synonymWhite steel(Common name of high-speed steel) generally refers to high-speed steel
High speed steel (HSS) is a kind of steel with high hardness andAbrasion resistanceAnd highHeat resistanceOfchisel tool steel, also known as high speed tool steel orSharp steel, commonly known as white steel.High speed steel is FW. It was created by Taylor and M. White in 1898.
High speed steelProcess performanceGood, good combination of strength and toughness, so it is mainly used to make complex thin blades and impact resistant metalsCutting tool, can also manufacture high-temperature bearings andCold extrusion dieEtc.In addition to the high speed steel produced by smelting, it has appeared again since the 1960sPowder metallurgy high speed steelIt has the advantage of avoiding the problems caused by smelting productioncarbidesegregationCaused byMechanical propertiesReduction and heat treatment deformation.
Chinese name
high speed steel
Foreign name
High Speed Steels
Features
highhardnessHigh wear resistance and heat resistance
In 1898, Taylor F.W., an American mechanical and management engineer, andMetallurgyWhite M. developed and invented high-speed steel, and made systematic cutting experiments.At that time, they determined that the composition of high-speed steel was C-0.67% and W-18.91%,Cr-5.47%, Mn-0.11%, V-0.29%, F-margin, and laterW18Cr4VThe ingredients are very close.High speed steel cutterSteel can be cut at a speed of 30m/min, which is more efficient than that used in the pastCarbon tool steelandAlloy tool steelIt was several times higher than that of the United States at that timeMachinery industryProduction has won a hugeeconomic performance。
Since the middle of the 20th century, science and technology have developed rapidlyDifficult to machine materialsThe performance of general high-speed steel is no longer used, so high-performance high-speed steel andPowder metallurgy high speed steelThe performance of high-speed steel tool material has been greatly improved due to its successive appearance.
Manufacturing process
Announce
edit
High speed steelheat treatmentThe process is complex and must go through a series of processes such as quenching and tempering.When quenching, due to itsThermal conductivityThe difference is generally carried out in two stages.First preheat at 800~850 ℃ (to avoid causing large thermal stress), then rapidly heat it to the quenching temperature of 1190~1290 ℃ (the temperature varies with the actual use of different brands), and then oil cooling orAir coolingOr gas filled cooling.The factory adopts salt furnace for heatingVacuum furnaceIt is also widely used.After quenching, part of the internal structure remains (about 30%)retained austenite Not transformed intoMartensite, which affects the properties of high-speed steel.In order to transform the residual austenite and further improve the hardness and wear resistance, it is generally necessary to carry out 2~3 times of tempering at 560 ℃ for 1 hour each time.
ManufacturingMethod: Usuallyelectric furnaceIn production, the powder metallurgy method was used to produce high speed steel, so that the carbide was evenly distributed on the matrix as extremely small particles, which improved the service life.
Application: It is used to manufacture various cutting tools.asTurning tool, drill bitHob、Machine saw bladeAnd molds with high requirements.
Specification and composition
Announce
edit
Specification and appearance
Specifications mainly includeRound steelandsquare steel、board。The surface of steel shall be well processed, and there shall be no visible cracks, folds, scarsHairline。Cold drawingThe steel surface shall be clean, smooth, free of inclusions andOxide scaleEtc.
Chinese National Standard (the first line, the second line) and Japanese Industrial Standard
Main types
Announce
edit
High speed steel is a kind of complex steel, and its carbon content is generally between 0.70 and 1.65%.It contains more alloying elements, with the total amount up to 10-25%.
③ High molybdenum high-speed steel (containing 0~2% tungsten and 5~10% molybdenum);
④ Vanadium high-speed steel can be divided into general vanadium content (1~2% vanadium content) and high vanadium content (2.5~5% vanadium content) high-speed steel according to different vanadium content;
② Special purpose high speed steel: including cobalt high speed steel and superhard high speed steel (hardness HRC68~70), mainly used to manufacture hard to cut metals (such asSuperalloy、titanium alloyandHigh strength steelThe commonly used steel grades areW12Cr4V5Co5、W2Mo9Cr4VCo8Etc.
Features: high strength, good thermoplasticity, heat resistanceGrindabilitySlightly inferior to W18Cr4V, it can be grinded with ordinary jade grinding wheel.
Main purpose: suitable for productionThermoformingTools and tools that bear impact and have weak structure.
Steel grade: W14Cr4VMnRE
Hardness HRC: 64-66
Bending strength/GPa: about 4.0
Impact toughness/(MJm²）: about 0.31
Hardness at 600 ℃ HRC: 50.5
Main purpose:Cutting propertyIt is equivalent to W18Cr4V and suitable for making hot rolling tools.
main performance
Announce
edit
also calledWind steelorSharp steel, also known as white steel.intendquenchIt can harden even when cooled in air and is very sharp.It is a complexAlloy steel, containing tungsten, molybdenum, chromium, vanadium, cobalt, etcCarbide forming element。alloying elementThe total amount is about 10-25%.It's inhigh speed cuttingproduceHigh feverIt can still maintain high hardness under the condition (about 500 ℃),HRCIt can be above 60.This is the main characteristic of high-speed steel——Redness。andCarbon tool steelQuenched andLow temperature temperingLater, although the hardness is very high at room temperature, when the temperature is higher than 200 ℃, the hardness drops sharply, and at 500 ℃, the hardness has dropped toAnnealed stateTo a similar extent, the ability to cut metal is completely lost, which limits the use of carbon tool steel for cutting tools.High speed steel can be used to manufacture cutting tools because of its good red hardness, which makes up for the fatal shortcomings of carbon tool steel.
High speed steel is generally not madetensile strengthInspection, mainly metallographic and hardness inspection.
1. High speed steel shall not have obviousdecarbonization 。The microstructure shall be free of fishbone like eutectic ledeburite.
2. The nonuniformity of carbide in high-speed steel has the greatest impact on the quality. Metallurgical and mechanical departments attach great importance to the level of carbide nonuniformity.According to different uses of steel, different grade requirements can be put forward for carbide unevennessNext shouldLess than level 3.
3. Cutting tools are made of high-speed steel, except that they have high hardness andAbrasion resistanceIn addition to sufficient toughness, there is also an important factor that is red hardness.(Red hardness means that when the tool is in high-speed cuttingRed feverThe ability to resist softening under the condition of.)
A measureRednessThe method is to heat the steel to 580 ～ 650 ℃, hold it for 1 hour, then cool it, repeat this for 4 times, and then measure itshardnessValue.High speed steelquenching temperature Generally close to the melting point of steel, such asTungsten high-speed steel1210~1240 ℃, 1180~1210 ℃ for high molybdenum high-speed steel.Tempering at 540~560 ℃ for three times is generally required after quenching.Increasing quenching temperature can increase the red hardness of steel.To improveHigh speed steel cutterIts surface can be strengthened, such as low temperature cyanidation, nitridationSulfo nitrocarburizingEtc.
Inspection of high-speed steelcarbideThe nonuniformity is related to the corrosion time of the sample.In relevant standards, it is often ignored that corrosion should be appropriate and not excessive.Practice has proved that if there is excessive corrosion, the carbide will be blackened, showing the false appearance of improving the degree of unevenness, and it is possible to misjudge the low-quality high-speed steel asHigh quality steelThis is particularly important.
