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Metallographic corrosion method for multiphase austenitic stainless steel weld metal

A technology for austenitic stainless steel and weld metal, applied in the field of metallographic corrosion of multiphase austenitic stainless steel weld metal, can solve the problems of metallographic structure observation, difficulty in simultaneous display and resolution, deterioration of weld metal mechanical properties and Corrosion performance and other issues, to achieve the effect of easy quantitative control, good reproducibility, corrosion conditions and simple operation

Active Publication Date: 2021-04-16
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the austenitic stainless steel weld containing δ ferrite will decompose and form M during long-term service at high temperature. 23 C 6 Carbide and σ-equal intermetallic compounds will deteriorate the mechanical properties and corrosion properties of the weld metal. In order to study the precipitation mechanism of different phases and their influence on the properties of the weld metal, it is necessary to observe the morphology of different phases in metallography , but due to the existence of multiple phases, it is difficult for the existing metallographic etchant to display and distinguish all the existing phases at the same time, so it is troublesome for the observation of the metallographic structure. Metallographic Corrosion Method of Multiphase Austenitic Stainless Steel Weld Metal

Method used

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  • Metallographic corrosion method for multiphase austenitic stainless steel weld metal
  • Metallographic corrosion method for multiphase austenitic stainless steel weld metal
  • Metallographic corrosion method for multiphase austenitic stainless steel weld metal

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Embodiment 1

[0031] Prepare the mixed aqueous solution (metallographic corrosion solution) of iron trichloride, hydrochloric acid and nitric acid, specifically: the hydrochloric acid of 40g ferric chloride, 30ml concentration 37wt%, the nitric acid of 20ml concentration 65wt% and 80ml water are mixed and made, Afterwards, soak the 316H weld metal sample in the as-welded state in the metallographic corrosion solution for 50 seconds. After taking it out, rinse the sample with water and alcohol in turn, and dry it with hot air. The metallographic photos are as follows: Image 6 As shown, the delta ferrite did not fall off during the corrosion process, and the delta ferrite in the austenite matrix can be clearly distinguished.

Embodiment 2

[0033] Prepare an aqueous solution of ferric chloride, hydrochloric acid, and nitric acid. The specific ratio is: 40g ferric chloride + 30ml concentration of 37wt% hydrochloric acid + 20ml concentration of 65wt% nitric acid + 80ml water. Soak the sample in the solution for 40s, after taking it out, rinse the sample with water and alcohol in turn, and dry it with hot air. The metallographic photos are as follows: Figure 7 As shown, under this aging condition, the delta ferrite is partially decomposed into M 23 C 6 ,M 23 C 6 and δ ferrite did not fall off during the corrosion process, and the M in the austenite matrix can be clearly distinguished 23 C 6 and delta ferrite.

Embodiment 3

[0035] Prepare ferric chloride, hydrochloric acid, nitric acid aqueous solution, specific ratio is: 40g ferric chloride+30ml concentration 37wt% hydrochloric acid+20ml concentration 65wt% nitric acid+80ml water, after that 750 ℃ / 20h aging state 316H weld metal sample Soak in the solution for 30s, after taking it out, rinse the sample with water and alcohol in turn, dry with hot air, and the metallographic photos are as follows: Figure 8 As shown, under this aging condition, the delta ferrite is completely decomposed into M 23 C 6 and σ phase, M 23 C 6 Both the σ and σ phases did not fall off during the corrosion process, and the δ ferrite transformation products in the austenite matrix can be clearly distinguished.

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Abstract

The invention discloses a metallographic corrosion method for multi-phase austenitic stainless steel weld metal, and belongs to the technical field of metallographic corrosion. The method comprises the following operation processes: firstly, preparing a mixed aqueous solution of ferric trichloride, hydrochloric acid and nitric acid, then soaking a test sample into the solution for 25-60 seconds, taking out the test sample, sequentially washing the test sample with water and alcohol, and drying the test sample with hot air. By adopting the metallographic corrosion method disclosed by the invention, delta ferrite in an austenitic stainless steel weld joint in a welded state and delta ferrite decomposition products after long-term high-temperature aging can be clearly displayed, the delta ferrite and the decomposition products thereof are prevented from falling off in a large amount in corrosion, and support is provided for subsequent analysis of the types of the delta ferrite decomposition products. Corrosion conditions and operation are simple, quantitative control is easy, reproducibility is good, and the method is suitable for metallographic structure corrosion of multi-phase austenitic stainless steel weld metal containing a small amount of delta ferrite and decomposition products of delta ferrite.

Description

technical field [0001] The invention relates to the technical field of metallographic corrosion, in particular to a method for metallographic corrosion of multiphase austenitic stainless steel weld metal. Background technique [0002] In the fusion welding process of austenitic stainless steel, hot cracking tends to occur when the structural restraint is too large. In order to prevent cracks in the welding process, it is usually desirable to form a certain amount of δ ferrite in the weld structure. Since the δ / γ phase interface energy is low, while the γ / γ interface energy is relatively high, the presence of δ ferrite can effectively reduce the formation of eutectic liquid film on the interface, thereby reducing the tendency of hot cracking during welding solidification. However, the austenitic stainless steel weld containing δ ferrite will decompose and form M during long-term service at high temperature. 23 C 6 Carbide and σ-equal intermetallic compounds will deteriorat...

Claims

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Application Information

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IPC IPC(8): G01N1/32C23F1/28
Inventor 陆善平魏世同李依依
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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