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Tarui T.,Bar and Wire Rod Research Laboratory | Kubota M.,Muroran R and D Laboratory
Nippon Steel Technical Report | Year: 2012

Evaluating the delayed fracture characteristics of steel materials on the basis of the hydrogen amount has been made possible largely by establishment of the know-how of hydrogen charging and hydrogen analysis, as well as development of the gas chromatograph and quadrupole mass spectrometer that permit measuring extremely small amounts of hydrogen contained in steel with an accuracy of 0.01 ppm. In addition, hydrogen thermal desorption spectroscopy using those hydrogen analyzers has made it possible to separate non-diffusible hydrogen from diffusible hydrogen in steel and estimate the existence state of hydrogen in steel. On the other hand, alloy carbides having a fine and coherent stain field help trap hydrogen. Takahashi et al. charged deuterium into steel material containing fine TiC precipitates and analyzed the condition of the hydrogen in the steel using a three-dimensional atom probe (3DAP).


Fujita T.,Bar and Wire Rod Research Laboratory | Tarui T.,Bar and Wire Rod Research Laboratory | Oohashi S.,Production Div.
Nippon Steel Technical Report | Year: 2013

It is necessary to give initial stretch on tire cord because they are stretched in tire production procedres. However, it is difficult to predict initial stretch in complicated cord structures. We have studied how to predict initial stretch in complicated cord using FEM. We suppose Young's modulus of initial stretch in the state that wire does not contact at all, and that Young's modulus of elastic stretch is equal to the one of cord in the state that wire makes full contact. It was shown that the initial stretch can be predicted by FEM.


Kada O.,Bar and Wire Rod Research Laboratory | Hashimura M.,Bar and Wire Rod Research Laboratory | Fujita T.,Bar and Wire Rod Research Laboratory
Nippon Steel Technical Report | Year: 2013

Through the many types of manufacturing processes in customers, special steel bars and wire rods are manufactured to the auto parts such as engine and power train. For the manufacturing process to produce the final part of steel, Nippon Steel is working on technology development, including both the steel and manufacturing technology. This paper introduces the efforts of technology solutions for special steel bars and wire rods is important in that position, and then some of examples of analysis such as prediction of die stress in forging process, prediction of material properties after hot forging, and prediction of thermal distortion in heat treatment process. Osamu KADA Senior Researcher Bar & Wire Rod Research Lab. Steel Research Laboratories 20-1 Shintomi, Futtsu, Chiba 293-8511.

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