Author: M. SEMCHYSHEN Publisher: ISBN: Category : Languages : en Pages : 1
Book Description
The progress of work aimed at explaining the strengthening mechanisms operative in several molybdenum-base alloys is described. The optimum carbon contents for conventionally processed molybdenum-base alloys containing titanium, hafnium, zirconium, and titanium + zirconium are defined. The possibilities of increasing the strengths and reducing the optimum carbon content of these materials through solution and aging heat treatments are discussed. Attempts to prepare wrought sections of molybdenum-base alloys containing nominally 10% Cb and/or 10% Ta were only marginally successful owing to difficulties encountered in working the vacuumarc-cast ingots. A series of experiments is described wherein various melting and deoxidation practices are evaluated in connection with the 50% Mo-50% W alloy. Alloys based on tungsten or on various molybdenum-tungsten ratios have received considerable attention. Considerable difficulty was encountered in converting certain of the alloys of this type to bar stock. Outstanding elevated-temperature tensile and stressrupture properties are reported for a number of the compositions that were successfully converted to wrought stock. (Author).
Author: M. SEMCHYSHEN Publisher: ISBN: Category : Languages : en Pages : 125
Book Description
The influence of in-process solution and solution and aging treatments on the properties of several molybdenum-base alloys is described. Alloys of molybdenum with titanium and/or zirconium were processed to bar stock by extrusion and rolling procedures. Extruded bars were prepared for rolling to final size either by heating to the minimum recrystallization temperature or by the application of optimum solution or solution and aging treatments. The latter procedures resulted in significantly higher recrystallization temperatures and tensile strengths than the procedure involving recrystallization prior to rolling. The high elevated temperature strengths obtained for the molybdenum-base alloys studied resulted from a critically dispersed carbide phase. A limited amount of work indicated that a dispersion hardenable molybdenum-beryllium alloy could be worked by extrusion. Room temperature hardnesses approaching 500 DPH were developed by the application of the proper solution and aging treatments to the extruded molybdenum-beryllium alloy. (Author).
Author: George A. Reimann Publisher: ISBN: Category : Tungsten alloys Languages : en Pages : 84
Book Description
A satisfactory melting technique was established for the production of fine-grained, homogeneous, high quality, W base alloy ingots. The 88W-6Mo6Cb alloy originally selected for the program was discarded because of ingot cracking and replaced by a 92W-6Mo-2Cb alloy. The redcution of columbium from 6 to 2% permitted the production of sound 3-1/2 inch diameter ingots, 6 to 9 inches in length. Macroexamination revealed a mixture of fine, equiaxed grains and short, thin columnar grains. Seven ingots of the 92-6-2 composition were extruded successfully at 4000 F, using ratios of 4.4;1, 5.7:1, and 7.5:1. The extruded material was forged and rolled to determine workability. A time, temperature, recrystallization study was conducted on forged specimens of the 92-6-2 alloy. (Author)
Author: M. Semchyshen Publisher: ISBN: Category : Materials at high pressures Languages : en Pages : 86
Book Description
A number of complex molybdenum-, molybdenumtungsten-, and tungsten-base alloys were consolidated by the vacuum-arc-casting technique. Successful extrusions were realized from all of the vacuum-arc-cast ingots. Extrusion constants well above those of earlier experiments were measured, indicative of the good elevated-temperature strength and concomitant high resistance to extrusion of the materials studied. Rolled bars were studied from the standpoint of recrystallization behavior, transition temperature, tensile properties as a function of temperature and, to a limited extent, creep-rupture properties. A carbon synergism was studied in the alloys Mo + 3% Ti + 0.5% Zr and Mo + 25% W + 1.25% Ti + 0.1% Zr from the standpoint of elevated temperature strength. In the case of both alloys, the carbon contents yielding the highest elevated temperature strengths also resulted in the highest transition temperatures as measured by the tensile test. An alloy based on Mo-50% W, and containing 0.8% Ti and 0.3% Zr, displayed exceptionally high strengths at elevated temperatures. The tensile transition temperature of this material was, however, above room temperature. (Author).
Author: M. Semchyshen Publisher: ISBN: Category : Languages : en Pages : 101
Book Description
Solid-solution-strengthened tungsten-base alloys were vacuum-arc-cast with relatively large additions of tantalum, Columbium, and/or molybdenum. Machined blanks from the ingots were extruded to round bar stock at temperatures from 3600 to 4000 F. Extrusion recoveries varied considerably from heat-to-heat. Elevated-temperature tensile tests were performed on specimens machined from available extruded bar stock. Strengths were well above those reported for unalloyed tungsten, but were below those resulting from earlier studies on dispersion-strengthened tungsten-base alloys. Molybdenum-base alloy sheets were prepared representing two compositions and three thermomechanical histories. Compositions studied were Mo + 1.25% Ti + 0.3% Zr + 0.1% C (TZC), and Mo + 0.3% Zr + 0.03% C. The thermomechanical variables imposed were solution heat treatments at various stages during the working schedules. Recrystallization behavior, bend transition temperatures, and tensile properties were quite sensitive to working schedules. Earlier work at this Laboratory indicated that in-process solution treatments at temperatures sufficiently high to effect increases in tensile strength usually resulted in increased transition temperatures. The present work has shown that a much more favorable trade-off between strength and transition temperature can result from the proper placement of the solution treatment in the working schedule.
Author: Gordon D. McArdle Publisher: ISBN: Category : Languages : en Pages : 17
Book Description
Tungsten-base alloys were prepared by the vacuum-arc-casting process. Charges blended to obtain each of the aim compositions contained small additions of carbon to effect deoxidation during arc melting. One heat of the W + 0.05% Zr composition was deoxidized with boron. Poor recoveries of wrought bar stock were experienced when conversion was attempted by conventional extrusion and rolling procedures. When the blanks were encapsulated in molybdenum, extruded and swaged to 1/2-in.-diameter bar stock, good recoveries were obtained. Tensile and creeprupture strengths of alloys were higher than those observed for unalloyed tungsten of comparable carbon content. The variation in strength and, workability from alloy to alloy was noticeably sensitive to residual carbon and boron contents. Tensile transition temperatures were markedly influenced by the degree of deoxidation achieved during arc melting. (Author).
Author: M. SEMCHYSHEN
Author: M. Semchyshen
Author: Peter L. Raffo
Author: M. SEMCHYSHEN
Author: George A. Reimann
Author: M. Semchyshen
Author: M. Semchyshen
Author: M. Semchyshen
Author: U.S. Atomic Energy Commission
Author: Gordon D. McArdle