The performance of alloy material of bucket tooth

The performance of alloy material of bucket tooth
The performance of alloy material of bucket tooth  is by the metallographic structure decision, and certain tissue depends on chemical ingredients and thermal treatment process, and chemical ingredients of the present invention is to confirm like this:
Carbon: improve with carbon content, the hardness of steel improves, and impact toughness descends.Carbon is one of of paramount importance element of solution strengthening, and simultaneously carbon dissolves in the matrix, with dislocation interaction is arranged and gathers partially and near dislocation line, form the Ke Shi air mass, has both increased σ i, make k again yIncrease, by Hall-Petch formula σ s=σ i+ k y -1/2(σ in the formula iBe the dislocation suffered friction resistance that in crystal, moves, k yBe the pinning coefficient), σ sTo raise, and cause the hardness of steel also to improve, toughness reduces.In addition, carbon content is low excessively, and fluidity molten steel is poor, cast and feeding difficulty, and molten steel is long tap to tap time, and energy consumption is high.Wear resistance and safe handling in order to ensure bucket tooth are controlled at 0.39-0.44% with the bucket tooth carbon content.
Chromium: chromium has solution strengthening, improve the hardening capacity of steel, increase effects such as the anti-tempering of steel is stable, with the increase of its content in steel, possibly form (Fe, Cr) 3C, (Fe, Cr) 73, (Fe, Cr) 236Etc. multiple carbide.Chromium solubleness in austenite is very big, strengthens austenite but does not reduce toughness.Chromium stops when tempering or delays separating out and assemble of carbide, makes it keep disperseing, and helps improving intensity and hardness, and stable performance.But the chromium too high levels is prone to carbide on the crystal boundary, reduces the toughness of steel.Take all factors into consideration, the chromium content of bucket tooth is controlled at 0.8-1.0%.
Manganese: manganese not only has stronger desulfurization and deoxidizing capacity, still improves the element of hardening capacity, can the refine pearlite tissue, improve the plastic brittle transition temperature of hardness and wear resistance, reduction steel, and under the condition that does not reduce plasticity, improve intensity.But the solution strengthening effect of manganese is little, often makes crystal grain thick and temper brittleness is arranged, and too high levels can reduce the toughness of cast steel, and the manganese content of taking all factors into consideration bucket tooth is controlled at 1.2-1.5%.
Silicon: silicon reduces the fusing point of steel, improves fluidity molten steel, and the massfraction of silicon increases at 0.45% o’clock by 0.25% in low-alloy cast steel; Because good desoxydatoin; Flowability improves significantly, and the massfraction of silicon improves hot cracking tendency in 0.40% scope the time.Silicon can also improve the yield tensile ratio of cast steel, plays solution strengthening and the effect that improves temper resistance simultaneously, and silicon also has good deoxidizing capacity, but toughness is had adverse influence.When silicone content is too high, be prone to form column crystal, increase hot cracking tendency.Therefore, the silicone content of cast steel bucket tooth is controlled at 0.6-0.8%.
Calcium: calcium and oxygen have very big avidity, and the deoxidizing capacity of calcium is very strong, and calcium has good degassing effect to molten steel.Calcium also has remarkable effect to inclusion in the cast steel rotten; Add an amount of calcium and can change the strip sulfide inclusion in the cast steel into globular CaS or (Ca; Mn) S is mingled with; An amount of calcium also significantly reduces sulphur in the gathering partially of crystal boundary, and calcium hot-cracking resistance when reducing cast steel fragility and improving the cast steel casting is very useful.To make that inclusion increases in the cast steel but add too much calcium, it is unfavorable that the cast steel flexible is improved, and suitable calcium contents is 0.02-0.05% in the bucket tooth.
Boron: boron adds in the steel as trace element, can significantly improve the hardening capacity of steel, adds 0.001%B and is equivalent to 0.85%Mn, 0.45%Cr in role aspect the raising hardening capacity; 0.35%Mo (Wen Fanyi, the improved route of ferrous materials high performance, industrial レ ァ メ タ Le, 1995; 110:8), boron can significantly improve mechanical property, particularly impelling strength simultaneously; Add-on is too much, and the fragility of steel is increased, and takes all factors into consideration its content is controlled at 0.0020-0.0045%.
Aluminium and titanium: containing B-abrasion resistant cast steel and have excellent mechanical property, but have the dispersed big deficiency of performance data, mainly is the absorption and the relatively poor instability that causes performance of distributional stability of boron, and this chemically reactive with boron is relevant.Boron chemical property in molten steel is extremely active, and is very big with the avidity of nitrogen, oxygen and carbon in the steel, is easy to generate nitride; Oxide compound and carbide containing boron become block and granular intracrystalline and the crystal boundary of being distributed in, and have reduced the content of solid solution boron; The effect that improves hardening capacity is weakened, and the carbide containing boron on the crystal boundary also reduces toughness, before adding boron, adds the deoxidation of the aluminium degree of depth; And the residual quantity of aluminium is controlled at 0.05-0.08%, can obviously improve the toughness that contains B-abrasion resistant cast steel.The aluminium add-on is too much, can reduce fluidity molten steel, and increases the contraction and the hot cracking tendency of cast steel.In addition, contain B-abrasion resistant cast steel before adding boron, add the content that titanium fixed nitrogen also can improve solid solution boron in the matrix, help improving the hardening capacity and the toughness that contain B-abrasion resistant cast steel.Titanium and nitrogen combine the tiny TiN particle of formation, also have the effect that promotes the solidified structure refinement, help improving the obdurability and the wear resistance of cast steel, and suitable titanium content is controlled at 0.03-0.06%.
Yttrium: the shape of inclusion in the wearable cast steel, particularly sulfide, size, distribution and quantity seriously influence the performance of steel, especially plasticity and toughness.Without the rotten low-alloy wear-resistant steel of handling of rare earth, mostly inclusion is long strip shape and has corner angle, and The amount of inclusions is more, and fracture mode is quasi-cleavage crack.Rare earth adds the effect that has desulfurization, degasification in the steel; Thermodynamic condition and application practice according to the re inclusion generation; The avidity of REE and oxygen and sulphur is significantly greater than manganese and aluminium etc., and REE easily and oxygen, sulphur generation conjugation reaction generates globular RE 22S, RE 23Deng re inclusion, improved the brittle rupture that low-alloy wear-resistant steel produces along crystal boundary significantly.Therefore, after the rotten processing of rare earth, The amount of inclusions obviously reduces, and inclusion is tending towards nodularization and is evenly distributed in the steel, and the toughness of steel is improved, and a large amount of dimples will occur on the impact fracture.But excessive rare earth adds affiliation causes re inclusion to be broken chain distribution, diminishes the plasticity and the toughness of steel on the contrary.
In addition, wish to get HS, high-toughness wear-resistant cast steel material, all hope to obtain the lath martensite tissue, its substructure is a dislocation type.And the factor that influences martensite substructure is very complicated, controlled by chemical ingredients, particularly increases the volume(tric)fraction of twin crystal martensite along with the increase of carbon content in the steel sharp, and causes the toughness decline of steel thus.Because of carbon content in the cast steel of the present invention up to 0.39-0.44%, be prone to brittle twin crystal martensite after the quenching.Add rare earth element yttrium and can promote the martensitic transformation of twin crystal martensite dispiration significantly, cause the low-alloy wear-resistant steel flexible to improve.
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