found that the difficulty of producing boron steel in the continuous casting stage
Some researchers
believe that use boron-containing molten iron produce boron steel can reduce
costs, but while oxygen blowing, the high concentration of oxygen in the
converter will reduce the yield rate of boron, this is the difficulty of use boron-containing
hot metal to produce boron steel.com.25%, except added boron separately,
also can be added to a variety of alloys such as manganese boron, chromium
boron, manganese-titanium boron, manganese vanadium boron, chromium-manganese
boron and many other alloys; surface treated boron steel is mainly the infiltration
carbon boron steel, the carbon mass fraction is generally less than 0.
At the same time, boron can also
improve the high temperature strength and creep strength of the heat resistant
steels, improve the red hardness of high speed steel and the cutting ability of
cutter. For nearly 10
years, the international steel mills continue to accelerate the development and
production of boron steel, boron steels smelting technology constantly mature,
the variety of boron steel is also expanding.
The main types of boron steels have alloy
structural boron steel, low alloy high strength boron steel and spring boron
steel and so on. Such as the bad hardenability,
leading to the strength, hardness have fluctuations.
In Boron steel production, if not control
well the craft and boron content will bring many problems. In the best austenitizing temperature,
the hardenability effect of boron is the best. Generally
considered that 0.25%, this
type of steel with better performance of carburized, the carburized layer does
not form a large amount of residual austenite, thus have high hardness,
abrasion resistance, good fatigue resistance, and small notch sensitivity.0020% of the mass fraction of the acid soluble
boron is the best, can increase the yield of boron in refining, and the added
amount of boron is more stable.
Use boron-containing molten iron as raw
material produce boron steel can reduce costs.
Thus it can be seen
the molten steel maintain the molten state for a long time and prolong clotting
time is the main reason lead to slab defective. The more
boron powder content, boron phase along the grain boundary sheet consecutive
precipitation, it will weaken the toughness of boron steel. Generally increases as the carbon content increases, the
role of the boron is gradually reduced.
Boron occurs eliguation while the boron stainless steel shower pipe steel solidified, lead to the slab have defects. Researchers use boron-containing
molten iron as raw materials to produce boron steel, hot metal through desulphurization,
desilication, pretreatment loaded into the converter, adding slagging agent,
and then supply for oxygen blowing. The studies show that the mass
fraction of the boron in steel should be about 0. They thought that, even if add a small amount of boron in steel, the
slab will also produce surface cracks, internal cracks and center segregation,
even appears bleed-out. According to the requirement of boron steel
components, adding silicon, manganese and carbon, and the steel temperature was
controlled at 1560 ~ 1610,
then casting into ingots, and finally obtain boron steel.mhcmp.
Some research institutions
found that the difficulty of producing boron steel in the continuous casting
stage. Quenched and tempered boron steel has high strength,
high toughness, high abrasion resistance, can be used in automobiles, tractors,
machine tools, mining machinery, power plant equipment. From this point of view, boron steel not only enhance the overall
performance of the steel, but also reduce the production cost.0010%, too low or too high can not produce the best results. Although it is possible to
adjust the added amount of titanium in the steelmaking to improve these
problems, but what was worth to noting is that the effect of general alloy elements
improving the hardenability is increased with its content in the steel, while
there is an optimum content of boron powder. After added boron, the solidification of the molten steel in the continuous casting will melt again, by in situ analysis showed
that boron segregated at the grain boundaries and dendrite. Alloy structural boron steel used more often, including
quenched and tempered boron steel, surface treated boron steel and cold
deformation boron steel.
Hardenability effect of boron in steel is
related to the amount of boron, carbon content and the austenitizing
temperature of steel. The carbon mass
fraction of these steels are more than 0.0005% to 0
