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Method for improving flaw detection qualification rate of low-carbon, low-aluminum and high-chromium forging round steel

A pass rate and round forging technology, which is applied in forging, smelting of ferritic heat-resistant steel, and pouring fields, can solve the problems of low pass rate and achieve the effects of improving quality, reducing central cracks, and increasing compression ratio

Active Publication Date: 2021-12-10
SHANXI TAIGANG STAINLESS STEEL CO LTD
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Problems solved by technology

[0003] The requirements for the physical quality of ferritic heat-resistant steel are very high, and the flaw detection defect equivalent after forging is required to be ≤ φ2mm. At present, according to this standard, the pass rate is low, only 50-60%

Method used

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  • Method for improving flaw detection qualification rate of low-carbon, low-aluminum and high-chromium forging round steel
  • Method for improving flaw detection qualification rate of low-carbon, low-aluminum and high-chromium forging round steel

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Embodiment Construction

[0011] 80 tons were smelted at one time, using electric furnace smelting + LF furnace refining + VD degassing process to smelt and cast three furnaces. After upsetting and drawing forging, the pass rate of flaw detection has been greatly improved. The details are as follows:

[0012] Electric furnace smelting part:

[0013] 1. Use strong oxidation operation to reduce the content of gas and inclusions in steel. End point C, P control target C ≤ 0.05%, P ≤ 0.008%. Electric furnace tapping temperature: T≥1750℃. It is strictly forbidden to drop slag when tapping.

[0014] 2. Put the synthetic slag and alloy into the bag online, and the alloy should be baked for more than 30 minutes.

[0015] 3. During the tapping process of the electric furnace, 150Kg of aluminum deoxidizer is added along with the steel flow.

[0016] Refining part of LF furnace:

[0017] 1. When the temperature T≥1560℃, add 200kg of silicon-calcium powder to the slag to make reduced slag. After adjusting th...

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Abstract

The invention relates to the field of smelting, pouring and forging of ferrite heat-resistant steel. The method for improving the flaw detection qualification rate of the low-carbon, low-aluminum and high-chromium forging round steel adopts electric furnace smelting, LF furnace refining, VD treatment, die casting and forging for production, during die casting, the temperature from a steel ladle to a casting table is controlled to be 70-80 DEG C higher than a liquidus, argon seal protection is adopted during pouring, the die temperature is required to be 80-100 DEG C, low-carbon casting powder is adopted for pouring, the steel ladle is hung to the center of a die, the distance from the steel ladle to the bottom of the die is 150-200 millimeters, in the pouring process, a high-calorific-value heat generating agent is added into the die, and the heating temperature is made to be greater than 1500 DEG C. therefore, the feeding capacity of molten steel is improved, cracks in the center of a cast ingot are reduced, and the cracks can be reduced in the subsequent forging machining process.

Description

technical field [0001] The invention relates to the fields of smelting, pouring and forging of ferritic heat-resistant steel. Background technique [0002] Ferritic heat-resistant steel (high chromium steel forging round) serves under high temperature and high pressure conditions, and its composition has low carbon (C:0.07-0.13%), low aluminum (Al≤0.015%), high chromium (Cr:8-10 %), has good oxidation resistance and thermal strength, and is widely used in power plant boilers, petrochemical and other industries. [0003] The requirements for the physical quality of ferritic heat-resistant steel are very high, and the flaw detection defect equivalent after forging is required to be ≤φ2mm. At present, according to this standard, the pass rate is low, only 50-60%. Contents of the invention [0004] The inclusions in the molten steel of ferritic heat-resistant steel remain in the steel ingot after solidification, causing discontinuity in the steel matrix. Therefore, in order t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22D7/00B22D7/10B22D37/00C21C5/52C21C7/06C21C7/10C21C7/00B21J5/06
CPCB22D7/00B22D7/104B22D37/00C21C5/52C21C7/06C21C7/10C21C7/0056B21J5/06Y02P10/20
Inventor 原凌云李建军赵志钢王会亮王育田张锦文
Owner SHANXI TAIGANG STAINLESS STEEL CO LTD
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