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Method for reducing hot cracking sensitivity in laser additive repair process of die steel

A laser additive and mold steel technology, applied in additive processing, additive manufacturing, etc., can solve problems such as difficulty in guaranteeing the internal quality of laser additive repair, high temperature gradient of local molten pool, and performance degradation of repaired parts, so as to avoid The generation of thermal cracks, the reduction of the formation of chain eutectic phase, and the effect of reducing thermal stress

Active Publication Date: 2021-03-26
CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, since laser additive repair is a process of instantaneous heating, melting and rapid cooling of a mobile heat source, the local melt pool has the characteristics of high temperature gradient, fast cooling rate and multiple thermal cycle effects during the repair process.
At present, the internal quality of laser additive repair is difficult to guarantee, especially defects such as thermal cracks are prone to occur, resulting in a sharp decline in the performance of repaired parts

Method used

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  • Method for reducing hot cracking sensitivity in laser additive repair process of die steel
  • Method for reducing hot cracking sensitivity in laser additive repair process of die steel

Examples

Experimental program
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Effect test

Embodiment 1

[0016] Take Cr12MoV steel as an example.

[0017] Step 1: First, polish, ultrasonically clean and dry the Cr12MoV mold repair area, and use electromagnetic induction heating equipment to preheat the substrate to 280°C;

[0018] Step 2: Use a thermal imager to monitor the molten pool during the laser additive manufacturing process, obtain the surface temperature information of the molten pool, and calculate the average temperature gradient G and cooling rate ξ at the boundary of the molten pool;

[0019] Step 3: According to 5.5×10 3 °C / m≤G≤1.5×10 5 ℃ / m, and 5.5×10 3 ℃ / s≤ξ≤1.5×10 5 ℃ / s principle to optimize the process parameters;

[0020] Step 4: The optimized process window obtained is as follows: the laser power is 1550W, the scanning speed is 16mm / s, the spot diameter is 4.0mm, the powder feeding amount is 27.5g / min, the overlapping amount is 50%, and the height direction increment Z is 0.30 mm / layer; the repair powder material is a mixed powder of Cr12MoV die steel, p...

Embodiment 2

[0025] Take H13 steel as an example.

[0026] Step 1: First, polish, ultrasonically clean and dry the repaired area of ​​the H13 steel mold, and use electromagnetic induction heating equipment to preheat the base material to 280°C;

[0027] Step 2: Use a thermal imager to monitor the molten pool during the laser additive manufacturing process, obtain the surface temperature information of the molten pool, and calculate the average temperature gradient G and cooling rate ξ at the boundary of the molten pool;

[0028] Step 3: According to 5.5×10 3 °C / m≤G≤1.5×10 5 ℃ / m, and 5.5×10 3 ℃ / s≤ξ≤1.5×10 5 ℃ / s principle to optimize the process parameters;

[0029] Step 4: The optimized process window obtained is as follows: the laser power is 1500W, the scanning speed is 15mm / s, the spot diameter is 4.0mm, the powder feeding amount is 30g / min, the overlapping amount is 50%, and the height direction increment Z is 0.30mm / layer; the repair powder material is a mixed powder of H13 die ...

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Abstract

The invention discloses a method for reducing hot cracking sensitivity in the laser additive repair process of die steel. The method comprises the following steps that a base material is preheated to280 DEG C; a thermal imager is adopted to monitor a molten pool in the laser additive manufacturing process, molten pool surface temperature information is obtained, and the average temperature gradient G and the cooling rate xi of the boundary of the molten pool are calculated; the process parameters are optimized according to the principle that G is greater than or equal to 5.5 * 103 DEG C / m andsmaller than or equal to 1.5 * 105 DEG C / m and Xi is greater than or equal to 5.5 * 103 DEG C / s and smaller than or equal to 1.5 * 105 DEG C / s to obtain an optimized process window, wherein the laserpower is 1400-1600 W, the scanning speed is 14-16 mm / s, the spot diameter is 3.5-4.5 mm, the powder feeding amount is 25-32 g / min, the overlapping amount is 50% and the height direction increment Z is 0.25-0.35 mm / layer; and a high-quality additive repair part is obtained. According to the method, the internal quality of the laser additive repair part can be effectively improved.

Description

technical field [0001] The invention relates to the field of laser metal material processing, in particular to a method for reducing hot crack sensitivity in the process of laser additive repair of mold steel. Background technique [0002] Dies are prone to various forms of failure during service, such as wear, cracks, fatigue, fracture, etc. If the mold is scrapped due to damage or failure, it will cause serious economic losses. Laser additive repair technology has the characteristics of low thermal damage to the substrate, small deformation and high flexibility, and has broad application prospects in the field of mold repair and remanufacturing. However, since laser additive repair is a process of instantaneous heating, melting and rapid cooling of a mobile heat source, the local melt pool has the characteristics of high temperature gradient, fast cooling rate and multiple thermal cycle effects during the repair process. At present, the internal quality of laser additive...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F7/06B22F10/28B22F10/85B22F10/38B22F1/00B33Y50/02B33Y10/00B33Y70/00
CPCB22F1/0003B22F7/062B22F2007/068B33Y10/00B33Y50/02B33Y70/00
Inventor 李聪肖斌陈荐邱玮李微何建军
Owner CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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