Accès libre

Evaluation of cracking risk of 80MnSi8-6 nanobainitic steel during hot forging in the range of lower temperature limits

À propos de cet article

Citez

Fig. 1.

Microstructure of 80MnSi8-6 steel in delivery condition
Microstructure of 80MnSi8-6 steel in delivery condition

Fig. 2.

Test stand with main equipment
Test stand with main equipment

Fig. 3.

Results of numerical simulation of open-die forging process: a) temperature distribution in the material, including localization of the area of low temperature range; b) effective stress distribution; c) plastic strain distribution
Results of numerical simulation of open-die forging process: a) temperature distribution in the material, including localization of the area of low temperature range; b) effective stress distribution; c) plastic strain distribution

Fig. 4.

Examples of dependencies used in numerical simulation: a) stress-strain curve in 600, b) hydraulic press characteristic, c) changes of density and specific heat of the material depending on the temperature
Examples of dependencies used in numerical simulation: a) stress-strain curve in 600, b) hydraulic press characteristic, c) changes of density and specific heat of the material depending on the temperature

Fig. 5.

The microstructure of samples P1_600 – a), b); P2_600 – c), d) and macrostructure of the cracking area in sample P2_600
The microstructure of samples P1_600 – a), b); P2_600 – c), d) and macrostructure of the cracking area in sample P2_600

Fig. 6.

Distribution of true principal strain (ε) during compression of sample P4_700 of 80MnSi8-6 steel obtained by methods: a) digital image correlation using DIC Q400 system with Istra4D software, and b) numerical FEM modeling with QForm software
Distribution of true principal strain (ε) during compression of sample P4_700 of 80MnSi8-6 steel obtained by methods: a) digital image correlation using DIC Q400 system with Istra4D software, and b) numerical FEM modeling with QForm software

Fig. 7.

The strain distribution maps obtained from measurements with the DIC system and based on numerical simulation results, together with force changes over time obtained from FEM simulation and direct measurement on the press for specimens deformed at 600°C and 700°C: P600_1 – a), P600_5 – b), P600_10 – c), P700_1 – d), P700_5 – e), P700_10 – f)
The strain distribution maps obtained from measurements with the DIC system and based on numerical simulation results, together with force changes over time obtained from FEM simulation and direct measurement on the press for specimens deformed at 600°C and 700°C: P600_1 – a), P600_5 – b), P600_10 – c), P700_1 – d), P700_5 – e), P700_10 – f)

Fig. 8.

Summary of FEM modeling results, including the distribution of the damage parameter according to the Cockcroft-Latham damage criterion for the analyzed variants of the compression test
Summary of FEM modeling results, including the distribution of the damage parameter according to the Cockcroft-Latham damage criterion for the analyzed variants of the compression test

Effect of deformation process parameters on specimen condition

Sample labeling Temperature, °C Traverse velocity, mm/s Crack
P1_600 600 1 No
P2_600 600 10 Yes
P3_700 700 1 No
P4_700 700 10 No
P5_900 900 1 No

Maximum damage criterion value determined for individual samples

Sample Temperature, °C Velocity, mm/s Cockrofta – Lathama criterion
P600_1 600 1 306
P600_5 5 267
P600_10 10 367
P700_1 700 1 297
P700_5 5 268
P700_10 10 360

DIC Q-400 system parameters [31]

System components System parameters
Cameras Max resolution 5 MPx 2448 × 2050 pixel
   Pixel size 3.45 μm × 3.45 μm
Shutter time 4 μ sec- 2 sec
Objectives 1.9/35             Focal length 34.9 mm
Focal distance (F-number) 1.9
Light source                   Monochromatic
Wavelength Red (620-750nm)
Calibration plates GI-06-WMB                   9×9 Object size 60 mm

Chemical composition of 80MnSi8-6 steel [%wt.]

Element C Si Mn P S Cr Mo V Fe
Content, mass % 0.79 1.55 1.9 0.003 0.003 1.3 0.25 0.11 Bal.
eISSN:
2083-134X
Langue:
Anglais