Tab. 1: Chemical composition of the X 2 CrNiMoN 22 5 3 alloy in weight-% 
Ne 
. weighty ov} Vb se TE 
"nominal value < 0,03 <2 [<0035]<0,015] 21-23 | 2,5-3,5{ 4,5-6,5]0,1-0,22 fo 
With regard to the planned test programme, cylindrical samples were carved out of the relevant ma- 14 
terial in rolling direction. Cyclic heat treatments were carried out on these samples with the tempera- x 
ture alternating between room temperature and the temperature of solution heat treatment (1050;C). m 
The holding time at 1050;C was 30 minutes per thermocycle. In order to investigate the influence of 
different cooling rates, the samples were cooled in different media. 
EXPERIMENTAL SET-UP 
DETERMINATION OF THE THERMALLY-INDUCED DEFORMATION 
In order to determine the amount of thermally-induced plastic deformation, dilatometer investiga- 
tions were carried out at a computer-controlled quenching and transformation dilatometer of the 
MMC type. It was possible to concertedly heat and cool the sample, which had been put into a 
photogrammetric camera (<0,0001 mbar), by means of a surrounding inductance coil. The tempera- 
ture was directly recorded by a Pt-PtRh thermocouple and was outlined in a Al-T curve together 
with the change of length. After each cycle, the irreversible amount of deformation was determined 
by equalising the initial length and the final length of the sample at room temperature. 
[HE 
QUANTITATIVE DESCRIPTION OF THE MICROSTRUCTURE Um 
In the course of a quantitative analysis of the microstructural changes, a metallographic investigation re 
of the thermally cycled samples was first of all carried out. The microstructure of the electrolyticly- 1 
polished samples was developed by means of the Beraha II etchant. Changes of the phase geometry X 
were determined by means of an all-automatic image-analysing computer with magnification being N 
200:1. oe 
em 
tify 
MEASUREMENT OF THE RESIDUAL STRESSES 
The changes of the phase-specific inherent stress condition were described in the course of x-ray 
investigations. These investigations were carried out by means of a Philips multi-purpose diffracto- 
meter of the PW 3050 MRD type with an open Euler s balance. The distribution of the x-ray inten- 
sity was evaluated and the resulting stresses were calculated by means of the sin®¥ procedure. The 
relevant characteristic values were taken from the literature listed below (5). 
2304