JFMS is a candidate material for nuclear fusion reactor in Japan. It is a material for high temperature use. Structural materials of fusion reactor will be exposed in neutron irradiation. In order to research the basic property of the material under irradiation, low temperature strength of JFMS and its electron beam welded joint is investigated under various irradiated condition in this experiment.
It was shown, as testing results, that decreasing of strength and elongation at low temperature of base metal and electron beam welded joint of JFMS increases with increasing of neutron fluence.

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A heavy thick (100mm) 100kgf/mm² class high tensile strength steel plate (H-T100) and the submerged-arc welding (SAW) consumables have been developed. The developed HT100 steel plate has uniform mechanical properties in the through-thickness direction, and has good weldability comparable to that of 80kgf/mm² class high tensile strength steel plate (HT80) against hydrogen cracking and bearing rather high heat input of 60kJ/cm. The developed SAW consumables has been certified the weld metal has good resistance for cold cracking due to the ultra low hydrogen content in addition to good toughness and has good workability even in applying a narrow gap welding.
The characteristics of HT100 steel plate and its welded joints obtained are as follows:
(1) The newly developed HT100 steel plate whose chemistry consists of. 13%C-0.12%Si-0.87%Mn-2.97%Ni-Cr-Mo-V-B, has been successfully manufactured by using the low-temperature-quenching and tempering process.
(2) The pre-heat temperature for preventing weld cracking was 100°C, which was evaluated by an oblique Y-groove cracking test. The maximum hardness on HAZ was lower than 400 in Vickers hardness. These results prove that the weldability of the HT100 steel plate is same that of HT80 steel plate.
(3) By the addition of optimum amount of carbonate, fluoride and MgO into agglomerated flux hydrogen content in the weld metal can be decreased in ultra low level and oxygen content can be adjusted in the optimum range. The slag detouchability is also improved so good as to use in a narrow gap welding.
(4) The tensile strength of weld joint was 101kgf/mm² for the weld heat input of
47kJ/cm and 100kgf/mm² for 60kJ/cm, respectively. An absorbed energy of Charpy test at -12°C notched in a fusion line was 11.1kgf m for 47kJ/ cm welding and 7.1kgf·m for 60kJ/cm, respectively. The Charpy test results show that these welded joints are safety enough against brittle fracture in spite of adoption of rather high heat input welding.

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Laser surface coating of titanium was investigated to improve the corrosion resistance of carbon steel plate.
Titanium powder was pre-coated to carbon steel plates using organic flux and surface meltings were carried out for the coated surface with a CO₂ laser beam of 3kw input power under the atmospher of argon. And to study the nature of laser surface coating layer, metallurgical examinations, X- ray analysis and corrosion tests were conducted for the coated plates.
The obtained results were as follows.
(1) This laser surface coating technique produced defect-free Ti coating layer with the thickness of maximum 0.5mm.
(2) The Ti-coated steel exhibited the almost same resistance to corrosion as that of commercial purity titanium in the electrochemical crevice corrosion and pitting corrosion tests in which 3% NaCl solution were used.
(3) The Ti-coated steel indicated lower weight loss than commercial type 316L steel in the corrosion/erosion test in which test specimens were rotated in the 3% NaC solution containing Al₂O₃ particles.

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In the preceding paper (JHPI, vol. 17, p. 140-149), the authors have proposed the new procedure of eddy current testing for the characterization of defects using the tilted encircling coil. This technique have been successfully used to sort, to locate and to size the defects in the wall of zircalloy cladding tubes under the condition of a specific test frequency. One of important factors affecting the characters of the output signals in eddy current testing is considered to be the test frequency in general.
The work described in this paper is a continuation of the previous work and experimental one carried out to examine the effects of test frequency on the characteristics of the tilted coil response signals to various types of defects in the zircalloy cladding tubes. The experimental results show that the tilted coil eddy current technique to characterize the defects in the zircalloy cladding tube is available in the range of test frequency of 32kHz-256kHz, though the optimum test frequency is present for the detection of defects in the thin-walled cladding tubes.

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The quality of the welded joints in pressure vessels are very importance factor for safety of pressure vessels.
Recently, the manufacturing techniques were significantly developed on material, design and fabrication but some of the tests and their evaluation could not follow these advanced manufacturing techniques. This paper describes about investingatoion the mechanical tesing on the welded joint in various pvessure vessel codes of technically advanced countries and a proposal on some idea for evaluation of mechanical tests, mainly concerning tensile properties of welded joints.

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Rolled titanium clad plates which Sumitomo metal industries, ltd. developed are characterized by Fe/Ni composite insert metal in Ti/ C-steel interface. These composite insert type-rolled titanium clad plates have better bonding strength than single (Fe) insert type-rolled clad plates and explosion bonded clad plates specially after heat treated condition. This excellent bonding characteristic is carried out by minimizing TiC precipitation in Fe/Ti interface where Ni insert hinders C deffusion from C-steel through Fe insert.
This paper presents these characteristics on bonding strength and the latest experiences on forming of rolled titanium clad and design data, especially relationship between drawing ratio and clad plate thickness in head forming and fatigue test results on T fillet welded joint.
Sumitomo metal industries, ltd. has already applied these titanium clad steel plates to various plants such as power plant condenser (tube sheets), pulp and paper industries (bleaching towers) and some chemical plant vessels, etc.

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