Study On The Water-air Spray Quenching Process Performance Of High Strength Boron Steel22MnB5

Heat treatment has a great influence on the performance of the steel. As the best heattreatment process of improving steels’ performance, quenching process plays an importantrole in the final performance and quality of the materials. So it has been research focus. As akind of new quenching medium, water-air spray has many advantages. Its cooling range isvery wide and between forced air quenching and water quenching, which not only ensures itscooling rate greater than critical quenching cooling rate, but also is not too severe, and solvethe contradiction between mechanical properties and quenching distortion. Water-air spray iscomposed of water and air, so its energy consumption is very low and has no pollution. Inaddition, water-air spray zone is planar and uniform. The boron steel22MnB5is a kind ofrelatively common used low-carbon steel. Its chemical composition is simple, but quenchingperformance is very good, so worthy of further promoting. Therefore, it has importantsignificance about researching water-air spray quenching22MnB5.This paper is about water-air spray quenching boron steel22MnB5. First, basicperformance of water-air spray quenching boron steel22MnB5was studied. The resultsshowed that the hardness of boron steel22MnB5after quenching had greatly improved, andits microstructure was lath martensite. The hardenability of water-air spray quenching boronsteel22MnB5was good, and its hardenability curve had obvious three phases. Analysis ofcomparing it to other quenching media showed that cooling capacity of water-air spray wasbetter than air and forced air. Although cooling capacity of water-air spray was worse thanwater, the performance of them had little difference, and the steel’s deformation of water-airspray quenching was very small. So the steel after water-air spray quenching had relativelybetter overall performance. On this basis, heat treatment process parameters of water-air sprayquenching boron steel22MnB5were optimized. Orthogonal experiment showed that whenthe heating temperature was900℃, holding time was5min and began quenching temperaturewas700℃, the steel hardness reached maximum539.7HV. Response surface experimentsshowed that after water-air spray quenching, the highest predictive value of steels’ hardnesswas532.02HV, and now the heating temperature was896.10℃, holding time was6.55min,and began quenching temperature was720.91℃. Finally, the affected law of water-air sprayheight and water-air spray jet angle on boron steel22MnB5mechanical properties distribution was researched. Experiment results showed that with the increase of height of the water-airspray, effective hardening zone area S of steels was basically unchanged firstly, then began todecline. After reaching the minimum value, S began to increase. After reaching maximumvalue, S began to decrease again until had no effective hardening zone. When the water-airspray jet angle changed, with the jet angle increases, size inhomogeneity of hardnessdistribution increased first, then began to decrease after reaching the maximum. Thenonuniformity of hardness distribution increased all the time as the jet angle increased. Inaddition, with the increase of jet angle, the effective hardening zone area increased first, thenbegan to decline when it reached maximum.