Heat treatment organizes the influence that reachs hardness to 5Cr8MoVSi

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5Cr8NoVSi steel is the new steel with our country more in recent years application is planted, basically use on pattern of impact resistance industry and thin blade cutting tool. But, the research of heat treatment technology to 5Cr8MoVSi steel is at present less, produces industry pattern often produces hardness to be mixed not high rupture invalidation phenomenon. Accordingly, the article studied technology of 5Cr8MoVSi steel heat treatment is right in some detail hardness and the influence that organize a structure. 1, if experimental data and composition of data of experimental means test express 1 to show. Sample anneal, quench, temper all undertakes in crucible resistor furnace, quench use oily medium refrigeration. With diffraction of ray of D/max Ⅲ A X appearance analyses photograph structure and leftover austenite to measure, mensurable metallographic law measures integral of object of austenite grain number, carbonization number and dimension, martensite dimension, JXA-733 electron bougie analyses microstructure and composition. Express chemical composition of 5Cr8MoVSi of steel of 1 industry pattern / %CMnSiCrMoVSP 0.






45 ≤ 0.

02 ≤ 0.

032, experimental result and analysis 2.

1 anneal sample is HB218 via hardness of 840 ℃ anneal, anneal microstructure is bulbiform pearlite. The average size of carbide is 0.

94µm, bulk mark is about 0.

32. Carbide photograph with M23C6, give priority to, have M7C3 and MC next. 2.

2 quench quench experimental temperature is 880 ℃ , 900 ℃ , 930 ℃ , 950 ℃ , 1000 ℃ , 1050 ℃ . Along with quench temperature lifts, quench hardness lifts. When 1000 ℃ quench, hardness is HRC60; When 1050 ℃ quench, hardness is HRC60.

3. Quench the organization is martensite, odd carbide and leftover austenite. When 950 ℃ quench, martensite by acicular martensite and composition of martensite of attrib wattle shape, the proportion that is aimed at martensite is larger, odd carbide submits little grain form or drop record distributings; The martensite when 1000 ℃ quench still by acicular martensite and composition of martensite of attrib wattle shape, odd carbide shows bit of shape to distributing, leftover austenite is placed between martensite needle or batten; When 1050 ℃ quench, martensite is given priority to with martensite of attrib wattle shape, only a few acicular martensite (<10%) , leftover austenite estimates increase, odd carbide is few, size is smaller also. Metallographic analysis makes clear: Along with temperature form tall, austenite brilliant granuality greatens, martensite needle lengthens, odd carbonization quantity decreases, dimension decrescent, quench austenite quantity follows sample remains to quench temperature lifts and lift, when 1000 ℃ quench, leftover austenite is measured about 10% . Grain dimension follows austenite to quench temperature lifts and lift, quench attrib wattle or martensite is acicular dimension is as corresponding as brilliant size dimensions also. Express 5Cr8MoVSi of steel of 2 industry pattern to quench temperature is opposite the influence of austenite brilliant granuality, leftover austenite, martensite and odd carbide quenchs temperature / ℃ austenite grain is spent / austenite measures µm remains / % quench size of shape of carbide of martensite the rest / µm bulk.

3- is acicular + a few attrib wattle shape 60.





0 9509.




9 100011.


74 attrib wattle shape + acicular 110.




28 attrib wattle shape + a few acicular 240.


3 photographs analysis makes clear, quench sample is main photograph with A martensite, it is leftover austenite G next ' , odd carbide is M7C3, MC, have the M23C6 of minim. After with anneal carbide photograph analysis contrasts knowable, when 1000 ℃ quench, m23C6 dissolves for the most part, and so a few because M7C3 and MC carbide is hard to dissolve, become main and odd carbide. 2.

When temperature of 3 temper temper is less than 380 ℃ , lift along with temper temperature, temper hardness is reduced. In this interval, basically be martensite decomposes a process, martensite contains carbolic quantity to reduce, the square of martensite crystal structure is spent (C/a) drops. In 480-500 ℃ temper, have 2 apparent sclerotic appearances. 485 ℃ temper is highest hardness is HRC58, than quenching hardness low 2HRC is controlled. 2 sclerosis basically is the effect of MC(VC) precipitation sclerosis. Lift along with temper temperature, the quantity reduces leftover austenite. Decompose through temper remains austenite only less, through 3 temper remains austenite quantity can be reduced 6% the left and right sides. 3, content of carbon of 5Cr8MoVSi of steel of discussion industry pattern is 0.

55% , quench martensite configuration is mixed for attrib wattle shape acicular. When quenching below inferior temperature, odd carbide is measured more, in the austenite area that nears carbide, because carbide is deliquescent of the carbon in the process diffuse show gradient to distributing, accordingly, have local tall carbon area. Local tall carbon area becomes in cooling process change trains acicular martensite, its substructure is twin brilliant. Quench below higher temperature, odd carbonization owner if a few VC and M7C3, deliquescent rate is very slow, accordingly content of carbon of major austenite area is changed equably, although austenite is right now average carbolic content is high, but to tall carbon austenite, its content is low still. Quench in higher temperature so when, scale of attrib wattle martensite increases. Attrib wattle martensite is compared acicular martensite tenacity is tall, accordingly, this steel can quench below higher temperature. But batten is when 300-400 ℃ temper, because the carbide edge batten of separate out distributings, can show temper brittleness. So, quench below higher temperature, when obtaining the microstructure that gives priority to with martensite of attrib wattle shape, should keep away from temper brittleness area, or with higher temperature temper (450-520 ℃ ) , perhaps be in inferior temperature temper (150-250 ℃ ) . If need inferior temper hardness, should raise temper temperature (520 ℃ above) just can keep away from temper brittleness area. Right now nevertheless need controls temper system strictly, otherwise, temper hardness can change along with temper temperature produce very big change. Additional, to leftover austenite the quantity asks to reduce be versed in to the smallest Bao Ren mould, temper or 3 temper should have 2 times after quenching. 4, anneal of ℃ of 5Cr8MoVSi840 of steel of conclusion industry pattern, hardness is HB218, average size is carbide grain 0.

94µm, carbide bulk mark is 0.

32, carbide type is given priority to with M23C6, have a few MC and M7C3. 5Cr8MoVSi of industry pattern steel quenchs temperature is 980-1050 ℃ suitably, highest hardness is HRC60-61. Along with quench temperature lifts, quench martensite is mixed by attrib wattle shape acicular martensite organization transfers to be given priority to with martensite of attrib wattle shape. Odd carbide is with MC and M7C3, m23C6 carbide dissolves for the most part when quench. 5Cr8MoVSi of industry pattern steel passes temper only, the quantity reduces leftover austenite not quite, accordingly, should undertake 2 times or 3 temper. In 480-510 ℃ temper, have sclerotic appearance 2 times, temper hardness can rise HRC58-60. CNC Milling