JPS586925A - Production of forged steel product - Google Patents

Abstract

PURPOSE:To produce superior forged steel products with conserved energy by heating steel to temps. just above its Ac3 point then subjecting this steel to cooling to the temp. in the gamma recrystallization region and forging followed by cooling to the temp. in the non-recrystallization region and forging further cooling to temps. in the two phase region and forging then cooling. CONSTITUTION:The initial gamma grains obtained by heating steel to temps. just above its Ac3 point and sizing the grains thereof are cooled to the temp. in the gamma recrystallization region and are forged, whereby the grains are fined. These are cooled to the temp. in the non-recrystallization region and are forged to introduce deformation zones in the respective crystal grains so that ferrite (alpha) is dispersed and deposited with the deformation zones as nuclei. The grains are cooled to the temp. in the two phase region and are forged to apply working to the dispersed and deposited fine grains alpha so that the grain fining is more accelerated by the recrystallization of the alpha, or the formation of subgrains, the restoration of the low structure, etc. Finally, these are air cooled or cooled with spray water, after which they are allowed to cool by air, whereby the remaining relatively large gamma grains are transformed to fine pearlite, bainite or martensite.

Description

[Detailed description of the invention] The present invention relates to the om:st process for steel forgings.

Conventionally, the forged steel product Kl1 is formed (conventionally by press die forging), and the fins are heated again and quenched and tempered.

After hot forming, it is quenched at a temperature of 100°C and then tempered. Quenching and tempering are performed to improve the O strength and Il properties of the formed crystal, but in the ζO method, the heating process, hot forming,
Hardening and tempering are required for 2 to 30 minutes, and energy consumption is high.
Improving quality by applying granulation to the production of forged steel products, Engineering 11
This is to promote the rationalization of O-sha.

In other words, 1) the present invention is a weight-forming press (Auste tie) (
r) Recrystallization zone processing (However, in order to lower the deformation resistance, processing is normally carried out at a sufficiently high temperature of 11＠・℃ or higher, but for steel materials with coarse grains and medium diameter, the hot forming temperature may be slightly lowered. In some cases, O processing is added by suppressing the growth rate of O crystal grains after lowering and recrystallization, non-recrystallization region processing, r+7 etsy) (#) Features include two-phase region processing and accelerated cooling. It is also O.

That is, in the present invention, the steel is heated just above the fAoH point.

Next, cool to Kr recrystallization range temperature and forge, then cool to non-recrystallization range temperature and forge, cool to IK22 phase temperature and forge, and finally cool with air or t Forged steel product O1 characterized by cooling with water or spray water and cooling with air before and after.
This invention relates to a manufacturing method.

tksIP, in the above method, Canada Nibres O manuscript (,
A hot forming press equipped with a rolling machine and a control device such that setting (rolling speed, etc.), midway stop and restart can be performed in accordance with the forging material O cooling speed f (elapsed time after heating) K. It is also possible to adopt the M Shimo Liu Go Press (tentative name). ζO control process is hot working OIIS, press O deceleration, reduction blade gradual increase, stop position, restart time.

It is necessary to have the ability to operate the micro press (O instructions) via a pressure control system consisting of a p-pressure press, a control valve, the rotation of a boost pump, etc.

Next, the present invention will be specifically explained.

FIG. 1 shows the process related to the O processing heat treatment W& of the present invention, and shows the process for 116 mmtX4? mWX4? mj (44k)
Dimensions oasso carbon steel pieces 2Smt x 14? m
WX14? mj () When heat treatment is applied to forged steel material v
It is y4.

In the figure, heating of a steel billet directly above one point at one company (900
~? 50℃), 2 is r recrystallization zone press (840℃ or higher)
&[Non-recrystallization region press (740℃ or higher), 4 is two-phase region press (7!O~6・0℃), 5 is accelerated cooling to around 350℃ (with spray water) 20-31℃ 7 2), 6 is air cooling treatment (slow cooling), and 7#i is air cooling after pressing, which is applied to pigeonhole O steel, where the required strength and II properties can be obtained by grain refining even without rapid cooling.

In the ζO method, the grain size is regulated by heating just above the 101 point (1) to obtain good initial r grains, r recrystallized grains! The grains are refined by recrystallization. Subsequently, deformation bands O are introduced into each O crystal grain using a non-recrystallization zone press 5, so that ferrite Cl) is dispersed and precipitated using the deformation bands as nuclei.

Next, the fine grains that are precipitated in two dispersed form are processed using a two-phase press 4, and further processed by recrystallization, formation of linear nap grains, and recovery of the underlying structure (dislocation cell structure seen under an electron microscope). Promotes fine grain and refinement.

Relatively large austenite (y) left in 4
For grains, cool 5. or fine pearlite (by 7)
yp), bainite (B) '''Naruha!
Ruthenai) (M) K metamorphoses.

Finally, generation of transformation stress O is suppressed by slow cooling to 60°C. To ensure the required strength and toughness, a final temperature of 40°C or a starting temperature of 1°C or 70°C can be obtained in advance to obtain some test data for the trial forged product. The line is displayed by selecting it.

Figure 2 shows normal quenching and tempering fs temperature a2sc
) This is the well-known Omitter tissue seen in the case of tjllL round)
, the hardness is Ivffiffili-21-, FIG. ! ,! 1.4 (press near 720°C),
In pigeonhole Ot black tissue, subjected to processing heat treatment by controlled press according to S, 4.

at) Dispersion and particle refining are effectively performed.

#+l+P〇 Three-phase mixed color fine grain structure.

The hardness is 1iHv271~2.0.

Figure 4 shows le z, s, 4 (48@1: nearby press)
, 7, a mold aIIi texture generated from processed CO recrystallization and residual r grains is observed in the oi black structure. .

Although it is pressed in a low temperature range, it has a complete recovery structure. The hardness is ilv 211-2, using a control brace.
The effect of the heat treatment process is shown below.

As mentioned above, the conventional method (after hot processing) is performed using the one-piece method.

A forged steel product that is in no way inferior to the conventional method can be obtained by heating and cooling process S at 1 fiO without going through the repeated heating process S required for quenching and tempering.

[Brief explanation of drawings]

FIG. 1 shows the forging of the present invention. Warm III% Pressure. There are many graphs showing the time course of steel thickness, etc. No.! Figures 4 to 4 are micrographs showing the steel Di microstructure obtained by the conventional method and Hon-Yaaki O forging. Sub-agent 1) Clearance agent Ryo Hagiwara - 1 Figure 7-7--~920 (9CM) -95011) ・ Direction, 40% 7th reduction Q40.51-2.0 m
m/sec: 2 °'°・701 (t゛cx□)8
0 Lower speed &0.29 0.51 mm/sec/
740.42+ +Fish 7, Rumor K) 3゛・720 \ Pressure) uLoj3-0.29mm/sec,
u , , /'+ 680'251x149"X
I49ffiL7゛゛11440 "Par: 1"\9, q: Explosion, 1\, Bi: 1'''S +,,,X\Sl'
＼ 2nd figure source 3 figure 4

Claims (1)

[Claims] After heating the steel to just above the temperature point, it is cooled to the recrystallization temperature fK and forged, then cooled to the non-recrystallization temperature in the second phase for forging, and further cooled to the two-phase temperature for forging. It is characterized by a final cooling with air or cooling with spray water followed by cooling with air. Forged steel product O1L manufacturing method.