A Method for Quickly Discovering the Variation of Carburizing Temperature Field Without Relying on Temperature Measuring System

Abstract

The invention relates to the technical field of carburizing process monitoring, in particular to a method for quickly discovering changes in the carburizing temperature field without relying on a temperature measuring system. The sample and the carburized workpiece should keep the same grade; Step 2: Detect the intermediate sample, perform normal etching on the observation surface of the intermediate sample according to the etching medium corresponding to the grade of the intermediate sample, and observe the structure of the carburized layer; Step 3: Complete the intermediate At the same time as the conventional infiltration layer structure detection of the sample, the transition layer structure of the intermediate sample is also measured; Step 4: Judging overheating: judge according to the pro-eutectoid ferrite morphology shown by the grain boundary, and the judgment principle is: a. Mixed crystal image; b. Widmanstattenite characteristics and its intra-grain morphology. The invention can effectively solve the early identification of temperature field fluctuations in the carburizing process, so as to timely adopt corresponding process adjustments within the same furnace cycle, eliminate rework such as normalizing in the later stage, and ensure batch reliability and stability of key structural components.

Description

technical field [0001] The invention relates to the technical field of carburizing process monitoring, in particular to a method for quickly discovering the change of the carburizing temperature field without relying on a temperature measuring system. Background technique [0002] Carburizing and quenching products are widely used in key structural parts of important components such as high-power diesel engines. For a long time, due to the high temperature (generally ≥910 °C) in the carburizing process, the depth of the effective hardened layer is deep (long carburizing cycle), essential For materials with large grain size, such as temperature field fluctuation during the intermediate process of carburization, it will directly lead to problems such as coarse structure and increase of carbide grade, resulting in various defects such as cracks during processing and performance degradation during service stage. In the actual control process, due to factors such as instrument st...

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Problems solved by technology

[0002] Carburizing and quenching products are widely used in key structural parts of important components such as high-power diesel engines. For a long time, due to the high temperature maintained during the carburizing process (generally ≥910°C), the depth of the effective hardened layer is deep (long carburizing cycle), essential For materials with large grain size, if the temperature field fluctuates during the carburizing process, it will directly lead to problems such as coarse structure and higher carbide grade, resulting in cracks in the processing process and performance degradation in the service stage.

In the actual control process, due to factors such as instrument stability, thermocouple placement, signal error, and inspection cycle during operation, the fluctuations in the temperature field during the carburizing process (especially high temperature) are difficult to detect early, which is not conducive to timely adoption. Corrective actions resulting in batch quality issues occurring

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