Generally considered to carbon steeland alloy element

About the mechanism on the boron to improvehardenability have been proposed a variety of claims, wherein the moreconsistent understanding is: because boron delayed ferrite nucleation process(but does not affect the thermodynamic properties of the austenitic or ferriticmatrix, also means that the boron can reduce the nucleation rate of theferrite, but does not affect the growth rate as well as the rate of formationof pearlite and martensite) increasing steel’s hardenability. Austenite grainboundary segregation of boron atoms reduce the differences of the variousmechanisms by what means is that boron to postpone the nucleation rate of ferritic,which has: boron reduced the self diffusion capacity of the iron in theaustenite grain boundaries, The boron atom Segregation reduced nucleationposition, the role of M23 6 boron carbide (B, C) and doctrine.About the mechanism of boron improve the hardenability,scientists has conducted a lot of researches, and continues even in thecurrent. The role of the boron to improve hardenability have many differentfeatures from the other alloying elements.

There are (1) with a very strongability to improve the hardenability. According to the metal powder supplier, 0.0010%to 0.0030% boron can be respectively equal to 0.6% manganese, 0.7% chromium,0.5% molybdenum and 1.5% nickel, and therefore its ability to improve thehardenability of the above alloying elements hundreds of times or eventhousands of times, and therefore only a small amount of boron can save a lotof expensive alloying elements.(2) with the optimum content and thecontent is minimal. Usually alloy elements improve the hardenability effect andgrowth with its content in the steel is increased, but there is an optimumcontent range of boron powder, Roll Forming Machine too much ortoo little of improving hardenability unfavorable, but this amount is verysmall, approximately 0.0010%, generally control in 0.0005% to 0.0030%.(3) the effect of boron’s hardenability isrelated to the composition of the steel.

Generally considered to carbon steeland alloy element content increasing, but the boron improve hardenability is decreasing.Therefore, low-carbon, low-alloy steel, boron hardenability effect is the mostsignificant.(4) the boron’s hardenability is related toaustenitizing conditions. Early studies have shown that there is a specialrelationship between them, that in a particular austenitizing temperature, the hardenabilityeffect of boron is good; when the temperature rises again, despite theaustenite grain growth, the impact of boron’s hardenability will be dropped.Some recent studies have found that the a titanium fixed nitrogen, boron steelin a certain austenitizing temperature range almost no change in hardenability.These phenomena are associated with quenching of the alloy elements in generalpermeability effect austenitizing temperature relationship.