Consolidation and hardening of PM-HIP hot work tool steel H13 in a single step process: Experiment and Simulation

Transcription

1 Consolidation and hardening of PM-HIP hot work tool steel H13 in a single step process: Experiment and Simulation Ali Rajaei, Yuanbin Deng, Christoph Broeckmann 1 Anna Weddeling, Werner Theisen 2 Tool 2016, the 10 th international tooling Conference Bratislava, October Insitut for Materials Applications in Mechanical Engineering RWTH University Aachen 2 Chair of Materials Technology Ruhr University Bochum

2 Introduction Hot Isostatic Pressing HIP-Process (1) Capsule production (3) Evacuation (5) Hot isostatic pressing (2) Filling powder and pre-consolidation (4) Sealing (6) HIPed component 2

3 Temperature [ C] Temperature [ C] Motivation Conventional HIP and Heat treatment Heat-treating furnace HIP-Chamber time [h] HIP with integrated rapid cooling 1200 Combined HIP-unit time [h] Advantages Reducing: Time Energy Process infrustructure and The risk of cracking during hardening 3

4 Content 1 Introduction and motivation 2 characterization 3 Process Modelling and Simulation in ABAQUS 4 5 Outlook 4

5 44.5 mm Experimental setup HIP-unit Sample 44.5 mm LWT Ruhr University Bochum Quintus QIH 9 Material Capsule: Stainless steel 304 (1.4301) Compact: Gas atomized powder ( µm) Hot work tool steel H13 (1.2344) C0.38 Cr5.2 Mo1.2 V0.91 Si1.08 Mn 0.38 [ m / o ] 5

6 Temperature-Pressure profile Temperature [ C] HIP Cycle 1: HIP + Quenching Temperature Pressure Time (s) Pressure [MPa] Temperature [ C] HIP Cycle 2: HIP + Slow cooling Temperature Pressure Time (s) Pressure [MPa] Cycle 1 Max. temperature = 1075 C Cooling rate = 30 C/s Cycle 2 Max. temperature = 1175 C Cooling rate = 0.3 C/s 6

7 inelastic strain (volume change) Material model for HIP-cycle input Pressure Temperature Mechanical Analysis Elastic, Plastic ε el, ε pl Creep ε cr Thermal Expansion ε th output Strain, Stress (deformation) λ T, ρ, c p T, ρ, E T, ρ, ν T, ρ initial density Material properties (temperature and dencity dependent) updated density Densification analysis updated density Mass Conservation 7

8 Material model for Quenching input thermal conditions λ T, ξ i, c p T, ξ i, ρ T, ξ i Thermal analysis Temperature profile T, T latent heat Metallurgical analysis output microstructure T ξ i Material properties (temperature and phase dependent) E T, ξ i ε pl, ν T, ξ i, σ y T, ε pl, ξ i Phase fractions i ξ i = 1 T, T Mechanical analysis Elastic, Plastic ε el, ε pl Thermal Expansion ε th Transformation strain ε tr Transformation plasticity ε tp residual stress 8

9 Simulation of the HIP-cycle Visualization of deformation and density Video 9

10 Cross section of the sample qualitative comparison Experiment Simulation-after quenching 20 mm 10

11 Cross section of the sample quantitative comparison Simulation D2 D1 D3 H3 H2 H1 HIP + slow cooling [mm] Dimension Initial Experiment Simulation H H H D D D Cycle 2 Max. temperature = 1175 C Cooling rate = 0.3 C/s 11

12 Microstructure of the HIPed sample needle shape structure Process temperature = 1175 C Cooling rate = 0.3 C/s Sample preparation Polished and etched with nital (a solution of alcohol and nitric acid) 20 µm 12

13 Microstructure of the HIPed sample grain growth towards capsule Process temperature = 1175 C Cooling rate = 0.3 C/s Sample preparation Polished and etched with nital (a solution of alcohol and nitric acid) 200 µm Capsule Tool steel 13

14 Microstructure of the HIPed sample Dark field graph Capsule Tool steel 200 µm Process temperature = 1175 C Cooling parameter = 0.3 C/s Sample preparation Polished and etched with nital (a solution of alcohol and nitric acid) 14

15 Hardness [HV10] Hardness of the HIPed samples Sample 1 Sample Distance from the left side [mm] 15 Cycle 1 Max. temperature = 1075 C Cooling rate = 30 C/s Cycle 2 Max. temperature = 1175 C Cooling rate = 0.3 C/s

16 constituent phase fractions [-] constituent phase fractions [-] Simulated phase fractions 1.1 Sample Sample Austenite Martensite Austenite Bainite Martensite Temperature [ C] Cycle 1 Max. temperature = 1075 C Cooling rate = 30 C/s Temperature [ C] Cycle 2 Max. temperature = 1175 C Cooling rate = 0.3 C/s

17 Simulation of the Quenching Residual Stresses Cycle Von Mises Stress [MPa] Max principle Stress (abs) [MPa]

18 Simulation of the Quenching Residual Stresses Cycle Von Mises Stress [MPa] Max principle Stress (abs) [MPa] 18

19 Outlook Effect of pressure on phase transformations Heat convection during quenching Austenite grain growth Effect of austenite grain size on: Phase transformations Mechanical properties Precipitations Diffusion between powder and capsule Effect of oxidation and powder quality 19 Residual stress measurements

20 Thank you for your attention M.Sc. Ali Rajaei IWM Institute for Materials Application in Mechanical Engineering RWTH Aachen University Augustinerbach Aachen

21 Microstructure of the HIPed sample needle shape structure Process temperature = 1075 C Cooling parameter = 0.1 (t 800 t 500 = 100 s) Sample preparation Polished and etched with nital (a solution of alcohol and nitric acid) 21