Laser additive manufacturing and a method for preparing thin-walled preforms by laser metal deposition and follow-up rolling. This can solve the problems that when the existing laser metal deposition technology prepares the thin-walled preforms, the limit width size of a molten pool at high power affects the forming wall thickness of the preforms so that it is difficult to prepare preforms with wall thickness less than 2 mm, and the problems of poor surface quality and low accuracy of preforms due to convex and concave peaks caused by the interlayer overlapping, but also can solve the problems that a laser beam with a preset trajectory cannot act on the end surfaces of the preforms due to preform deformation caused by residual stress in a printing process so that the preforms cannot be continuously formed.

In thickness control processing, transfer processing of an entry thickness He(N) is performed (step S1). In the transfer processing, data of the entry thickness He(N) is transferred from a position P11 to a position P12 at the same speed as the speed of a material to be rolled M. Subsequently, an amount of change in a thickness ΔH(N) is calculated (step S2). The amount of the change in the thickness ΔH(N) is calculated based on data of a delivery thickness Hd(N) and data of a transferred thickness Hc(N) transferred to the position P12 at a timing when the data of the delivery thickness Hd(N) is measured. Then, a target entry thickness He(N)_tgt is calculated (step S3). Subsequently, a manipulated amount of rolling speed VR(N−2) and VR(N−k) are calculated (step S4).

In thickness control processing, transfer processing of an entry thickness He(N) is performed (step S1). In the transfer processing, data of the entry thickness He(N) is transferred from a position P11 to a position P12 at the same speed as the speed of a material to be rolled M. Subsequently, an amount of change in a thickness ΔH(N) is calculated (step S2). The amount of the change in the thickness ΔH(N) is calculated based on data of a delivery thickness Hd(N) and data of a transferred thickness Hc(N) transferred to the position P12 at a timing when the data of the delivery thickness Hd(N) is measured. Then, a target entry thickness He(N)_tgt is calculated (step S3). Subsequently, a manipulated amount of rolling speed VR(N−2) and VR(N−k) are calculated (step S4).

A hot and cold composite formed square and rectangular steel tube and a production method for the same are provided. The radius of an outer corner of the square and rectangular steel tube meets the following conditions: when t is less than or equal to 6 mm, R is greater than 0 and less than 2.0 t; when t is greater than 6 mm and less than or equal to 10 mm, R is greater than 0 and less than 2.5 t; when t is greater than 10 mm, R is greater than 0 and less than 3.0 t, wherein t is the wall thickness of a straight tube part of the square and rectangular steel tube; R is the radius of each of the outer corners of the four corners of the square and rectangular steel tube; and the wall thickness of each corner of the square and rectangular steel tube is between 1.0 t and 1.8 t.

A hot and cold composite formed square and rectangular steel tube and a production method for the same are provided. The radius of an outer corner of the square and rectangular steel tube meets the following conditions: when t is less than or equal to 6 mm, R is greater than 0 and less than 2.0 t; when t is greater than 6 mm and less than or equal to 10 mm, R is greater than 0 and less than 2.5 t; when t is greater than 10 mm, R is greater than 0 and less than 3.0 t, wherein t is the wall thickness of a straight tube part of the square and rectangular steel tube; R is the radius of each of the outer corners of the four corners of the square and rectangular steel tube; and the wall thickness of each corner of the square and rectangular steel tube is between 1.0 t and 1.8 t.

In a method for producing a flat steel product made of high-strength manganese steel, a hot or cold strip is provided with an alloy composition containing (in wt %): C: 0.0005 to 0.9; Mn: 4 to 12; Al: up to 10; P: <0.1; S: <0.1; N: <0.1; the remainder being iron, including unavoidable steel-alloying elements, with optional addition of one or more of the following elements (in wt %): Si: up to 6; Cr: up to 6; Nb: up to 1; V: up to 1.5; Ti: up to 1.5; Mo: up to 3; Sn: up to 0.5; Cu: up to 3; W: up to 5; Co: up to 8; Zr: up to 0.5; Ta: up to 0.5; Te: up to 0.5, B: up to 0.15. The hot or cold strip is flexibly rolled to a final thickness at a temperature of 60° C. to below Ac3 prior to a first rolling step.

In thickness control processing, transfer processing of an entry thickness He(N) is performed (step S1). In the transfer processing, data of the entry thickness He(N) is transferred from a position P11 to a position P12 at the same speed as the speed of a material to be rolled M. Subsequently, an amount of change in a thickness ΔH(N) is calculated (step S2). The amount of the change in the thickness ΔH(N) is calculated based on data of a delivery thickness Hd(N) and data of a transferred thickness Hc(N) transferred to the position P12 at a timing when the data of the delivery thickness Hd(N) is measured. Then, a target entry thickness He(N)_tgt is calculated (step S3). Subsequently, a manipulated amount of rolling speed VR(N−2) and VR(N−k) are calculated (step S4).

In thickness control processing, transfer processing of an entry thickness He(N) is performed (step S1). In the transfer processing, data of the entry thickness He(N) is transferred from a position P11 to a position P12 at the same speed as the speed of a material to be rolled M. Subsequently, an amount of change in a thickness ΔH(N) is calculated (step S2). The amount of the change in the thickness ΔH(N) is calculated based on data of a delivery thickness Hd(N) and data of a transferred thickness Hc(N) transferred to the position P12 at a timing when the data of the delivery thickness Hd(N) is measured. Then, a target entry thickness He(N)_tgt is calculated (step S3). Subsequently, a manipulated amount of rolling speed VR(N−2) and VR(N−k) are calculated (step S4).

A method for producing a semifinished product with locally different material thicknesses may involve preparing a multilayer, metal material composite, which has a plurality of layers with different ductilities, and rolling the material composite in a method for flexible rolling through a rolling gap formed between two rollers. The rolling gap may be configured such that regions with different material thicknesses are formed. In some cases, the multilayer, metal material composite is rolled at room temperature. Further, the plurality of layers of the multilayer, metal material composite may include a first outer layer disposed on a first side of a middle layer and a second outer layer disposed on a second side of the middle layer, with the second side of the middle layer being opposite the first side.

A method for producing a semifinished product with locally different material thicknesses may involve preparing a multilayer, metal material composite, which has a plurality of layers with different ductilities, and rolling the material composite in a method for flexible rolling through a rolling gap formed between two rollers. The rolling gap may be configured such that regions with different material thicknesses are formed. In some cases, the multilayer, metal material composite is rolled at room temperature. Further, the plurality of layers of the multilayer, metal material composite may include a first outer layer disposed on a first side of a middle layer and a second outer layer disposed on a second side of the middle layer, with the second side of the middle layer being opposite the first side.