12Cr10Mo1Co3钢低温粉末包埋渗铝工艺研究OA

To enhance high-temperature steam oxidation resistance of steam pipelines,an aluminized layer was fabricated on 12Cr10Mo1Co3 steel using a low-temperature solid powder pack cementation.The phase composition,morphology,thickness and hardness of the aluminized layer were analyzed by XRD,SEM,EDS and microhardness testing,and then the effects of aluminizing parameters on layer structure and kinetics were investigated.The results showed that when the particle size of the infiltration agent was 200 mesh,the aluminized layer formed a brittle Fe2Al₅ phase(hardness>800HV0.01),which was prone to cracking due to the mismatch of thermal expansion coefficients between the infiltration layer and the substrate.When the particle size of the infiltration agent was 250 or 300 mesh,the aluminum alloy layer formed a more ductile FeAl phase,which was dense and defect-free.The aluminizing treatment significantly increased the surface hardness of the substrate(≈ 430HV0.01).In the temperature range of 650～730℃,the increase in temperature led to a larger difference in the interdiffusion rate of Al/Fe,resulting in an increase in the porosity of the infiltration layer and an increase in surface roughness.The growth of the infiltration layer followed a parabolic pattern.With the extension of the holding time,the growth rate decreased due to the decrease in the Al concentration gradient.The increase in the weight per unit area of the sample was linearly related to the thickness of the infiltration layer,and the calculation results were consistent with the experimental data.At an infiltration temperature of 690℃,with a particle size of 250 mesh and a holding time of 8 hours,a crack-free FeAl aluminized layer with a thickness of approximately 12.7 µm could be obtained.