Vacuum Heat Treatment Process of Alloy Door Structural Steel

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Taking into account the characteristics of vacuum heating, the following points need to be paid attention to when performing vacuum heat treatment of alloy structural steel

(1) To prevent coarse grain size, the quenching temperature should be 5~10℃ lower than the lower limit of the specified temperature or lower.

(2) Prevent volatilization of elements. Backfill to N2 to below 13.3Pa.

(3) Quick cooling is required to eliminate temper brittleness.

Table 1 is the vacuum heat treatment process specification of commonly used alloy structural steel

Steel grade	Quenching			Temper			Mechanical properties (not less than)
	Tempera ture /℃	Vacuum /Pa	cool down	Tempera ture /℃	Vacuum /Pa	cool down	Rm/（N/ mm2）	Rp0.2（/N/ mm2）	A/%	Z/%	Ak/【(N.m) /cm2】
45Mn2	840	1.3	oil	550	5.3*104 ~7.3*104	oil Air cold N2Fast cooling	882.6	735.5	10	6	441.3
30SiMn2MoV	870	1.3	oil	650	1.3~0.13		882.6	784.5	12	9	490.3
16SiMn2WV	860	1.3	oil	200	Air furnace	Air cold	1176.7	882.6	10	8	441.3
20Mn2TiB	860	1.3	oil	200	Air furnace	Air cold	1127.7	931.6	10	7	441.3
30Mn2MoTiB	870	1.3	oil	200	Air furnace	Air cold	1471	–	9	5	392.2
40CrMn	840	1.3	oil	520	5.3*104 ~7.3*104	Fast cooling	980.6	833.5	9	6	441.3
25CrMnSiA	880	1.3	oil	450	5.3*104N2	Fast cooling	1078.7	882.6	10	5	392.2
30CrMnSiA	880	1.3	oil	520	10-1&5.3*104	Fast cooling	1078.7	882.6	10	5	441.3
50CrV	860	1.3~ 0.13	oil	500	Air furnace	Fast cooling	1074.8	1127.7	10	–	392.2
35CrMo	850	1.3~ 0.13	oil	550	Air furnace	Fast cooling	980.6	833.5	12	8	441.3
40CrMnMo	850	1.3	oil	600			980.6	784.5	10	8	441.3
20CrMnMo	850	1.3	oil	200	Air furnace	Air cold	1176.7	882.6	10	7	441.3
25Cr2MoV	1040	1.3~ 0.13	oil	700	0.13	Fast cooling	735.5	588.36	16	6	490.3
25Cr2MoV	900	1.3~ 0.13	oil	620	0.13	Fast cooling	931.6	784.5	14	8	539.3
38CrMoAl	940	1.3	oil	640	0.13	N2 Ar Forced cooling	980.6	833.5	14	9	490.3
20Cr3MoWV	1050	1.3	N2 oil	720	0.13		784.5	637.4	14	7	392.2
40Cr	850	1.3~ 0.13	oil	500	N25.3*104	Fast cooling	980.6	784.5	9	6	441.3
40CrNi	820	1.3~0. 13oil	oil	500	N25.3*104	Fast cooling	980.6	784.5	10	7	441.3
12CrNi3	860	1.3~ 0.13	N2oil	200	–	Air cold	931.6	686.4	11	9	490.3
37CrNi3	820	1.3~ 0.13	N2oil	500	0.13， 5.3*104	N2 Forced cooling	1127.7	980.6	10	6	490.3
40CrNiMo	850	1.3~ 0.13	oil	600		Fast cooling	980.6	833.5	12	10	539.3
30CrNi2MoV	860	1.3~ 0.13	oil	650		Fast cooling	882.6	784.5	12	9	490.3
45CrNiMoV	850	1.3~ 0.13	oil	460	N25.3*104	Fast cooling	1471	1323.8	7	4	343.2
18CrNi4W	950	1.3	oil	200	–	Air cold	1176.7	833.5	10	10	441.3
25CrNi4W	850	1.3~ 0.13	N2	550	N25.3*104	N2 Forced cooling	1078.7	931.6	11	9	441.3
30CrNi3	820	1.3~ 0.13	N2 oil	500	–	Fast cooling	980.6	784.5	9	8	441.3

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