CN1079838C

CN1079838C - Technique for eliminating grinding crack

Info

Publication number: CN1079838C
Application number: CN98100663A
Authority: CN
Inventors: 张自国
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-03-03
Filing date: 1998-03-03
Publication date: 2002-02-27
Anticipated expiration: 2018-03-03
Also published as: CN1227875A

Abstract

The present invention discloses a new technology for eliminating grinding cracks. Before carburization alloy steel component parts which need to be ground are ground, a quenched martensite organization is eliminated or reduced by a simple heat treatment technology to improve the strength of the carburization alloy steel component parts and close microscopic cracks, and thus, the grinding cracks can be thoroughly eliminated.

Description

Prevent that carburized parts from producing the heat treating method of grinding crack

The present invention relates to metal heat treatmet, it is a kind of method of utilizing metal heat treatmet technology to eliminate grinding crack.

In process of production, often because after the ground finish, piece surface crackle occurs and causes part to be scrapped, the for example speed regulator in the aeronautical product, feathering pump, wind stick, master on the blower fan in the product for civilian use, passive gear and frock and mould, grinding crack often occurs, particularly appear at perviousness such as GCrl5 and 18Cr2Ni4WA, 12Cr2Ni4A, 18CrMnTi, 20CrMnTi, 20CrMnMo preferably on the carburizing alloy steel part easier generation grinding crack.

General theory is thought: the major cause that causes this grinding crack is a grinding condition, therefore improves on grinding process and tests, yet produce little effect.

Purpose of the present invention promptly is to solve above-mentioned part is easy to produce grinding crack in grinding process problem, and in experimental study for many years with on a kind of new theoretical basis, propose a kind of new technology of new elimination grinding crack, prevent that promptly carburized parts from producing the heat treating method of grinding crack.

The objective of the invention is to be achieved through the following technical solutions: for the carburizing alloy steel part that needs grinding, its treatment process is: (1) carburizing: identical with common process; (2) quench: go into stove and be warmed to 790 ℃～840 ℃, quenchant is no more than 50 ℃ for oil, oily temperature, big part in oil cooling time greater than 30 minutes; (3) tempering: go into stove and be warmed to 150 ℃～220 ℃, be no more than 2 hours after the quenching and promptly carry out tempering, soaking time in the stove 〉=3.5 hours, water-cooled 〉=5 minute of coming out of the stove then; (4) double tempering: go into stove and be warmed to 150 ℃～220 ℃, promptly carry out double tempering after the tempering, soaking time in the stove 〉=2.5 hours, water-cooled 〉=5 minute of coming out of the stove then; (5) three tempering: go into stove and be warmed to 150 ℃～220 ℃, promptly carry out three tempering behind the double tempering, soaking time in the stove 〉=2.5 hours, the air cooling of coming out of the stove then.With the carburizing alloy steel part that needs grinding by tempering and again tempering process make quenched martensite be transformed into tempered martensite, improve its intensity, thereby and also can make micro-flaw effectively be made up this vulnerable area of eliminating high-carbon alloy steel, effectively avoid the generation of grinding crack.

Through adopting improvement technology of the present invention to produce utmost point obvious effects, basically thoroughly eliminated grinding crack (see Table, table two) through practicing in a large number, the back of quenching in the table is an existing conventional technology through a tempered only, quench after once, double tempering and once, secondary, three tempered be improvement technology of the present invention.It is remarkable that this technology has effect, and technology is simple, technology maturation, the advantage that is easy to grasp, and general treatment facility gets final product, and just can use under the situation that need not increase any investment.

Table one

Numbering	Title	Material	Quench		A tempering		Double tempering		Three tempering	Crackle rate %	Remarks
			Quench		A tempering		Double tempering		Three tempering			℃	Medium	℃	h	℃	h	℃	h
			1	Shaft pinion	20CrMnTi	Ooze back direct quenching		160±10	3			℃	Medium	℃	h	℃	h	℃	h		100	Severe crack
2	Shaft pinion	20CrMnTi	1	Shaft pinion	20CrMnTi	Ooze back direct quenching		160±10	3	840±10	Oil	160±10	3	160±10	3			0			100	Severe crack
2	Shaft pinion	20CrMnTi	3	The 8M gear shaft	20CrMmTi	840±10	Oil	160±10	3.5	840±10	Oil	160±10	3	160±10	3			0			≥80
4	The 8M gear shaft	20CrMnTi	3	The 8M gear shaft	20CrMmTi	840±10	Oil	160±10	3.5	840±10	Oil	160±10	3.5	160±10	3.5	160±10	3. 5	0	Process stipulation carbide rank is ≯ 7 grades		≥80
4	The 8M gear shaft		5	The 8M gear	840±10	Oil	200	3.5		840±10	Oil	160±10	3.5	160±10	3.5	160±10	3. 5	0	Process stipulation carbide rank is ≯ 7 grades	≥80

6	The BM.9M gear	20CrMnTi	840±10	Oil	200	3.5	200	3.5			≤50
6			840±10	Oil	200	3.5	200	3.5			≤50		7	840±10	Oil	200	3.5	200	3.5	200	3. 5	0
8			4.7M, 6M blower fan gear shaft	20CrMnTi	Ooze back direct quenching		180	3.5					7	840±10	Oil	200	3.5	200	3.5	200	3. 5	0	100
8	9	840±10			Ooze back direct quenching		180	3.5					Oil	180	3.5					≥50			100
10	9	840±10			840±10	Oil	180	3.5	180	3.5	180	3. 5	Oil	180	3.5					≥50		0
10	11	The 6M gear			840±10	Oil	180	3.5	180	3.5	180	3. 5	20CrMmTi	840±10	Oil	180	3.5	180	3.5			0	＜5

Table two

Numbering	Title	Material	Quench		Deepfreeze		A tempering		Double tempering		Three tempering		Crackle rate %	Remarks
			Quench		Deepfreeze		A tempering		Double tempering		Three tempering				℃	Medium	℃	h	℃	h	℃	h	℃	h
			1	Bearing figure	GCr15	840±10	Oil			170±10	3				℃	Medium	℃	h	℃	h	℃	h	℃	h		≥50	Crackle about 30% after the assembling break-in
2	840±10	Oil	1			840±10	Oil			170±10	3		-75±5	1.5	170±10	4	The mill back increases by 120 ℃ of 2h of timeliness				＜1	Crackle about 0.5% after the assembling break-in				≥50	Crackle about 30% after the assembling break-in
2	840±10	Oil	3			Driving and driven gear	12Cr2Ni4A [carburizing]	790±10	Oil			160±10	-75±5	1.5	170±10	4	The mill back increases by 120 ℃ of 2h of timeliness				＜1	Crackle about 0.5% after the assembling break-in	3			≥50	Crackle about 30% after the assembling break-in
4	790±10	Oil	3	-75±5	1.5			790±10	Oil			160±10	160±10	3.3	120	2			＜1	Crackle about 0.5% after the assembling break-in			3			≥50	Crackle about 30% after the assembling break-in
4	790±10	Oil	5	-75±5	1.5			Driving and driven gear	18Cr2Ni4WA [carburizing]	840±10	Empty oil		160±10	3.3	120	2			＜1	Crackle about 0.5% after the assembling break-in		160±10	3			≥50	Crackle about 30% after the assembling break-in
6	840±10	Empty oil	5	-75±5	1.5	160±10	3.16			840±10	Empty oil		120	2			＜1	Crackle about 0.5% after the assembling break-in				160±10	3			≥50	Crackle about 30% after the assembling break-in
6	840±10	Empty oil	7	-75±5	1.5	160±10	3.16			Spherical slide block	GCr15	840±10	120	2			＜1	Crackle about 0.5% after the assembling break-in	Oil			160±10	3.5			50	Crackle appearred in 8 years in assembling back stock
8	Slurry cover nut	18Cr2Ni4WA [generation material]	7	840±10	Oil			160	4	Spherical slide block	GCr15	840±10					100	Crackle deeply＞0.3	Oil			160±10	3.5			50	Crackle appearred in 8 years in assembling back stock
8			9	840±10	Oil			160	4	840±10	Oil						100	Crackle deeply＞0.3		160	4	150	5		0
10			9	840±10	Oil			160	4	840±10	Oil		120	2	160	3	0			160	4	150	5		0
10			11	840±10	Oil			160	4	Gear	12Cr2Ni4A	790±10	120	2	160	3	0		Oil			160	4			79	Add up 19,15 crackles are arranged
12	790±10	Oil	11			160	4	150	2			790±10			0	Add up 20			Oil			160	4			79	Add up 19,15 crackles are arranged
12	790±10	Oil	13			160	4	150	2			Gear			0	Add up 20	18Cr2N14WA	840±10	Oil			160	4			100	Add up 10
14	840±10	Oil	13			160	4	150	3				0	Add up 15				840±10	Oil			160	4			100	Add up 10

Embodiment one: the gear shaft made from 20CrMnTi improved its heat Treatment of Carburized technology before grinding:

(1) carburizing: identical with common process

(2) quench: go into the stove 840 ℃ of quenchants of heating and be no more than 50 ℃, for oil, oily temperature

± 10 ℃ of big parts were greater than 30 minutes cooling time in oil;

(3) tempering: go into stove and heat and be no more than 2 hours after 180 ℃ of quenchings and promptly carry out tempering, in the stove

± 10 ℃ of soaking time 〉=3.5 hour, the water-cooled of coming out of the stove then cooling

(room temperature) 〉=5 minute;

(4) double tempering: go into stove and heat and to carry out double tempering after 180 ℃ of tempering, in the stove during insulation

Between ± 10 ℃ 〉=2.5 hours, the water-cooled of coming out of the stove then cooling (room temperature)

〉=5 minutes.

Embodiment two: with the gear shaft that 20CrMnTi makes, its 1～4 procedure is identical with embodiment one, increases five processes in addition again:

(5) three tempering: go into stove and heat and to carry out three tempering behind 180 ℃ of double temperings, protect in the stove

± 10 ℃ of warm time 〉=2.5 hour, the air cooling of coming out of the stove then.

Below be embodiment three and embodiment four,, two kinds of technologies listed in same form for improvement technology of the present invention and existing conventional technology are compared:

Embodiment three:

Part name: driving and driven gear material: 12CrNi4A[carburizing part]
				Common process	Quench: 790 ± 10 ℃, oil	Improve technology	Quench: 790 ± 10 ℃, oil
Tempering: 160 ± 10 ℃, 240 minutes, empty [notes]: more than be to use technology before 82 years	Deepfreeze :-75 ± 5 ℃, 90 minutes, sky				Quench: 790 ± 10 ℃, oil		Quench: 790 ± 10 ℃, oil
	Deepfreeze :-75 ± 5 ℃, 90 minutes, sky	Tempering: 160 ± 10 ℃, 240 minutes, sky
	Quench: 790 ± 10 ℃, oil	Tempering: 160 ± 10 ℃, 240 minutes, sky	Tempering: 150 ± 10 ℃ 〉=120 minutes
Deepfreeze :-75 ± 5 ℃, 90 minutes, sky	Quench: 790 ± 10 ℃, oil	Increase by 120～150 ℃, the timeliness operation of 2h after the grinding	Tempering: 150 ± 10 ℃ 〉=120 minutes
Deepfreeze :-75 ± 5 ℃, 90 minutes, sky	Tempering: 160 ± 10 ℃, 240 minutes, sky

Embodiment four:

Part name: bearing figure material: GCr15
Part name: bearing figure material: GCr15				Common process	Quench: 840 ± 10 ℃, oil	Improve technology	Quench: 840 ± 10 ℃, oil
Tempering: 170 ± 10 ℃, 240 minutes, empty [notes]: more than be to use technology before 82 years	Tempering: 150 ± 10 ℃, 120 minutes, sky				Quench: 840 ± 10 ℃, oil		Quench: 840 ± 10 ℃, oil
	Tempering: 150 ± 10 ℃, 120 minutes, sky	Deepfreeze :-75 ± 5 ℃, 90 minutes, sky
	Quench: 790 ± 10 ℃, oil	Deepfreeze :-75 ± 5 ℃, 90 minutes, sky	Tempering: 170 ± 10 ℃, 240 minutes, sky
Deepfreeze :-75 ± 5 ℃, 90 minutes skies	Quench: 790 ± 10 ℃, oil	Increase by 120～150 ℃, the timeliness operation of 2h after the grinding	Tempering: 170 ± 10 ℃, 240 minutes, sky
Deepfreeze :-75 ± 5 ℃, 90 minutes skies	Tempering: 170 ± 10 ℃, 240 minutes, sky

Claims

1. one kind prevents that carburized parts from producing the heat treating method of grinding crack, and for the carburizing alloy steel part that needs grinding, its carburizing, quenching technology are identical with common process:

(1) carburizing:

(2) quench: go into stove and be warmed to 790 ℃ of quenchants and be no more than 50 ℃, for oil, oily temperature

～840 ℃ of big parts in oil cooling time greater than 30 minutes; It is characterized in that: before carrying out ground finish, also will carry out following thermal treatment process:

(3) tempering: go into stove and be warmed to and be no more than 2 hours after 150 ℃ of quenchings and promptly carry out tempering, in the stove

～220 ℃ of soaking time 〉=3.5 hour, water-cooled 〉=5 of coming out of the stove then

Minute;

(4) double tempering: go into and promptly carry out double tempering after stove is warmed to tempering, soaking time in the stove

150 ℃～220 ℃ 〉=2.5 hours, water-cooled 〉=5 minute of coming out of the stove then;

2. the carburized parts that prevents according to claim 1 produces the heat treating method of grinding crack, and it is characterized in that: carry out three tempering after carrying out double tempering again, its concrete technology is as follows:

(5) three tempering: go into and promptly carry out three tempering after stove is warmed to double tempering, insulation in the stove

150 ℃～220 ℃ time 〉=2.5 hour, the air cooling of coming out of the stove then.

3. the carburized parts that prevents according to claim 1 produces the heat treating method of grinding crack, it is characterized in that: between tempering and double tempering technology, increase cold treatment process together, its concrete technology is as follows: cooling is 90 minutes under negative 75 ℃ ± 5 ℃ low temperature, air cooling.