Sintering behaviour of compacted water-atomised iron powder: effect of initial state and processing conditions

Figures & data

Figure 1. EBSD maps depicting the deformation effects of plain powder and green samples compacted at 400 and 800 MPa, respectively. Left column (a, c, e): Grain boundary maps with low-angle grain boundaries as red lines and high-angle grain boundaries as black lines. Right column (b, d, f): KAM maps illustrating the prevalence of small (θ < 2°) misorientations.

Figure 2. Low-temperature isothermal sintering of samples compacted at three different pressures and sintered at different temperatures; (a) 600°C, (b) 700°C, (c) 800°C.

Figure 3. Fractographic images of compacts sintered at 700°C: (a) 400 MPa, (b) 600 MPa, (c) 800 MPa, (d) 800 MPa, N₂.

Figure 4. Fe75 sintering cycle matrix. (a) Varying compaction pressure at 10°C min^–1, (b) with added carbon. (c) Isothermal shrinkage at 1350°C for four sintering conditions, (d) with added carbon.

Figure 5. Sintering curves of Fe75 and Fe75+C compacted at 800 MPa and heated at 10°C min^–1. The CTE references are included as dotted lines.

Table 1. Sintering shrinkages in different regions of Fe45, Fe45 + C, Fe75 and Fe75 + C samples.

	Sintering shrinkages (%) measured by dilatometry
Region\sample	400, HR5	400, HR10	400, HR30	600, HR5	600, HR10	600, HR30	800, HR5	800, HR10	800, HR30
Fe45
Ferrite	0.34	0.36	0.36	0.60	0.67	0.57	0.98	0.96	0.86
Austenite (excluding iso.)	0.14	0.13	0.06	0.16	0.21	0.04	0.12	0.10	0.07
Isothermal	0.13	0.19	0.28	0.09	0.07	0.18	0.08	0.11	0.19
Fe45 + 0.4 wt-% C
Ferrite	0.55	0.53	0.53	0.92	0.90	0.82	1.07	0.93	0.88
Austenite (excluding iso.)	0.44	0.28	0.12	0.36	0.29	0.16	0.47	0.45	0.35
Isothermal	0.34	0.43	0.55	0.24	0.33	0.41	0.23	0.33	0.43
Fe75
Ferrite	0.38	0.38	0.47	0.62	0.59	0.53	0.92	0.88	0.77
Austenite (excluding iso.)	0.20	0.16	0.17	0.10	0.07	0.05	0.10	0.09	0.04
Isothermal	0.14	0.19	0.32	0.07	0.09	0.16	0.07	0.09	0.15
Fe75 + 0.4 wt-% C
Ferrite	0.54	0.51	0.52	0.90	0.79	0.83	1.10	0.97	0.81
Austenite (excluding iso.)	0.25	0.16	0.05	0.19	0.13	0.01	0.34	0.24	0.20
Isothermal	0.28	0.33	0.39	0.19	0.23	0.28	0.19	0.25	0.34

Figure 6. Sintering curves of Fe75 and Fe75+C compacted at 800 MPa and heated at 10°C min^–1. Methodology for determining the sintering shrinkage in each region.

Figure 7. Fractional shrinkage in each region of (a) Fe75 and (b) Fe75 + C samples.

Figure 8. Final sintered densities of (a) plain Fe45 and Fe75 and (b) carbon-containing Fe45 and Fe75 samples.