摘要
The effect of austempering of 0.45% carbon steel in hot bitumen on the hardness, impact strength, tensile properties and microstructure were investigated. The hardness values, impact strengths and tensile strengths of the austempered samples increased almost linearly from the austempering time of 1 hour to 3 hours after which they all dropped. At the austempering time of 3 hours the maximum values of hardness, impact strength and tensile strength of 496.2HV, 149J and 706.2 N/mm2respectively were attained. These values are 24.5%, 4.9% and 25.8% higher than the hardness values, impact strength and tensile strength respectively of the as-received steel. The high impact strength and tensile strength recorded despite the high hardness value was probably due to the formation of bainite structure and the diffusion of carbon from the bitumen into the steel samples.
The effect of austempering of 0.45% carbon steel in hot bitumen on the hardness, impact strength, tensile properties and microstructure were investigated. The hardness values, impact strengths and tensile strengths of the austempered samples increased almost linearly from the austempering time of 1 hour to 3 hours after which they all dropped. At the austempering time of 3 hours the maximum values of hardness, impact strength and tensile strength of 496.2HV, 149J and 706.2 N/mm2respectively were attained. These values are 24.5%, 4.9% and 25.8% higher than the hardness values, impact strength and tensile strength respectively of the as-received steel. The high impact strength and tensile strength recorded despite the high hardness value was probably due to the formation of bainite structure and the diffusion of carbon from the bitumen into the steel samples.
