Abstract: According to a several embodiment, provided is a method for manufacturing a molded object, including a material preparing step to prepare a material powder obtained by removing carbon from medium carbon steel or high carbon steel until a carbon content is 0.1 mass % or less, a molding step to form a desired molded object by a lamination molding method repeating the steps of: a recoating step to uniformly spread the material powder on a molding table to form a material powder layer; and a sintering step to irradiate a predetermined portion of the material powder layer with a laser beam to form a sintered layer; and a carburization step to subject the molded object to carburization after the molding step is performed.

Abstract: A lamination molding apparatus, includes a material layer former to form a material layer; a first emitter to form a solidified layer by irradiating the material layer with a first beam; and a thermal adjuster to adjust a temperature of at least a portion of the solidified layer to at least one of a predetermined first temperature and a predetermined second temperature. The temperature of at least the portion of the solidified layer is adjusted to the first temperature, and then to the second temperature. When the first temperature is referred to as T1, the second temperature is referred to as T2, a martensite start temperature of the solidified layer is referred to as Ms, and a martensite finish temperature of the solidified layer is referred to as Mf, all of the following relations of T1?Mf, T1>T2, and T2?Ms are satisfied.

Abstract: A lamination molding apparatus, includes a material layer former to form a material layer; a first emitter to form a solidified layer by irradiating the material layer with a first beam; and a thermal adjuster to adjust a temperature of at least a portion of the solidified layer to at least one of a predetermined first temperature and a predetermined second temperature. The temperature of at least the portion of the solidified layer is adjusted to the first temperature, and then to the second temperature. When the first temperature is referred to as T1, the second temperature is referred to as T2, a martensite start temperature of the solidified layer is referred to as Ms, and a martensite finish temperature of the solidified layer is referred to as Mf, all of the following relations of T1?Mf, T1>T2, and T2?Ms are satisfied.

Abstract: Provided is a method for manufacturing a molded object, where change in dimension of the molded object after molding is small, and the molded object has required hardness. According to a several embodiment, provided is a method for manufacturing a molded object, including a molding step to form a desired molded object by repeating the steps of a recoating step to uniformly spread a material powder on a molding table to form a material powder layer, and a sintering step to irradiate a predetermined portion of the material powder layer with a laser beam to form a sintered layer, and a carburization step to subject the molded object to carburization, where the material powder is an iron-based material with a carbon content of 0.1 mass % or lower.