How to quickly test the quality of Heat-resistant Steel Castings
First, the furnace before the test
Heat-resistant Steel Castings before the test is an indispensable part of its production process, it is directly related to the quality of heat-resistant steel parts. Timely and accurate judgment of the situation of iron liquid, you can quickly take measures to control the quality of Heat-resistant Steel Castings. Misjudgment before the furnace will cause a lot of cast scrap, waste modeling man-hours, so the furnace before the timely and accurate judgment is much more important than the post-furnace inspection. Actual production commonly used in the furnace before the test of the situation of molten iron are the following.
1, the surface crust and flames judge method
Rare earth magnesium Heat-resistant Steel Castings with low magnesium content, and rare earth elements, iron surface and pure magnesium Heat-resistant Steel Castings are not the same, the surface is not so much oxide, flames are not so much and powerful. But when the additional 1/3 of the liquid when the liquid will escape the magnesium light and white flames, shaped like candle. According to the number of flames, height to determine the situation and magnesium residue, the higher the flames, the more powerful, that good. Especially in the pouring, from the molten iron flow can be seen in the flames, such as the height of 25 ~ ffice: smarttags "/> 50mm, that is good; if the flames less than 15mm, then worse. Piece of iron liquid surface to see the formation of oxide film, and silver white rolling highlights, that is good, but the oxide film is too thick, then the liquid temperature is low.
2, triangular test block method
At present, by observing the test block to judge the situation is a commonly used method. The size of the test block used in the factory, the size of the different, the majority of factories using triangular test block.
3, casting process to determine
(1) Heat-resistant Steel Castings iron pouring into the mold, such as the pouring cup has been down to the concave, and the surface is very smooth, that good; such as the upper part of the gates of a layer of hard shell, Indicating that the liquid temperature is low.
(2) During the pouring process, the sand-shaped surface splashing round flat iron beans with pits (pits), indicating good.
4, black border identification method
After the ball is finished, the sample spoon is poured into a test piece with a thickness of about 10mm, cooled to dark red, quenched after breaking, if found on the surface of the test piece has a black side, then the bad, and the darker the thicker, Resulting in a recession, this time, such as iron liquid temperature can add additional alloy. From the test block can be seen: such as the test block around the arc-shaped, and the middle of the depression, and some also have a road wrinkles, it also means good; such as the test piece on the surface of the wheat-like point, Oxidation, easy to decline. In this case, the furnace should be modified.
5, observe the solid state of molten iron
After treatment, remove a small amount of molten iron, pour into the Ф30mm cylindrical metal type, observed during the solidification of molten iron from the surface of the phenomenon of emission, and according to the amount of molten iron to determine the situation of iron liquid. Good iron liquid, solid during the show a lot of graphite expansion force, the surface of the molten iron in the beginning of the solidification of some decline in the surface of the shell after a small amount of molten iron from the case of gushing; and poor iron liquid surface emission less.
6, rapid observation before the furnace
All of the above methods are the use of Heat-resistant Steel Castings to determine the characteristics of a certain situation, but the production of various conditions vary widely, the method has limitations, and the rapid observation of the furnace can be more to avoid many factors Of the interference, direct observation of the situation.
Second, after the furnace metallographic examination
(1) after the metallographic examination of the main observation of microstructures such as graphite morphology and sub-characteristics of metal matrix inclusions, etc. through the metallographic analysis of the pieces of the amount of material for a change in the real base.
(2) rare earth magnesium Heat-resistant Steel Castings steel chemical composition analysis can also be said to be a means of detection, such as the discovery of problems, ingredients can be adjusted to avoid major quality problems. In addition, there are mechanical properties of the test and heat-resistant steel parts of the non-destructive testing.