Causes of defects in aluminum alloy smelting process and improvement measures

September 13, 2019

[China Aluminum Industry Network] 1. Pinhole defects Aluminum alloy pinhole defects:

1 furnace material and aluminum alloy melting tool baking is not sufficient;

2 The melting temperature of the aluminum alloy is too high or the melting time is too long;

3 The molten aluminum stays too long after deterioration;

4 Alloy refining is not good; 5 Workplace is too humid.

Prevention methods:

1 Charges and tools should be thoroughly dried;

2 control the melting temperature, generally does not exceed 7400C, does not exceed the pouring temperature, but also to prevent the local overheating of the alloy in the melting process;

3 Operate quickly and shorten the smelting time as much as possible;

4 Refining operations should be careful, refining is a better way to prevent blowholes;

5 After the metamorphism, the alloy liquid should be poured in 8-15 minutes and should be poured in time. 6 Keep the smelting site dry.

2. Causes of aluminum alloy oxide slag inclusion aluminum oxide slag defects:

1 The charge is not clean, and the amount of returned charge is too much;

2 The molten slag in the alloy liquid was not removed; 3 After the modification treatment, the standing time was not enough.

Preventive measures: After the charge is blown, the charge is controlled within 70% of the charge quality. The degassing and slag removal must be thorough. After the deterioration, sufficient time for standing is ensured so that the slag has enough time to sink or float.

3. Shrinkage and shrinkage defects Causes of aluminum alloy shrinkage and shrinkage defects:

1 The alloy grain is coarse;

2 stroke alloy casting temperature is too high;

3 cast casting system design is unreasonable.

Prevention methods:

1 The effects of alloy fluid refining and deteriorating operations have a great influence on this kind of defects, so they must be in place;

2 Strictly control the temperature of liquid aluminum to prevent overheating. In the case of ensuring that the casting does not produce insufficient water, a low pouring temperature should be used as far as possible, and the pouring temperature generally should not exceed 7300C;

3 Rationally design the pouring system so that the molten metal can be filled smoothly;

4 appropriate adjustment of the composition, control of the content of the appropriate impurities to enhance the fluidity of the molten metal is also effective.

We can produce the lower-temperature steel pipe according to the ASTM A333 and ASME SA333 standards, and the and the production diameter from 8" to 48" in OD and wall thickness from 9.53 mm up to 140mm. We have been sold the GR.6 steel pipe about 20000 tons to date and the property of -45℃ impact value is about 100J, better than the standard`s requirements.

Yangzhou Chengde has the full capability to do every test in-house, from mechanical testing, chemical analysis, PMI, UT/Hydrotest etc. Chengde`s lab is qualified to ISO 17025 and CNAS standard, being proven the repeatability of accurate testings.

Each alloy pipe is subject to PMI before dispatch. The INNOV-X system performs non-destructive chemical analysis via simultaneous detection and quantification of fluorescent x-rays of multiple elements in test sample. 

ASTM A333 Steel Pipe

Astm A333 Pipe

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