Showing papers on "Weldability published in 1968"

Cracking Parameter of High Strength Steels related to heat affected zone cracking

Abstract: Weld cracking susceptibility, or simply, weldability, is a most significant problem in utilizing high strength steels.A new formula, based on the result of restraint weld cracking test, is herein proposed for the calculation of the cracking parameter Pc: Pc=C, %+Si, %/30+Mn, %/20+Cu, %/20+Ni, %/60+Cr, %/20+Mo, %/15+V, %/10+5B, %+t, mm/600+H, cc/100g/60(t: plate thickness, H: diffusible hydrogen in weld metal)Cracking parameters calculated from this formula have a good correlatioh with the test data obtained from the y-groove restraint carcking tests using 200 types of high strength steel.The carbon equivalents adopted in JIS and the result of weld carcking tests correspondingly indicate that the steel with higher carbon equivalent is more susceptible to weld cracking. However, data are scattered so widely that the carbon equivalents cannot be applied for estimating weld cracking susceptibilities of high strength steels.Since the carbon equivalent specified in JIS does not include the terms of diffusible hydrogen and plate thickness, even the steels with the same carbon equivalents reveal a higher cracking susceptibility when their diffusible hydrogen content or plate thickness value increases.Comparing with some typical carbon equivalents, which have been suggested so far, Pc's present the best agreement in predicting the weld cracking susceptibilities.Although there is a weak trend that the higher the maximum hardness in HAZ, the higher the weld carcking susceptibility is, the maximum hardness does not represent strictly the weld cracking susceptibility.The relationship is investigated between cracking parameters, Pc's, and the preheating temperature to prevent weld cracking and the following equation is obtained.T(°C)=1440 Pc-392

Aluminum alloy for electric conductor

Abstract: This aluminum alloy for electric conductor consists of a ternary Al-Mg-RE alloy containing less then 0.6 weight percent of one or more of rare earth metals and has improved castability, weldability, fatigue strength and antisoftening characteristics on heating at a high temperature and is applicable to the continuous casting and rolling method and the rolling method using large ingots for the purpose of easily manufacturing aluminum alloy conductor having excellent characteristics.

Refractory Metals in Space Electric Power Conversion Systems

Abstract: The status of refractory alloy applications to space electric power conversion systems is reviewed with emphasis on the work related to alkali metal Rankine cycle systems for future power requirements exceeding 100 kw. Columbium and tantalum alloys are considered for alkali metal containment for periods exceeding 10,000 hours at temperatures near 2000°F. In addition, molybdenum alloys are considered for alkali metal vapor turbine wheel and blade applications where weldability is not essential. Results and conclusions from corrosion and erosion tests of refractory alloys in alkali metals are presented. The fabrication of power plant development components from refractory alloys is discussed.

Weldable, ultrahigh tensile steel having an excellent toughness

Abstract: A weldable, ultrahigh tensile steel prepared by adding V and Cu to a low-carbon steel containing Ni and Mo, to which there may be further added W, Nb and Ta, characterized by being able to stand a low temperature and possessing a good weldability and an excellent toughness at a very high level of the strength, particularly the toughness in the welding heat-affected zone, said properties being particularly imparted by the addition of V and Cu.

Weldable,nonmagnetic austenitic manganese steel

Abstract: A WELDABLE, NONMAGNETIC AUSTENITIC MANGANESE STEEL OF THE HADFIELD TYPE AND COMPATIBLE WELD METAL WHICH WILL REMAIN NONMAGNETIC AND TOUGH AS WELDED AND WITHOUT THE REQUIREMENT OF POST-WELD HEAT TREATMENT COMPRISING .3% CARBON, 13% MANGANESE, 5% NICKEL, 3 TO 5% CHROMIUM, 1% MOLYBDENUM AND .5% VANADIUM.

Nickel-copper alloy

Abstract: AN AGE HARDENABLE NICKEL-COPPER ALLOY HAVING MARKEDLY IMPROVED WELDABILITY AND MACHINABILITY WHICH ALLOY CONTAINS NOT MORE THAN ABOUT 0.1% CARBON, NOT MORE THAN ABOUT 0.5% TITANIUM, ABOUT 2.5% TO ABOUT 3.5% ALUMINUM, ABOUT 63% TO ABOUT 70% NICKEL AND THE BALANCE, EXCEPT FOR INCIDENTAL ELEMENTS AND IMPURITIES, ESSENTIALLY COPPER.

The Evaluation of the Weldability of Structural Alloys with the Varestraint Test.

Abstract: : The development of a sub-scale version of the VARESTRAINT test is described which permits the evaluation of the hot cracking sensitivity of materials with thicknesses of 1/8-in and below The hot cracking tendency of several plate and sheet materials was evaluated using the standard and sub-scale versions of the VARESTRAINT test, respectively The heat-to-heat variation in hot cracking sensitivity was studied for 22 Heats of D6AC and significant differences were observed Metallographic studies of the morphology of hot cracking are presented for each alloy A mathematical analysis of the thermally induced strains around the weld puddle is presented for 2014T-6 aluminum (Author)

Influence of Surface Treatment on Mechanical Properties of Pressure Welds

Abstract: Surface treatment of the interface to be welded is one of the most important factors affecting the weld characteristics especially in the pressure welding such as solid phase welding.The purpose of this study is to investigate the influences of the surface treatment technique and interval of time between the surface finishing and welding upon the mechanical properties of the pressure welds of aluminium alloys, copper and carbon steels. The following results were obtained.1. Filing away surface treating gave higher weld strength characteristics than wire and emery polishing, and was as effective as the fricative scratch treating of the intimate surface each other.2. Increase of exposure time between the surface finishing and welding decreased the ductility rather than the tensile strength of the welds.3. Maximum strength of the welds of cold working material such as aluminium and copper was obtained by making at the recrystallization temperature of the metal.4. When the welding temperature was chosen at low temperature of 200-300°C, the pressure weldability of alclad 24S-T3 was better than that of 24S-T3, therefore it is expected that welding temperature can be lowered by the method with the incert metal.

The occurrence of massive ferrite in the heat affected zones of some welded high-strength structural steels corroding in sea water

Abstract: Heavy local corrosion has been reported to occur close to welding joints in high-strength structural steels when used without protection in sea water. Such corrosion damage has been investigated in detail in several steels where high strength combined with weldability is aimed at by means of high manganese and low carbon contents. To obtain additional information on the phenomenon, the zones affected by welding heat in these steels were studied by the authors in an electron microscope. The results, on which a preliminary report is given below, indicate that the heavily corroding areas in the heat affected zones consist predominatingly of massive ferrite. ( Author )

Development of New High Strength Special Steel Propeller for Big Ships

Abstract: A new special stainless steel which is very suitable for propeller material has been developed. The steel has the corrosion fatigue strength in sea water larger than 40 kg/mm2, twice as large as that of nickel-aluminum bronze. It has also excellent anti-erosion property about thirty times as strong as that of nickel-aluminum bronze. Using this steel for propeller, many merits will be realized as follows : (1) Lightening.(2) Improvement in propelling efficiency.(3) Decrease in vibrational troubles by increasing the number of propeller blades and/or by reducing the blade thickness.(4) Easiness in making huge propellers. (building up by welding) This steel has the material features just appropriate for large castings, since the slower the cooling velocity is, the larger its strength and elongation become. There is no problem to make the large casting of this steel of sound structure, and the weldability is fine in spite of its high hardness. The propeller of this material can be cast as a whole, but for the saving of machining hours which are liable to increase due to its high hardness, it is desirable to cast blades of accurate dimension separately to make them into a complete propeller by welding.The unlikable characteristic of stainless steel, susceptibility to pitting corrosion resulting in deterioration of fatigue strength, is avoidable by using cathodic protection. The propeller of 1. 8m in diameter used for testing purpose for about one year showed the effect of cathodic protection under -0.8V (saturated calomel electrode scale) was perfect.To know the method of manufacturing the large propeller by welding, a propeller of 5. 7 m in diameter was made tentatively. The proper control of chemical composition in the melting process was rather easy, and the castings were perfectly sound even in the inner side of massive part. It is presumed that the dimensional deviations concerning pitch, rake and inter-blades angle due to casting, welding and heat-treatment can be corrected without any difficulty by taking countermeasures against the deviation previously at the time of moulding and by optimum setting in the building-up process.The propeller of this steel will presents marked contributions to the improvement in propelling efficiency and to the prevention of troubles concerning vibration and propeller shaft system of huge tankers.