Dependence of pre-treatment structure on spheroidization and turning characteristics of AISI1040 steel

Figures & data

Table 1. Spheroidization treatment cycle representations

Notation used	Heat treatment conditions
A	As-bought AISI1040 specimen
A3	As-bought 3 h spheroidized AISI1040 specimen
A6	As-bought 6 h spheroidized AISI1040 specimen
A9	As-bought 9 h spheroidized AISI1040 specimen
N	Normalized AISI1040 specimen
N3	Normalized 3 h spheroidized AISI1040 specimen
N6	Normalized 6 h spheroidized AISI1040 specimen
N9	Normalized 9 h spheroidized AISI1040 specimen
H	Hardened AISI1040 specimen
H3	Hardened 3 h spheroidized AISI1040 specimen
H6	Hardened 6 h spheroidized AISI1040 specimen
H9	Hardened 9 h spheroidized AISI1040 specimen

Figure 1. Heat treatment cycle for AISI1040 steel. (a) As-bought spheroidized specimen. (b) Normalized-spheroidized specimen. (c) Hardened-spheroidized specimen.

Figure 2. Machinability specifications. (a) Turning test sample. (b) Carbide insert.

Table 2. Details of machining parameters for machinability tests on AISI1040 steel specimen

Machining parameters
Spindle speed, n (rpm)	720	750	780
Feed, f (mm/rev)	0.13	0.26	0.39
Depth of cut, d (mm)	0.2	0.4	0.6

Figure 3. Scanning electron microscope microstructure of AISI1040 workpiece. (a) As-bought. (b) Normalized. (c) Hardened. (d) As-bought 9 h spheroidized. (e) Normalized 9 h spheroidized. (f) Hardened 9 h spheroidized.

Figure 3. (Continued).

Figure 3. (Continued).

Figure 4. Surface roughness (S_R) study with constant spindle speed (n, rpm) and depth of cut (d, mm) by varying feed (f, mm/rev) for AISI1040 steel.

Figure 5. Surface roughness (S_R) study with constant feed (f, mm/rev) and spindle speed (n, rpm) by varying depth of cut (d, mm) for AISI1040 steel.

Figure 6. Surface roughness (S_R) study with constant feed (f, mm/rev) and depth of cut (d, mm) by varying spindle speed (n, rpm) for AISI1040 steel.

Figure 7. Tool wear (T_W) study with constant spindle speed (n, rpm) and depth of cut (d, mm) by varying feed (f, mm/rev) for AISI1040 steel.

Figure 8. Tool wear (T_W) study with constant spindle speed (n, rpm) and feed (f, mm/rev) by varying depth of cut (d, mm) for AISI1040 steel.

Figure 9. Tool wear (T_W) study with constant depth of cut (d, mm) and feed (f, mm/rev) by varying spindle speed (n, rpm) for AISI1040 steel.

Table 3. T_w and S_R values for AISI1040 as-bought-spheroidized steel

Sl. No.	Feed, f (mm/rev)	Depth of cut, d (mm)	Spindle speed, n (rpm)	Tool wear, Tw (mm)	Surface roughness, SR (μm)
1	0.13	.2	720	0.035	3.73
2	0.13	.2	750	0.046	4.56
3	0.13	.2	780	0.052	5.3
4	0.13	.4	720	0.034	2.73
5	0.13	.4	750	0.024	2.81
6	0.13	.4	780	0.04	3.12
7	0.13	.6	720	0.02	4.68
8	0.13	.6	750	0.037	4.73
9	0.13	.6	780	0.047	5.62
10	0.26	.2	720	0.068	2.38
11	0.26	.2	750	0.058	3.54
12	0.26	.2	780	0.072	3.53
13	0.26	.4	720	0.08	2.38
14	0.26	.4	750	0.067	2.42
15	0.26	.4	780	0.087	2.84
16	0.26	.6	720	0.072	4.63
17	0.26	.6	750	0.081	5.38
18	0.26	.6	780	0.09	5.27
19	0.39	.2	720	0.072	3.61
20	0.39	.2	750	0.064	3.02
21	0.39	.2	780	0.071	3.64
22	0.39	.4	720	0.065	3.61
23	0.39	.4	750	0.07	2.86
24	0.39	.4	780	0.112	3.8
25	0.39	.6	720	0.053	4.98
26	0.39	.6	750	0.07	5.61
27	0.39	.6	780	0.085	5.36

Table 4. ANOVA for T_w for the as-bought-spheroidized specimen of AISI1040 steel

Parameter	DF	Seq SS	Contribution %	Adj SS	Adj MS	P-Value
Feed (mm/rev)	2	0.008248	67.53	0.008248	0.004124	<.001
Depth of cut (mm)	2	0.000094	0.77	0.000094	0.000047	.738
Spindle Speed (rpm)	2	0.000812	6.65	0.000812	0.000406	.095
Error	20	0.003059	25.05	0.003059	0.000153
Total	26	0.012214

Table 5. ANOVA for S_R for the as-bought-spheroidized specimen of AISI1040 steel

Parameter	DF	Seq SS	Contribution %	Adj SS	Adj MS	P-Value
Feed (mm/rev)	2	1.5447	4.99	1.5447	0.7723	.059
Depth of cut (mm)	2	22.2528	71.91	22.2528	11.1264	<.001
Spindle speed (rpm)	2	2.4260	7.84	2.4260	1.2130	.016
Error	20	4.7214	15.26	4.7214	0.2361
Total	26	30.9449

Figure 10. Residual plots of T_W for as-bought-spheroidized AISI1040 steel. (a) Normal probability plot (b) versus fits. (c) Histogram (d) versus order.

Figure 11. Residual plots of S_R for as-bought-spheroidized AISI1040 steel. (a) Normal probability plot (b) versus fits. (c) Histogram (d) versus order.

Figure 12. Main effect plots of T_W for as-bought-spheroidized AISI1040 steel. (a) Feed. (b) Depth of cut. (c) Spindle speed.

Figure 13. Main effect plots of S_R for as-bought-spheroidized AISI1040 steel. (a) Feed. (b) Depth of cut. (c) Spindle speed.

Figure 14. Combined optimized factors for T_W and S_R for as-bought-spheroidized AISI1040 steel. (a) Composite desirability. (b) Surface roughness. (c) Tool wear.

Table 6. Validation result for predicted and experimental values

Machining parameters			Predicted values		Experimental values		% Error of tool wear (TW)	% Error of surface roughness (SR)
Cutting speed (n) (rpm)	Feed (f) (mm/rev)	Depth of cut (d) (mm)	Tool wear (TW) (mm)	Surface roughness (SR) (μm)	Tool wear (TW) (mm)	Surface roughness (SR) (μm)
780	0.39	0.6	0.038	2.91	0.039	2.89	<5%	<5%