Performance heat treatment method of sa508-3 large forgings for nuclear capacitors

Abstract

The invention discloses a performance heat treatment method for an SA508-3 large forging for a nuclear power vessel. The method is used for performing heat treatment on the forging for the nuclear power vessel, the material of the forging is SA508-3, the external diameter is 3.5-6.5 m, the height is not larger than 5m, and the wall thickness is 100-250 mm. The method comprises the following steps: step 1, first-time quenching, namely putting the forging into a furnace to heat to 600-700 DEG C, and then preserving heat for 4-5 hours, then heating to 880-920 DEG C at a temperature rising rate of less than or equal to 100 DEG C per hour, preserving heat for 4-5 hours, then discharging from the furnace, and cooling the forging with water to the room temperature; step 2, second-time quenching; step 3, tempering, namely heating the forging to 635-660 DEG C at the temperature rise rate of less than or equal to 100 DEG C per hour, preserving heat for 4-5 hours, and discharging from the furnace for cooling in the air. The method adopts multiple times of quenching operation before high-temperature tempering, refines organization through multiple times of quenching, finally obtains the needed performance through tempering adjustment, can increase the low-temperature toughness of the large forging for nuclear power on the basis of ensuring the qualified strength, and therefore meets the performance requirement of the large forging for nuclear power.

Description

technical field [0001] The invention relates to a heat treatment method, in particular to a performance heat treatment method for SA508-3 large forgings used in nuclear capacitors. Background technique [0002] Nuclear capacitors play a vital role in ensuring the safe operation of nuclear power plants throughout the 40-60-year service cycle, so nuclear capacitors are generally assembled and welded by high-performance large forgings. [0003] General requirements for SA508-3 large forgings for nuclear capacitors are as follows: [0004] 1. It has high room temperature strength and high temperature strength, and the technical index is measured by room temperature tensile test and high temperature tensile test; [0005] 2. Sufficient toughness, especially low temperature toughness, which is generally measured by Charpy impact test or drop weight test. From the perspective of safety, it is generally required that the toughness of the forging material should be improved as much...

AI Technical Summary

Problems solved by technology

[0013] The above-mentioned heat treatment process of conventional quenching + high temperature tempering can meet the performance requirements of most large nuclear power forgings, but there are still some forgings due to defects (such as poor composition and serious segregation) caused by the previous process. Conventional properties Toughness after heat treatment is lower than specification requirements

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