High-hardness non-magnetic nickelless stainless steel and manufacturing method thereof

Abstract

The invention discloses high-hardness non-magnetic nickelless stainless steel. The steel is composed of, by weight, 0.15%-0.20% of C, 0.2%-0.8% of Si, 17.0%-19.0% of Mn, 13.5%-14.5% of Cr, 0.25%-0.30% of N, 0.5%-0.8% of Cu, 0.0015%-0.0040% of B, and the balance Fe and inevitable impurities, and the elements simultaneously meet the following relations that the sum of C and N is larger than or equal to 0.43%, (Cr+Mo+1.5*Si) / (30*N+30*C+0.25*Cu+0.5*Mn) is greater than or equal to 1.00 but smaller than or equal to 1.20, and the temperature of Md <30 / 50> is lower than or equal to -100 DEG C. The steel is in a full austenitic mode (without delta phase being produced) in the solidification process, the hardness reaches HV425-497 at the room temperature, and the yield strength is 1100-1350 MPa. Meanwhile, the steel is kept non-magnetic after reaching high strength through deformation hardening at the room temperature and is nickelless, and demagnetizing heat treatment is not needed after deformation, so that the cost is remarkably reduced; and the steel can be widely applied to spinning, electron, instruments and meters and other industries with the requirements for high hardness, abrasion resistance and non-magnetism.

Description

Technical field [0001] The invention relates to nickel-free stainless steel and a manufacturing method thereof, in particular to a high-hardness non-magnetic nickel-free stainless steel and a manufacturing method thereof. Background technique [0002] Hard stainless steel refers to quenching and tempering rolling (deformation hardening) of stainless steel plates or steel strips, giving the steel strips a certain amount of cold rolling reduction, and without annealing after cold working to obtain hard stainless steel products. Hard stainless steel is generally stronger and harder than the same material after solution treatment (or annealing treatment). Therefore, the material is more wear-resistant and has a longer service life. Commonly used hard stainless steels are mainly S30400 (304) and S30100 (301) among the 300 series austenitic stainless steels. [0003] Hard stainless steel is commonly used in textile, electronics, instrumentation and other industries. Take the tex...

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Problems solved by technology

[0006] This process of changing from non-magnetic to magnetic not only occurs in the process of cold working and rolling hardening to increase hardness, but also occurs in the process of end users processing stainless steel into desired components, parts or shapes. The process is inevitable, and it is impossible to use other processes in the subsequent process to eliminate the magnetism generated by this process (degaussing heat treatment can partially eliminate the magnetic phase of cold working, but the cost is high and it is easy to cause deformation of parts)

Therefore, the application of 304 or hard 304 in the non-magnetic field is limited to occasions that do not require high magnetic properties. For those fields that require weak or completely non-magnetic fields, 304 cannot meet the requirements.

[0007] The problem with 304 is that the price is higher, 8% Ni accounts for more than 50% of the cost of 304 stainless steel

The matrix structure of this material is stable, and after 20% to 80% deformation, it is still a single-phase austenite structure, and its magnetic permeability is stable, but its nickel content is as high as 12.0 to 13.9%, so although it has excellent non-magnetic properties, but significantly increased cost

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