Heat treatment method for large-scale Cr12Mov workpiece

Abstract

The invention relates to a heat treatment method for a large-scale Cr12Mov workpiece, which comprises the following steps of: performing heat preservation on the workpiece for 12 to 20 hours at conventional annealing temperature, performing hydrogen diffusion annealing, reducing the furnace temperature to 600 to 650 DEG C, performing heat preservation for 40 to 100 hours, reducing the furnace temperature again, taking the workpiece out of a furnace when the furnace temperature is below 450 DEG C, and cooling to room temperature naturally, wherein the specific time is in proportion to the sizeof the workpiece; hardening and tempering the workpiece, performing heat preservation at the temperature of between 1,050 and 1,150 for 2 to 6 hours, taking the workpiece out of the furnace, performing oil cooling to the temperature of between 160 and 200 DEG C, heating in the furnace to the temperature of between 760 and 800 DEG C, tampering for 3 to 8 hours, taking the workpiece out of the furnace, and cooling to the room temperature naturally; and quenching the workpiece subjected to finish machining, performing heat preservation in the furnace at the temperature of 800 DEG C for 3 to 4 hours, heating to the temperature of between 1,000 and 1,030 DEG C for heat preservation for 3 to 6 hours, quenching at constant temperature, and tampering at the temperature of between 200 and 220 DEG C for three times. In the workpiece treated by the method, the toughness is improved greatly, the surface hardness is more than Rockwell hardness (HRC) 60, and the production efficiency is improved greatly.

Description

Technical field: [0001] The invention relates to a general method or equipment for heat treatment, in particular to a heat treatment method for large Cr12MoV workpieces that can improve workpiece quality, reduce scrap rate and increase economic benefits. Background technique: [0002] The current heat treatment methods for Cr12MoV workpieces mainly include the following: (1) Conventional spheroidizing annealing, which is to heat the furnace for 8-10 hours when the furnace temperature rises to 850-870 ° C, and then cool down to 730-750 ° C for 10-12 hours , Cooled in the furnace to below 500°C and released from the furnace; (2) After finishing machining, it is heated to 980-1020°C for quenching; after quenching, it is tempered once at 200-220°C. This traditional heat treatment method is only suitable for general small workpieces, that is, when the thickness of the workpiece is less than 100mm and the diameter is less than 450mm, it has little effect on the quality. The struc...

AI Technical Summary

Problems solved by technology

This traditional heat treatment method is only suitable for general small workpieces, that is, when the thickness of the workpiece is less than 100mm and the diameter is less than 450mm, it has little effect on the quality. The structure of workpiece is uneven, the cutting performance is poor, and because the harmful gas cannot overflow, it is quenched after finishing machining, so that the surface of the workpiece generates a large tensile force, which is easy to crack and deform, which affects the quality and has a high scrap rate.