5results about How to "Fine grain structure" patented technology

The invention relates to the technical field of bolt production, and particularly discloses a high-strength bolt machining process and device. Comprising the following steps: S1, material selection: selecting an alloy steel blank containing C, Si, Mn, Cr, Mo, V and the balance of Fe; s2, cold heading forming is conducted, specifically, the alloy steel blank is placed in a multi-station cold heading machine, and a bolt blank is formed through continuous cold heading and forging; s3, heat treatment is conducted, specifically, the bolt blank is subjected to quenching treatment and then subjected to tempering treatment, and a bolt base body is obtained; and S4, surface treatment is conducted, specifically, phosphating treatment is conducted on the surface of the bolt base body in sequence to form a phosphating layer, the composite coating is coated, and the high-strength bolt is obtained. The high-strength bolt machining process can be used for manufacturing connecting components requiring high reliability under complex working conditions such as heavy load, vibration and impact, and the high-strength bolt machining process has the advantages that the toughness, fatigue resistance and delayed fracture resistance are improved while high strength is kept.

The application relates to the technical field of electroplating, and discloses a chromium electroplating process for improving the hardness of a connector terminal, which comprises the following steps: performing surface pretreatment on the connector terminal, removing surface impurities through ultrasonic cleaning and micro-etching treatment; performing heating treatment on the connector terminal; performing electroplating treatment on the connector terminal by using an electroplating solution comprising trivalent chromium salt, boron nitride nanoparticles, ferroferric oxide nanoparticles, nickel ions, sodium dichromate and chromium alloy additives, so as to form a chromium plating layer; performing passivation treatment on the plating layer; performing low-temperature treatment on the plating layer; and spraying a protective layer on the chromium plating layer. Through the trivalent chromium salt and the sodium dichromate, the trivalent chromium salt is used to reduce hexavalent chromium ions into trivalent chromium, the toxicity of the hexavalent chromium is reduced, the sodium dichromate is used to provide a stable chromium source, the deposition of chromium elements in the electroplating process is ensured, the pollution of hexavalent chromium to the environment and the harm of hexavalent chromium to the health of operators are solved, and the environmental protection and safety of the electroplating process are improved.

The application discloses a method for improving notch sensitivity of a GH2909 alloy forge piece and the GH2909 alloy forge piece, and comprises the following steps: S1, selecting a rod-shaped blank to be heated for the first time and kept warm; S2, heating the rod-shaped blank in S1 for the second time and keeping warm; S3, placing the rod-shaped blank in S2, which reaches the keeping-warm time, into a forging equipment to be forged into a shape; S4, rapidly cooling the forge piece obtained in S3; S5, performing surface defect treatment on the cooled forge piece; and S6, performing aging heat treatment on the forge piece after the surface defect treatment. The GH2909 forge piece produced by the method has no persistent notch sensitivity problem, and a forge piece with qualified structure and mechanical properties can be obtained.

The invention relates to the technical field of forming machining of non-ferrous metal thin strips, in particular to a machining method of a special-shaped high-conductivity Cu-Fe-P alloy plate strip. By optimizing the element ratio of the Cu-Fe-P series alloy, the conductivity of the Cu-Fe-P series alloy is improved. The special-shaped high-conductivity Cu-Fe-P alloy plate strip is prepared through the working procedures of smelting, semi-continuous casting, homogenizing annealing and hot rolling cogging, solution treatment, primary cold rolling deformation, primary aging treatment, secondary cold rolling deformation, secondary aging treatment, surface treatment, precision mechanical forming machining and the like. According to the special-shaped high-conductivity Cu-Fe-P alloy plate strip and the preparation method thereof, the multi-pass cold rolling deformation and the multi-stage aging treatment process are combined, a fine and uniform grain structure and a stable precipitated phase are obtained, the prepared special-shaped Cu-Fe-P alloy plate strip still has high hardness while high conductivity is kept, and the special-shaped high-conductivity Cu-Fe-P alloy plate strip product is obtained through precision mechanical forming machining.

This invention discloses a metal alloy nut and its preparation method. The nut is composed of the following components by mass percentage: Cr 20.0-23.0%, Mo 8.0-10.0%, Fe≤5.0%, Nb 3.15-4.15%, Ti 0.4-1.0%, Al 0.4-0.8%, Co≤1.0%, C≤0.08%, Si≤0.5%, Mn≤0.5%, P≤0.015%, S≤0.010%, with the balance being Ni. Its internal thread has a 30° wedge-shaped anti-loosening structure, and the thread surface has a Ni-P coating and a MoS2 lubricating layer. Annular stress relief grooves are provided on both end faces. The preparation method includes: powder metallurgy billet preparation, hot forging near-net-shape forming, gradient heat treatment, precision machining, and surface functionalization treatment. This invention achieves a nut with a tensile strength of ≥800MPa at 650℃, a room temperature tensile strength of ≥1200MPa, an elongation of ≥15%, and a material utilization rate of ≥85% through the synergistic control of alloy composition and gradient heat treatment. It is suitable for extreme environments such as aero engines and nuclear reactors.