Based on the concept of the technological trajectory in developing countries, the innovation process in these economies begins as latecomer firms interact with mature foreign companies and acquire knowledge and technology from the developed world. The dynamism of this process can, through open innovation approaches, turn latecomers themselves into sources of technology and innovation. However, the processes and mechanisms that focal firms employ in open innovation to raise their technological capability have not yet been fully identified and documented. This study aims to identify and historically analyze the open innovation patterns of Iran's steel industry from the perspective of technological learning. To this end, a case study method and a qualitative content analysis approach were adopted, and data were gathered through semi-structured interviews with 19 experts from four stakeholder groups (policymakers, steel producers, engineering firms, and academic research institutes) until theoretical saturation was reached. The findings reveal three main patterns: "the instructive organization as an integration of inbound and outbound knowledge flows," "the creation of engineering companies as spin-off firms," and "the creation and development of an innovation ecosystem for knowledge-frontier technologies." The historical analysis shows that each pattern has a definite starting point but no end point, persisting as overlapping layers that remain active to the present; moreover, over time the key actors and dominant learning mechanisms in each period shift, moving the industry from incremental toward radical innovation. T