Process Research On Vacuum Hot Roll-Clad Stainless Steel/Pipeline Steel

With increasing the demand of energy,the corrosion of the pipelines become very significant.In fact,the corrosion resistance of the plain low alloy steel pipes is relatively low,but the alloy pipeline containing high ratio of Ni element with higher corrosion resistance has a very expensive cost.Therefore,it must be need to find a new pipeline with low cost and high corrosion resistance.In this case,the invention of corrosion-resistant alloy clad pipes will effectively solve this problem.This clad pipe consisted of the corrosion resistance alloy and low alloy high strength steel,thereby greatly reducing the cost of the pipelines.In this paper,we use the vacuum hot roll-cladding technology to manufacture stainless steel/pipeline steel clad plates,which exhibited excellent properties.This paper mainly studies the effects of surface treatment,controlled rolling and controlled cooling processes,and the addition of Fe and Ni foils on the microstructure and mechanical properties of the clad plate.Finally,establishing the production route of process for the stainless steel/pipeline steel clad plates.The following conclusions were made:(1)The surface polishing by steel wire brush cannot completely remove the interfacial oxidation layer.However,the acid washing or abrasive belt grinding can completely clean the oxidation layer.Therefore,the number of interfacial inclusions can be reduced,effectively improving the interface bonding strength.There are very few Al-Si-Mn oxide inclusions at the interface.(2)With the increase in the reduction ratio,the more effective combination was achieved at the interface,and the interfacial inclusions are refined by the severe deformation.The basal plate of X65 pipeline steel was composed of fine acicular ferrite and granular bainite via the TMCP technology,which will improve mechanical properties of the basal plate.(3)Reduction ratio and cooling process created a clear effect on the intergranular corrosion of the clad 316L stainless steel.With the increase in the reduction ratio,the intergranular corrosion of 316L stainless steel became more detrimental.The controlling cooling process resulted in improvement of the intergranular corrosion,because of the shorter sensitizing temperature duration for the 316L stainless steel.(4)After the addition of Fe interlayer,X65 pipeline steel and 316L stainless steel have achieved an excellent metallurgical bonding,but Fe interlayer cannot prevent the diffusion of alloy elements from 316L stainless steel to X65 pipeline steel.There are still intergranular corrosion in the 316L stainless steel,and the bonding strength of the interface decreased slightly.However,Ni interlayer did not only improves the interface bonding strength,and also prevent the diffusion of alloy elements from 316L to X65 and no obvious intergranular corrosion was observed at 316L stainless steel.(5)One's steel corporation in China has produced the 316L/X65 clad plates by vacuum hot roll-clad process.The interface bonding strength,mechanical properties of X65 basal plate and 316L clad plate,and intergranular corrosion resistance of 316L stainless steel reached the technical objectives,showing a reasonable hot roll-clad process for the stainless steel/pipeline steel.