seamless steel pipe: hot rolled is relative to the cold-rolled, cold rolling
is below the recrystallization temperature of the rolling, and hot rolled is
carried out at above the recrystallization temperature of the rolling.
hot rolled seamless steel
pipe can damage the cast microstructure of the steel ingot, refinement of
the crystal grains of the steel, and eliminate the defects of the
microstructure, so that the the steel organization compacting, improve the
mechanical properties. This improvement is reflected in the rolling direction,
so that the steel is no longer to a certain extent isotropic; pouring the
formation of bubbles, cracks, and osteoporosis, under high temperature and
pressure can also be welded together.
After the hot rolling, the nonmetallic inclusions in the interior of a steel
(mainly sulfides and oxides, as well as the silicate) was pressed into a sheet,
stratified (laminated) phenomenon appears. The layering of the steel in the
thickness direction by the pull performance deteriorated significantly, and may
appear in the weld shrinkage interlayer tear. Weld shrinkage induced local
strain often reach several times the yield point strain, the strain is much
greater than the load caused;
Residual stress caused by uneven cooling. The residual stress is the stress
of internal self-phase equilibrium in the absence of external force, the
hot-rolled steel of various cross-sectional has a residual stress such Usually
steel sectional dimension is the greater, the greater the residual stresses.
Residual stress is self-phase equilibrium, but the steel members in the
performance external force or have a certain influence. Such as deformation,
stability, anti-fatigue may adversely.
Hot-rolled steel products, poor control of thickness and edge width. We are
familiar with the thermal expansion and contraction, even if the beginning of
the hot-rolled out are standard length, thickness, or there will be some
negative final after cooling, this negative differential edge width wider the
increasing thickness of the performance of the more obvious. So for large steel
for steel edge width, thickness, length, angle, and sideline no law requires too