Effect of sulfide morphology on mechanical properties of free-cutting stainless steel 1Cr17MoS
ZHANG Jun1,2, ZHANG Xiu-li1,2, LI Zao-yu1,2, YANG E1,2
1. Special Metallurgical Products Research Institute, Daye Special Steel Co., Ltd., Huangshi 435001, Hubei, China; 2. Hubei Provincial Key Laboratory of High-quality Special Steel, Huangshi 435001, Hubei, China
Abstract：Sulfide morphology in free-cutting stainless steels 1Cr17MoS is shown different with different control techniques in steelmaking practice. For 1Cr17MoS steels with traditional steelmaking practice and forging process, sulfides presented thin and long stringers with the length of 50-80 μm and aspect ratio of 5-12,the sizes of sulfides were generally between 1 μm and 5 μm and most sulfides were less than 3 μm. However, for 1Cr17MoS steels with the addition of microalloying elements in steelmaking practice and forging process, spindle and globular sulfides were formed with the length of 10-30 μm and aspect ratio of 2-5, sizes of sulfide were generally between 3 μm and 20 μm and most sulfides were between 10 μm and 20 μm. The longitudinal and transverse tensile tests of 1Cr17MoS steel with different sulfide morphology were carried out. It is testified that fractures in 1Cr17MoS steels are dimple fractures in longitudinal tensile test at both conditions, the quantity and size of dimples are influenced by the quantity and thickness of sulfides, while the morphology of dimples have no obvious effect on mechanical properties of steels. The transverse tensile fractures of 1Cr17MoS steels are mainly quasi-cleavage fractures, and also have partial dimple fractures at both conditions. In traditional steelmaking practice with no sulfide morphology treatment, sulfide stringers break the continuities of matrix for test steel, which accelerate the brittle rupture of transverse tensile fractures. However, with sulfide morphology treatment in steelmaking practice, sulfides in spindle and globular shapes occur as dimples in fracture, which lead to better transverse tensile properties due to the remained plastic properties.
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ZHANG Jun, ZHANG Xiu-li, LI Zao-yu, YANG E. Effect of sulfide morphology on mechanical properties of free-cutting stainless steel 1Cr17MoS[J]. China Metallurgy, 2022, 32(6): 134-138.
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2022, Vol. 32 
