the aluminum alloys and stainless  steel in modulus, density, and strength at intermediate  temperatures. Titanium is 30 percent stronger than steel,  but is nearly 50 percent lighter. It is 60 percent heavier than  aluminum, but twice as strong. Titanium and its alloys are used chiefly for parts that require  good corrosion resistance, moderate strength up to 600 °F  (315 °C), and lightweight. Commercially pure titanium  sheet may be formed by hydropress, stretch press, brake  roll forming, drop hammer, or other similar operations. It is  more difficult to form than annealed stainless steel. Titanium  can also be worked by grinding, drilling, sawing, and the  types of working used on other metals. Titanium must be  isolated from magnesium, aluminum, or alloy steel because  galvanic corrosion or oxidation of the other metals occurs  upon contact. Monel$^{®}$ rivets or standard close-tolerance steel fasteners  should be used when installing titanium parts. The alloy  sheet can be formed, to a limited extent, at room temperature.  The forming of titanium alloys is divided into three classes: Over 5 percent of all titanium in the United States is produced  in the form of the alloy Ti 6Al-4V, which is known as the  workhorse of the titanium industry. Used in aircraft turbine  engine components and aircraft structural components, Ti  6Al-4V is approximately 3 times stronger than pure titanium.  The most widely used titanium alloy, it is hard to form.  The following are procedures for cold forming titanium 6Al- 4V annealed with stress relief (room temperature forming): 3.  A powerful press brake is required to form titanium  parts. Regular hand-operated box and pan brakes  cannot form titanium sheet material. 2.  Stress relieves the part as follows: heat the part to  a temperature above 1,250 °F (677 °C), but below  1,450 °F (788 °C). Keep the part at this temperature  for more than 30 minutes but less than 10 hours. 1.  It is important to use a minimum radius chart when  forming titanium because an excessively small radius  introduces excess stress to the bend area. •  Cold forming with no stress relief •  Cold forming with stress relief •  Elevated temperature forming (built-in stress relief) 1.  It is more easily formed when hot than are other  metals. 2.  Spring-back is reduced, resulting in greater dimensional  accuracy. Description of Titanium Working Titanium 4-85