Double quenching technique for 9Cr2Mo leveler roll

Abstract

The double liquid quenching process of 9Cr2Mo straightening roller includes the first quick cooling in water to avoid high temperature decomposition of overcooling austenite to the martensite transformation temperature, and the subsequent cooling in oil for martensite transformation to raise the hardness, reduce quenching deformation and avoid cracking. Before being loaded to furnace, the straightening roller has its end surfaces and central through hole covered with plates to reduce the quench cooling of these parts and ensure hardness of HRC 35-40.

Description

Technical field: [0001] The invention relates to the technical field of production and manufacture of bar straightening machines, in particular to a two-liquid quenching process for 9Cr2Mo straightening rollers. Background technique: [0002] At present, in the production and manufacturing process of the bar straightening machine, the straightening roller whose material is 9Cr2Mo is the key component, and the heat treatment process of the straightening roller is complicated and difficult, and has become the key to production. The straightening roll needs overall quenching, the hardness of the roll body is above HRC54, and the toughness of the core is guaranteed, but the following problems exist in the quenching process: 1) Due to the large cross-section, the hardness of the roll body is difficult to reach HRC54 during oil quenching; For this kind of material, the cooling is too intense and it is easy to crack; 2) The hardness of the roll body is required to be greater than H...

AI Technical Summary

Problems solved by technology

The straightening roll needs overall quenching, the hardness of the roll body is above HRC54, and the toughness of the core is guaranteed, but the following problems exist in the quenching process: 1) Due to the large cross-section, the hardness of the roll body is difficult to reach HRC54 during oil quenching; For this kind of material, the cooling is too intense and it is easy to crack; 2) The hardness of the roll body is required to be greater than HRC54, so the quenching deformation should be controlled according to the amount of grinding, which is more difficult for such a large piece; 3) The hardness of the roll body should reach HRC54 or more , in order to ensure the toughness of the core and subsequent machining, the hardness requirements of the end face and the core are reduced to HRC35-40, which is not easy to ensure at the same time during overall quenching; 4) The edge of the straightening roller is easy to overheat when heated, and easy to crack when quenched

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