Fig. 1. Equilibrium solidification path of 300M steel

Fig. 2. Microstructure of laser welded joint of 300M steel.(a)Welded joint; (b) weld metal[1 in Fig. 2(a)]; (c) HAZ[2 in Fig. 2(a)]; (d) HAZ1[3 in Fig. 2(a)]; (e) base material[4 in Fig. 2(a)]

Fig. 3. Hardness distribution of 300M steel laser welded joints

Fig. 4. Stress-strain curves of 300M steel laser welded joints

Fig. 5. Fracture morphology of 300M steel welded joint. (a) Substrate; (b) welded joint; (c) welded joint+heat