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The effect of heat treatment on the organization and mechanical properties of 316L stainless steel with different nitrogen content

The effect of heat treatment on the organization and mechanical properties of 316L stainless steel with different nitrogen content

Time:2022-04-02 Source:Wuxi Jianuo Special Steel Co., Ltd.

316L stainless steel for 00Cr17Ni14Mo2 ultra-low carbon steel, better than 0Cr17Ni14Mo2 toughness and acid resistance, with good intergranular corrosion resistance, good overall performance and process performance, is currently more commonly used austenitic stainless steel. But this steel in 450 ~ 850 ℃ stay in the chloride prone to intergranular corrosion, so should stop solid solution treatment to ensure its corrosion resistance. Participate in nitrogen will improve the stability of austenite phase in 316L austenitic stainless steel, reducing its composition at high temperatures σ ferrite; through solid solution strengthening to improve the strength, but will make the layer error can be reduced, resulting in α martensite, reducing toughness. To this end, researchers will be different nitrogen content 316L stainless steel in different solid solution temperature to stop the experimental research, after analyzing its organization in different solid solution temperature, mechanical properties and impact fracture, to explore the impact of changes in solid solution temperature, to improve the application and consumption of 316L to provide a strong basis.

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Experimental steel for vacuum induction melting, its main chemical composition is shown in Table 1.

Specimens were forged and hot-rolled into plates 110mm wide and 12mm thick.

In the two chemical compositions of 316L stainless steel hot-rolled plate sampling, set solid solution temperature of 950, 1000, 1050, 1100 and 1150 ℃, holding 40min after water cooling. Metallographic corrosion for 1gKMnO4 + 98mLH2O + 10mLH2SO4 mixed solution, using a 50 ℃ water bath heating corrosion, time 90min. precipitate inspection corrosion selected 5gCuCl2 + 25mLCH3CH2OH + 30mLHCl proportion of the mixed solution. In the metallurgical microscope to stop the grain size inspection, and after supporting the SiscIAS8.0 metallurgical analysis software on the grain size rating, using S-4300 cold field emission scanning electron microscope on the fracture and precipitates to stop the inspection and analysis.

The results indicate that.

(1) 316L stainless steel grain size is affected by the solid solution temperature, high solid solution temperature to accelerate the grain growth, grain size increases gradually with the increase in solid solution temperature, and the grain will be too large to incur its processing and use of poor performance, can be after the participation of nitrogen to control the growth of 316L solid solution disposal grain size.

(2) with the solid solution temperature, 316L stainless steel tensile strength and yield strength are reduced, different nitrogen content of 316L stainless steel in different solid solution temperature after disposal have excellent plastic deformation ability.

(3) The impact fracture of 316L stainless steel with different nitrogen content is plastic tough fossil shape after solid solution treatment, tough fossil presence of massive inclusions or second phase particles and obvious ripple slip traces at the bottom, 316L impact specimen fracture is tough fossil, while the impact fracture of 316LN is mostly along the crystal fracture, the layer is tough fossil fracture, clarifying that this steel has good impact resistance.