Engineering topics
Publications and source records attributed to Monroe, R. E..
Characterizations of flight and ground based samples from the metals melting experiment are detailed. The characteristics were determined by nondestructive investigation, visual observation, metallographic examination, and post-test measurements. Comparisons of the flight and ground based discs showed that an electron beam heat source can be used in zero gravity for cutting, welding, or melting.
Information developed to characterize flight and ground based samples from the metals melting experiment is detailed in this report. Included are the characteristics determined by nondestructive examination, visual observation, metallographic examination and posttest measurements. Comparisons of the flight and ground based discs showed that an electron beam heat source can be used successfully in zero gravity for cutting, welding, or melting. Few differences were observed that could be attributed to the absence of gravity in these operations.
Information developed to characterize flight and ground based samples from the Exothermic Brazing Experiment is detailed. Included is information developed from metallographic observation, chemical analysis, and measurements of component dimensions. Comparisons of the flight and ground based specimens showed that good quality brazes were obtained. Effects of the zero gravity processing were noted on liquid metal flow and braze alloy-base metal reactions. Unusual metallurgical structures exhibited in the nickel brazes made in Skylab were the result of composition variations apparently related to the time-temperature cycle characteristic of this braze.
The metallographic characterization, analysis, and property measurement of ground samples for comparison with those processed on Skylab are described. Experiments on metals melting and exothermic brazing are summarized, and results are presented.
The joining of four types of nickel-base materials is described: (1) high-nickel, nonheat-treatable alloys, (2) solid-solution-hardening nickel-base alloys, (3) precipitation-hardening nickel-base alloys, and (4) dispersion-hardening nickel-base alloys. The high-nickel and solid-solution-hardening alloys are widely used in chemical containers and piping. These materials have excellent resistance to corrosion and oxidation, and retain useful strength at elevated temperatures. The precipitation-hardening alloys have good properties at elevated temperature. They are important in many aerospace applications. Dispersion-hardening nickel also is used for elevated-temperature service.
Al weld metal compositions and hydrogen content effects on weld porosity, locating hydrogen in weld by radioactive tracers
Vacuum effects on resistance spot welds in aluminum, stainless steel and titanium alloys, noting X ray and tensile shear test results
Diffusion bonding for leaktight joints in connectors using intermediate metal system of Au-Cu-Au
Resistance spot welds in Al, Ti and stainless steel in air and hard vacuum, showing feasibility for space assembly
Thermal stresses during welding, and buckling after welding
Investigation of aluminum alloy welds reveals that the combinations of metallic elements with hydrogen are not capable of producing weld porosity themselves, rather they tend to increase the amount of porosity only in the presence of arc contamination by water vapor.
Plasma arc welding as method to simultaneously clean and weld aluminum alloy plate
Tensile strength and X ray analysis of resistance spot welded aluminum and stainless steel alloys
State-of-art of metal-metal bonding in space environment - bibliography
Designing, forming, machining, and assembling for joining titanium and titanium alloys with mechanical fasteners
Nickel and nickel- base alloys are amenable to joining with many of the familiar joining processes. Some new joining processes also have been used successfully. In general, conventional joining procedures are used with only slight required modifications, depending on the particular alloy to be welded. However, some special precautions must be taken. Harmful materials must be removed from the joint or surrounding areas or they may damage the weld and the nearby heated parent metal. Some high-strength age hardenable alloys are prone to cracking in or near joint areas, unless the material is in the proper condition of heat treatment prior to joining operations. Foreign material and flux residues left from joining operations can cause trouble in subsequent service if not removed. Procedures for joining these alloys have been developed that eliminate or minimize the usual difficulties that have been experienced. When proper procedures are employed, joining of nickel and nickel- base alloys can be performed satisfactorily.
Effects of factors associated with aluminum base plate and filler wire on occurrence of weld defects