Understanding Critical Point, Quenching Temperature & Ms Point in Steel

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Critical point of common steel

GradeCritical point
/ ℃
Ac1Ac3 or AccmAr1Ar3
10725870682850
10Mn2A720830620714
12CrNi3A695800659726
100CrNi3A680–––
12Cr2Ni4A670780575660
100Cr2Ni4A670–––
15725870685850
15Mn735863685840
15SiMn2MoVA722848491–
15Cr735870720–
15CrMnA750848––
15CrMnMoVA765870––
18Mn2CrMoB741854––
18Cr2Ni4WA655~695–––
20735855680835
20Mn735854682835
20Mn2690820(610)(760)
20Mn2B730835613730
20MnVB720840635770
20MnTiB（720）843625795
20MnMoB738850693750
20Cr766838702799  
20CrV768840704782
20CrMnB–890622749
20CrNi735805660790
20CrNi3A710790––
20Cr2Ni4A705770575660
22CrMnMo710830620740
30732813677796
30Mn2718804627727
30Mn734812675796
30SiMnMoV740845––
30Si2Mn2MoWV739798––
30CrMnSi760830670705
30CrMo757807693763
30CrMnTi765790500740
30CrMnSiNi2A750~760805~830––
30CrNi3705750––
35SiMn750830645–
35CrMoV755835600–
35CrMo755800695750
35CrMnSi760830670705
38Cr740780693730
38CrMoAl800840730–
37CrNi3710770640–
38CrSi763810680755
40724790680760
40Mn726790689768
40Mn2713766627704
40MnB730780650700
40MnVB730774639681
40Cr743782693730
40CrV755790700745
40CrMnMo735780680–
40CrSi755850––
40CrMnSiMoV780830––
40CrMnSiMoVRe725850625715
40Cr 5M02VSi853915720830
40SiMnMoVRe765900625730
40CrNi731769660702
40CrNiMo710790––
40CrMo730780––
45724780682751
45Mn2715770640720
45Mn2V725770––
45Cr721771660693
50720765690720
50Mn720760660–
50Mn2710760596680
50Cr721771660692
50CrV752788688746
50CrMn750775––
55727774690755
55Si2Mn775840––
55Si2MnB764794––
55Si2MnVB765803––
60727766690743
60Mn727765689741
60Si2Mn755810700770
65727752696730
65Mn726765689741
70730743693727
85723737–695
T7730770700–
T8730–700–
T10730800700–
T11730810700–
T12730820700–
SiMn760865708–
9SiCr770870730–
CrWMn750940710–
3Cr2W8V8201100790–
3Cr2W88101100––
W18Cr4V8201330760–
W9Cr4V2810–760–
3Cr 3Mo 3VNb836~948–771~923–
Cr12V810–760–
 Cr12MoV815–––
Cr 12Mo8101200760–
5C rMnMo710760650–
5CrNiMo710770680–
GCr15745900700–
GCr15SiMn770872708–
1Cr13730850700820
2Cr13820950780–
3Cr13780~850–––
4Cr13790~850–––
Cr17Ni2810–710–
9Cr18830–810–
4Cr9Si2900970810870
4Cr10Si2Mo850950700845
 Mn13––––

Quenching heating temperature and Ms point of common steel

GradeQuenching heating temperature
(℃)		Ms
/℃
10900~920(water)or no heat treatment450
10Mn2A850~857(water)–
12CrNi3A860（oil）780~810（oil）（420）
100CrNi3A860（oil）780~810（oil）150
12Cr2Ni4A860（oil）780（oil）400
100Cr2Ni4A880（oil）780（oil）125
15890~920(water)450
15Mn850~900(water)410
15SiMn2MoVA880（oil）275
15Cr 860（oil）  780~810（oil）–
15CrMnA840~870(oil)810~840(oil)400
15CrMnMoVA965~985(air or oil)372
18Mn2CrMoB920(air or oil)320
18Cr2Ni4WA950(air)860~870(oil)310
100Cr2Ni4WA–75
20900~950(water)425
20Mn850~900(water)（420）
20Mn2860~880(water)880~910(oil)370
20Mn2B860~880(oil)–
20MnVB860~880(oil)230
20MnTiB 860~890(oil)–
20MnMoB850~890 (oil)–
20Cr860~880(oil)（390）
20CrV 870~900(oil)–
20CrMnB860~880(water or oil)–
20CrNi840~880(water or oil)（410）
20CrNi3A820~-840(oil)（340）
20Cr2Ni4A（330）
22CrMnMo830~850(oil)–
30850~890(water or oil)380
30Mn2820~840(water)830~850(oil)340
30Mn850~900(oil)355
30SiMnMoV850~890(oil)
30Si2Mn2MoWV950(oil)310
30CrMnSi870~890(oil)320
30CrMo850~880(water or oil)345
30CrMnTi870~890(oil)–
30CrMnSiNi2A890~900(oil)314
30CrNi3830(oil)305
35SiMn880~900(oil)（330）
35CrMoV900~920(water or oil)–
35CrMo820~840(water)830~850(oil)271
35CrMnSi850~870(oil)–
38Cr860(oil)250
38CrMoAl930~950(oil)（370）
37CrNi3820(oil)（280）
38CrSi900~920(water or oil)（330）
40830~880(water or oil)（340）
40Mn820~860(water or oil)–
40Mn2810~850(oil)（340）
40MnB820~860(oil)–
40MnVB830~870(oil)–
40Cr830~860(oil)（355）
40CrV880(oil)218
40CrMnMo840~860(oil)–
40CrSi900~920(water or oil)（320）
40CrMnSiMoV920 (oil)290
40CrMnSiMoVRe930 (oil)270
40Cr 5M02VSi1000(air)325
40SiMnMoVRe930 (oil)300~305
40CrNi820~840271
40CrNiMo850(oil)320
40CrMo820~840(water)360
45780~860(water or oil)（345）
45Mn2810~840(oil)320
45Mn2V840-860 (water)310
45Cr820 ~ -840 (oil)（355）
50820~850 (water or oil)（320）
50Mn780 ~ 840  (water or oil)320
50Mn2810-840 (oil)325
50Cr820 (oil)250
50CrV860 (oil)（270）
50CrMn840~860 (oil)（250）
55790~830(water)820~850 (oil)（290）
55Si2Mn850~880(water or oil)（280）
55Si2MnB870(oil)–
55Si2MnVB880(oil)–
60780~830(water or oil)270
60Mn790~820(oil or 160℃nitrate)270
60Si2Mn840~860(water or oil)305
65780~830(water or oil)270
65Mn790-820(oil or 160℃nitrate)270
70780~830(water or oil)230
85780~820(water or oil)220
T7800~820(water)250~300
T8780~820(water)225~250
T10770~790(water)175~210
T11770~790(water)200
T12770~790(water)–
SiMn780~840(water, oil or nitrate)(250)
9SiCr860~870(oil)(170)
CrWMn800~830(oil)(250)
3Cr2W8V1050~1100(oil)(340)
3Cr2W81075~1130(oil)330
W18Cr4V1280~1300(oil)(220)
W9Cr4V21225~1240(oil)(200)
3Cr 3Mo 3VNb1060~1090(oil)385
Cr12V1040~1080(oil)180
 Cr12MoV1040~10501120~1130(air or)(<185)
Cr 12Mo950~1000(oil)(225)
5C rMnMo820~850(oil)(220)
5CrNiMo830~860(oil)(220)
GCr15820~850(oil)(240)
GCr15SiMn820~840(oil)–
1Cr13980~1050(oil)(350)
2Cr13980~1050(oil)320
3Cr13980~1050(oil)(240)
4Cr13980~1050(oil)145~270
Cr17Ni2950~970(oil)357
9Cr181050~1075(oil)–
4Cr9Si21000~1050(oil)–
4Cr10Si2Mo1010~1050(oil or air)–
 Mn131050(oil or water)200

Note: the data in brackets in the table need further study because:

1. Different data provide different data for the same steel type, but only one is selected in this table:

2. The data of the same steel type is gathered from different data.

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