JPH06179016A - Method for preventing crack in heattreatment of precipitation hardening type alloy bar and wire rod - Google Patents

Abstract

PURPOSE:To obtain a product excellent in quality which is free from cracking defect by drawing a bar and a wire rod, then, bending them repeatedly. CONSTITUTION:After the wire rod 2 cold-worked by a drawing device blooms and forges an ingot, it is faced, cut, then, forged by a press, a hammer, etc., to be worked into a round bar of a prescribed diameter, then, (faced) cut into a prescribed length, and then it is hot-rolled by grooved rolls into a coil shape. After it is drawn by a drawing die 1, the wire rod 2 drawn out of the drawing die 1 is passed through many rollers 3 to receive repeated bendings. As a result of this repeated bending, the tensile stress left on the surface of the wire rod 2 is reduced and the stress distribution of the wire rod 2 is uniformized, consequently, even when the wire rod 2 passes the brittle temperature area(700-900 deg.C) in the time of the succeeding heat treatment, a crack is prevented from being generated in the product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precipitation hardening alloy rod and wire for preventing heat treatment cracking of a bar and a wire made of a precipitation hardening alloy such as a Ni-based alloy.

[0002]

2. Description of the Related Art Heretofore, rods and wires made of this kind of precipitation hardening alloy have been manufactured by melting to form ingots and forging the ingots to a predetermined size. However, in the case of dimensioning by forging in this way, there is a problem that the dimensional accuracy of the obtained product is poor. Therefore, in order to solve this problem, hot or cold drawing is performed to obtain a product having a predetermined size.

[0003]

However, in the product obtained by such a drawing process, when the product is heat-treated, cracks may occur in the product depending on the conditions. Therefore, as a result of the investigation by the inventors of the present invention, as a result of tensile processing remaining on the surface of the product when the product is subjected to a drawing process, the product has a saizing temperature range (700 to 900) during heat treatment. It has been found that when the time of passing through (.degree. C.) is long, the product cracks due to the difference in residual stress between the surface and the inside of the product. And, this phenomenon is remarkable especially in the case of cold drawing.

The present invention has been made in view of the above findings, and an object thereof is to reduce the tensile stress on the surface of a product or to make the stress distribution uniform.
It is an object of the present invention to provide a precipitation hardening alloy rod and a method for preventing heat treatment cracking of a wire rod which can obtain a product of good quality without causing defects such as cracks in the product even when heat treated.

[0005]

In order to achieve the above object, the first aspect of the present invention is that the rod and the wire are repeatedly drawn after the rod and the wire are drawn. According to the second aspect of the present invention, after the rod and the wire rod are drawn, the surface of the rod and the wire rod is shot peened.

[0006]

According to the first aspect of the present invention, the drawn bar and wire are repeatedly bent to make the stress distribution of the bar and wire uniform, so that the bar and wire are heat-treated in the subsequent step. Even if the steel passes through the azeiZation temperature range, it is possible to prevent the rod and the wire from cracking. Further, according to claim 2 of the present invention, the surface of the drawn bar and the wire is subjected to shot peening to remove the residual stress on the surface of the bar and the wire, so that the bar and the wire are subjected to a heat treatment in a subsequent step. Even if it passes through the azeiZation temperature region, it is possible to obtain a good quality rod and wire without impairing the soundness of the rod and wire.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

In the drawing, reference numeral 1 is a drawing die for drawing a wire rod 2 made of a precipitation hardening type alloy (Ni-based alloy), and on the downstream side of the drawing die 1, a number of rollers 3 for repeated bending work are provided. It is arranged.

The wire 2 to be cold-worked by the drawing device constructed as described above is manufactured in advance by melting to prepare an ingot, and after this ingot is slab-forged,
Chamfering, cutting, forging with a press, hammer, etc. to form a round bar with a specified diameter, then (face cutting) cutting to align to a specified length, and then hot rolling with groove rolls Then, it is formed into a coil and subsequently subjected to heat treatment for cold drawing.

After being drawn by the drawing die 1, the wire 2 drawn from the drawing die 1 is repeatedly bent by being passed between a number of rollers 3. As a result of the repeated bending work, the tensile stress remaining on the surface of the wire 2 is relaxed and the stress distribution of the wire 2 is made uniform, so that the wire 2 is kept in the zeating temperature range during the subsequent heat treatment. Even when passing through (700 to 900 ° C.), the product is prevented from cracking.

Further, in the above embodiment, the bending of the wire 2 is repeatedly performed to suppress the residual tensile stress on the surface of the wire 2. However, the present invention is not limited to this, and instead of the repeated bending. In addition, residual stress may be removed by subjecting the surface of the wire 2 to shot peening.

[0012]

As described above, according to the first aspect of the present invention.
Since the rod and the wire are repeatedly drawn after the rod and the wire are drawn, this repeated bending makes it possible to make the stress distribution uniform and to perform the heat treatment. Even though the product does not crack, a product of good quality can be obtained. Further, according to claim 2 of the present invention, after the rod and the wire rod are subjected to the drawing process, the surface of the rod and the wire rod is subjected to shot peening. Therefore, the residual stress of the surface of the rod and the wire rod is caused by the shot peening. By removing, even if the rod and the wire pass through the zeitization temperature region during the heat treatment of the subsequent step, the soundness of the rod and the wire is not impaired, and the bar and the wire having good quality can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

[Explanation of symbols]

 1 Drawing die 2 Wire rod 3 Roller

Claims (2)

[Claims] 1. A method of preventing heat treatment cracking of a precipitation hardening alloy rod and a wire rod, which comprises subjecting the rod and the wire rod to a drawing process and then repeatedly bending the rod and the wire rod. 2. A method for preventing heat treatment cracking of a precipitation hardening alloy rod and a wire rod, which comprises subjecting the rod and the wire rod to drawing and then subjecting the surface of the rod and the wire rod to shot peening.