PL14879B1

PL14879B1 - A method of hardening building and structural steel containing copper.

Info

Publication number: PL14879B1
Application number: PL14879A
Authority: PL
Filing date: 1929-03-12
Publication date: 1931-11-30

Description

W celu uzyskania dla zwyklej budowla¬ nej i konstrukcyjnej stali wielkosci stosun¬ ku granicy plynnosci do wytrzymalosci po¬ wyzej 70%, konieczne bylo dotychczas poddawanie tej stali ulepszaniu. W celu przeprowadzenia tego sposobu konieczne bylo ogrzanie stali do temperatury powy¬ zej górnego punktu zwrotnego (punkt Ac3) i nastepne ochladzanie jej od tempe¬ ratury, lezace] powyzej tego punktu i na¬ stepne wyzarzanie w temperaturach, leza¬ cych ponizej punktu Acx.Wynalazek polega na tern, 'ze osiaga sie ten sam rezultat jedynie przez wyza¬ rzenie stali tak, iz specjalne ogrzewanie bez stosowania naglego ochladzania lub z ochladzaniem powolnem staje sie zbytecz¬ ne. Wynikajaca stad pod wzgledem go¬ spodarczym korzysc jest zupelnie jasna.Wynalazek opiera sie na zjawisku, ze przy stalach, zawierajacych powyzej 0,6% miedzi oraz do 0,5% wegla, nastepuje wsikutek- wyzarzania utwardzanie, wyróz¬ niajace sie przez podwyzszenie jej grani¬ cy plynnosci, wytrzymalosci oraz zmniej¬ szenie sie wydluzenia, kurczenia i ciagliwo- sci. Powiekszenie granicy plymnosci jest znaczniejsze, niz powiekszenie wytrzyma¬ losci tak, iz stosunek granicy plynnosci do wytrzymalosci dochodzi do 70 — 80%.Najkorzystniejsza temperatura wyza¬ rzania zalezy od skladu chemicznego, znaj¬ duje sie jednak zawsze ponizej punktu Ax (dolna granica mniej wiecej przy 400°).Czas wyzarzania, wymagany do osiagniecia maksymalnego wzrostu wytrzymalosci, wy¬ nosi c^tia^lnniejf 6&frriis\it Ochladzanie mo¬ ze sie odbywac na powietrzu. Przekrocze¬ nie czasu trwania wyzarzania nie pociaga przytem za soba niekorzystnych skutków.Ten nowy sposób pozwala uzyskac po¬ wiekszenie ponad 50% granicy plynnosci dla stali, zawierajacej miedz, i wytrzyma¬ losci ponad 20%. Silny spadek ciagliwo- sci, wykluczajacy w niektórych przypad¬ kach praktyczne zastosowanie tego sposo¬ bu, moze byc unikniety tak, ze obróbka, wzglednie ostateczne nadanie Wlasciwego granica plynnosci wytrzymalosc na rozciaganie wydluzenie kurczenie ciagliwosc | Zaznacza sie jeszcze, ze przy szybkiem ochlodzeniu w wodzie przy temperaturze 930° osiagnieta granica plynnosci wynosila tylko 37,5 kg/mm2, zas wytrzymalosc na rozciaganie ^— 46 kg/mm2. PLIn order to obtain a ratio of the strength limit to strength of more than 70% for common building and structural steel, it has hitherto been necessary to subject this steel to an improvement. In order to carry out this process, it was necessary to heat the steel to a temperature above the upper turning point (Ac 3 point) and then to cool it from a temperature lying above that point and annealing at temperatures below the Ac x point. The invention consists in the fact that the same result is achieved only by the envisioning of the steel, so that special heating without sudden cooling or with slow cooling becomes superfluous. The resulting economic advantage is quite clear. The invention is based on the fact that steels containing more than 0.6% copper and up to 0.5% carbon result in hardening as a result of annealing, distinguished by increasing its limits to fluidity, strength and reduction in elongation, shrinkage and tendency. The increase in the flow limit is greater than the increase in strength, so that the ratio of the liquid limit to the strength is up to 70-80%. The most favorable annealing temperature depends on the chemical composition, but is always below the point Ax (the lower limit is about at 400 °). The annealing time required to achieve the maximum increase in strength is equal to 6%. Cooling may take place in air. Exceeding the duration of the annealing does not entail any adverse effects. This new method makes it possible to obtain an increase of more than 50% of the liquid limit for steel containing copper and a strength of more than 20%. A strong drop in continuity, excluding in some cases the practical application of this method, can be avoided so that the treatment, or the final imparting of the correct liquidity limit, tensile strength, elongation, contraction, can be avoided. It is also noted that with quick cooling in water at a temperature of 930 °, the achieved liquidity limit was only 37.5 kg / mm2, while the tensile strength was ^ - 46 kg / mm2. PL

Claims

Patent claims. 1. The method of hardening building and structural steel containing copper, characterized by the fact that steel containing more than 0.6% copper and up to 0.5% carbon is annealed at a temperature below the Ac1 point for as long as (at least 60 min) until the enlargement! at the temperature of 900 ° -800 ° C, the material is then annealed after cooling in air as described above. The benefits obtained by using the present method are shown in the example below. A material was used with the following composition: 0.0% C, 0.41% Mn, 0.011% P, 0.014% S, 0.05% Si, 1.01% Cu. Flat iron with dimensions of 300 × 20 mm was rolled from a cast block. The following strength results were achieved. 26.1 43.0 22.6 60.0 23.0 46.0 57.6 15.6 57.0 4.0 46.2 kg / mma 59.2 17.5% 60.05 $ 22, 4 mkg / cm tensile strength and tensile strength will reach a certain imaximum, since elongation, contraction and ductility will decrease correspondingly with the increase of the above strength.

2. The method of claim. 1, characterized by the fact that the final shape of the material is completed before planting, within the temperature range from 900 to 800 ° C. V er e inigte Sta hi w e rk e Akf i en g es 11 sc h a f t. Deputy: Inz. Th. Raczynski, patent attorney As usual, rolled; air-cooled as usual rolled; air cooled; formed at 600 °. Final rolling temperature of 820 °, air-cooled; enumerated at 600 °. Print by L. Boguslawski and Ski, Warsaw. PL