How to control the layered structure of seamless steel pipes?

1. Improve the plastic ductility of structural steel pipes from the following aspects

①Improve the cleanliness level of molten iron and reduce hazards;
②Increase the proportion of equiaxed crystals of rolled billets:
③Formulate effective refrigeration rules and regulations to prevent internal cracks in the billet;
④Use the slow cooling process for the withdrawn cast billet or continuous rolling billet to reduce the internal stress, thereby ensuring that the structure and physical properties of the finished rolled pipe and the finished product structural steel pipe meet the standard specifications.

2. Effectively manipulate the heating temperature

Select the best heating temperature according to the measurement curve of thermosetting plastics. It is necessary to pay attention to sufficient heat insulation time for the heating of the finished rolled pipe to reduce the deformation immunity and improve the ductility of the structural steel pipe.

3. Reduce the roll speed ratio

The roll speed ratio is an important parameter of the hole-breaking processing technology. During the transition from low to high roll speed ratio, there is a critical value of the roll speed ratio that has just begun to appear. When the roll speed is relatively low, the finish-rolled tube is very easy to produce cavities; when the roll speed is relatively high, the finish-rolled tube and structural steel tube are very easy to produce hierarchical defects. In order to facilitate the elimination of the layered defects of the finish-rolled pipe and the structural steel pipe, the roll speed ratio should be reduced to below the critical value of the roll speed ratio at which the layer has just started.

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