Heat treatment process of important screw of marine diesel engine

Abstract

The invention relates to an important bolt of a marine diesel engine, in particular to a material selection and material heat treatment process for an important bolt of a marine diesel engine. It uses 40CrNiMoA steel to roll into a stud with a diameter of 50≤￠≤120mm, and the rolling ratio of the rolled piece is>6; it is welded with a low-carbon steel plate or a heat-resistant stainless steel plate with a thickness of about 25mm during heat treatment. Lifting and loading tool for bolt heat treatment. Through the effective heat treatment of the 40CrNiMoA material, the method of the invention makes various large-section 40CrNiMoA round steels used as localized substitute materials for the powerful bolts of large low-speed diesel engines, and achieves optimal performance and is the most economical and reasonable.

Description

Technical field: [0001] The invention relates to an important bolt of a marine diesel engine, in particular to a material selection and material heat treatment process for the bolt of a marine diesel engine. Background technique: [0002] The material grade of the strong bolts of the high-power low-speed marine diesel engine produced by the Danish B&W Design Company produced by domestic low-speed diesel engine manufacturers is ScrNi (see Table 1 for mechanical performance requirements and Table 2 for chemical composition). This grade is a Danish standard, and there is no corresponding material grade in the national standard. In the past, domestic medium and low-speed diesel engines have always used PCrNiMo forging materials with higher performance as the substitute material for strong bolts, which has a large performance margin and high cost. With the increasingly fierce competition in the diesel engine market and the sharp drop in machine prices, this material is becoming ...

AI Technical Summary

Problems solved by technology

The above-mentioned problem can be effectively solved by using a crane for discharging from the furnace, but there is still a problem that one batch of workpieces needs to be discharged three times, and each time the workpiece is discharged due to the difference in the temperature of the furnace, the method of discharging and the temperature of the cooling medium, resulting in the deformation of each layer of workpieces after cooling. The performance is different, in other words, a physical sample in the furnace cannot very effectively replace the performance of the other two layers of workpiece

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