A production process of multi-alloy diffusion anti-corrosion layer for iron and steel parts at low temperature

Abstract

The invention discloses a production technology for multicomponent alloy diffusion of anticorrosive coatings of steel parts at a low temperature, and relates to the technical field of metal anticorrosive treatment technologies. The steps of carbonization degreasing, shot blasting rust removal, anticorrosive coating diffusion, discharging and inspection are executed; then washing, passivating and washing are conducted; and a finished product is in a brighter silver greyish white color after being dried, and micrometal gloss is available. According to the production technology, through multicomponent alloy diffusion of the anticorrosive coatings at the low temperature, the appearance has a silvery grey color, and diffusion layers are flat, smooth and free from the defects of zinc edges, zincthorns, uneven thicknesses and the like; different color and luster requirements can be met after passivation or the organic coating aftertreatment technology, the diffusion anticorrosive coatings and matrices are well combined, adhesive force is high and peeling and disengaging can be avoided; the binding force of the diffusion anticorrosive coatings and aftertreatment layers is greatly enhancedafter the diffusion anticorrosive coatings are subjected to shot blasting and high-pressure air blowing-down deashing treatment; and meanwhile, salt spray corrosion resistance of the compound anticorrosive coatings is greatly improved, the anticorrosive life is long, and neutral salt spray tests can reach 2400 hours or above without red rust.

Description

technical field [0001] The invention relates to the technical field of metal anti-corrosion treatment technology, in particular to a production process of a multi-element alloy diffusion anti-corrosion layer for iron and steel parts at low temperature. Background technique [0002] As is known, the existing anti-corrosion treatment processes for steel parts include hot-dip galvanizing, hot-dip galvanizing, electro-galvanizing, cold mechanical galvanizing, Dacromet, powder coating, spraying anti-corrosion paint or anti-corrosion coating, thermo-mechanical galvanizing, etc. ; At present, high-speed rail, rail transit equipment, bolts, spikes, track fasteners and catenary hardware are installed in open-air environments, exposed to wind, sun, rain, severe cold, high temperature, rain, sandstorms, severe air pollution, especially acid rain. The conditions are harsh, and the existing anti-corrosion processes and methods cannot meet the requirements of the product. Especially with...

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Problems solved by technology

[0003] The existing anti-corrosion measures for high-speed rail and rail transit equipment mainly include electro-galvanizing, cold-dip galvanizing, anti-corrosion paint or anti-corrosion coating, powder coating, dacromet coating, nitriding, hot-dip galvanizing, and thermo-mechanical galvanizing; However, the electro-galvanizing and cold-dip galvanizing processes produce a large amount of polluting wastewater, and the treatment is difficult and expensive, and the components will be crisp and have a short corrosion-resistant life. They are not suitable for components that require more than 20 years of corrosion protection and strong requirements These two processes are not suitable; the nitriding hardness is high and wear-resistant, and the combination is good, but the corrosion resistance is not enough; the anti-corrosion layer made by dacromet coating, powder coating, spray anti-corrosion paint or anti-corrosion coating has poor bonding force and poor corrosion resistance. Abrasion, bump resistance, and scratch resistance are relatively poor, and the corrosion resistance effect of paint is poor; Not wear-resistant; the hot-dip galvanizing process generally has a higher processing temperature of 450-600 ° C. Although the hot-dip galvanizing process can obtain a thick coating, the anti-corrosion layer produced by this process can reach more than 20 years, but due to the process temperature Higher, due to the decrease of component strength and spring property due to annealing, at the same time, there is an additional gap before hot-dip galvanizing for fasteners, the thickness of the coating is difficult to control, the surface quality is not high, and it is easy to nodulate, especially the groove of the threaded parts It is easy to be filled and cannot be used. At the same time, hot-dip galvanizing is seriously polluted and consumes a lot of energy; and thermomechanical galvanizing adopts the principle of atomic infiltration and diffusion, and heats the infiltrating agent and steel parts in a galvanizing furnace to a certain 410- At 440 ℃, the active zinc atoms will diffuse into the steel parts from the surface to the inside; at the same time, iron atoms will also diffuse from the inside to the outside. As a result of this reaction and diffusion, a zinc-iron alloy layer is formed on the surface of the steel parts. The high process temperature generally needs to reach 410-440 ℃, and the holding time needs to be longer. At the same time, the process contains a lot of air (oxygen) and moisture in the furnace, which will cause the surface of the zinc powder to oxidize and cause the zinc powder to bond; Oxidize rapidly with the workpiece to form an oxide film, which will hinder the diffusion of zinc atoms into the workpiece; in addition, for some medium carbon spring steel and structural steel that are heat treated and strengthened by quenching and tempering, such as the material of round steel for making high-speed iron spring bars is 60Si2Mn , the commonly used tempering temperature is 380 ° C, the use of this process will reduce the mechanical properties of the spring bar, other high-strength steels, spring steels, and alloy steels also have the problem of decreasing strength and spring properties due to annealing when using this process