With the increasing interest in computational materials science data, a systematic construction and representation of workflows is needed to make them findable, accessible, interoperable and reusable (FAIR) for the scientific community. Recently, there have been a lot of efforts to develop domain specific ontologies for materials data, but there is still a strong need to semantically link data across different scales and to integrate them into workflow representations. We present an approach for the construction of ontologies from computational workflows, using pyiron, our integrated development environment (IDE) for computational materials science. We demonstrate how the metadata that are contained in the class hierarchy of the underlying python code can be connected with domain specific ontologies. The approach is demonstrated for the simulation of elastic properties of materials. We further show how the such designed workflow ontology can be employed for query purposes and for a graphical representation of workflows.