Application of new nitrided steel in manufacturing of diesel engine plunger and barrel assembly

Abstract

The invention relates to application of new nitrided steel in manufacturing of a diesel engine plunger and barrel assembly. The application comprises the following steps of 1, pretreatment before nitriding, 2, workpiece cleaning before nitriding, 3, surface nitriding treatment, 4, workpiece grinding, and 5, workpiece vacuum coating. The diesel engine plunger and barrel assembly made of the new nitrided steel has the advantages of aluminum-containing nitrided steel and aluminum-free nitrided steel, the defects of the aluminum-containing nitrided steel and the aluminum-free nitrided steel are overcome, and after composite heat treatment, the use performance of a low-speed diesel engine plunger pump can be improved, and emission is reduced.

Description

technical field [0001] The invention relates to a diesel engine component, in particular to the application of a new nitrided steel in the manufacture of a diesel engine plunger pair. Especially for the heat treatment of plunger couples of marine low-speed diesel engines. Background technique [0002] At present, most of the Wärtsilä, Sulzer and B&W series low-speed machine plunger couples and some medium-speed machine and governor parts are made of 38CrMoAl and 32Cr3Mo1V nitrided steel. 38CrMoAl is a kind of aluminum-containing nitriding steel. After nitriding treatment, it can obtain high surface hardness and good wear resistance, but it is overheating sensitive, the surface of the nitriding layer is more brittle, and the vein nitride is poor. , The ability to resist high-frequency impact is low, and subsequent processing is prone to grinding cracks; large-diameter plungers and plunger sleeves cannot be hardened during quenching and tempering, and free ferrite is easily p...

AI Technical Summary

Problems solved by technology

38CrMoAl is a kind of aluminum-containing nitriding steel. After nitriding treatment, it can obtain high surface hardness and good wear resistance, but it is overheating sensitive, the surface of the nitriding layer is more brittle, and the vein nitride is poor. , The ability to resist high-frequency impact is low, and subsequent processing is prone to grinding cracks; large-diameter plungers and plunger sleeves cannot be hardened during quenching and tempering, and free ferrite is easily produced, which will adversely affect the performance of the product

32Cr3Mo1V nitrided steel belongs to a kind of aluminum-free nitriding steel. Compared with 38CrMoAl, the hardenability and brittleness of the nitrided layer after nitriding are significantly improved. However, the hardness after nitriding is low, so that the fatigue resistance, low wear resistance

[0004] The heat treatment properties and mechanical properties after heat treatment of an alloy nitrided steel disclosed in this patent document can be regarded as a suitable choice for the manufacture of diesel engine plunger parts.

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