CS220147B1

CS220147B1 - Method of heat treatment of steels with higher strengths

Info

Publication number: CS220147B1
Application number: CS804481A
Authority: CS
Inventors: Jiri Raiman; Karel Matuska
Original assignee: Jiri Raiman; Karel Matuska
Priority date: 1981-11-02
Filing date: 1981-11-02
Publication date: 1983-03-25

Abstract

Vynález se týká způsobu tepelného zpracování ocelí o vyšších pevnostech legovaných kombinacemi legujících prvků jako mangan — vanad, mangan — vanad — dusík, mangan — nikl — vanad — dusík, mangan — molybden, mangan — chrom — nikl — — vanad a mangan — chrom — nikl — molybden — vanad s přísadou kovového hliníku, případně s přísadou mikrolegujících prvků, jako niobu, zirkonu a titanu. Tyto oceli se po jejich zakalení žíhají na teplotě v rozmezí 650 až 750 °C s prodlevou dvou minut na každý milimetr jejich tloušťky, minimálně však po dobu dvou hodin, načež se nechají vychladnout volně na vzduchu.The invention relates to a method of heat treatment of steels with higher strengths alloyed with combinations of alloying elements such as manganese — vanadium, manganese — vanadium — nitrogen, manganese — nickel — vanadium — nitrogen, manganese — molybdenum, manganese — chromium — nickel — — vanadium and manganese — chromium — nickel — molybdenum — vanadium with an addition of metallic aluminum, or with an addition of microalloying elements such as niobium, zirconium and titanium. After hardening, these steels are annealed at a temperature in the range of 650 to 750 °C with a delay of two minutes for each millimeter of their thickness, but for at least two hours, after which they are allowed to cool freely in air.

Description

Vynález se týká způsobu tepelného zpracování ocelí o vyšších pevnostech legovaných kombinacemi legujících prvků jako mangan — vanad, mangan — vanad — dusík, mangan — nikl — vanad — dusík, mangan — molybden, mangan — chrom — nikl — — vanad a mangan — chrom — nikl — molybden — vanad s přísadou kovového hliníku, případně s přísadou mikrolegujících prvků, jako niobu, zirkonu a titanu. Tyto oceli se po jejich zakalení žíhají na teplotě v rozmezí 650 až 750 °C s prodlevou dvou minut na každý milimetr jejich tloušťky, minimálně však po dobu dvou hodin, načež se nechají vychladnout volně na vzduchu. 220147 220147BACKGROUND OF THE INVENTION The present invention relates to a method for heat treatment of steels with higher strengths alloyed with combinations of alloying elements such as manganese - vanadium, manganese - vanadium - nitrogen, manganese - nickel - vanadium - manganese - molybdenum, manganese - chromium - nickel - - vanadium and manganese - chromium - nickel-molybdenum-vanadium with the addition of metallic aluminum, optionally with the addition of micro-alloying elements such as niobium, zirconium and titanium. After quenching, these steels are annealed at a temperature of 650 to 750 ° C with a delay of two minutes for each millimeter of their thickness, but at least for two hours, and then allowed to cool freely in the air. 220147 220147

Vysmález se týká, způsobu tepelného zpracování ocelí o vyšších pevnostech, které· jsou legovány manganem a vanadem, nebo manganem, vanadem a dusíkem, nebo manganem, niklem, vanadem a dusíkem, nebo manganem a enolybdenem a nebo manganem, chromém, niklem, molybdenem a vanadem.The term relates to a method of heat treatment of steels with higher strengths, which are alloyed with manganese and vanadium, or manganese, vanadium and nitrogen, or manganese, nickel, vanadium and nitrogen, or manganese and enolybdenum and or manganese, chromium, nickel, molybdenum, and vanadium.

Je známo vyrábět hutní výrobky Jako plechy, tyče, pásy, výkovky a výlisky pro ocelové konstrukce a konstrukce strojních zařízení, které jsou vystaveny zvýšenému statickému a chemickému namáhání z ocelí o vyšších pevnostech s vysokou hodnotou meze kluzu, čemuž vyhovují oceli s přísadami legujících prvků v kombinacích mangan a vanad, dále mangan, vanad a dusík, dále mangan, nikl, vanad a dusík, dále mangan, molybden, dále mangan, chrom, nikl a vanad a mangan, chrom, nikl, molybden a vanad s přísadou kovového hliníku od 0,005 do 0,07 % hmot. s případnou přísadou směsi legujících prvků, jako niobu, zirkonu a titanu v rozmezí od 0.01 do 0,1 °/o hmot. Tyto oceli vykazují po tepelném zpracování vysokou hodnotu mezikluzti, kde tepelné zpracování spočívá v zakalení nebo normalizaci s následným popouštěním v rozmezí teplot 600 až 660 °C.It is known to produce metallurgical products such as sheets, bars, strips, forgings and stampings for steel structures and machine structures that are subjected to increased static and chemical stresses from steels with higher strengths with a high yield strength, which is matched by steels with alloying elements in combinations of manganese and vanadium, manganese, vanadium and nitrogen, manganese, nickel, vanadium and nitrogen, manganese, molybdenum, manganese, chromium, nickel and vanadium and manganese, chromium, nickel, molybdenum and vanadium with 0.005 % to 0.07 wt. optionally adding a mixture of alloying elements such as niobium, zirconium and titanium in the range of 0.01 to 0.1% by weight. These steels exhibit a high value of intermediate slip after heat treatment, where the heat treatment consists in turbidity or normalization followed by tempering in the temperature range of 600 to 660 ° C.

Nevýhodou těchto ocelí je, že vykazují nízkou plasticitu, což omezuje možnost jejich praktického použití.The disadvantage of these steels is that they exhibit low plasticity, which limits their practical use.

Uvedené nevýhody těchto ocelí se odstraní způsobem jejich tepelného zpracování podle vynálezu, jehož podstata spočívá v tom, že po jejich zakalení se žíhají na teplotě v rozmezí 650 až 750 °G s prodlevou dvou minut na každý milimetr jejich tlouštky minimálně však po dobu dvou hodin, načež se nechají volně vychladnout na vzduchu. Výhodou způsobu tepelného zpracování ocelí podle vynálezu je, že se u nich dociluje významného zjemnění feritického sekundárního zrna. Tuto strukturu lze klasifikovat jako dispersní, případně nepravou duplexní strukturu s velmi jemným zrnem, řádově dKG 5 μΐη. Toto velice jemné zrno, tvořící se jak po hranicích sekundárního zrna « fáze, tak uvnitř zrna a fáze, znamená výhodné spojení vysokých mechanických hodnot mikrolegované oceli s plasticitnými hodnotami a houževnatostí rázem, jakož iThe disadvantages of these steels are eliminated by the heat treatment process according to the invention, which, after quenching, anneals at a temperature of 650 to 750 ° C with a delay of two minutes for each millimeter of their thickness for at least two hours, whereupon they are allowed to cool freely in the air. An advantage of the steel heat treatment method of the invention is that they achieve a significant refinement of the ferritic secondary grain. This structure can be classified as a disperse, or false duplex structure with very fine grain, in the order of dKG 5 μΐη. This very fine grain, formed both at the boundaries of the secondary grain of the phase and within the grain and phase, means the advantageous combination of high mechanical values of microalloyed steel with plasticity and impact strength as well as

Claims

OBJECT The method of heat treatment of steels with higher strengths of alloyed combinations of alloying elements such as manganese - vanadium, manganese - vanadium - nitrogen, manganese - nickel - - vanadium - manganese - molybdenum, manganese - chromium - nickel - vanadium and manganese - chrome - nickel - molybdenum - vanadium, with the addition of metallic aluminum, or fracture toughness. This means that the strength and plasticity of the steel is higher. Thus, it is the development of a false duplex structure that carries superplasticity phenomena in steel when it is cold formed. Its further advantage is that it significantly weakens the scattering factor of the leakage of the individual properties of the individual pieces of the product) with the same heat, which is a known phenomenon in the present heat treatment process, thus allowing the optimum properties of these to be exploited. steel. An example is a method; heat treatment of steel sheet 115 mm in steel, chemical composition carbon 0.18 wt%, manganese 1.2 wt%, silicon 0.28 wt%, chromium 0.35 wt%, nickel 0.19 wt% ., vanadium; 0.15 wt%, phosphorus 0.017 wt%, sulfur 0.013 wt%, and the rest iron; The plate was heated to 900 ° C with a delay of 2 hours and then cooled with a stream of air, whereupon it was heated to a tempering temperature of 700 ° C with a delay of 5 hours. It was found that the steel shows the club limit Re = 370 MPa, strength limit Rm = 580 MPa, ductility A5 = 29%, notch toughness at normal temperature KVC = 90-120 J cm-2, tested on three test bars, where the zero ductile temperature of the NDT was 0 ° C. In addition, a 22 mm thick sheet of steel with a carbon composition of 0.17% by weight, 1.14% by weight manganese, 0.34% by weight silicon, 1.21% by weight silicon was also subjected to a heat treatment process according to the invention. , chromium 0.58 wt%, molybdenum 0.29 wt%, vanadium 0.1 wt%, aluminum 0.04 wt%, niobium 0.05 wt%, phosphorus U; , sulfur 0.008% wt. and the rest iron. This plate was heated to 1880C with a delay of 30 minutes and then cooled with a stream of air, whereupon it was heated to 090 ° C with a delay of 2 ° C. The measurement revealed that the steel had a yield strength Re = 688722 MPa, breaking strength Rm · · 827 MPa, ductility As = 18% ·, notch toughness at normal temperature KVC = = 101 to 116 J. cm 2 tested on · three test bars, where the temperature ductility of the NDT was °20 ° C. with the addition of micro-alloying elements such as niobium, zirconium and titanium, characterized in that they are annealed at 650 to 750 ° C with a delay of two minutes for each millimeter of their thickness, but at least for two hours and then allowed to cool freely in the air.