Font Size: a A A

Study On Microstructure And Properties Of New High-chromium Stainless Steel Surfacing Alloys

Posted on:2019-02-11Degree:MasterType:Thesis
Country:ChinaCandidate:F G GuanFull Text:PDF
GTID:2371330572460401Subject:Engineering
Abstract/Summary:PDF Full Text Request
The guide roller is a key core component in the rolling guide device of the continuous casting machine.Its function is to clamp the rolled piece and accurately and stably introduce it into the roll hole type to ensure the normal rolling of the rolling piece.The guide roller is a kind of rotary body structure,and the outline is generally determined according to the applicable rolling stock.Generally,bearings are arranged at both ends of the guide roller,with a hole in the middle and a guide roller shaft installed in the hole.When the guide roller is driven by the impact or friction of the rolling stock,it will perform a flexible rotary motion around the roller shaft under the action of the bearing.The speed of rolling of modern rod and wire is generally high,and the impact force of the rolling stock on the guide roller is about 1000°C.The guiding roller always works in the environment of alternating hot-and-cold state.In doing so,the guide roller cracks,wears,breaks and other accidents frequently occur,causing the rolling stop production,which seriously lowers the rolling production efficiency.Because of more consumption of the guide rolls at high cost,it is important to increase the life of the guide rolls.In this paper,the continuous casting machine guide roller is used as the base material,and the 50Cr13 surfacing alloy material is deposited on the guide roller.The welding used is 320A,the welding voltage is 30V,and the wire feeding speed was kept at 3.6cm per minute,in order to meet the processing conditions,a total of 5layers were deposited on the surface of the guide roll.using metallographic microscope?OM?,scanning electron microscope?SEM?,energy dispersive instrument?EDS?,X-ray.Diffraction apparatus?XRD?,Vickers hardness tester,MMW-1 wear tester and other equipment,The microstructure,composition and the hardness of the surfacing alloy is analyzed,It is founded that the interface of the surfacing layer is well bonded,and the fusion line is clearly visible.There is no impurity,and there are certain diffusion phenomena such as Cr and C at the interface of the surfacing layer.Based on this,the welding process in the surfacing process is optimized,and with the composition of the 50Cr13 wire surfacing alloy is kept unchanged.0.92%Mo is added to increase,the content of Mn was increased from 0.97%to 1.22%,the content of Ni was increased from 0.4%to 1.66%,the content of C was reduced from 0.3%to 0.22%,and the content of Si was increased from 0.9%to 0.96%.Therefore,a new type of martensitic stainless steel welding alloy was developed.Through comparative analysis method,the microstructure and hardness of the two surfacing alloys were observed after tempering at different temperatures.As the tempering temperature increases,it can be seen from the overall change trend of microhardness:new Markov After the tempering at 200°C,the vaults of the microhardness increases,and the microhardness increases and reaches a peak of 600HV0.2,but it still maintains a good hardness at high temperature,reflecting to some extent.Its good high temperature wear resistance;while the 50Cr13 wire surfacing sample is tempered at 200°C,the microhardness first rises,and then the hardness decreases with the increase of tempering temperature,especially when the tempering temperature is 600°C and 800°C,the hardness drops sharply.When the tempering temperature is 1000°C,the 50Cr13 surfacing sample appears to be secondary hardened.According to X-ray diffraction,the surface layer of 50Cr13 wire surfacing alloy has secondary hardening phase FeNi.The hardness of the 50Cr13 wire surfacing alloy sample after the tempering at 1000°C is greatly increased.Both surfacing alloys have martensite+retained austenite+?Cr,Fe?7C3,while the new martensitic stainless steel surfacing alloy has more carbide precipitation than50Cr13 wire surfacing alloy,the precipitation of fine carbide precipitates can effectively improve the hardness of the surfacing alloy and make the surfacing alloy have good temper softening resistance,resulting in further increase in hardness.The new martensitic stainless steel surfacing alloy has more carbides,which results in the hardness of the surfacing layer being 20HV0.250HV0.2.2 higher than that of the 50Cr13wire surfacing alloy surfacing layer,and the hardness of the fusion zone is also significantly higher,the wear-resisting of the surfacing roller is better.The wear resistance of the new martensitic stainless steel surfacing alloy is higher than that of the 50Cr13 wire surfacing alloy.The results show that the wear mechanism of the two surfacing alloys is abrasive wear.the wear marks of the surfacing layer of the new martensitic stainless steel surfacing alloy are shallower and denser.Low,wear resistance is the best,and 50Cr13 wire surfacing alloy has deep scratches.The weight loss of the new martensitic stainless steel alloy steel ring is173.5mg,which is 73.4mg less than the former total weight loss?G,The wear resistance of the new martensitic stainless steel wire surfacing alloy increases by29.9%,resulting in higher wear resistance.
Keywords/Search Tags:Continuous casting machine guide roll, Surfacing welding, Flux cored wire, Wear resistance, Tempering
PDF Full Text Request
Related items