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Preparation method of gradient coating for surface strengthening of blanking die

A technology of surface strengthening and punching die, applied in the field of preparation of gradient coating, can solve the problems of cracks and peeling in the coating, large difference in hardness, toxic electroplating products, etc., to reduce wear, improve service life, and improve resistance The effect of abrasion and corrosion resistance

Active Publication Date: 2020-01-31
WUHAN UNIV OF TECH
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Problems solved by technology

[0003] At present, the common mold surface heat treatment process schemes include traditional carburizing, nitriding, carbonitriding, PVD, CVD, electroplating, etc., but compared with TRD (Thermal Reactive Diffusion) technology, the surface coating formed by it has hardness. Insufficient (carburizing, nitriding, carbonitriding), poor bonding strength (PVD), etc., some will cause serious pollution (electroplating, etc.) and produce toxic products
The carbide coating prepared in the TRD salt bath has high hardness, strength, wear resistance and corrosion resistance. Zhang Wenjie and others invented a salt bath co-penetration agent (CN 103103476B), which overcomes the single chromizing and single chromizing. The disadvantage of infiltrating niobium is that Cr can be obtained on the metal surface 3 C 2 -NbC gradient coating, but with underlying Cr 3 C 2 The thickness of the layer is thin (1-2μm), and the ratio of the thickness of the niobium layer (8-9μm) to the thickness of the chromium layer is too large (about 4.5), resulting in poor overall continuity of the coating and uneven distribution of the phase structure. Shows inhomogeneous transition of cladding hardness, cladding cross-sectional hardness from matrix-Cr 3 C 2 Layer - NbC layer changes from 600HV-1400HV-3100HV, Cr 3 C 2 The hardness difference between the NbC layer and the NbC layer is large (△=1700HV), and there is uneven stress transition in the coating layer, which is prone to problems such as cracks, peeling, and cracking in the coating layer.

Method used

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  • Preparation method of gradient coating for surface strengthening of blanking die
  • Preparation method of gradient coating for surface strengthening of blanking die
  • Preparation method of gradient coating for surface strengthening of blanking die

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preparation example Construction

[0035] refer to figure 1 and figure 2 , a method for preparing a gradient coating for surface strengthening of a blanking die, comprising the following steps:

[0036] Step S10, preheating, cleaning and machining the mold;

[0037] Step S20, carry out TRD salt bath salt preparation: the formula of salt bath is: anhydrous borax: 70-75%, chromium donor: 8-12%, niobium donor: 4-6%, reducing agent: 3- 6%, activator: 8-10%, according to the above ratio, first heat the crucible to 820-850°C, gradually add borax until all borax is melted, then add metal donor and activator and stir until they are all melted, finally, Add the reducing agent (in a small amount sequentially) until it melts to form a salt bath, and keep it warm for 1-2 hours;

[0038] Step S30, performing salt bath chromium-niobium co-infiltration treatment: immerse the mold in a molten salt bath, the first stage temperature is 880-910°C, and the holding time is 2-3.5h; the second stage temperature is 930-940°C, hold...

Embodiment 1

[0050] (1) According to the TRD salt bath formula, weigh the corresponding anhydrous borax: 71%, chromium trioxide: 10%, niobium pentoxide: 5%, boron carbide: 4%, sodium fluoride : 10%.

[0051] (2) According to the above ratio, heat and dry the borax in the well-type tempering furnace at 200°C for 1 hour, take it out and mix it with the metal donor powder evenly, then add it to the crucible in turn, and heat up step by step according to the program of the resistance furnace control cabinet. Keep warm at 820°C, after all the salt is melted, slowly add a small amount of B 4 Add C powder and NaF and stir until they all melt to form a salt bath, and keep warm for 1h.

[0052] (3) After grinding and polishing the surface of the Cr12MoV steel workpiece, place it in 5wt% hydrochloric acid for 1min to remove rust, then remove the acid solution with alcohol, then passivate the surface with 5wt% nitric acid solution for 30s, and dry it.

[0053] (4) Immerse the treated workpiece in a...

Embodiment 2

[0062] (1) According to the TRD salt bath formula, weigh the corresponding anhydrous borax: 72%, chromium trioxide: 8%, niobium pentoxide: 4%, Al powder: 6%, sodium fluoride : 8%, rare earth silicon magnesium 2%.

[0063] (2) According to the above ratio, heat and dry the borax in the well-type tempering furnace at 200°C for 1 hour, take it out and mix it with the metal donor powder evenly, then add it to the crucible in turn, and heat up step by step according to the program of the resistance furnace control cabinet. Keep warm at 820°C. After the salt is completely melted, slowly add a small amount of Al powder, sodium fluoride and rare earth in sequence, and stir while adding until all the salt is melted to form a salt bath, and keep warm for 1 hour.

[0064] (3) After grinding and polishing the surface of the Cr12MoV steel workpiece, place it in 5wt% hydrochloric acid for 1min to remove rust, then use alcohol to remove the acid solution, then treat the surface with 5wt% nit...

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Abstract

The invention discloses a preparation method of gradient cladding for blanking die surface reinforcing. The preparation method comprises the following steps that a die is preheated, cleared and machined; TRD salt bath salt preparation is conducted, specifically, a salt bath formula comprises, by mass, 70-75% of borax anhydrous, 8-12% of a chrome supplying agent, 4-6% of a niobium supplying agent,3-6% of a reducing agent and 8-10% of an activating agent; salt bath chrome and niobium co-soaking treatment is conducted, specifically, the die is soaked in a molten salt bath, the temperature of thefirst stage is 880-910 DEG C, and the heat-preservation time is 2-3.5 h; the temperature of the second stage is 930-940 DEG C, and the heat-preservation time is 2-3 h; the temperature of the third stage is 980-1040 DEG C, and the heat-preservation time is 3-4 h; and the die is taken out and then tempered after being subjected to oil quenching. According to the preparation method of the gradient cladding for blanking die surface reinforcing, the phenomenon that stress transition of the cladding is uneven is avoided, the service performance of the die is improved, and the service life of the die is prolonged.

Description

technical field [0001] The invention relates to the technical field of metal materials, in particular to a preparation method of a gradient coating used for surface strengthening of a blanking die. Background technique [0002] With the continuous development and use of fine blanking technology, especially the stamping of thick steel plates has attracted widespread attention due to its high productivity, superior stamping quality and rich economic benefits. It provides semi-refined blanks for cutting, It has many comprehensive benefits such as saving processing hours and energy consumption, reducing costs, and improving product quality. Compared with thin plate punching, thick plate punching requires greater punching force, and surface wear and heat generation are also more serious. For some molds with sharp corners, lugs or folded intersections, the contact stress during punching is much greater than The average stress, even exceeding the allowable compressive stress of th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23C10/26C21D1/18C23C28/04
CPCC21D1/18C23C10/26C23C28/04Y02P10/20
Inventor 王华君牛龙飞朱春东高野王洪福刘维甘康康
Owner WUHAN UNIV OF TECH
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