Basic Research On Preparation And Properties Of Boron Steel With Iron Bearing Boron

Micro amounts boron can improve the hardenability of boron steel, and increase the strength of steel greatly without harming its ductility. But for a long time, the use of boron steel have been influenced due to the imperfection of smelting process and the instability of heat treatment properties. Recent years, as people being familiar with the mechanism of boron in steel, it has promoted the development and application of boron steel. Boron steels have comprehensive application in tractor, machine tool and the preparation of various mechanical parts. So, boron can save or replace parts of scarce resources, such as Nickel, Molybdenum; In addition, because of boron having the ability of capturing neutron, boron also has wide applications in nuclear industry.Traditional smelting process of boron steel use boron ferroalloy was used as additive. But the utilization of boron was low and the cost of production is high. In this case, basing the comprehensive utilization of source, in this paper, pig iron containing boron is used as material to melt boron steel directly. Experimental steels are designed in low carbon, a few chromium and manganese are added, which are melted in vacuum induction furnace. Contrasting the effect of different boron contents and austenitizing temperatures on the properties of experimental steel. Selecting some sample steels with good comprehensive properties to do the test of impact abrasive wear, and by means of SEM, analysis the mechanism of impact fracture and wear. It shows that:(1) Experimental steels are treated by hot rolling and with water cooling mode, its have good comprehensive properties. When boron contents are0.001%, a experimental steel which tensile strength is1180MPa, yield strength810MPa, impact toughness65J, elongation14.3%, contraction of area48.7%.(2) When boron contents are0.003%, the mechanism of impact fracture of experimental steel is cleavage fracture. When boron contents range from0.001%to0.003%, with the increment of it, tensile strength and impact toughness of experimental steel reduced, when boron contents range from0.003%to0.005%, tensile strength and impact toughness of experimental steel increased.(3) Experimental steels which had been treated with hot rolling is quenched and low temperature tempered, when boron contents are0.001%, it have a good comprehensive properties in1000℃, when boron contents range from0.002%to0.005%, it have a good comprehensive properties in800℃.(4) In the test of low-stress impact abrasive wear, when the hardness is equivalent, the higher toughness, the wear resistance higher. Scanning the features of the worn surface by means of SEM, which shows that fatigue wear is main wear mechanism and cutting wear is secondary.