Integrated HIP heat treatment of high-speed steel
Influence of an integrated HIP heat treatment on microstructure and mechanical properties of a PM tool steel: experiment and simulation
Motivation
Hot isostatic pressing (HIP) is a manufacturing process used to consolidate metal powders. It is used to produce high-speed steel cutting tools with high wear resistance at elevated process temperatures. The powders are completely compacted in a pressure vessel under isostatic pressure at elevated temperatures. HIP technology is characterised by a slow cooling rate. Therefore, to achieve the desired microstructure of a martensitic matrix with embedded primary and secondary carbides, additional heat treatment is required after the HIP process. However, due to its high cooling rate, Ultra Rapid Quenching Hot Isostatic Pressing (URQ-HIP) allows the quenching heat treatment to be integrated into the HIP process. This eliminates the need for subsequent hardening. Process time and manufacturing costs can be significantly reduced by using rapid cooling HIP technology.
Objectives
- Development of an integrated HIP heat treatment with isothermal holding steps
- Investigation of the influence of HIP technology with rapid cooling on the microstructure and mechanical properties
- Identification of efficient heat treatment parameters to design ideal carbide conditions and to influence fatigue strength
- Development of a simulation model to predict the microstructure and precipitation morphology
Project Contents
- Powder characterisation and sample production
- Material consolidation using HIP technology with rapid cooling and isothermal holding stages
- Computer-aided image analysis of the morphology of the primary carbides
- Transelectron microscopy (TEM) analysis of the secondary carbides
- EBSD investigations to determine the austenite grain size and dislocation density
- Mechanical characterisation of the material under quasi-static and cyclic loading
- Investigation of crack propagation
- Micro compression and nano indentation testing
- FE simulation of rapid cooling
- Simulation of integrated hardening with holding steps
- Simulation of tempering
Project partners
Chair of Materials Technology at Ruhr University Bochum
Funding
Funded by German Research Society
