Tungsten wire, cathode heater and vibration service lamp filament

A method of manufacturing a tungsten wire containing 1 to 10% by mass of rhenium and having a wire diameter of 20-90 μm, the method comprising the steps of:

• heating and rolling a tungsten sintered body containing 1 to 10% by mass of rhenium, wherein said rolling process utilizes a process rate of 40 to 75% for a rolling process with one heating process;
• performing a recrystallization heat treatment;
• heating and swaging the rolled sintered body after the recrystallization heat treatment;
• heating and wire drawing the swaged sintered body;
• and
• performing a strain removal heat treatment of said tungsten wire at a temperature of 1200 to 2300° C. at a time when a diameter of the tungsten wire formed by the swaging process or the wire drawing process is 100 μm or less;
• said tungsten wire having a point which indicates a 5% elongation within a quadrangle formed by joining points with straight lines, where values of x and y are point (20, 73), point (20, 83), point (90, 72), and point (90, 56), in this order, wherein the wire diameter of said tungsten wire is represented by x μm, and the elongation of the tungsten wire is 5% after electrically heating with an electric current which is a ratio of y % to a fusion current (FC) at said wire diameter x μm, and wherein a semi-logarithmic system of coordinates is expressed by a horizontal axis using a logarithmic scale of said wire diameter x and a vertical axis using a normal scale of ratio y to said fusion current.

A method of manufacturing a tungsten wire containing more than 10% by mass but 30% by mass or less of rhenium and having a wire diameter of 20-90 μm, the method comprising the steps of:

• heating and rolling a tungsten sintered body containing 10 to 30% by mass of rhenium, wherein said rolling process utilizes a process rate of 40 to 75% for a rolling process with one heating process;
• performing a recrystallization heat treatment;
• heating and swaging the rolled sintered body after the recrystallization heat treatment;
• heating and wire drawing the swaged sintered body;
• and
• performing a strain removal heat treatment of said tungsten wire at a temperature of 1200 to 2300° C. at a time when a diameter of the tungsten wire formed by the swaging process or the wire drawing process is 100 μm or less;
• said tungsten wire having a point which indicates a 2% elongation within a quadrangle formed by joining points with straight lines, where values of x and y are point (20, 55), point (20, 63), point (90, 51), and point (90, 39), in this order, wherein the wire diameter of said tungsten wire is represented by x μm, and the elongation of the tungsten wire is 2% after electrically heating with an electric current which is a ratio of y % to a fusion current (FC) in said wire diameter x μm, and wherein a semi-logarithmic system of coordinates is expressed by a horizontal axis using a logarithmic scale of said wire diameter x and a vertical axis using a normal scale of ratio y to said fusion current.

A method of manufacturing a tungsten wire containing more than 10% by mass but 30% by mass or less of rhenium and having a wire diameter of 20-90 μm, the method comprising the steps of:

• heating and rolling a tungsten sintered body containing 10 to 30% by mass of rhenium, wherein said rolling process utilizes a process rate of 40 to 75% for a rolling process with one heating process;
• performing a recrystallization heat treatment;
• heating and swaging the rolled sintered body after the recrystallization heat treatment;
• heating and wire drawing the swaged sintered body;
• and
• performing a strain removal heat treatment of said tungsten wire at a temperature of 1200 to 2300° C. at a time when a diameter of the tungsten wire formed by the swaging process or the wire drawing process is 100 μm or less;
• said tungsten wire having a point which indicates a 5% elongation within a quadrangle formed by joining points with straight lines, where values of x and y are point (20, 53), point (20, 60), point (90, 48), and point (90, 37), in that order, wherein the wire diameter of said tungsten wire is represented by x μm, and the elongation of the tungsten wire is 5% after electrically heating with an electrical current which is a ratio of y % to a fusion current (FC) at said wire diameter x μm, and wherein a semi-logarithmic system of coordinates is expressed by a horizontal axis using a logarithmic scale of said wire diameter x and a vertical axis using a normal scale of ratio y to said fusion current.