Stress rupture tests with 40 ton tester were conducted at 500 and 600°C for large welded specimens of stainless clad steel, Mn-Mo-Ni steel ASTM A 302 B claded with AISI 304 L, which is essential to nuclear applications. The large specimen, 38 mm thick and 40 mm wide, showed much inferior property to usual small welded specimen. The results of test at 600°C under a stress of 12 kg/mm2 are : (1) The rupture time of transverse as-welded specimen was 55 % of base metal. (2) The rupture times of transverse welded specimens decreased through heat treatment after welding at 550, 650 and 870°C × 1.5 hr as low as to 40, 60 and 90 %, respectively, of as welded specimen. (3) Machining the reinforcement flush with the surface of base metal increased the rupture time of 550°C × 1.5 hr heat treated specimen by 1.5 times. (4) Longitudinal welded specimen was approximately equivalent to base metal in rupture time. (5) Transverse specimen manually welded showed about 50% longer rupture time than submerged-arc welded specimen. Macroscopic and microscopic examinations showed that cracking in rupture occurred along bond in the graphitized heat-affected zone of base metal. The initiation of cracking occurred mostly at the intersection between the surface of bond of stainless weld metal and the cladding surface, viz., the line along which concentration of strees and local strain were most extreme. Crack initiation in backing steel ocurred frequently at the toe of carbon steel weld metal. If the bottom of stainless weld metal were made smooth with cladding surface, the rupture time of transverse welded specimen would become identical to base metal. The test results at 500°C, however, showed 45 degrees shear type fracture which is different from that at 600°C in which fracture occurred along bond.
Distribution and segregation of sulphur (sulphide) in weld-metals were investigated on the sulphur prints on various sections of single or multi pass weld-metals. As the results of this experiment, the following conclusions were obtained. (1) Sulphur was uniformly distributed in weld metal in macrographic inspection and such a remarkable segregation as usually found in steel ingot was not present. This is caused by rapid cooling rate and small volume of molten pool. (2) The colour of the suphur print on weld metal was remarkably linghter than that on steel plate in spite of the same amount of sulphur, because the sulphides in weld metal were distributed as fine paricles. (3) The light and fine stripes perpendicular to the dendric structure were found on sulphur print, which is explained by the mechanism of solidification in welding. Waves on bead surface testified that solidification progressed intermittently, and, therefore, sulphur was segregated parallelly to the trace of solidification line. (4) Sulphur in weld metal showed almost the same distribution with no relation with Mn and S contents, because sulphur in molten weldmetal existed as not Mn or Fe sulphide but at the solute in steel.
In this paper, anthers describe the results of some experiments on Al-steel electrode made of composite core wire, which is composed of mild steel tube and Al wire folded up in it. We deal with the following items, that is, melting behavior of composite core wire, chemical reactions between the coating materials and molten metal at elevated temperature, scaling and cracking test of weld metals. Conclusions were summerized as follows ; (1) Al and steel in the composite core wire melt uniformly and make the homogeneous Fe-Al alloy in spite of their difference of M.P.. (2) The higher the coating percentage of lime-fluorite type electrode is, the higher Si and C in deposit metal are reduced from coating, and Al is oxidized, while Mn is not affected. (3) When Al content of deposit metal is less than 2%, oxidation resistance at high temperature is the same as mild steel, but at 4 to 7%, it equals to 18Cr-or 13 Cr-steel and upward 10%, it is more excellent to 18 Cr-8 Ni-steel. (4) Cracking tendency of welds is reduced with increase of Al content. The weld metal of higher Al content cracks at about 400 to 500°C, but that of the lower Al cracks even at room temperature.
It has been well known that ferritic stainless steel has been embrittled by heating in the vicinity of 475°C or by slow cooling through that range. This report describes the mechanical properties of 475°C embrittled specimens for 18, 25Cr alloy steel and their weld metal. Moreover, their resistances against scaling in the enviroment of air oxidation, cementation and V2O5 fuse salt are mentioned.
The low temperature welding of iron castings with Ni-electrodes, with oxy-acetylene welding rods and brazing with silver alloy were investigated. The results are summarized as follows : (1) Wormy-flake graphite cast iron was welded by using Fe 45-Ni 55 arc-welding rods ; the tensile strength of those welds was 18 to 27 kg/mm2. Sound weldment was obtained by buttering, but its deposited metals were hardened by the formation of Ni-martensite. (2) Wormy-flake graphite cast iron was welded with two bronze alloys and one iron-carbon alloy. Various appearances of the fracture in tensile test pieces were observed with the different rods. The tensile strength of 29 kg/mm2 was obtained by one of the bronze alloy rods. (3) Ordinary cast iron, wormy-flake graphite cast iron and nodular graphite cast steel were brazed with a silver brazing alloy at 700°C, and examined by the Damon-type shearing test. For ordinary. cast iron and wormy-flake graphite cast iron, the brazing parts were stronger than the base metals. Nodular graphite cast steel was fractured at the brazing part which was sliped by the shearing stress, and peak values of the shearing strength were obtained with about 0.06 to 0.12 mm clearance.
In this investigation, were studied that how the heat treatments after welding affect the weld properties of titanium alloys (5%% Al-2.5% Sn-Ti, 2% Al-2% Mn-Ti and 5% Al-3% Mn-Ti alloys) which thought to be practical. These titanium alloys, except 5% Al-3% Mn-Ti alloy, have considerably good weld properties in as welded, and to do the properties excellently, the following heat treatments are available after welding. 1) For 5% Al-2.5% Sn-Ti alloy, give water cooling after heated in 800 to 900°C 2) For 2% Al-2% Mn-Ti, 5% Al-3% Mn-Ti, and 8% Mn-Ti alloys, give water cooling after heated in 650 to 700°C And the properties of welds of such heattreated, in high temperature, are as good as the base metal.