CN102211131A - Square steel sand burial cooling process - Google Patents

Abstract

The invention provides a square steel sand burial cooling process which comprises the following steps: 1) burying a forge piece into sand, wherein the initial temperature of the forge piece buried in sand is 700-800 DEG C; 2) taking out the forge piece from the sand. By utilizing the square steel sand burial cooling process provided by the invention, grains of square steel can be prevented from growing too much so as to be beneficial to internal stress diffusion; the deformation possibility is small, and white points can be eliminated and reduced.

Description

Square steel buries but technology of sand cooling

Technical field

The invention belongs to the forging field, relate to a kind of cooling means, what relate in particular to that a kind of square steel that is used for forging molding cools off buries but technology of sand cooling.

Background technology

Finish forge to form forging after, need cool off forging, in other words be exactly to make the forging heat scatter and disappear to reach the process of balance until forging temperature and environment temperature.The factor that influences the forging cooling velocity has two aspects, the one, external condition, the 2nd, interior condition; For external condition, as whether having cooling system, environment of living in whether to ventilate etc.; For interior condition, as forging wall thickness, internal structure etc., the thick place of wall thickness is than the local rapid heat dissipation of wall thickness, because the big entrained energy of thickness is also many, the heat radiation nature is just slow, and secondly surface texture is than internal structure rapid heat dissipation, is that from inside to outside radiant type is scattered and disappeared because heat scatters and disappears.Cooling velocity is certain to quality influential, and forging cooling is the process of shrinkage in expanding with heat and contract with cold, and is fast if contract in position of forging, and it is slow to contract in position, and forging is subjected to the internal stress effect, can cause the generation of situations such as forging distortion, forging defect.When at present forging being cooled off, or carry out the air cooling, or carry out sand cooling, because the blindness of cooling makes cooled foundry goods that very big cooling stress be arranged, the crystal grain that is easy to generate crackle and steel is too grown up.Particularly small-sized forging, because the martensite transfor mation of forging surface and core is not to take place simultaneously, the temperature stress when causing structural stress with cooling superposes and makes the forging surface form crackle.To crack in order preventing to cool off after the forging, should to adopt slow cooling, generally is to be placed on forging in the furnace wall about 200 ℃ or to cool off in the asbestos incubator, or changes in 600 ℃ of stoves insulation over to and cool off with stove.

Summary of the invention

In order to solve the above-mentioned technical problem that exists in the background technology, the invention provides that the diffusion of internal stress is too grown up, helped to a kind of crystal grain that prevents steel, square steel not yielding and that can eliminate and reduce white point buries but technology of sand cooling.

Technical solution of the present invention is: the invention provides a kind of square steel and bury but technology of sand cooling, its special character is: described square steel bury sand cooling but technology may further comprise the steps:

1) forging is imbedded in the sand, the initial temperature that described foundry goods is imbedded in the sand is 700～800 ℃;

2) forging is taken out from sand.

When imbedding forging in the sand above-mentioned steps 1), the thickness that described sand body covers forging is not less than 20 centimeters.

Above-mentioned steps 2) temperature that forging takes out from sand in is not higher than 150 ℃.

Advantage of the present invention is:

Square steel provided by the present invention bury sand cooling but technology and tradition blindly bury sand cooling different be to the temperature that begins to bury sand, bury sand and cover various conditions such as the thickness of steel and the temperature of shaking out and all limit, make steel casting prevent that after forge finishing cooling the crystal grain of steel from too growing up, helping the diffusion of internal stress, not yielding and play and expand the hydrogen effect, eliminate and reduce the harm of white point, easy to use, simple to operate, cooling effect is remarkable.

The specific embodiment

The invention provides a kind of square steel and bury but technology of sand cooling, this square steel bury sand cooling but technology may further comprise the steps:

1) foundry goods is imbedded in the sand, the initial temperature that described foundry goods is imbedded in the sand is 700～800 ℃; The thickness that described sand body covers foundry goods is not less than 20 centimeters;

2) forging is taken out from sand, the temperature of taking-up is not higher than 150 ℃.

Claims (3)

1. a square steel buries but technology of sand cooling, it is characterized in that: described square steel bury sand cooling but technology may further comprise the steps:

1) foundry goods is imbedded in the sand, the initial temperature that described forging is imbedded in the sand is 700～800 ℃;

2) foundry goods is taken out from sand.

2. square steel according to claim 1 buries but technology of sand cooling, it is characterized in that: when imbedding foundry goods in the sand in the described step 1), the thickness that described sand body covers foundry goods is not less than 20 centimeters.

3. square steel according to claim 1 and 2 buries but technology of sand cooling, it is characterized in that: described step 2) the medium casting temperature of taking out from sand is not higher than 150 ℃.