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Nitrogen treatment and destressing process

A nitriding and stress-relieving technology, applied in metal material coating process, coating, solid-state diffusion coating, etc., can solve problems such as large nitriding deformation, control nitriding deformation, eliminate heat treatment stress, and improve resistance to nitriding. The effect of wear capacity

Inactive Publication Date: 2012-05-16
徐金兰
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AI Technical Summary

Problems solved by technology

However, after the overall nitriding treatment, the wear resistance of the inner surface of the cylinder liner is improved, but the nitriding deformation is relatively large, and the cylinder liner product must be machined to eliminate the deformation of the product

Method used

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Embodiment Construction

[0008] The technical solution adopted by the present invention to solve the technical problem is: the cylinder liner blank is put into the tempering furnace after rough machining the inner hole and rough turning outer circle, and the temperature is raised to 240 °C at a speed of not higher than 50 °C per hour, and the temperature is kept For 1 hour, the temperature is evenly raised to 460°C, and the temperature is maintained for 1 hour. After such heat treatment, the semi-finished product is then machined, and the product meets the size requirements of the finished cylinder liner. Clean the qualified cylinder liner and put it into the nitriding furnace, and feed ammonia gas into the furnace and slowly raise the temperature at a rate of less than 50°C / H, and empty the air in the furnace, and ensure that it is discharged under the premise of 200°C. Empty the air in the furnace, and raise the temperature to 510°C-510°C at a rate not higher than 50°C / H, and keep the ammonia decomp...

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Abstract

The invention provides a nitrogen treatment and destressing process and adopts a technical scheme which is characterized by comprising the following steps of: placing a blank of a cylinder sleeve into a tempering furnace after rough machining of an inner bore and rough turning of an excircle; heating to 240 DEG C at a speed of not more than 50 DEG C per hour and keeping warm for 1 hour; uniformly heating to 460 DEG C and keeping warm for 1 hour; uniformly heating to 560 DEG C and keeping warm for 2 hours; taking the blank of the cylinder sleeve out from the tempering furnace after cooling to about 260 DEG C at a speed of less than 30 DEG C / H per hour; putting the machined cylinder sleeve, which passes an inspection, into a nitriding furnace after being cleaned and introducing ammonia into the nitriding furnace; slowly heating the nitriding furnace at the speed of less than 50 DEG C / H and emptying air in the nitriding furnace at 200 DEG C; heating to 510-510 DEG C at the speed of not more than 50 DEG C / H; keeping warm for 4 hours in the condition that the ammonia resolution ratio is 60-70%; keeping warm for 3 hours at a temperature of 510-520 DEG C in the condition that the ammonia resolution ratio is 70-80%; and cooling to 180 DEG C at the speed of not more than 50 DEG C / H and taking the cylinder sleeve out of the nitriding furnace.

Description

Technical field [0001] The invention relates to a cylinder liner nitriding treatment and a stress relief process. Background technique [0002] The cylinder liner is the core part of the engine and is also a vulnerable part. The failure mode of the cylinder liner is mostly the early wear of the cylinder liner caused by the non-wear resistance of the inner hole. In order to improve the wear resistance of the inner hole, the method of nitriding the cylinder liner as a whole is often used. However, after the overall nitriding treatment, the wear resistance of the inner surface of the cylinder liner is improved, but the nitriding deformation is relatively large, and the cylinder liner product has to be machined to eliminate the deformation of the product. At the same time, the wear-resistant layer of the product is also removed. Contents of the invention [0003] In order to improve the wear resistance of cylinder liner products and reduce the inner hole deformation caused b...

Claims

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Application Information

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IPC IPC(8): C23F17/00C21D1/30C23C8/24
Inventor 严方张加中徐金兰
Owner 徐金兰
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