Abstract
Developing heat treat systems and control plans that produce consistent direct harden (quench and temper) results with a high percent martensite and the corresponding proper mechanical properties is challenging for large components or large batch sizes. In this study, large section bars in alloys suitable for water quenching were austenitized and quenched under controlled flow conditions. The bars were primarily examined by several as-quenched hardness versus depth traverses in order to be sure localized non-martensitic regions (soft areas) would be detected. The tests allowed for some key insights into defining the adequacy of direct harden water quench systems, including the idea of agitation thresholds required for each alloy grade or hardenability level to prevent soft spots (spotty hardening) on large section steel components.
