A case hardening steel includes as a chemical composition, by mass %, C: 0.10% to 0.40%, Si: 0.01% to 0.80%, Mn: 0.1% to 1.5%, Cr: 0.35% to 2.0%, Al: 0.01% to 0.05%, REM: 0.0001% to 0.050%, O: 0.0001% to 0.0030%, Ca: 0.0050% or less as necessary, Ti: less than 0.005%, N: 0.015% or less, P: 0.03% or less, S: 0.01% or less, and the balance consists of Fe and impurities. The case hardening steel also includes a composition inclusion which is an inclusion containing REM, O, S, and Al, or an inclusion containing REM, Ca, O, S, and Al, to which TiN is adhered.

A case hardening steel includes as a chemical composition, by mass %, C: 0.10% to 0.40%, Si: 0.01% to 0.80%, Mn: 0.1% to 1.5%, Cr: 0.35% to 2.0%, Al: 0.01% to 0.05%, REM: 0.0001% to 0.050%, O: 0.0001% to 0.0030%, Ca: 0.0050% or less as necessary, Ti: less than 0.005%, N: 0.015% or less, P: 0.03% or less, S: 0.01% or less, and the balance consists of Fe and impurities. The case hardening steel also includes a composition inclusion which is an inclusion containing REM, O, S, and Al, or an inclusion containing REM, Ca, O, S, and Al, to which TiN is adhered.

The present disclosure provides a method for producing a high nitrogen steel by a duplex melting process of a pressurized ladle refining and a pressurized electroslag remelting, which relates to the technical field of high nitrogen steel melting. In the present disclosure, the molten steel is subjected in sequence to a nitrogen alloying, a deep deoxidation and a deep desulfurization by adding a nickel-magnesium alloy and rare earth in the pressurized ladle furnace, and a combination of a blowing nitrogen from the bottom of the pressurized ladle and a pressurized nitriding at the interface of gas and the molten steel is used to achieve a high-efficiency nitrogen alloying, a uniform nitrogen distribution, and a decreased impurity content in the ingot; then the ingot is subjected to a pressurized electroslag remelting to obtain a high nitrogen steel.

Process for manufacturing a slag conditioning agent for steel desulfurization wherein a dried slag material obtained from secondary steelmaking process is mixed with quicklime particles to produce a slag conditioning agent.

A device and a method for continuous desulphurisation of liquid iron provided by a blast furnace process or a direct reduction process.

The present disclosure provides a method for producing a high nitrogen steel by a duplex melting process of a pressurized ladle refining and a pressurized electroslag remelting, which relates to the technical field of high nitrogen steel melting. In the present disclosure, the molten steel is subjected in sequence to a nitrogen alloying, a deep deoxidation and a deep desulfurization by adding a nickel-magnesium alloy and rare earth in the pressurized ladle furnace, and a combination of a blowing nitrogen from the bottom of the pressurized ladle and a pressurized nitriding at the interface of gas and the molten steel is used to achieve a high-efficiency nitrogen alloying, a uniform nitrogen distribution, and a decreased impurity content in the ingot; then the ingot is subjected to a pressurized electroslag remelting to obtain a high nitrogen steel.

A method and system for predicting an addition amount of slagging lime during ladle furnace (LF) refining, and an LF refining method are provided. The method includes: S1: calculating an actual sulfur distribution ratio in combination with a Kungliga Tekniska Högskolan (KTH) model and a least square method by using LF refining parameters; S2: calculating, according to a principle of sulfur mass conservation, a mass of final slag by using the LF refining parameters and the actual sulfur distribution ratio obtained in S1; and S3: calculating, according to a principle of material conservation during LF refining, an addition amount of slagging lime during the LF refining by using the LF refining parameters and the mass of the final slag obtained in S2, thereby predicting the addition amount of the required slagging lime.

Disclosed is a slag discharging method in a process of producing ultra-low phosphorus steel, which relates to the technical field of iron and steel smelting, and in which molten steel is mixed with lime first to produce basic slag; then converting is performed with oxygen to increase the oxidizability of the basic slag; and a carbon-containing reducing agent is finally added, so that in the process that the carbon is oxidized to release a large amount of carbon monoxide gas, phosphates are captured, and the basic slag is rapidly foamed and overflows from the opening of the steel ladle, so that conditions are no longer available for rephosphorization. Also disclosed is a method for producing ultra-low phosphorus steel, which includes the above-described slag discharging method in a process of producing ultra-low phosphorus steel, and refining and ingotting after slag discharge.

The invention discloses a method for preparing a stainless steel seamless tube with ultra-high cleanliness for an integrated circuit and an IC industry preparation device, and a stainless steel seamless tube with ultra-high cleanliness. The stainless steel seamless tube which comprises, by mass, C≤0.010%, P≤0.020%, S≤0.010%, Mn≤0.10%, Si≤0.30%, Se≤0.010%, Al≤0.010%, Cu≤0.20%, Cr16.50-17.00%, Ni14.50-15.00%, Mo2.20-2.50%, N≤0.010%, Ni≤0.010%, Ti≤0.010% and the balance Fe and impurities is prepared through a: a stainless steel refining process; b: a vacuum induction melting and vacuum consumable remelting process; c: a stainless steel forging process; d: a hot piercing process; e: a cold working process; f: an inner bore electrolytic polishing, pickling and passivation process; and g: a cleaning process. The stainless steel seamless tube with ultra-high cleanliness prepared through these processes meet the requirements for ultra-high cleanliness and high performance of 316L stainless steel tubes for a semiconductor preparation device.

The invention discloses a method for preparing a stainless steel seamless tube with ultra-high cleanliness for an integrated circuit and an IC industry preparation device, and a stainless steel seamless tube with ultra-high cleanliness. The stainless steel seamless tube which comprises, by mass, C≤0.010%, P≤0.020%, S≤0.010%, Mn≤0.10%, Si≤0.30%, Se≤0.010%, Al≤0.010%, Cu≤0.20%, Cr16.50-17.00%, Ni14.50-15.00%, Mo2.20-2.50%, N≤0.010%, Ni≤0.010%, Ti≤0.010% and the balance Fe and impurities is prepared through a: a stainless steel refining process; b: a vacuum induction melting and vacuum consumable remelting process; c: a stainless steel forging process; d: a hot piercing process; e: a cold working process; f: an inner bore electrolytic polishing, pickling and passivation process; and g: a cleaning process. The stainless steel seamless tube with ultra-high cleanliness prepared through these processes meet the requirements for ultra-high cleanliness and high performance of 316L stainless steel tubes for a semiconductor preparation device.