SU1281867A1 - Method of determining residual stresses of ring specimens in pickling - Google Patents

Abstract

The invention relates to measurement. and can be used to determine the residual stresses of ring specimens. The aim of the invention is to improve the accuracy by eliminating the torque acting on the sample and ensuring uniform etching conditions. One end of sample 3 is fixed at two points located at a distance of 1 / 8TGP from one another, where D ;, is the internal diameter of the sample, which excludes torque. The internal surface of the sample is etched and a change in the distance between its ends is recorded. In the process of etching, the acid solution is mixed in the etch zone, bounded by the internal surface of the sample, with a piston mixer. The diameter of the narrower part of the mixer is half the size of its expanded part. The ratio of the internal diameter of the sample 3 (D) and the diameter of the narrower part of the mixer (d) is chosen from the ratio 75, which ensures uniform etching conditions. The density of the acid solution is continuously monitored by a hydrometer 4, located at a distance of 5 Do from the etching zone. 1 3.p. f-ly, 2 ill. with (L

Description

The invention relates to a measurement technique and can be used to determine the residual stresses of ring specimens.

The aim of the invention is to increase the accuracy by eliminating the torque acting on the sample and ensuring uniform etching conditions.

FIG. 1 shows a device that implements a method for determining residual stresses on; FIG. 2 shows section A-A in FIG. one.:

The device contains a piston mixer 1 placed in a bath 2 with an etching solution. The narrowed part of the mixer faces sample 3, and in the bath are also placed the areometer 4, the indicator 5, and the forked holder 6 of the sample.

The procedure for determining the residual stresses of the annular specimens is carried out as follows.

Prior to etching, fix one end of sample 3 with holder 6 at two points a, b located 1 / 8D apart from each other, where DO is the internal diameter of sample 3. Place sample 3 in an etching bath 2 with an acid solution previously applied a protective coating on the outer and side surfaces of the sample. In the process of etching, the metal layers are removed from the inner surface of the sample, which causes a change in the distance of 1 1 to the ends of the sample, and this is recorded by indicator 5. The measured values determine the residual stress

in the sample.

During the entire etching process, the acid solution is mixed in the etching zone bounded by the inner surface of the annular sample 3 using a piston mixer 1 made in the form of a truncated cone, the narrowed part of which faces the Zin sample two times smaller than its expanded part. -The ratio of the internal diameter of the sample and the diameter of the narrower part of the mixer is determined from the condition

0, I-1 / 0.75, where dp is the diameter of the narrower part 55

mixer

Continuously throughout the etching process, the raft is monitored.

five

five

0

0

five

acid solution with a hydrometer, which is placed at a distance of 2 from the etching zone. . An example. The annular specimen is fixed at one end at two points spaced apart from the / 8 PBO distance from one another. Cover the surface of the sample with the exception of its inner surface with a lacquer layer to prevent etching of this surface and place the sample in bath 2 with an acid pickling solution with an initial concentration of 20%.

An indicator of the type IRP-1 measures the change in the distance between the ends of the sample during the etching process.

Continuously, in the process of etching, the density of the mortar killing solution is controlled by a hydrometer 4, which is placed at a distance of 2D 1 0.5 V ", and the acid solution is stirred by a piston mixer, the diameter of the narrowed part of which is 2 times smaller than its expanded part, and for ensuring the conditions of uniform etching of the ratio of the internal diameter of the sample D and the diameter of the narrowed part d is chosen from the condition 75. Fixing the end of sample 3 at two points located at a distance of l / 8ltD eliminates the torque that is created by the weight of sample 3 and introduces an error in the measurement.

Invention Formula

Claims (2)

1. Method for determining residual stresses of ring specimens during etching, which consists in cutting the specimen in the radial direction, fixing one end of the specimen, placing the specimen in an acid pickling bath, etching the specimen, measuring the change in the distance between the specimen ends and from the measured values, the residual stresses are determined, characterized in that, in order to improve the accuracy, by eliminating the torque acting on the sample and ensuring uniform etching conditions The said sample end is fixed at two points located at a distance equal to I / 8 TT Dp one from where D is the internal diameter of the sample, a protective coating is applied to the outer and side surfaces of the sample, the acid solution in the etching zone bounded by the inner surface of the sample is continuously mixed with a truncated cone during the etching process , the density of the acid solution is continuously monitored by a hydrometer, which is located 18674 are at a distance of 2D -1 0.50 „from the pickling zone, and the ratio of the internal diameter of the sample and the diameter of the narrower part of the mixer is determined by 5 of 75, where d is the diameter of the narrowed part mixer 2. The method according to p. 1, which is different from 10 to y and in that the diameter of the narrower part of the mixer is half the size of its expanded part. -4-l puz. 2