摘要:
A fine ferrite-based steel is disclosed, wherein at least 60% of the ferrite grain boundary is a large angle grain boundary of at least 15°, and the mean ferrite grain size is not more than 2.5 &mgr;m. The fine ferrite-based steel of the invention has a high strength and a long fatigue life.
摘要:
The present invention provides a steel material for induction quenching, containing 0.3% to 0.7% of C, 1.1% or less of Si, 0.2% to 1.1% of Mn, 0.05% to 0.6% of Mo, 0.06% or less of S, 0.025% or less of P, 0.25% or less of Al, 0.3% or less of Cr on a mass basis, and the balance being Fe and unavoidable impurities. The steel material has a ferrite structure and a pearlite structure, the total volume fraction of the ferrite structure and the pearlite structure is 90% or more, the thickness of the ferrite structure is 30 μm or less, and the average prior austenite grain diameter of a hard layer obtained by induction quenching is 12 μm or less. Since having superior machinability and superior fatigue strength after induction quenching, this steel material is suitable, for an automobile drive shaft, constant velocity joint, and the like.
摘要:
An impact resistant structure of a helicopter having an energy absorber positioned under a floor of the helicopter and directly connected to a cabin frame of the helicopter. The energy absorber is arranged in accordance with a distribution of a ground reaction force on a general ground at a time of crash situation. The energy absorber also includes a plurality of independent hollow tubes of fiber reinforced composite material integrally formed by bundling only the hollow tubes. The hollow tubes are arranged so as to reduce a number of intersecting wall surfaces of the hollow tubes.
摘要:
A method of manufacturing a thick steel product of high strength and high toughness having excellent weldability with minimal variation of material properties, comprises heating a steel raw material to the temperature of Ac.sub.3 to 1350.degree. C., hot rolling and then cooling at the cooling rate of 10.degree. C./sec. or less. The steel raw material has the following composition:C: 0.001-0.25 wt %;Mn: 1.0-3.0 wt %;Ti: 0.005-0.20 wt %;Nb: 0.005-0.20 wt %;B: 0.0003-0.0050 wt %; andAl: 0.01-0.100 wt %balance substantially Fe and incidental impurities. The composition has a transformation start temperature (Bs) of 670.degree. C. or less. Since the steel product obtained by the method has no variation in physical properties regardless of variation in cooling rate, it is possible to supply steel products of high strength and high toughness which have uniform microstructure and properties along their thickness direction and are excellent in weldability.
摘要:
A component for machine structural use having improved fatigue strength. The component for machine structural use is produced by subjecting at least a part of a steel material to hardening, and the hardened structure is controlled such that the average grain diameter of former austenitic grains is 12 μm or less and the maximum grain diameter does not exceed four times the average grain diameter.
摘要:
One aspect of the present invention provides an impact resistant structure of a helicopter, which includes: an energy absorber positioned under a floor of the helicopter and directly connected to a cabin frame of the helicopter. The energy absorber is arranged in accordance with a distribution of a ground reaction force on a general ground at a time of crash situation. Another aspect of the present invention provides an energy absorber includes: a plurality of independent hollow tubes of fiber reinforced composite material integrally formed by bundling only the hollow tubes. The hollow tubes are arranged so as to reduce a number of intersecting wall surfaces of the hollow tubes.
摘要:
A non heat-treated steel of high strength, toughness and machinability which can be used in its as-worked state without calling for any special treatment after working. It contains less than 0.05 wt % C, 0.005 to 2.0 wt % Si, 0.5 to 5.0 wt % Mn, 0.1 to 10.0 wt % Ni, more than 1.0 to 4.0 wt % Cu, 0.0002 to 1.0 wt % Al, 0.005 to 0.50 wt % S and 0.0010 to 0.0200 wt % N.
摘要:
A steel for machine structural use with a better strength-ductility-toughness balance than maraging steel and applications thereof are provided. The steel for machine structural use with excellent strength, ductility, and toughness contains, in percent by mass, more than 0.30% to 0.5% of carbon, 1.0% or less of silicon, 1.5% or less of manganese, 0.025% or less of aluminum, 0.3% to 0.5% of molybdenum, and 0.0005% to 0.01% of boron, and the balance is iron and incidental impurities. The steel has a structure including at least 90% by volume of martensitic structure. The martensitic structure includes blocks having a size of 1.5 μm or less. Dissolved boron is contained in an amount of at least 0.0005% and is present at boundaries of prior austenite grains in a concentration at least 1.5 times that in the prior austenite grains.
摘要:
The present invention provides a machine structural part composed of 0.3% to 0.7% of C, 0.30% or less of Si, 0.2% to 2.0% of Mn, 0.005% to 0.25% of Al, 0.005% to 0.1% of Ti, 0.05% to 0.6% of Mo, 0.0003% to 0.006% of B, 0.06% or less of S, 0.020% or less of P, 0.0030% or less of O on a mass basis, and the balance being Fe and unavoidable impurities. In addition, the machine structural part has a hard layer on at least a part of a surface thereof formed by induction quenching, an average prior austenite grain diameter of the hard layer is 7 μm or less, and the maximum diameter of a non-metal inclusion composed of oxides is 15 μm or less. Since having a high fatigue strength, this machine structural part is suitable for an automobile drive shaft, constant velocity joint, and the like.
摘要:
A magnetic recording and/or reproducing apparatus comprises a first magnetic head mounted on a carriage and a second magnetic head mounted on an arm which swings to and from the carriage, for engagement with a first and second side respectively of a flexible magnetic disc. The first and second magnetic heads are mounted on the carriage and the arm respectively via first and second gimbal plates. The elastic modules of the first gimbal plate is chosen such that the resonance of the first and second magnetic heads due to external vibration is avoided.