Abstract: A non-magnetic austenitic steel with good corrosion resistance and a high hardness is provided. The non-magnetic austenitic steel comprises less than 0.15 wt % of carbon, less than 1.5 wt % of titanium, from 19 wt % to 26 wt % of chromium, from 3.5 wt % to 7.0 wt % molybdenum, from 11 wt % to 20 wt % nickel, from 2.0 wt % to 7.0 wt % of manganese, less than 0.8 wt % of nitrogen, less than 0.5 wt % of niobium, less than 0.5 wt % of vanadium, less than 1.2 wt % of silicon, less than 4 wt % of copper, and less than 2 wt % of tungsten and the balance being iron.

Abstract: The present teaching is generally directed to soft magnetic alloys. In particular, the present teaching is directed to soft magnetic alloys including Samarium (“Sm”). In a non-limiting embodiment, an Sm-containing magnetic alloy is described including 15 wt % to 55 wt % of Cobalt (“Co”), less than 2.5 wt % of Sm, and 35 wt % to 75 wt % of Iron (“Fe”). The Sm-containing magnetic alloy may further include at least one element X, selected from a group including Vanadium (“V”), Boron (“B”), Carbon (“C”), Chromium (“Cr”), Manganese (“Mn”), Molybdenum (“Mo”), Niobium (“Nb”), Nickel (“Ni”), Titanium (“Ti”), Tungsten (“W”), and Silicon (“Si”). The Sm-containing magnetic alloy may further have a magnetic flux density of at least 2.5 Tesla.

Abstract: A non-magnetic austenitic steel with good corrosion resistance and a high hardness is provided. The non-magnetic austenitic steel comprises less than 0.15 wt % of carbon, less than 1.5 wt % of titanium, from 19 wt % to 26 wt % of chromium, from 3.5 wt % to 7.0 wt % molybdenum, from 11 wt % to 20 wt % nickel, from 2.0 wt % to 7.0 wt % of manganese, less than 0.8 wt % of nitrogen, less than 0.5 wt % of niobium, less than 0.5 wt % of vanadium, less than 1.2 wt % of silicon, less than 4 wt % of copper, and less than 2 wt % of tungsten and the balance being iron.

Abstract: The present teaching is generally directed to soft magnetic alloys. In particular, the present teaching is directed to soft magnetic alloys including Samarium (“Sm”). In a non-limiting embodiment, an Sm-containing magnetic alloy is described including 15 wt % to 55 wt % of Cobalt (“Co”), less than 2.5 wt % of Sm, and 35 wt % to 75 wt % of Iron (“Fe”). The Sm-containing magnetic alloy may further include at least one element X, selected from a group including Vanadium (“V”), Boron (“B”), Carbon (“C”), Chromium (“Cr”), Manganese (“Mn”), Molybdenum (“Mo”), Niobium (“Nb”), Nickel (“Ni”), Titanium (“Ti”), Tungsten (“W”), and Silicon (“Si”). The Sm-containing magnetic alloy may further have a magnetic flux density of at least 2.5 Tesla.

Abstract: The present invention discloses a method for fabricating a porous spherical iron-based alloy powder, a powder thereof and a sintered body thereof. The method comprises steps: mixing an iron oxide powder and an alloying powder to form a mixed powder; spray-granulating the mixed powder to form a spherical spray-granulated powder; and placing the spherical spray-granulated powder in a reducing environment and heating it to a temperature of lower than 700° C. to obtain a porous spherical iron-based alloy powder having high flowability, high compressibility, superior sinterability and low cost.

Abstract: A method of producing a workpiece includes: providing a first powder, with a hardness of the first powder being less than 250 HV, and with a mean particle size of the first powder being less than 20 ?m; mixing the first powder and a second powder to form a mixed powder, with the mixed powder including carbon, chromium, iron, and elements selected from the group consisting of molybdenum, nickel, copper, niobium, vanadium, tungsten, silicon, cobalt, and manganese; adding a binder and water to the mixed powder; applying a spray drying process to granulate the mixed powder to form a spray-dried powder; applying a dry pressing process to the spray-dried powder to form a green part; applying a debinding process to the green part to form a debound body; and sintering the debound body into a workpiece having a hardness of higher than 250 HV.

Abstract: This invention presents a method for manufacturing sintered and carburized porous stainless steel parts, comprising steps of: sintering stainless steel powders to obtain a porous sintered stainless steel, wherein the porous sintered stainless steel comprises a three dimensional network skeleton structure with a large number of interconnected pore channels; and carburizing the porous sintered stainless steel by a non-halogenated carbon-bearing gas, wherein the porous sintered stainless steel being maintained at a carburizing temperature below 600° C. such that carbon atoms can be implanted into the porous sintered stainless steel and converts a surface portion of the skeleton structure, that is in contact with the carbon-bearing gas in the interconnected pore channels, into a carburized layer. A carburized layer is formed and spread over a skeleton structure of the sintered porous body. Thereby, the strength, surface hardness, and core hardness of the sintered body are significantly increased.

Abstract: The present invention discloses a method for fabricating a porous spherical iron-based alloy powder, a powder thereof and a sintered body thereof. The method comprises steps: mixing an iron oxide powder and an alloying powder to form a mixed powder; spray-granulating the mixed powder to form a spherical spray-granulated powder; and placing the spherical spray-granulated powder in a reducing environment and heating it to a temperature of lower than 700° C. to obtain a porous spherical iron-based alloy powder having high flowability, high compressibility, superior sinterability and low cost.

Abstract: A powder metallurgical method for fabricating a high-density soft magnetic metallic material comprises steps of providing an initial powder; using a spray drying process to fabricate the initial powder into a spray-dried powder; placing the spray-dried powder in a mold and compacting the spray-dried powder under a compacting pressure and a compacting temperature to form a green compact; and sintering the green compact at a sintering temperature to form a soft magnetic metallic material. The spray-dried powder, which is fabricated by the spray drying process, has superior flowability, compactability and compressibility and is suitable for the press-and-sinter process. The soft magnetic metallic material fabricated by the present invention is outstanding in sintered density and magnetic performance. The present invention adopts the inexpensive press-and-sinter process and has a low fabrication cost.

Abstract: This invention presents a sintered and carburized porous stainless steel part with improved strength and hardness and method thereof. The sintered and carburized porous stainless steel part has a porous body with a relative density between 30% and 89%, which is sintered from a stainless steel powder, wherein exposed pore surfaces inside the porous body are carburized without forming carbides and without using an activation process in advance. A carburized layer is formed and spread into the core of the sintered porous body. Thereby, the strength, surface hardness, and core hardness of the sintered body are significantly increased.

Abstract: A method for fabricating fine reduced iron powders comprises the following steps: heating fine iron oxide powders having a mean particle size of smaller than 20 ?m to a reduction temperature of over 700° C. to reduce the fine iron oxide powder into iron powders that are partially sintered into iron powder agglomerates; and performing a crushing-spheroidizing process on the iron powder agglomerates to obtain individual iron powders having a mean particle size of smaller than 20 ?m. The method can reduce iron oxide powers into iron powders having a rounded shape and a high packing density and a high tap density, which are suitable for the metal injection molding process and the inductor fabrication process. The reduced iron powder may further be processed using an annealing process and a second crushing-spheroidizing process in sequence to further increase the sphericity, packing density, and tap density of the reduced iron powder.

Abstract: A method of producing a workpiece is disclosed. The method includes: providing a first powder, a hardness of the first powder being less than 250 HV, and a mean particle size of the first powder being less than 20 ?m; mixing the first powder and a second powder to form a mixed powder; the mixed powder includes carbon, chromium, iron, and elements selected from the group consisting of molybdenum, nickel, copper, niobium, vanadium, tungsten, silicon, cobalt, and manganese; adding a binder and water to the mixed powder; applying a spray drying process to granulate the mixed powder to form a spray-dried powder; applying a dry pressing process to the spray-dried powder to form a green part; applying a debinding process to the green part to form a debound body; and sintering the debound body into a workpiece having a hardness of higher than 250 HV.

Abstract: A method for improving surface mechanical properties of non-austenitic stainless steels comprises steps of: providing a non-austenitic stainless steel material; placing the non-austenitic stainless steel material in an environment containing at least one austenite-stabilizing element, and implanting the austenite-stabilizing elements into a surface of the non-austenitic stainless steel material to form a modified layer enriched with the austenite-stabilizing elements; and placing the non-austenitic stainless steel material in a carbon-bearing atmosphere to make the modified layer in contact with the carbon-bearing atmosphere, and maintaining the non-austenitic stainless steel material at a carburizing temperature below 600° C. to implant carbon into the modified layer to form a carburized layer.

Abstract: A method for fabricating fine reduced iron powders comprises the following steps: heating fine iron oxide powders having a mean particle size of smaller than 20 ?m to a reduction temperature of over 700° C. to reduce the fine iron oxide powder into iron powders that are partially sintered into iron powder agglomerates; and performing a crushing-spheroidizing process on the iron powder agglomerates to obtain individual iron powders having a mean particle size of smaller than 20 ?m. The method can reduce iron oxide powers into iron powders having a rounded shape and a high packing density and a high tap density, which are suitable for the metal injection molding process and the inductor fabrication process. The reduced iron powder may further be processed using an annealing process and a second crushing-spheroidizing process in sequence to further increase the sphericity, packing density, and tap density of the reduced iron powder.

Abstract: A low-temperature stainless steel carburization method comprises steps: providing a stainless steel material; placing the stainless steel material in a halogen-free reducing environment and maintaining the stainless steel at a first temperature ranging 1,050 to 1,400° C.; and placing the stainless steel material in a carbon-bearing atmosphere and maintaining the stainless steel material at a second temperature lower than 600° C. to implant carbon atoms into the stainless steel material to form a carburized layer on the surface of the stainless steel material. A halide-bearing gas or solution is not to be applied to activate the passivation layer, so the fabrication cost would be reduced and the safety of carburization process would be enhanced. Besides, the environment can be prevented from halide pollution.

Abstract: A method for improving surface mechanical properties of non-austenitic stainless steels comprises steps of: providing a non-austenitic stainless steel material; placing the non-austenitic stainless steel material in an environment containing at least one austenite-stabilizing element, and implanting the austenite-stabilizing elements into a surface of the non-austenitic stainless steel material to form a modified layer enriched with the austenite-stabilizing elements; and placing the non-austenitic stainless steel material in a carbon-bearing atmosphere to make the modified layer in contact with the carbon-bearing atmosphere, and maintaining the non-austenitic stainless steel material at a carburizing temperature below 600° C. to implant carbon into the modified layer to form a carburized layer.

Abstract: A method for enhancing strength and hardness of powder metallurgy stainless steels comprises steps of fabricating a stainless steel powder into a green compact; placing the green compact in a reducing environment and maintaining the green compact at a sintering temperature to form a sintered body; and placing the sintered body in a carbon-bearing atmosphere and maintaining the sintered body at a carburizing temperature below 600° C. to implant carbon atoms into the sintered body and form carburized regions in the sintered body. Thereby, the strength and hardness of powder metallurgy stainless steels can be improved. As the carburizing temperature is lower than 600° C., chromium would not react with carbon. Therefore, the strength and hardness of powder metallurgy stainless steels can be enhanced and the superior corrosion resistance is still preserved.

Abstract: A low-temperature stainless steel carburization method comprises steps: providing a stainless steel material; placing the stainless steel material in a halogen-free reducing environment and maintaining the stainless steel at a first temperature ranging 1,050 to 1,400° C.; and placing the stainless steel material in a carbon-bearing atmosphere and maintaining the stainless steel material at a second temperature lower than 600° C. to implant carbon atoms into the stainless steel material to form a carburized layer on the surface of the stainless steel material. A halide-bearing gas or solution is not to be applied to activate the passivation layer, so the fabrication cost would be reduced and the safety of carburization process would be enhanced. Besides, the environment can be prevented from halide pollution.

Abstract: A powder composition and a sintered body thereof are presented. The powder is a martensitic stainless steel powder for powder injection molding without deformation problems during sintering. The powder composition includes 0.80-1.40 weight percent (wt %) of carbon (C), less than 1.0 wt % of silicon (Si), less than 1.0 wt % of manganese (Mn), 15.0-18.0 wt % of chromium (Cr), 0.10-2.50 wt % of titanium (Ti), and the remainder iron (Fe). The powder can be sintered with a sintering temperature varying within 50° C. and can reach a high density without distortion, and thereby a good dimensional stability is obtained.

Abstract: A steel powder and their sintered body comprise iron as its primary component and further comprise from 1.4 to 2.0% by weight of carbon, less than 1.0% by weight of silicon, less than 1.0% by weight of manganese, from 11.0 to 13.0% by weight of chromium, from 0.3 to 2.3% by weight of titanium, less than 0.75% by weight of a combination of copper and nickel, and less than 5.0% by weight of at least one strengthening element. During sintering, titanium carbide inhibits grain coarsening, whereby the sintering window can be expanded to about 50° C.