Method for evaluating protective capability of weathering steel rust layers based on freezing-unfreezing treatment

A technology of protection ability and evaluation method, applied in the field of corrosion of iron and steel materials in the atmospheric environment

Inactive Publication Date: 2013-01-09
UNIV OF SCI & TECH BEIJING
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

[0006] These methods are all evaluations of the existing protective ability of the rust layer. However, under external damage conditions (for example: in the north with a large temperature difference between day and night, the influence of dew that penetrates into th

Method used

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  • Method for evaluating protective capability of weathering steel rust layers based on freezing-unfreezing treatment
  • Method for evaluating protective capability of weathering steel rust layers based on freezing-unfreezing treatment
  • Method for evaluating protective capability of weathering steel rust layers based on freezing-unfreezing treatment

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Example Embodiment

[0021] Example 1

[0022] In this embodiment, the evaluation method for the protection ability of the weathering steel rust layer based on the freezing-thawing treatment includes the following steps:

[0023] Step 1. Obtain a variety of weathering steel samples with rust layers to be tested;

[0024] Step 2. Perform freeze-thaw treatment on the weathering steel sample. The freeze-thaw treatment is to soak the weathering steel sample in deionized water for 30 minutes to make the rust layer absorb enough water, and then take it out until the surface does not drip. Put it into a freezer with a temperature of -18°C and freeze it for 1 hour, then take it out and put it in a drying box at 25°C for drying, and the drying time is 24 hours;

[0025] When freezing and thawing the weathering steel samples, the rust layer of the weathering steel samples can absorb enough water by spraying the weathering steel samples, instead of soaking the weathering steel samples;

[0026] Step 3. Usi...

Example Embodiment

[0030] Example 2

[0031] Select two test steels 1# and 2# with different chromium content and the same other components (see Table 1 for the composition of the test steel):

[0032] Steel C Mn Si S P Cu Cr Ni Bt 1 # 0.045 0.86 0.32 0.0052 0.0055 0.48 0.96 0.37 0.0014 2 # 0.051 0.85 0.33 0.0045 ﹤0.005 0.48 1.46 0.36 0.0013

[0033] Table 1 Chemical composition of test steel (wt%)

[0034] Samples with dimensions of 10 mm × 10 mm × 5 mm and 60 mm × 40 mm × 5 mm were cut from the rolled steel sheet for accelerated spray test. Each test steel is divided into two parallel groups. The two groups of samples are placed in the test room for exposure. The exposure frame faces the south and the horizon at 45o, and there is sunlight. During the test, the indoor temperature is kept at about 26 ℃, and the average indoor relative humidity is 54. %about. One group of test steels was subjected to freeze-thaw treatm...

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Abstract

The invention provides a method for evaluating the protective capability of weathering steel rust layers based on freezing-unfreezing treatment. The method comprises the following steps of: (1) collecting various weathering steel samples to be measured and with rust layers; (2) performing freezing-unfreezing treatment on the weathering steel samples; (3) analyzing influence of the freezing-unfreezing treatment on change of fissures of the rust layer of each weathering steel sample; (4) analyzing influence of the freezing-unfreezing treatment on change of the alternating-current impedance fitting resistance value of the rust layer of each weathering steel sample; and (5) evaluating the protective capability of the rust layers of the weathering steel samples, determining that the protective capability of the weathering steel samples is high if the increment of the fissures of the rust layers and the change of the alternating-current impedance fitting resistance values of the rust layers of the weathering steel samples are low, and determining that the protective capability of the weathering steel samples is low if the increment of the fissures of the rust layers and the change of the alternating-current impedance fitting resistance values of the rust layers of the weathering steel samples are high. According to the method, destructiveness conditions of the outside are considered, particularly the capability of the rust layers resisting a frost environment in a northern cold region, the compactness of the weathering steel rust layers is judged from a brand-new angle, the protective capability of the weathering steel rust layers can be reflected really, and accordingly a judgment result is real and reliable.

Description

technical field [0001] The invention belongs to the corrosion of iron and steel materials in the atmospheric environment, and in particular relates to the evaluation of the protection performance of the weather-resistant steel rust layer. Background technique [0002] The corrosion performance of bare steel in the atmospheric environment is mainly achieved by the resistance of the corrosion progress to the stable and dense corrosion product layer formed on the surface. At present, the evaluation of the hindering effect of the corrosion product layer mainly includes weight loss method, corrosion product analysis and electrochemical method. [0003] The weight loss method is to measure the corrosion progress of steel in a certain environment by using the weight loss per unit area or thinning per unit area of ​​steel after removing surface corrosion products. This is the simplest and most effective macro-analysis method for evaluating the atmospheric corrosion of metals, which...

Claims

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Application Information

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IPC IPC(8): G01N17/02G01N1/42
Inventor 张旭杨善武张文华贺信莱尚成嘉王学敏郭晖
Owner UNIV OF SCI & TECH BEIJING
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