The Influence Of Alloying Elements On The Microstructure And Properties Of 40mnbh Steel

In this paper, the use and the development of quenched and tempered alloy bearing steel were reviewed. Meanwhile, the factors that influence the hardenability of 40MnBH steel were also discussed. For BOF of Huai-steel, few residual elements are produced during it smelts the boron-contained steel and poor hardenability assurance capability compared to EF, the effects of alloy elements on hardenability and mechanical properties, and the heat-treatment process were studied systematically.In the aspects of the alloy elements effects on the properties, the effects of boron, titanium and chromium on the hardenability, impact toughness and tensile properties of the steel were studied. As a result, to stabilize the hardenability properties, the B_sol should be around 0.0020%. Titanium added can ensure the boron effect on the hardenability. For the steel 40MnBH, the best titanium content should be around 0.02%. If the titanium content excesses this value, excessive titanium will be combined to form the inclusions in the steel. Then, the hardenability and integrate mechanical properties will be lowered. The chromium content in the steel should be at a range of 0.10%～0.20%. Hence, the hardenability of the steel can meet the requirement. For the aspect of the boron effect on the impact toughness, the relation between the rule of boride appearance andα_k would be impaired. For the steel 40MnBH, which is contained excessive boron leading theα_k value to decrease, the value ofα_k, would increase through normalizing at a temperature of 930℃preliminary and the quenched and tempered process. So, the waster's retrieval can be realized. According to the results, the inner-controlled chemistry composition, which was fit for the BOF production in Huai-steel, was determined.In the aspect of heat-treatment process, the effect of austenitizing temperature on the hardenability and integrate mechanical properties, and the tempering temperature on integrate mechanical properties were studied. The appropriate heat-treatment process should be quenched at a temperature of 850℃, and tempered at a temperature of 500℃.