The report summarizes the advancements made in the development and welding of steels possessing yield strengths greater than 150,000 psi. Steels discussed include the medium carbon, low-alloy martensitic steels; low carbon alloy martensites; and nickel maraging steels. Almost all programs which have the objective of developing high-strength steels have an equally important phase concerned with filler metal development. Filler metals are also discussed. The new welding processes discussed are Narrow-Gap welding, electron-beam welding, plasma-arc welding, high-frequency resistance welding, electroslag welding, laser welding, and interrupted-arc (dip trasfer) MIG welding. (Author).

Recent studies of the developments in welding steels with yield strengths greater than 150 ksi have included low-alloy martensitic steels, medium-alloy martensitic steels, nickel maraging steels, and bainitic steels. Only weldments from medium-alloy martensitic steels and nickel maraging steels have mechanical properties approaching those of the base plate without a complete postweld heat treatment. The most serious problem with the other steel is low toughness in the weld fusion zone. Adequate weld metal toughness under conditions of elastic strain can be obtarined over the entire 150 to 225 ksi yield-strength range only if the tungsten-arc welding process is used. Processes with higher deposition rates can produce comparable weld deposits only in the lower portion of the range. Above a yield strength of 200 ksi, 18Ni maraging steel weldments have the best combination of strength and toughness. Below 200 ksi, the HP 9-4-25 medium-alloy martensitic steel and 12Ni maraging steel weldments have nearly equal properties.

This memorandum represents a combined effort by the U.S. Naval Applied Science Laboratory, Brooklyn, New York, and the Defense Metals Information Center to summarize new information on welding thick Ti plate. Thick plate of Ti continues to be of interest to the aerospace and defense industries for possible use in submersibles, armored vehicles, large space boosters, high-speed aircraft, and for pressure vessels. This memorandum generally is limited to information on welding Ti plate that is (1) at least 1 in. thick and (2) that is not covered by DMIC Report 185, The Status and Properties of Titanium Alloys for Thick Plate, June 14, 1963. The general requirements for welding Ti are not repeated here, since they are well documented in references mentioned in the inroduction to the memorandum. Sections have been prepared to cover material developments, welding-process developments, weld properties, and residual welding stresses. (Author).

This memorandum describes the fusion-welding characteristics, mechanical properties, and stress-corrosion behavior of high-strength, weldable aluminum alloys. These are defined as alloys in which sound welds can be produced and in which at least 50 and 70 percent of the maximum base-metal strength can be retained in the as-welded and post-weld-treated conditions, respectively. Careful selection of joining method and filler metals as well as close control of joining-process parameters is necessary to produce high-strength aluminum weldments. Highest strengths and weld-joint efficiencies in high-strength weldable alloys are achieved with the use of postweld aging and/or mechanical treatments. The best combination of highest strengths and good welding characteristics is found in the 2000 and 7000 alloy series. As compared with the 2000 and 5000 alloy series, the 7000 alloy as a class suffer three major property disadvantages: (1) their tendency to be notch sensitive, (2) their tendency to exhibit low toughness at low temperatures, and (3) their much greater susceptibility to stress-corrosion cracking. Nonetheless, several relatively new 7000 series alloys have been developed which show reasonably good notch toughness to -423 F and which are considered competitive with the 2219 and 2014 alloys for cryogenic applications. (Author).

This memorandum briefly discusses the physical metallurgy, heat treatment, mechanical properties, stress-corrosion properties, and fabrication of the 9Ni-4Co-XC steels. This family of steels was developed specifically to meet the requirements of the aircraft and aerospace industries for materials possessing high strength and high toughness. By varying the composition and heat treatment, the 9Ni-4Co-xC steels can develop strengths in the 200 to 300 ksi tensile-strength range and reportedly possess high toughness. The lower carbon grades have excellent weldability, developing strength in the 180 to 200 ksi range with high toughness without the need for preheat or postweld-heat treatment. (Author).

The Memorandum discusses the current situation on the inclusion of fracture-toughness testing requirements in specifications for high-strength steels used for military applications. The Memorandum was prepared at the request of The Technical Cooperation Program (TTCP), and contains information from Canadian and British members of that program, as well as U.S. information. Military applications discussed include missile motor cases, aircraft landing gear, gun tubes, armor plate, and hydrofoils. (Author).

This memorandum summarizes information on refractory materials and composites that was presented at the Thirteenth Meeting of the Refractory Composites Working Group in Seattle, Washington on July 18-20, 1966. The memorandum is based on 34 papers that were presented at the meeting. They are reviewed and discussed briefly within the framework of the following four broad areas: materials technology, process technology, specific hardware applications and tests, and evaluation techniques. Included in the section on materials technology are discussions dealing with bulk refractory materials, coated systems, and fiber-reinforced composites. The section on process technology discusses cladding and general fabrication processes. The specific hardware applications and tests cover rocket-motor components, and cladding of a probe used in the glass industry. The section on evaluation techniques covers thermal testing, and non-destructive testing. (Author).