US2758922A - Alloys of titanium containing iron and vandium - Google Patents

Description

United States Patent 2,758,922 ALLOYS 0F TITANIUM CONTAINING IRON AND VANADIUM No Drawing. Application August 7, 1951, Serial No. 240,805

2 Claims. (Cl. 75175.5)

Robert H. Dickinson This invention relates to titanium base alloys and, more particularly, to alloys of titanium, iron and vanadium.

It is an object of the present invention to provide strong, ductile alloys of titanium.

Still another object of the present invention is to provide alloys of titanium consisting of iron, vanadium and titanium, with titanium as the base alloy and to which may be added carbon whereby stronger ductile alloys of titanium may be formed.

Another object of the present invention is to provide alloys of titanium, vanadium and iron, which have good resistance to oxidation and high hardness at elevated temperature, as Well as tensile properties improved over the metal titanium taken alone.

Still another object of the present invention is to provide means and methods for forming ductile alloys of titanium containing essentially iron and vanadium, and to which additions of carbon may be made.

It is also within the contemplation of the invention to provide means for making titanium base alloys containing iron, vanadium and titanium, to which there may be added carbon so as to improve the physical properties of titanium and to make fabrication thereof possible on a practical and industrial scale at low cost.

It has been discovered by the applicants that iron and vanadium form strong ductile ternary alloys with titanium. The addition of carbon to a titanium alloy of iron and vanadium materially affects the properties. The preferred range of carbon content is 0.25% to 0.75%. Below this range, the beneficial effects of the carbon decreases materially, and above this range, the elongation is reduced appreciably. In accordance with this finding, an alloy has been formed containing 2.5% iron, 2.5 vanadium and 0.32% carbon. This alloy has the following properties:

Ultimate tensile strength (p. s. i.) 160,000 Proportional limit (p. s. i.) 110,000 Elongation (per cent in 2") 8.6 Reduction in area (per cent) 33.6 Modulus of elasticity (p. s. i.) 16.8)( Electrical resistivity (ohm-cm.) 84.2)(10- a compari- Ultimate tensile strength (p. s. i.) 87,000 Proportional limit (p. s. i.) 53,000 Elongation (per cent in 2") 16 Modulus of elasticity (p. s. i.) 16 10 Electrical resistivity (ohm-cm.) 60 10 The hardness at 500 C. was 28 Rockwell A and ofi the scale at 600 C.

As the result of applicants work, it was found that the particular combination of iron and vanadium is very important. Alloys which contain iron or vanadium in combination with titanium singly are not as strong and have a lower proportional limit than the alloys fabricated of iron, vanadium and titanium. It has also been dis covered that alloys containing iron and titanium, or vanadium and titanium, are more diflicult to hot work than alloys containing iron, vanadium and titanium.

Thus, applicants have provided an invention in the discovery of an alloy whereby unexpected results are obtained through the combination of iron, vanadium and titanium in the same alloy.

As a basis of comparison, three alloys are presented below. The first alloy consists of 5% iron, 0.41% carbon, with the balance essentially all titanium; the second alloy consists of 5% vanadium, 0.38% carbon, with the balance being essentially all titanium; while the third alloy consists of iron, vanadium and titanium, plus an addition of carbon: viz. 2.5 iron, 2.5 vanadium, 0.32% carbon, the balance essentially all titanium.

1. Composition: 5% iron0.41% carbon-balance titanium Ultimate tensile strength (p. s. i.) 155,000 Proportional limit (p. s. i.) 87,000 Elongation (per cent in 2") 8.6 Forgeability Fair Composition: 5% vanadium0.38% carbonbalance titanium Ultimate tensile strength (p. s. i.) 130,000

Proportional limit (p. s. i.) 83,500 Elongation (per cent in 2") 14.1 Forgeability Fair 3. Composition: 2.5% iron-2.5% vanadium0.32%

carbonbalance titanium The marked increase in proportional limit is readily noticed. The total alloy content of the materials is comparable, the only difference being in the combination of iron and vanadium.

It has been found further that the tensile properties of titanium alloys containing iron and vanadium are dependent on the amount of iron and vanadium in the alloy. Tensile strength and proportional limit increase asthe amount of alloying agents increase. A corresponding decrease in ductility accompanies the increase in strength. In addition, the properties of each alloy can also be controlled by the forging temperature used to form the metal and the thermal treatment used after forging. To illustrate the efiects of composition and forging temperature, the following alloys are illustrative:

Composition 1.95% Fe, 3.39% Fe, 5.54% Fe, 2.54% v, 4.16% v, 4.02% v, 0.44% 0, 0.5% C, 0.45% C, Bal. T1 Bal. 'Il Bal. Ti

Ultimate Tensile Strength (p.

s. i.) 136, 800 151, 300 231, 000 Proportional Limit (p. s. i.) H.-. 88, 500 110,00 Elongation (percent in 2") 11.3 8. 6 1. 56 Modulus of Elasticity (p. s. i.-

X10 17. 4 Reduction in Area (percent) 31 33. 4 Electrical Resistivity (ohm-cm) 76 88 134 Hardness, Rockwell A" 68 69 73 Izod Impact (ft.-lbs.) 20

1 Approximately.

Norm-These alloys were forged at 925 C. to 950 C.

The effect of thermal treatments on an alloy consisting of 4.5% iron-5.5% vanadiumthe balance being essentially all titanium, is shown in the table below:

4.5% Iron-5.5% Vanadium-balance titanium Thermal Treatment Hot Forged Hot Hot Forged at 925 C. Forged at 925 0. Hot Forged to 950 0., at 1150 to 950 C. at 925 C. Heat C. and and to 950 C. Treated Furnace Furnace and Air 1 Hour at Cooled Cooled Cooled 800 C. and

Furnace Cooled Ultimate Tensile Strength (p. s. i.) 144, 000 153, 900 231, 000 146, 500 Proportional Limit (1). s. i.)- 102,000 114,000 105,000 Elongation (percent in 10.15 7.3 1. 56 7. 8 Modulus of Elasticity (p. s. LX 16. 9 16 17 Reduction in Area (percent) 23. 9 35. 8 Electrical Restivity (ohm-cm.) 92 95. 3 134 101 Hardness (Rockwell The iron-vanadium-titanium alloys can be quench hardened. Quenching into water from a temperature of 900 C. increases the hardness of a 2.1% iron-2.7% vanadium alloy of titanium from 63 Rockwell A to 75 Rockwell A. Drawing at 500 C. for 4 hours decreased the quenched hardness to 72 Rockwell A. The metal is hardened somewhat by quenching in air which accounts for the difference in properties of the 4.5 iron-5.5% vanadium-titanium alloy furnace cooled and air cooled after forging as shown above.

Titanium alloys containing iron and vanadium can be hot rolled and cold rolled for ductile sheet. The sheet can be cold rolled to full hard (37% reduction in thickness) and annealed. The as hot rolled sheet is not ductile due to the quenching action of the rolls on the thin metal and therefore the hot rolled sheet should be annealed. Annealing can be done in air or argon atmosphere at 700 C. The surface oxide formed during hot rolling should be removed prior to cold rolling if a good cold rolled surface is desired.

An alloy containing 1.1% iron and 1.4% vanadium was cold rolled to 0.032" thick in the annealed, hard, A hard, /2 hard and full hard conditions. This sheet had the following properties:

Ultimate Percent Hardness Minimum Tensile Elongation Rockwell Bend Strength in 2 A Radius (p. s. i.) (11101165) 107, 600 17 60 $1 a 119, 600 11. 3 62. 5 lg 126, 600 7. 4 63. 5 it 137, 000 6. 6 64. 5 V4 143, 500 6. 6 65. 5 Brittle of this alloy in the three. conditions just mentioned are shown below:

Hot Rolled Hot Rolled to 0.100 Hot to 0.063 Annealed, Rolled Annealed, Cold Rolled to 0.040 Cold Rolled to 0.063" Annealed to 0.040 Annealed,

Annealed Cold Rolled to 0.040" Annealed Ultimate Tensile Strength (p.

s. i. 131,000 131,000 132,000 Proportional Limit (p. s. i.) 111,000 104, 500 Yield Strength at 0.2% Ofiset S. i. 122, 500 123, 500 Elongation (percent in 2") 9.0 9. 2 8. 6 Minimum Bend Radius (inches):

Longitudinal 14 lv Transverse t 1e it The forming of alloys containing iron and vanadium in titanium is done by forging at a metal temperature not to exceed 1200 C. to the desired shape. The normal forging temperature of 925 C. to 950 C. does not cause excessive oxidation. Hot rolling can be done at a metal temperature of 750 C. to 800 C. Annealing at 700 C. relieves the effects of cold work.

The alloys here described can be made by any method known to the metal-working art it inert atmospheres, typified by argon or helium, are present when the alloy is melted or sintered. Vacuum can also be used. If melted, the crucible can be graphite, a highly refractory oxide, preferably thoria or stabilized Zirconia or the carbides of tungsten or boron. If arc melted, in which case an inert atmosphere or vacuum must still be used, the crucible can be water cooled copper. Powder metallurgical methods can also be used. The tensile properties of the alloys herein described will vary according to the method used, but are better than unalloyed titanium in every case.

While the present invention as to its objects and advantages has been described herein as carried out in specific embodiments thereof, it is not desired to be limited thereby, but it is intended to cover the invention within the spirit and scope of the appended claims.

What is claimed is:

1. A titanium base alloy consisting of 2.1% iron, 2.7% vanadium, the rest being titanium, having a Rockwell A hardness characteristic of from 63 to 75.

2. A base alloy of titanium consisting of 2.1% iron, 2.7% vanadium, 0.5% carbon, the balance titanium.

Alloys by National Bureau of Standards, December 1, 1943, page 449.

Journal of Metals, March 1950, pageSlS.

Claims (1)

1. A TITANIUM BASE ALLOY CONSISTING OF 2.1% IRON, 2.7% VANADIUM, THE REST BEING TITANIUM, HAVING A ROCKWELL "A" HARDNESS CHARACTERISTIC OF FROM 6O TO 75.