Abstract: A ferritic steel having tensile properties and fatigue properties capable of withstanding use in a hydrogen environment and a method of manufacture thereof are provided. By adding one or more element selected from among vanadium (V), titanium (Ti) and niobium (Nb) so that the steel includes, together with at least ferrite grains in the structure, a carbide or carbides of one or more element selected from among V, Ti and Nb, the reduction of area and the fatigue crack propagation rate of the ferritic steel in a hydrogen environment are improved. The advantages of the invention were confirmed in cases where the ferrite grains are small grains of 1 ?m or less in size, and in cases where the ferrite grains are coarse grains from several micrometers to 20 ?m in size, and moreover in cases where the ferrite grains are coarse grains from several micrometers to 60 ?m in size.

Abstract: There is provided a fatigue test method with which the crack growth can be checked for a plurality of cycle rates in a single test. At a first cycle rate f1 of 0.01 Hz, hydrogen has a greater effect on crack growth than at a second cycle rate f2 of 1 Hz. As a result, an area of large hydrogen effect (an area developed at the cycle rate f1) and an area of small hydrogen effect (an area developed at the cycle rate f2) appear alternately on the fatigue fracture surface, and since these two areas have different fracture surface morphologies, it is possible to see the boundary lines. Consequently, the lengths of the cracks developed under each set of conditions can be specified, and a fatigue crack growth curve can be acquired for each set of conditions.

Abstract: The present invention focuses on diffusible hydrogen and non-diffusible hydrogen that cause hydrogen embrittlement in an austenitic stainless steel, and provides the austenitic stainless steel having diffusible hydrogen and non-diffusible hydrogen removed therefrom, and a method for removing hydrogen therefrom. In order to remove diffusible hydrogen and non-diffusible hydrogen, which cause hydrogen embrittlement in the austenitic stainless steel, an aging treatment is performed to the austenitic stainless steel at a temperature ranging from 200 to 1100° C. while being kept in an air atmosphere. As a result, the hydrogen (H) content in the austenitic steel is removed to 0.001 wt % (1 wt ppm) or less.

Abstract: By focusing on the non-diffusible hydrogen that causes hydrogen embrittlement of austenitic stainless steel, the present invention provides an austenitic stainless steel in which the non-diffusible hydrogen is removed by maintaining the austenitic stainless steel in a vacuum of 0.2 Pa or less and heating at a heating temperature of 200° C. to 500° C. for 460 hours or less to remove the hydrogen (H) contained therein to a level of 0.00007 mass % (0.7 mass ppm) or less.

Abstract: By focusing on the non-diffusible hydrogen that causes hydrogen embrittlement of austenitic stainless steel, the present invention provides an austenitic stainless steel in which the non-diffusible hydrogen is removed by maintaining the austenitic stainless steel in a vacuum of 0.2 Pa or less and heating at a heating temperature of 200° C. to 500° C. for 460 hours or less to remove the hydrogen (H) contained therein to a level of 0.00007 mass % (0.7 mass ppm) or less.

Abstract: An ultra fine grain steel has a ferrite grain structure having an average grain size of 3 ?m or less and has a nitride layer formed on a surface of the steel. The nitride layer is formed without adding an alloy element such as Cr or Mo that is expensive and detrimental to recycling. Fatigue strength is enhanced by the nitride layer.

Abstract: An ultra micro indentation testing apparatus comprises: a lever stand provided with a center lever having a silicon probe and a diamond indenter disposed therein; a moving mechanism for moving the lever stand in a triaxial direction; in indentation mechanism for pushing the diamond indenter in a sample; a displacement gage for measuring a displacement of the silicon probe or the diamond indenter; and an optical picture device for positioning the silicon probe or the diamond indenter and observing the surface of the sample. The apparatus has, in combination, a hardness measuring function based on the measurement of the force and depth of the diamond indenter pushed in the surface of the sample, an atomic force microscopic function of acquiring the shape of the surface of the sample based on a displacement of the diamond indenter or the silicon probe, and an optical microscopic function of observing the surface of the sample by the optical picture device.

Abstract: There is provided a ultra micro indentation testing apparatus comprising: a lever stand (4) provided with a center lever (3) having a silicon probe (1) and a diamond indenter (2) disposed therein; a moving mechanism (7) for moving the lever stand (4) in a triaxial direction; aindentationg-in mechanism (6) for pushing the diamond indenter (2) in a sample; a displacement gage (10) for measuring a displacement of the silicon probe (1) or the diamond indenter (2); and an optical picture device (11) for use in positioning the silicon probe (1) or the diamond indenter (2) and observing the surface of the sample; wherein the apparatus has, in combination, all of the hardness measuring function based on measurement of the force and depth of the diamond indenter pushed in the surface of the sample, the atomic force microscopic function of acquiring the shape of the surface of the sample based on a displacement of the diamond indenter or the silicon probe, and the optical microscopic function of observing the surface o

Abstract: The present invention provides a method of designing a high fatigue strength in high tensile strength steel, comprising: obtaining values of tensile strength &sgr;B (unit thereof is MPa) and Vickers hardness Hv of the steel; measuring a flaw area of an inclusion, when a fracture origin is located only at a surface of the steel; and estimating, in designing the high fatigue strength steel, that a fatigue limit &sgr;w (unit thereof is MPa) of the steel satisfies either &sgr;w≧0.5 &sgr;B or &sgr;w≧1.6 Hv, when a square root of the flaw area, (area)½ (unit thereof is m), contained in the steel is no larger than 45.8/&sgr;B2 or 4.47/Hv2. According to the present invention, a method of evaluating high fatigue strength in high tensile strength steel, in which method a relationship between a flaw dimension (area) of ODA and the fatigue strength is considered, and a high fatigue strength material can be provided.

Abstract: A testing method is provided for determining the hardness of a micro region, using indentation curves indicating relations between observed penetration depths and indenting forces when an arbitrary shaped indenter is pushed into standard samples of plural types. The method involves (1) measuring relations between observed penetration depths and indenting forces when the arbitrary shaped indenter is pushed into standard samples of plural types, to prepare the indentation curves, (2) determining a reference function indicative of macro hardness, by standardizing the relations between the indenting forces and macro hardness at the same penetration depth as an index, for the indentation curves of the standard samples of plural types, (3) measuring a relation between the penetration depth and indenting force of an arbitrary sample, and (4) determining the hardness of a micro region from the measured value in step (3) according to the reference function as determined in step (2).

Abstract: The present invention provides a method of designing a high fatigue strength material in high tensile strength steel, comprising the steps of: obtaining the values of tensile strength &sgr;B (unit thereof is MPa) and Vickers hardness Hv of the steel; measuring the flaw area of inclusion, when the fracture origin is located only at the surface of the steel; and estimating, in designing the high fatigue strength material, that the fatigue limit &sgr;w (unit thereof is MPa) of the steel satisfies either &sgr;w≧0.5&sgr;B or &sgr;w≧1.6 Hv, when a square root of the flaw area, (area)½ (unit thereof is m), contained in the steel is no larger than 45.8/&sgr;B2 or 4.47/Hv2. According to the present invention, a method of evaluating high fatigue strength material in high tensile strength steel, in which method the relationship between the flaw dimension (area) of ODA and the fatigue strength is considered, as well as a high fatigue strength material, can be Provided.

Abstract: The auxiliary combustion chamber of a four-cycle stratified-charge piston engine is divided into a primary cavity, and a secondary cavity provided with a baffle. The primary cavity receives a relatively rich mixture which passes into the secondary cavity, and the main combustion chamber receives a relatively lean mixture. The primary cavity is in communication with a spark plug. A long torch passage insert piece connects the primary cavity with the central portion of the main combustion chamber, and one or more short torch passages connect the secondary cavity with a peripheral portion of the main combustion chamber. The purpose is to reduce emission of NO.sub.x without adversely affecting emissions of CO and HC, and to improve fuel economy.

Abstract: The auxiliary combustion chamber of a four-cycle stratified-charge piston engine is divided into a primary cavity and a secondary cavity both formed in an insert liner received in the cylinder head. The primary cavity receives a relatively rich mixture which passes into the secondary cavity, and the main combustion chamber receives a relatively lean mixture. A spark plug communicates with the primary cavity. A long torch passage connects the primary cavity with the central portion of the main combustion chamber, and one or more short torch passages connect the secondary cavity with a peripheral portion of the main combustion chamber. The purpose is to reduce emission of NO.sub.x without adversely affecting emissions of CO and HC, and to improve fuel economy.

Abstract: An exhaust reaction chamber assembly for use with an internal combustion engine having cylinders in line includes one or more chambers divided by a metal partition to form separate compartments sealed from each other. A downstream chamber which is not divided surrounds and encloses the divided chamber or chambers and also surrounds and encloses a major portion of the length of each of a plurality of exhaust branches which are connected to individual exhaust ports, respectively. In this way the temperature of the exhaust gases is maintained at a high level in order to promote rapid oxidation of HC and CO in the exhaust gases. Two exhaust reaction chamber assemblies are disclosed, one for a six cylinder engine and one for a four cylinder engine.