An NPR non-magnetic steel material for rock bolt and a production method thereof are disclosed. The NPR non-magnetic steel material for rock bolt has a composition, in weight percent, consisting of: C: 0.4-0.7%, MN: 15-20%, Cr: 1-18%, Si: 0.3-3%, Ca: 0.05-0.15%, Cu: ≤0.03%, Ni: ≤0.02%, S: ≤0.001%, P: ≤0.001%, and the rest being Fe and unavoidable impurity elements. The NPR non-magnetic steel material for rock bolt and the production method thereof effectively solve the problems of steel materials for rock bolt in the prior art such as strong magnetism, low tensile strength and low effective elongation. The NPR non-magnetic steel material for rock bolt has a fully-austenitized structure and is non-magnetic, its yield strength is adjustable in the range of 600-1000 MPa, and its elongation is adjustable in the range of 20-60%.

Various embodiments provide for a gas purging plug (10) with a ceramic refractory body (10k) with a first end (10u) and a second end (10o); the second end (10o) is in the mounted position of the gas purging plug (10) in contact with a metal melt (41); the first end (10u) is at least partially covered with a metal cover (12.1), the metal cover (12.1) comprises an opening (16) to which optionally a gas supply adapter (20) is connected; the gas purging plug (10) is designed in such a way, that a purging gas which is supplied via the gas supply pipe (30) to the opening (16) flows through the body (10k) and exits the body (10k) at the second end (10o); and wherein at least one electronic sensor (70, 70.1, 70.2, 70.3, 70.4) is in contact with the gas purging plug (10), to detect a mechanical vibration (81).

Various embodiments provide for a gas purging plug (10) with a ceramic refractory body (10k) with a first end (10u) and a second end (10o); the second end (10o) is in the mounted position of the gas purging plug (10) in contact with a metal melt (41); the first end (10u) is at least partially covered with a metal cover (12.1), the metal cover (12.1) comprises an opening (16) to which optionally a gas supply adapter (20) is connected; the gas purging plug (10) is designed in such a way, that a purging gas which is supplied via the gas supply pipe (30) to the opening (16) flows through the body (10k) and exits the body (10k) at the second end (10o); and wherein at least one electronic sensor (70, 70.1, 70.2, 70.3, 70.4) is in contact with the gas purging plug (10), to detect a mechanical vibration (81).

Ti, N, Al, Mg, and Ca concentrations are controlled in order to prevent aggregation of TiN inclusions. Furthermore, not only is a Fe—Cr—Ni alloy having superior surface property provided, but also a method is proposed in which the Fe—Cr—Ni alloy is produced at low cost using commonly used equipment. The Fe—Cr—Ni alloy includes C≤0.05%, Si: 0.1 to 0.8%, Mn: 0.2 to 0.8%, P≤0.03%, S≤0.001%, Ni:16 to 35%, Cr: 18 to 25%, Al: 0.2 to 0.4%, Ti: 0.25 to 0.4%, N≤0.016%, Mg: 0.0015 to 0.008%, Ca≤0.005%, O: 0.0002 to 0.005%, freely selected Mo: 0.5 to 2.5% in mass % and Fe and inevitable impurities as the remainder, wherein Ti and N satisfy % N×% Ti≤0.0045 and the number of TiN inclusions not smaller than 5 μm is 20 to 200 pieces/cm.sup.2 at a freely selected cross section.

An NPR non-magnetic steel material for rock bolt and a production method thereof are disclosed. The NPR non-magnetic steel material for rock bolt has a composition, in weight percent, consisting of: C: 0.4-0.7%, Mn: 15-20%, Cr: 1-18%, Si: 0.3-3%, Ca: 0.05-0.15%, Cu: ≤0.03%, Ni: ≤0.02%, S: ≤0.001%, P: ≤0.001%, and the rest being Fe and unavoidable impurity elements. The NPR non-magnetic steel material for rock bolt and the production method thereof effectively solve the problems of steel materials for rock bolt in the prior art such as strong magnetism, low tensile strength and low effective elongation. The NPR non-magnetic steel material for rock bolt has a fully-austenitized structure and is non-magnetic, its yield strength is adjustable in the range of 600-1000 MPa, and its elongation is adjustable in the range of 20-60%.

Gas purging system comprising a gas purging plug (10) and gas purging plug (10) for metallurgic applications and a gas supply pipe (30) connected to the gas purging plug (10), the gas purging plug (10) with a ceramic refractory body (10k) with a first end (10u) and a second end (100); the second end (100) is in the mounted position of the gas purging plug (10) in contact with a metal melt (41); the first end (10u) is at least partially covered with a metal cover (12.1), the metal cover (12.1) comprises an opening (16) to which optionally a gas supply adapter (20) is connected; the gas purging plug (10) is designed in such a way, that a purging gas which is supplied via the gas supply pipe (30) to the opening (16) flows through the body (10k) and exits the body (10k) at the second end (100); and wherein at least one electronic sensor (70, 70.1, 70.2, 70.3, 70.4) is in contact with the gas purging plug (10), to detect an oscillation waveform of a mechanical vibration (81). The gas purging system further comprises a data processing unit (80) for acquiring the oscillation waveform of a mechanical vibration (81) detected by the electronic sensor (70, 70.1, 70.2, 70.3, 70.4) of the gas purging plug (10) and for calculating a bubble index-signal (83) from the oscillation waveform of a mechanical vibration (81) detected; a control unit (100); wherein the control unit (100) is configured to: displaying the bubble index-signal (83) and/or varying the volume flow (102) through the gas supply pipe (30) depending on the bubble index signal (83) and/or -generating a warning signal (101) when the bubble index signal (83) lies outside a defined range.

Gas purging system comprising a gas purging plug (10) and gas purging plug (10) for metallurgic applications and a gas supply pipe (30) connected to the gas purging plug (10), the gas purging plug (10) with a ceramic refractory body (10k) with a first end (10u) and a second end (100); the second end (100) is in the mounted position of the gas purging plug (10) in contact with a metal melt (41); the first end (10u) is at least partially covered with a metal cover (12.1), the metal cover (12.1) comprises an opening (16) to which optionally a gas supply adapter (20) is connected; the gas purging plug (10) is designed in such a way, that a purging gas which is supplied via the gas supply pipe (30) to the opening (16) flows through the body (10k) and exits the body (10k) at the second end (100); and wherein at least one electronic sensor (70, 70.1, 70.2, 70.3, 70.4) is in contact with the gas purging plug (10), to detect an oscillation waveform of a mechanical vibration (81). The gas purging system further comprises a data processing unit (80) for acquiring the oscillation waveform of a mechanical vibration (81) detected by the electronic sensor (70, 70.1, 70.2, 70.3, 70.4) of the gas purging plug (10) and for calculating a bubble index-signal (83) from the oscillation waveform of a mechanical vibration (81) detected; a control unit (100); wherein the control unit (100) is configured to: displaying the bubble index-signal (83) and/or varying the volume flow (102) through the gas supply pipe (30) depending on the bubble index signal (83) and/or -generating a warning signal (101) when the bubble index signal (83) lies outside a defined range.

A spring steel having a superior fatigue life, and a manufacturing method for the same. The chemical components thereof are as follows in weight percentage: C: 0.52-0.62%, Si: 1.20-1.45%, Mn: 0.25-0.75%, Cr: 0.30-0.80%, V: 0.01-0.15%, Nb: 0.001-0.05%, N: 0.001-0.009%, O: 0.0005-0.0040%, P: ≤0.015%, S: ≤0.015%, and Al: ≤0.0045%, with the remainder being Fe and incidental impurities, wherein the following condition is also met 0.02≤(2Nb+V)/(20N+C)≤0.40. The spring steel of the present invention has a microstructure of tempered troostite+tempered sorbite, a prior austenite grain size less than 80 um, a size of alloy nitride and carbide precipitates being 5-60 nm, and a maximum width of single-grain inclusions being less than 30 pm. The spring steel has a handling strength greater than 2020 MPa, superior ductility and toughness (the reduction of area≥40%), and a fatigue life≥800,000 times, thereby meeting application requirements of high-stress springs in industries, such as automobiles, machinery, and the like.

Provided is an FeNiCr alloy that has excellent surface characteristics and enables formation of a blackened coating having excellent blackening characteristics and peeling resistance. The FeNiCr alloy has a chemical composition containing, by mass %, C, Si, Mn, P, S, Cr, Ni, Mo, Co, Cu, N, Ti, Al, O, and H, the balance being Fe and inevitable impurities, and satisfying formulae (1) to (4): (1) T1=11[% N]+0.1; (2) T2=39[% N]1.0; (3) A1=7.5[% N]+0.1; (4) A2=42.5[% N]+1.0, where [% M] represents content (mass %) of element M in the alloy, and T1, T2, A1, and A2 satisfy relationships T1<[% Ti]<T2 and A1<[% A1]<A2.

A method for treating molten metals (4) and/or slags in metallurgical baths comprises the introduction of a process gas into a melt bath. The process gas is accelerated to supersonic speed and is introduced below the melt bath surface (5) by means of at least one supersonic nozzle (6) with supersonic speed into the liquid phase of the molten metal (4) and/or into the slag and/or into the region of a phase boundary between molten metal and slag. The disclosure further relates to a metallurgical plant for treating molten metals.