Analysis of tempering temperature and vegetable oil quenchant viscosity effect on mechanical properties of 42CrMo4 steel

Figures & data

Table 1. Chemical composition of 42CrMo4 steel

Element (wt. %)	C	Si	Mn	S	P	Cr	Mo	Fe
Standard range (Rajan & S, 2011)	0.35–0.45	0.1–0.35	0.5–0.8	0.05	0.05	0.90–1.5	0.2–0.4	Balance
As-received	0.43	0.29	0.80	0.016	0.018	0.91	0.26	Balance

Table 2. Viscosity of quenchant oil

Quenchant oil	Kinematic viscosity (centistokes)
Karanja	30.77
Blended	32.63
Pinnay	41.12

Figure 1. As-received sample’s microstructure tempered at 350°C in different conditions: (a) Pinnay oil quench, (b) Blended oil quench, and (c) Karanja oil quench.

Figure 2. As-received sample’s microstructure tempered at 500°C in different conditions: (a) Pinnay oil quench, (b) Blended oil quench, and (c) Karanja oil quench.

Figure 3. Effect of quenchant viscosity and temperature of tempering on hardness and impact toughness of 42CrMo4 steel.

Table 3. Hardness and impact toughness result for various conditions

Temperature of tempering (°C)	Quenchant oil	Quenchant viscosity (centistokes)	Hardness (Rc)	Impact toughness (J)
350	Karanja	30.77	41	13
400	Karanja	30.77	40	31
450	Karanja	30.77	39	33
500	Karanja	30.77	37	38
350	Pinnay	41.12	40	16
400	Pinnay	41.12	37	28
450	Pinnay	41.12	36	30
500	Pinnay	41.12	35	32
350	Blended	32.63	44	14
400	Blended	32.63	42	24
450	Blended	32.63	40	35
500	Blended	32.63	39	40

Table 4. Results of ANOVA for impact toughness of the material

Factors	Df	Sum of squares	Adjusted MS	P-value	Relative contribution
Temperature of tempering	3	35.667	11.8889	<0.001	48.41
Oil viscosity	2	36.167	18.0833	<0.001	49.09
Error	6	1.833	0.3056
Total	11	73.667

Table 5. ANOVA results for the hardness of the material

Factors	Df	Sum of squares	Adjusted MS	P-value	Relative contribution
Temperature of tempering	3	851	283.667	<0.001	91
Oil viscosity	2	11.17	5.583	0.624	1.2
Error	6	65.5	10.917
Total	11	927.67

Table 6. Confirmation test results

Properties	Theoretical	Experimental			Average	% Error
		Trial 1	Trial 2	Trial 3
Hardness (Rc)	34.3	33	33	34	33.3	2.9
Impact toughness (J)	37.8	36.5	37	36.5	36.6	1.2

Rajan, T. V. S. C. P., & S, A. (2011). Heat Treatment Principles and Techniques. Prentice Hall of India Private Limited.

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