Towards determining the influence parameters on the distortion of gear wheels made from the steel grade 20MnCr5 (SAE 5120), in this work the analysis of the distortion of disks is presented. The parameter identification was performed by means of the design of experiments (DoE). According to a comprehensive approach to distortion engineering, the entire manufacturing chain was considered from casting to the final heat treatment. Due to the complexity of this manufacturing chain the investigation was divided into two parts, the processes before the final heat treatment and the final heat treatment process itself. Here, in part I, the results of the investigation of the processes before the final heat treatment are discussed while in part II the results of the final heat treatment are presented. Releasing the accumulated distortion potential of the influence parameters of the processes from casting to cutting by a standard case hardening led to characteristic size changes of the disks. For the shape changes the cutting strategy showed a high influence on the change of dishing. Assuming that the cutting strategy can continuously be varied there should be a strategy for which no change of the dishing occurs, which would provide the means for compensation of distortion.

A conventional hot rolled, low alloy carburizing steel (C: 0.21 wt.-%; Cr: 1.08 wt.%; Mn: 1.36 wt.%) has been investigated in terms of inhomogeneous phase transformations and anisotropic size changes during heating to austenitizing temperature and during slow cooling from austenitizing temperature to room temperature. A detailed study was executed on dilatometer specimens. The results were compared with the size changes of shafts with similar heat treatment. Ferrite nucleated first at selected chain-like positions and a pronounced ferrite/pearlite rodlike structure was formed. After reaustenitizing the rodlike structure appeared exactly at the same position. At intermediate transformation stages broad regions were still untransformed while other regions had an advanced transformation state. Dilatometer specimens with different orientations to the former rolling direction of the bar had different changes in length, which indicates an anisotropic size change. Cylindrical shafts showed a similar macroscopic size change like the small dilatometer specimens. For the dilatometer specimens as well as for the shafts the absolute valuese of the size change depended on the initial microstructure.

The influence and significance of several process parameters in a manufacturing chain of cylindrical bearing rings made of steel SAE 52100 (100Cr6) on the quench hardening distortion were identified using the method of Design of Experiments (DoE) and a statistical analysis of the results. The change in out-of-roundness can be explained by the used clamping technique during turning, which led to characteristic residual stress distributions in circumferential direction. Size alterations were smaller and depended also on clamping (height) resp. on clamping and an interaction of clamping and feed (radius). Other investigated factors like stirring during continuous casting, deformation ratio during forging and cooling after forging did not significantly influence shape or size changes. Density measurement was found to be a simple and effective method, to check size changes. The results confirm the necessity of concerning the whole manufacturing chain, to understand and influence heat treatment distortion. DoE has been proven to be a useful tool in this way.

Investigations within the SFB 570 "Distortion Engineering" showed that shafts produced of the low alloy steel SAE 5120 (EN 20MnCr5) changed curvature into a preferred direction after blank hardening. The changes of curvature could be correlated with a macroscopic structure, which was visible in the metallographic cross section of the hardened shafts. Due to a quantitative description of the orientation of the square structure within the metallographic cross section it could be shown that the changes of the orientation of the structure were similar to the changes of the preferred direction of the curvature of the blank hardened shafts.Metallographic structures in different sections became visible because of differences of the local corrosion behavior. Such differences cause in varieties of the local chemical composition or grain size. Therefore the local chemical analysis was characterized by means of EPMA measurements with highest resolution. Further the grain size was described by quantitative image analysis of the former austenite grain boundaries. Additionally, characteristic areas of the metallographic cross section were investigated by FEM measurements due to the fact that the grain size could be affected by elemental precipitations.The laminar EPMA-measurements (mapping) at blank hardened shafts of the element distributions concerning the substantial alloying elements C, Mn and Cr showed a square structure in the element distribution. Best reproduction of the square structure within the metallographic cross section could be reached by moving averages of the highly resoluted mappings and their standard deviations.Different distributions of the former austenite grain boundary were found within characteristic areas of the metallographic cross section. FEM measurements seem to point on the fact that differences of the former austenite grain size distributions could cause in varieties of the character and distribution of elemental precipitations.

Realising the system-oriented approach of "Distortion Engineering", the influence of multiple parameters on the distortion of cylindrical gears was investigated by design of experiments. Aim of this research work was to investigate the effect of production parameters before the final heat treatment. The established experimental design focuses on the analysis of two main parts of gear distortion. One part is the distortion of the teeth themselves; the other part is a displacement of the teeth due to the distortion of the disk-shaped base body. The selection of the varied parameters is partly based on results of a system-oriented experiment with disks. Therefore several influences on the base body distortion are known. In comparison to the analysis of disk distortion the interpretation of gear distortion measurements requires significantly extended effort. Besides a determination of the distortion of the complex involute tooth profile, it has to be distinguished between a change of the tooth profile and a change of the base body.