CA2206349A1 - Process for producing high quality, fine-grained structural steel with a stable anticorrosive layer for concrete-reinforcing mechanical apparatus and metal constructions engineering - Google Patents
Process for producing high quality, fine-grained structural steel with a stable anticorrosive layer for concrete-reinforcing mechanical apparatus and metal constructions engineeringInfo
- Publication number
- CA2206349A1 CA2206349A1 CA 2206349 CA2206349A CA2206349A1 CA 2206349 A1 CA2206349 A1 CA 2206349A1 CA 2206349 CA2206349 CA 2206349 CA 2206349 A CA2206349 A CA 2206349A CA 2206349 A1 CA2206349 A1 CA 2206349A1
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- weight
- mass
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- fact
- steel
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
- Coating With Molten Metal (AREA)
- Reinforcement Elements For Buildings (AREA)
Abstract
In a process for producing corrosion-resistant structural steel, an initial material is produced by admixture of alloy elements and is then subjected to a treatment having the following steps: (a) heating up to a reheating temperature from 1000 ~C to 1080 ~C; (b) cooling down to about 850 ~C at least partially during rolling; (c) slow and/or delayed cooling down to room temperature. According to the product analysis, the initial material has the following composition: 0.05 to 0.20 % by mass carbon, 1.5 to 2.00 % by mass copper, 1.50 to 1.80 % by mass manganese, 0.30 to 0.50 % by mass silicon, 0.04 to 0.06 % by mass niobium, 0.035 to 0.05 % by mass vanadium, 0.30 to 0.50 % by mass molybdenum, 0.04 to 0.06 % by mass aluminium, 0.015 to 0.02 % by mass nitrogen, 0.03 % by mass phosphorus, 0.02 % by mass sulphur, the residue being iron and accompanying elements.
Description
PROCESS FOR PRODUCING HIGH QUALITY, FINE-~RATN~n STRUCTURAL
STEEL WITH A STABLE ANTICORROSIVE LAYER FOR CONCRETE-REI~FORC~NG
MECMANICAL APPARATUS AND METAL CONSTRUCTIONS ENGINEERING
T~hni~la~a The~l~ ntinventionisc~n~f~rn~ with a meth~l fortheprod~lc~;onofsteelswhich find application in r~ L~a c~J~l~Le ~Llu~ ~_ as well as in the ~AJ~LLw~--tia~3 of ~~him-s an~ d~dLdLll~i~ lly~ the i~ rll~l with a nE~xod for Improving the ~ Lies of ~r~ion--rps;~t~nt steels s~teQfthea~
Theusu~s~uc~s~lshaves~en ~ ofless ~n700 N/n~n2, mos~y~und 500 N/mm2 COrrOSiOn-rP-S;Ct~nt SILU~ Stee1S with df~fin ~ copper c~ntPnt are ~ ;1~3 in WO
95/15405. Such s~X~s are~L~n~ by fi~t h~n~ the b~let m~t~n~l and then, du~ng the cooling process, rolling it at diLr~r~nt L~l~dlu~es, dep~lflin~ on the quali~ to be obl~.nfA
~s~n~e of the ~
The task of the present invention was to prwide co~)sion-re~nt s~eels with r~ved ~n~p~.Lies for the ~LLU~;~ULdL Stee1 area.
This goal was reached by the method de~bed in de~il Ia~er and c~ d in CIaim 1.
A steel which is sl~i~hlP for the ~locess a~ .liag to the invention has the following compocition copper 1.50 to 2.00 weight ~
carbon 0.05 to 0.20 weight %
m~ng~nP~e 1.50 to 1.80 weight %
silicon 0.30 to 0.50 weight %
niobium (coll-ml~i--m) 0.04 to 0.06 weight %
v~n~7;nm 0.035 to 0.05 weight %
molybdenum 0 30 to 0.50 weight %
~ll.. i.~l-............ 0.04 to 0.06 weight %
en 0.015 to 0.02 weaght %
phosphorus ~ 0.03 weight ~
sulfilr < 0.02 weight %
the re_t iron and accolllpally~lg~7~m~nt~
22295~40 .
.
By aUoying the above e~ m~ntC, for ~mrle, up to the total amounts given as ~r~r~lled amounts, a.l,il.~ r known standard steels can be altered so that they are able to form a corrosion-re-si~t~nt layer. Such alloyed steels are suitable for use in the method according to the invention.
I~e l,r.,r~led ~hPmi~l co..~l os;li~ n given above is a ~L~oll~ly pl~r~l.A pr~duct check analysis of the ini~l ,~ 1 to be used in this process. This initial m~tPn~l is produced by mPltin~ and mPt~ rgical ~rP~tm~nt, preferably ~i~pslllr~ n~ vacuum/ladle t~ n~ in the known ~ --~- an~ its check analysis .~h~~ have the c~~ L~ ling ~ - tion accor ;ng to the invention. With thR aid of the ~ol acl crdi~g to the inven-tion an~ using the materi~l with th~ (~ n~ition given above, very high quality can be achiev~d.
The te~ me course of-the six v~ hon~ of the meth~ acconli~g to the invention, as well as the develo~lnellt of the fine grains are shown in the fi~res.
l~lqef des~ tio~ of the r~... ~s Figure 1 shows the t~ ~time rli~ m of a m~thr~ for the ple~ n of structural ste~l of high~er-~Ll~,Lh quality without (with) ~--1~--~1 dis-~nlllti<~n (or .solllhility) of the micro--alloying elements upon r~h~ting.
Figure 2 shows the te~ /'dme ~i~m of a pl~f~led mf~.thod for the produc-tion of struc~ural steel of high-strength quality with degree of ~ .~1vti~n of the microalloying ont~ upon l.~h~t;~.g Figure 3 shows the le ~ /time rli~m of a mPth~l for the pro~uctinn of structural steel of high ~ l, quality wilhuu~ degree of ~1i.c.collltion of the microalloying Plem~ntc upon l~h~ p Figure 4 shows the te ..l~ J~me ~ of a pler~.l~ m-oth~l for the produc-tion of structural steel with very high ~ lh quality with degree of ~ ol~ltinn of the microalloying elçm~ntc upon l~he~ g 222g5-640 ~ CA 02206349 1997-05-28 Figure 5 shows the le",pel~ture/time fli~gr~m of a method for the pro~uct;on of structural steel of very high strength quality without degree of ~ tion of the microalloy-ing ~lem~ntc upon rçh.-~tin~.
Figure 6 shows the temperature/time diagram of a ~ re~d meth~ for the produc-tion of ~hu~;lul~l steel of very high strength quality (best quality) with degree Of ~ ol~ltion of the microalloying el~o-nn~nts upon rçh~tin~.
Figure 7 shows micrographs of the structural steel before rolling ~eft), at a ho11li time of 1000~C for 1 hour and quen~h~l in water (1000~C/1 h(lul/wa~;~) (right) in 100X
m~ nifi~tioll (above) and 500X m~gnifi~tion (bottom).
Figure 8 shows ~e micrographs of the crude rolled state with the plesellce of a submic~scol?;c PÇ~ in Figure 8A with a m~gnifi~*on of 1000X and in Figure 8B with a m~nifi~til n of 10,000X.
Figure 9 shows the micrographs of the quenched steel (1000~C/1 hu~/w~) with the presence of an enlarged submicn~ ic ~ e in Figure 9A with a m~gnifi-~*-~n of 1000X and in Figure 913 with a m~nifil~tion of 10,000X and Figure 10 shows microg~aphs of quP-nchP11 steel (1100~C/1 hou./w~), w_ich shows the increasing ~ ion of the submicroscopic ~ and the ~llcrease of the grain size, where Figure 10A was obtained with a m~gnific~tif n of lOOOX and Figure 10B was obtained with a m~gnific~tion of 10,000X.
The labeled areas in Figures 1 to 6 show ~e following A ~h~ting of normal billet;
B optional r~-h~ n~ of the billet slowly in order to dissolve the alloying ~1...".
better;
C holding time at the dissolution temperature for a period which preferably gives a particle size of 10 to 20 nm and a particle amount of 20 x 10~/mm2;
D rolling region;
E cooling region, preferably slow cooling in a cooling bed;
F cooling from the ~ $olution te~ dLul~ to the initial rolling lelll~ldlult;;G rapid cooling, for example, qu~nching in water after rolling from 850~C to 550~C with subsequent slow or delayed cooling.
Methods for ca,~ out the il-v~ on The method according to the invention is chara~ d by the fact that the initial 1 (billet) is r~h~t~l to a le~ of 1000 to 1080~C, eq~i~lly 1050-1080~C andis then subjected to a normal rolling process at corresponding normal rolling between the rehP~ting temperature and about 850~C (region D in the figures) with ~ulJse~lue~
quiet cooling in the bed. An especially economical method is obtained when the controLted rolling or a ~ lo" ~h~ni~l tre~tm~-nt is avoided.
The initial m~t~ l (billet) is first heated to a temperature of 1050~C to 1080~C(areas A + B in the figures). Lower tempe~,~ es, that is, below about 1000~C are possible while obtaining a similar result, but this is economi~lty less advantageous becau3e here the dissolution rate of the microalloying elem~nh is relatively low.
Preferably, the heating is done to the rehP~ting le"~ aLule at two diLr~r~ rates, ~at is, first, the heating is done at a normal rate to about 850~C (A) and then more slowly to 1050~C to 1080~C (13). During this h~tinp~ phase, already a part of the micr~alloying Pl~m~nt~ goes into solutinn~ for eY~mrl~ V, Nb. It is advantageous, for ~ oses of comp'~ ~ r~ olution of the microalloying rlP.~ present, to keep the steel for a penod of time, which corresponds preferably to the ,~ ~.y dissolution time of about 60 ~ t~ at 1050~C to 1080~C for 16 mm round rod steel, at a le~ above 1000~C, pl~r~al~ly in the range from 1050~C to 1080~C, e~i~lly preferably at about 1080~C (region C in the figures). At this ~e.~ ture, it is possible to reach a pl~rel-ed particle size from 10 to 20 nm and a number of particles of 20 x 106/mm2. Above a~L~ y 1090~C, the g~ain size grow~h is highly ~cPle~te~, so that operation above this l~, pel~tllre becomes critic~ and is preferably avoided.
Then the steel is subjected to a rolling process in the temperature range from the r~oht~ting temperature to a~pro,~imately 850~C (region D in the figures).
In the case of processes for the production of higher-strength qualities (see Figure l), the steel is subjected to a normal rolling process in the ~~ dLulG range from 1050~C to 1080~C to about 850~C (D).
HOWG~e1, high-strength qualities can also be produced with the m~thod according to the invention and the çh~mi~1 steel composition described above. For this pulpose, for PYzlmI~1e, the steel is brought to the r~h~tinf~ dLu-c;in two steps (espe~lly rapidly to 850~C and then slowly to a~çu~ fely 1065 + 15~C) and is kept there for a s 1m~nt1y long time in order to dissolve the microalloying e1Pm.ont~ (at al?pr"~i."~l~1y 1080~C for a~r~;m~t~ y 60 ~ tc~s) whereupon it-is subjected to a normal rolling ~r~ce5s in the lclll~Ld~ulG range from 1050~C, max. 108û~C, to about 900~C (see Figure 2).
However, with the m~od according to the invention, high sll~ ;lll and very high strength qualities can also be produced by ~h~n~ing the rolling co~iti~ns~
The m~th~ for producing high strength and very high strength qualities differs from those for higher strength qualities by the rolling te...lw.,.l...~.
For high-strength qualities or higher strength regions and ~l~pGlLies and thus improved mech~nic~l pr~pe,lies, according to the invention, the rolling is carried out at lower te~"~ s but above 850~C, ~ospe~11y in the range from about 980~C tô about 850~C (Figures 3 and 4, F and D), whereby the fine grain as well as the solid ~l~ n sL~ Ll,Pninf~ effects are Utili7~ WhiCh are inherent in the abovemPntion~ chf~mi~1 co.n~?osilion and are çh~r~c~ri~tic for it.
The cooling from about 850~C to ~mhi.ont ~..1l~.,.1.-.. can be done slowly in resting air, or preferably even with a delay, whereby the delay Su~ and increases the precipi-tation strengthening additionally (see Figures l~, E).
However, qualities up to very high strength can also be produced by carry~ng out the two-step heating to the dissolution temperature of the microalloying elPm~ont and hoklin~
there until complete ~ sollltion to mixed crystals is obtained and the rolling is camed out from appr~,cim~tPly 950~C to ap~ xim~t~ly 850~C (see Figure 4).
Very high strength qualities can also be produced when the steel, be~ se of its ehPmic~l composition, is first cooled in the ~e~ range from 1080~C to ~y~ .ly 980~C (Figure 5, F) and the rolling process is carried out starting from this ~ to about 850~C (Figure 5, D), namely, for very high strength qualities in a r.h~ .t~ ti~ rolling process in as few passes as possible, with a high degree of def,~ l;on and high ~ cily, as a result of which both the fine-grain-strengthenin~ as well as the solid .~lllti~ LJyUlening effects can be utili7f~d, followed and ~u~ ~d by the high action of ~L~;r~ ;on stIPM~h~n-ing, especially by copper, by q ~en~hin~ the steel from the final ro~ing ~ om about 850~C to about 550~C (Figure 5, G), followed by cooling in res~ng air or ~l~f~ly with a delay as a result of which the p~ ;on stren~th~-nin~ is s-l~poll~d even more and is ~nh~nee~l This quality is illlp~l~Ved even further when the two-step heating to the .colntion tem~ldlu-~ of the microalloying elern~nt~ and holciin~ at that lelll~ Ul~ iS
h~ until complete ~ ol~lti<)n to n~i~ed crystals (see Figure 6).
The invention will be e~pl~ined be3ow in more detail with an .
The results listed below are based on a melt which was produced in a high-r~uell~;y electric in~luction furnace with cover for the ~ulpose of possible dep~sii-g with argon te~ g gas and had the following ch~m~ cci.--posiLion in the product che~ analysis:
carbon 0.073%
copper 1.820%
m~ng~n~se 1.740%
silicon 0.341 %
niobi~lm 0.038 %
v~n~ m 0.043%
molybdenum 0.402%
0.048%
gell 0.0209to phosphorus < 0.0020%
sulfur 0.0023 %
However, the melt can also be produced in a convention~l electnc arc furnace, preferably with subsequent vacuum deg~e.~in~/ladle mPt~ rgy. The steels producedaccording to the invention will be ~ign~t~i below as TI-COR.
The development of ~e fine grain at the various ~ l;1;7.;ilg le..~ .t-,s and m~f~nific~tio~ are shown by the mi~;lu~;l~hs in Figures 7 to 10.
The infllTen~ of the ~ e~ ;on telll~UlC on ~e grain size is shown in the following Table 1:
T~ble1 ~-COR ~eel, d~ of~Nn~c~ ~tiontothe~
t~ealment grain ~ize accotding to NFA 0~102 (= ASTU 112) 950'Crl I '~. 7~
1~0-C/1 ~ '~. 7-8 1050~CJl I '~ 7~
1100-CIl I ~ 7 ~ gr~ t ~hc Elenphery llS0-C/lhw./~_ 2-3 ~th~c~n~utoO
This shows that, with the above steel co"l~osiLion, the ~ Pni~ l;on le~ e should be held at a ",~xi",~." of 1080~C in order to provide a fine grain size of 7-8 according to ASTM 112 (= NF A 04-102) and in order to p~c~/ellt rapid subseque~tco~ Pnin~ of the grains at a higher ~".~elature, with a .simn1t~neQusly optimum degree of di.csolution of the microalloying ~l~m~.nt.~ used for the targeted ~ul~03es.
The lcmpe~dlu~e/time ~ gr~m of the v~i~,Ls of structural steel with the same heating and ~lirr~ rolling ch~r~r-t~n~tics is shown in Figures 1 to 6.
The structural steel of the higher strength quality was ob~ined by rolling bclwtcll a~r~"~i"~ely 1080~C and ay~lu~umately 860~C, in the region of the fine-grain-~ g~ n-ing and solid sollltion ~ yu~Lling cnn.s;-l~r~l according to the invention.
~is steel, obtained with the ~e~ dlule profile co~ ollding to Figure 1, has the ~r~lLies listed in Table 2.
Table 2~ - ~u~i~e~
E~unple 1C mm ro~md d~l me~n of m~m 100 ~mples R~ tcn ilc ~ra~gth N/mm~ 8813 889 876 yield point O.1X N/mm~ 613 S 624 S94 R~ yield point 0.2% Nlmm~ 648.7 658 632 A elong~tion ~t bre~ % 20.42 20.6 ~0.1 Z ~ductios~ in~ whcnb~ % 62 70 63.0 62.0 E modulu~ of cbniciy ~N/mm~ 2103 Z17 205 E~ highe~tten ilc trength N . 180,270 191,400 171,000 ~, elon~an befo~e nec~ X 632 9.0 4 0 ~ tot l elong-tionL~, 200 mm !1; 6.61 ~5 4.4 R~tio of ~rength iocre~~ DIN 488m-COR ~teel ~S0/881 N/mm~ ~ +337 N/mm2 _ 613%.
Sllu~ilul~l steel of high-strength quality was obtained by rolling ~.1 980~C and870~C, ~n the règion of the ~ncreased fine~-str~n~th~nin~ and solid soluticn ~L~JyU~
ing considered according to the invention. This steel, which is produced acco~ g to the ~e~ t~ profile shown in Figure ~, has the high I~ n~ lu~ lies shown in Table 3:
, l'able 3~ ~ ~ ~lh aualitie~
E~unple 16 mm rolmd statistic~ll mean of m~rimmn m~imm 100 ~mpl~
R, ten~ilc ~rength N/mm~ 946.2 9S1 938 Rp., yield point O.l~i N/r~ SS4.9 571 54 yicldpoint0.2% N/r~m2 622.5 636 612 ~. elo~pdon Itb~ % 18.84 19.O 18.7 Z reducdon in ~ when b~g % S7.70 oO.O S6.0 E modulu~ of el~icity ~/mm~ 202.70 216 193 F~ hi~hc~t ten ile ~uength N 188,490 196,800 183,000 As elonlpdon befon~ neclcing % 5.95 75 4 S
~1 elong~don Lo 200 ~un ~i 6.47 7.9 4.9 ~do of ~rength incr~ae DIN 488/11-C0R Jteel 550/946 Nlmm~--+396 N/mm2 = 72.0%.
Structural steel of very-high-strength quality was ol~ d by rolling be~w~ll 980 and 870~C, ~e region of the increased fine-~ nin~ and solid.~)~ n ~ in~
considered according to the invention, wi~ sul~sequent rapid coolingl~,~ hi~-~ from 850~C
to 550~C, the region of additional high effect of ~r~i~ ;on sl~nr,ll.e~ espe~11y by copp~r, followed by a resting and/or del~yed cooling to enh~n~e the high p~;p;litl;o~
str~ngth~oning effect introduced by the pr~vious quen~hing, w~ the steel p~u~luced according to the L~~ ule/time ~i~nl of Figure S gave the following me~h~ni~l ~o~llies ~able 4):
22~95-640 Table4: Ve~ h~h~ql~iti~
E~nple 16 n round st~l ne~ of r~n min;m 100 sunpb~
R_ ten ilc ~engtil N/mm2 113S 1247 1069 ~ yield point 0 1% Ntmml 863.0 1017 803 Etp7 yieldpoinlo2!li N/mm~ 9~S 7 1064 863 A elong~tio l ~t bD~ % 17 0 18 5 IS 0 Z reduction in ~ when br~l~ng % 62.3 67 S9 E modulu- of el~ticiq lN/mm2 203 S0 216 182 P~ bighc t tc~lc Ircngtl~ N 222,9ao 237,000 212,~
A~ clong-tionbefore nec~ing % 4.2 S.S 25 l clong~tion L, 200 mrn % 4 7 6 0 3 0 C , DIN 488m-COR Jteel 550/113S N/mm~ = +585 N/mmZ = 106 5%
If the method is carried out with exactly the same steel co~ ~silion which was used for the previous exp~-nm~nt~ but, using the con~ii*on.c given in the le.,l~alul~/time curves according to Figures 2, 4 and 6, that is, with two-step heating, first rapidly to 850~C, and then slowly to 1080~C with a subsequent r~-sidence time at 1080~C (for ~p~ ly I
hour), then the microalloying elemPnt~ dissolve comrletely to form solid .snlllti..ns For the same steel co~ osilion as was used for the previous t~ ;"~Pnt.~, and with a Le-.l~ time curve accol.li,~g to Figure 2 with rolling in the region from 1080~C to 860~C, a tensile strength R,l, of an average of 1040 N/mm2 is obtained. With a method according to Figure 4, that is, rolling in the region between 950~C and 850~C, for the same col"~osiLion, a tensile strength R", of an average of 1230 N/mm2 is obtained, and for a m~thod according to the lell,pel~lur~/time curve according to Figure 6, that is, rolling in the region from 950 to 850~C and rapid cooling of the steel to 550~C, a tensile strength R", of an average value of even 1475 N/mm2 is obtained.
By oFhmi7~hon of the ~r~cess according to Figures 2, 4 and 6, that is, with two-step reh~hng, as well as with ophmi7.ing the steel co~ osilion, a .~i nific~nt i~ ve~l~ent of the . CA 02206349 1997-05-28 , above values for the tensile s~ength and yield point is possible with sim~ neous improve-ment of the to~l~hn~c properties.
STEEL WITH A STABLE ANTICORROSIVE LAYER FOR CONCRETE-REI~FORC~NG
MECMANICAL APPARATUS AND METAL CONSTRUCTIONS ENGINEERING
T~hni~la~a The~l~ ntinventionisc~n~f~rn~ with a meth~l fortheprod~lc~;onofsteelswhich find application in r~ L~a c~J~l~Le ~Llu~ ~_ as well as in the ~AJ~LLw~--tia~3 of ~~him-s an~ d~dLdLll~i~ lly~ the i~ rll~l with a nE~xod for Improving the ~ Lies of ~r~ion--rps;~t~nt steels s~teQfthea~
Theusu~s~uc~s~lshaves~en ~ ofless ~n700 N/n~n2, mos~y~und 500 N/mm2 COrrOSiOn-rP-S;Ct~nt SILU~ Stee1S with df~fin ~ copper c~ntPnt are ~ ;1~3 in WO
95/15405. Such s~X~s are~L~n~ by fi~t h~n~ the b~let m~t~n~l and then, du~ng the cooling process, rolling it at diLr~r~nt L~l~dlu~es, dep~lflin~ on the quali~ to be obl~.nfA
~s~n~e of the ~
The task of the present invention was to prwide co~)sion-re~nt s~eels with r~ved ~n~p~.Lies for the ~LLU~;~ULdL Stee1 area.
This goal was reached by the method de~bed in de~il Ia~er and c~ d in CIaim 1.
A steel which is sl~i~hlP for the ~locess a~ .liag to the invention has the following compocition copper 1.50 to 2.00 weight ~
carbon 0.05 to 0.20 weight %
m~ng~nP~e 1.50 to 1.80 weight %
silicon 0.30 to 0.50 weight %
niobium (coll-ml~i--m) 0.04 to 0.06 weight %
v~n~7;nm 0.035 to 0.05 weight %
molybdenum 0 30 to 0.50 weight %
~ll.. i.~l-............ 0.04 to 0.06 weight %
en 0.015 to 0.02 weaght %
phosphorus ~ 0.03 weight ~
sulfilr < 0.02 weight %
the re_t iron and accolllpally~lg~7~m~nt~
22295~40 .
.
By aUoying the above e~ m~ntC, for ~mrle, up to the total amounts given as ~r~r~lled amounts, a.l,il.~ r known standard steels can be altered so that they are able to form a corrosion-re-si~t~nt layer. Such alloyed steels are suitable for use in the method according to the invention.
I~e l,r.,r~led ~hPmi~l co..~l os;li~ n given above is a ~L~oll~ly pl~r~l.A pr~duct check analysis of the ini~l ,~ 1 to be used in this process. This initial m~tPn~l is produced by mPltin~ and mPt~ rgical ~rP~tm~nt, preferably ~i~pslllr~ n~ vacuum/ladle t~ n~ in the known ~ --~- an~ its check analysis .~h~~ have the c~~ L~ ling ~ - tion accor ;ng to the invention. With thR aid of the ~ol acl crdi~g to the inven-tion an~ using the materi~l with th~ (~ n~ition given above, very high quality can be achiev~d.
The te~ me course of-the six v~ hon~ of the meth~ acconli~g to the invention, as well as the develo~lnellt of the fine grains are shown in the fi~res.
l~lqef des~ tio~ of the r~... ~s Figure 1 shows the t~ ~time rli~ m of a m~thr~ for the ple~ n of structural ste~l of high~er-~Ll~,Lh quality without (with) ~--1~--~1 dis-~nlllti<~n (or .solllhility) of the micro--alloying elements upon r~h~ting.
Figure 2 shows the te~ /'dme ~i~m of a pl~f~led mf~.thod for the produc-tion of struc~ural steel of high-strength quality with degree of ~ .~1vti~n of the microalloying ont~ upon l.~h~t;~.g Figure 3 shows the le ~ /time rli~m of a mPth~l for the pro~uctinn of structural steel of high ~ l, quality wilhuu~ degree of ~1i.c.collltion of the microalloying Plem~ntc upon l~h~ p Figure 4 shows the te ..l~ J~me ~ of a pler~.l~ m-oth~l for the produc-tion of structural steel with very high ~ lh quality with degree of ~ ol~ltinn of the microalloying elçm~ntc upon l~he~ g 222g5-640 ~ CA 02206349 1997-05-28 Figure 5 shows the le",pel~ture/time fli~gr~m of a method for the pro~uct;on of structural steel of very high strength quality without degree of ~ tion of the microalloy-ing ~lem~ntc upon rçh.-~tin~.
Figure 6 shows the temperature/time diagram of a ~ re~d meth~ for the produc-tion of ~hu~;lul~l steel of very high strength quality (best quality) with degree Of ~ ol~ltion of the microalloying el~o-nn~nts upon rçh~tin~.
Figure 7 shows micrographs of the structural steel before rolling ~eft), at a ho11li time of 1000~C for 1 hour and quen~h~l in water (1000~C/1 h(lul/wa~;~) (right) in 100X
m~ nifi~tioll (above) and 500X m~gnifi~tion (bottom).
Figure 8 shows ~e micrographs of the crude rolled state with the plesellce of a submic~scol?;c PÇ~ in Figure 8A with a m~gnifi~*on of 1000X and in Figure 8B with a m~nifi~til n of 10,000X.
Figure 9 shows the micrographs of the quenched steel (1000~C/1 hu~/w~) with the presence of an enlarged submicn~ ic ~ e in Figure 9A with a m~gnifi-~*-~n of 1000X and in Figure 913 with a m~nifil~tion of 10,000X and Figure 10 shows microg~aphs of quP-nchP11 steel (1100~C/1 hou./w~), w_ich shows the increasing ~ ion of the submicroscopic ~ and the ~llcrease of the grain size, where Figure 10A was obtained with a m~gnific~tif n of lOOOX and Figure 10B was obtained with a m~gnific~tion of 10,000X.
The labeled areas in Figures 1 to 6 show ~e following A ~h~ting of normal billet;
B optional r~-h~ n~ of the billet slowly in order to dissolve the alloying ~1...".
better;
C holding time at the dissolution temperature for a period which preferably gives a particle size of 10 to 20 nm and a particle amount of 20 x 10~/mm2;
D rolling region;
E cooling region, preferably slow cooling in a cooling bed;
F cooling from the ~ $olution te~ dLul~ to the initial rolling lelll~ldlult;;G rapid cooling, for example, qu~nching in water after rolling from 850~C to 550~C with subsequent slow or delayed cooling.
Methods for ca,~ out the il-v~ on The method according to the invention is chara~ d by the fact that the initial 1 (billet) is r~h~t~l to a le~ of 1000 to 1080~C, eq~i~lly 1050-1080~C andis then subjected to a normal rolling process at corresponding normal rolling between the rehP~ting temperature and about 850~C (region D in the figures) with ~ulJse~lue~
quiet cooling in the bed. An especially economical method is obtained when the controLted rolling or a ~ lo" ~h~ni~l tre~tm~-nt is avoided.
The initial m~t~ l (billet) is first heated to a temperature of 1050~C to 1080~C(areas A + B in the figures). Lower tempe~,~ es, that is, below about 1000~C are possible while obtaining a similar result, but this is economi~lty less advantageous becau3e here the dissolution rate of the microalloying elem~nh is relatively low.
Preferably, the heating is done to the rehP~ting le"~ aLule at two diLr~r~ rates, ~at is, first, the heating is done at a normal rate to about 850~C (A) and then more slowly to 1050~C to 1080~C (13). During this h~tinp~ phase, already a part of the micr~alloying Pl~m~nt~ goes into solutinn~ for eY~mrl~ V, Nb. It is advantageous, for ~ oses of comp'~ ~ r~ olution of the microalloying rlP.~ present, to keep the steel for a penod of time, which corresponds preferably to the ,~ ~.y dissolution time of about 60 ~ t~ at 1050~C to 1080~C for 16 mm round rod steel, at a le~ above 1000~C, pl~r~al~ly in the range from 1050~C to 1080~C, e~i~lly preferably at about 1080~C (region C in the figures). At this ~e.~ ture, it is possible to reach a pl~rel-ed particle size from 10 to 20 nm and a number of particles of 20 x 106/mm2. Above a~L~ y 1090~C, the g~ain size grow~h is highly ~cPle~te~, so that operation above this l~, pel~tllre becomes critic~ and is preferably avoided.
Then the steel is subjected to a rolling process in the temperature range from the r~oht~ting temperature to a~pro,~imately 850~C (region D in the figures).
In the case of processes for the production of higher-strength qualities (see Figure l), the steel is subjected to a normal rolling process in the ~~ dLulG range from 1050~C to 1080~C to about 850~C (D).
HOWG~e1, high-strength qualities can also be produced with the m~thod according to the invention and the çh~mi~1 steel composition described above. For this pulpose, for PYzlmI~1e, the steel is brought to the r~h~tinf~ dLu-c;in two steps (espe~lly rapidly to 850~C and then slowly to a~çu~ fely 1065 + 15~C) and is kept there for a s 1m~nt1y long time in order to dissolve the microalloying e1Pm.ont~ (at al?pr"~i."~l~1y 1080~C for a~r~;m~t~ y 60 ~ tc~s) whereupon it-is subjected to a normal rolling ~r~ce5s in the lclll~Ld~ulG range from 1050~C, max. 108û~C, to about 900~C (see Figure 2).
However, with the m~od according to the invention, high sll~ ;lll and very high strength qualities can also be produced by ~h~n~ing the rolling co~iti~ns~
The m~th~ for producing high strength and very high strength qualities differs from those for higher strength qualities by the rolling te...lw.,.l...~.
For high-strength qualities or higher strength regions and ~l~pGlLies and thus improved mech~nic~l pr~pe,lies, according to the invention, the rolling is carried out at lower te~"~ s but above 850~C, ~ospe~11y in the range from about 980~C tô about 850~C (Figures 3 and 4, F and D), whereby the fine grain as well as the solid ~l~ n sL~ Ll,Pninf~ effects are Utili7~ WhiCh are inherent in the abovemPntion~ chf~mi~1 co.n~?osilion and are çh~r~c~ri~tic for it.
The cooling from about 850~C to ~mhi.ont ~..1l~.,.1.-.. can be done slowly in resting air, or preferably even with a delay, whereby the delay Su~ and increases the precipi-tation strengthening additionally (see Figures l~, E).
However, qualities up to very high strength can also be produced by carry~ng out the two-step heating to the dissolution temperature of the microalloying elPm~ont and hoklin~
there until complete ~ sollltion to mixed crystals is obtained and the rolling is camed out from appr~,cim~tPly 950~C to ap~ xim~t~ly 850~C (see Figure 4).
Very high strength qualities can also be produced when the steel, be~ se of its ehPmic~l composition, is first cooled in the ~e~ range from 1080~C to ~y~ .ly 980~C (Figure 5, F) and the rolling process is carried out starting from this ~ to about 850~C (Figure 5, D), namely, for very high strength qualities in a r.h~ .t~ ti~ rolling process in as few passes as possible, with a high degree of def,~ l;on and high ~ cily, as a result of which both the fine-grain-strengthenin~ as well as the solid .~lllti~ LJyUlening effects can be utili7f~d, followed and ~u~ ~d by the high action of ~L~;r~ ;on stIPM~h~n-ing, especially by copper, by q ~en~hin~ the steel from the final ro~ing ~ om about 850~C to about 550~C (Figure 5, G), followed by cooling in res~ng air or ~l~f~ly with a delay as a result of which the p~ ;on stren~th~-nin~ is s-l~poll~d even more and is ~nh~nee~l This quality is illlp~l~Ved even further when the two-step heating to the .colntion tem~ldlu-~ of the microalloying elern~nt~ and holciin~ at that lelll~ Ul~ iS
h~ until complete ~ ol~lti<)n to n~i~ed crystals (see Figure 6).
The invention will be e~pl~ined be3ow in more detail with an .
The results listed below are based on a melt which was produced in a high-r~uell~;y electric in~luction furnace with cover for the ~ulpose of possible dep~sii-g with argon te~ g gas and had the following ch~m~ cci.--posiLion in the product che~ analysis:
carbon 0.073%
copper 1.820%
m~ng~n~se 1.740%
silicon 0.341 %
niobi~lm 0.038 %
v~n~ m 0.043%
molybdenum 0.402%
0.048%
gell 0.0209to phosphorus < 0.0020%
sulfur 0.0023 %
However, the melt can also be produced in a convention~l electnc arc furnace, preferably with subsequent vacuum deg~e.~in~/ladle mPt~ rgy. The steels producedaccording to the invention will be ~ign~t~i below as TI-COR.
The development of ~e fine grain at the various ~ l;1;7.;ilg le..~ .t-,s and m~f~nific~tio~ are shown by the mi~;lu~;l~hs in Figures 7 to 10.
The infllTen~ of the ~ e~ ;on telll~UlC on ~e grain size is shown in the following Table 1:
T~ble1 ~-COR ~eel, d~ of~Nn~c~ ~tiontothe~
t~ealment grain ~ize accotding to NFA 0~102 (= ASTU 112) 950'Crl I '~. 7~
1~0-C/1 ~ '~. 7-8 1050~CJl I '~ 7~
1100-CIl I ~ 7 ~ gr~ t ~hc Elenphery llS0-C/lhw./~_ 2-3 ~th~c~n~utoO
This shows that, with the above steel co"l~osiLion, the ~ Pni~ l;on le~ e should be held at a ",~xi",~." of 1080~C in order to provide a fine grain size of 7-8 according to ASTM 112 (= NF A 04-102) and in order to p~c~/ellt rapid subseque~tco~ Pnin~ of the grains at a higher ~".~elature, with a .simn1t~neQusly optimum degree of di.csolution of the microalloying ~l~m~.nt.~ used for the targeted ~ul~03es.
The lcmpe~dlu~e/time ~ gr~m of the v~i~,Ls of structural steel with the same heating and ~lirr~ rolling ch~r~r-t~n~tics is shown in Figures 1 to 6.
The structural steel of the higher strength quality was ob~ined by rolling bclwtcll a~r~"~i"~ely 1080~C and ay~lu~umately 860~C, in the region of the fine-grain-~ g~ n-ing and solid sollltion ~ yu~Lling cnn.s;-l~r~l according to the invention.
~is steel, obtained with the ~e~ dlule profile co~ ollding to Figure 1, has the ~r~lLies listed in Table 2.
Table 2~ - ~u~i~e~
E~unple 1C mm ro~md d~l me~n of m~m 100 ~mples R~ tcn ilc ~ra~gth N/mm~ 8813 889 876 yield point O.1X N/mm~ 613 S 624 S94 R~ yield point 0.2% Nlmm~ 648.7 658 632 A elong~tion ~t bre~ % 20.42 20.6 ~0.1 Z ~ductios~ in~ whcnb~ % 62 70 63.0 62.0 E modulu~ of cbniciy ~N/mm~ 2103 Z17 205 E~ highe~tten ilc trength N . 180,270 191,400 171,000 ~, elon~an befo~e nec~ X 632 9.0 4 0 ~ tot l elong-tionL~, 200 mm !1; 6.61 ~5 4.4 R~tio of ~rength iocre~~ DIN 488m-COR ~teel ~S0/881 N/mm~ ~ +337 N/mm2 _ 613%.
Sllu~ilul~l steel of high-strength quality was obtained by rolling ~.1 980~C and870~C, ~n the règion of the ~ncreased fine~-str~n~th~nin~ and solid soluticn ~L~JyU~
ing considered according to the invention. This steel, which is produced acco~ g to the ~e~ t~ profile shown in Figure ~, has the high I~ n~ lu~ lies shown in Table 3:
, l'able 3~ ~ ~ ~lh aualitie~
E~unple 16 mm rolmd statistic~ll mean of m~rimmn m~imm 100 ~mpl~
R, ten~ilc ~rength N/mm~ 946.2 9S1 938 Rp., yield point O.l~i N/r~ SS4.9 571 54 yicldpoint0.2% N/r~m2 622.5 636 612 ~. elo~pdon Itb~ % 18.84 19.O 18.7 Z reducdon in ~ when b~g % S7.70 oO.O S6.0 E modulu~ of el~icity ~/mm~ 202.70 216 193 F~ hi~hc~t ten ile ~uength N 188,490 196,800 183,000 As elonlpdon befon~ neclcing % 5.95 75 4 S
~1 elong~don Lo 200 ~un ~i 6.47 7.9 4.9 ~do of ~rength incr~ae DIN 488/11-C0R Jteel 550/946 Nlmm~--+396 N/mm2 = 72.0%.
Structural steel of very-high-strength quality was ol~ d by rolling be~w~ll 980 and 870~C, ~e region of the increased fine-~ nin~ and solid.~)~ n ~ in~
considered according to the invention, wi~ sul~sequent rapid coolingl~,~ hi~-~ from 850~C
to 550~C, the region of additional high effect of ~r~i~ ;on sl~nr,ll.e~ espe~11y by copp~r, followed by a resting and/or del~yed cooling to enh~n~e the high p~;p;litl;o~
str~ngth~oning effect introduced by the pr~vious quen~hing, w~ the steel p~u~luced according to the L~~ ule/time ~i~nl of Figure S gave the following me~h~ni~l ~o~llies ~able 4):
22~95-640 Table4: Ve~ h~h~ql~iti~
E~nple 16 n round st~l ne~ of r~n min;m 100 sunpb~
R_ ten ilc ~engtil N/mm2 113S 1247 1069 ~ yield point 0 1% Ntmml 863.0 1017 803 Etp7 yieldpoinlo2!li N/mm~ 9~S 7 1064 863 A elong~tio l ~t bD~ % 17 0 18 5 IS 0 Z reduction in ~ when br~l~ng % 62.3 67 S9 E modulu- of el~ticiq lN/mm2 203 S0 216 182 P~ bighc t tc~lc Ircngtl~ N 222,9ao 237,000 212,~
A~ clong-tionbefore nec~ing % 4.2 S.S 25 l clong~tion L, 200 mrn % 4 7 6 0 3 0 C , DIN 488m-COR Jteel 550/113S N/mm~ = +585 N/mmZ = 106 5%
If the method is carried out with exactly the same steel co~ ~silion which was used for the previous exp~-nm~nt~ but, using the con~ii*on.c given in the le.,l~alul~/time curves according to Figures 2, 4 and 6, that is, with two-step heating, first rapidly to 850~C, and then slowly to 1080~C with a subsequent r~-sidence time at 1080~C (for ~p~ ly I
hour), then the microalloying elemPnt~ dissolve comrletely to form solid .snlllti..ns For the same steel co~ osilion as was used for the previous t~ ;"~Pnt.~, and with a Le-.l~ time curve accol.li,~g to Figure 2 with rolling in the region from 1080~C to 860~C, a tensile strength R,l, of an average of 1040 N/mm2 is obtained. With a method according to Figure 4, that is, rolling in the region between 950~C and 850~C, for the same col"~osiLion, a tensile strength R", of an average of 1230 N/mm2 is obtained, and for a m~thod according to the lell,pel~lur~/time curve according to Figure 6, that is, rolling in the region from 950 to 850~C and rapid cooling of the steel to 550~C, a tensile strength R", of an average value of even 1475 N/mm2 is obtained.
By oFhmi7~hon of the ~r~cess according to Figures 2, 4 and 6, that is, with two-step reh~hng, as well as with ophmi7.ing the steel co~ osilion, a .~i nific~nt i~ ve~l~ent of the . CA 02206349 1997-05-28 , above values for the tensile s~ength and yield point is possible with sim~ neous improve-ment of the to~l~hn~c properties.
Claims (9)
1. Method for the production of structural steel, whereby an initial material is produced which gives the following composition in the check analysis carbon 0.05 to 0.20 weight %
copper 1.50 to 2.00 weight %
manganese 1.50 to 1.80 weight %
silicon 0.30 to 0.50 weight %
niobium 0.04 to 0.06 weight %
vanadium 0.035 to 0.05 weight %
molybdenum 0.30 to 0.50 weight %
aluminum 0.04 to 0.06 weight %
nitrogen 0.015 to 0.02 weight %
phosphorus < 0.03 weight %
sulfur < 0.02 weight %
the rest being iron and accidentally accompanying elements, produced by alloying with alloying elements and subjected to treatment including the following steps:
a) heating to a reheating temperature of 1000°C-1080°C;
b) cooling to approximately 850°C at least partly with rolling;
c) slow and/or delayed cooling to room temperature.
copper 1.50 to 2.00 weight %
manganese 1.50 to 1.80 weight %
silicon 0.30 to 0.50 weight %
niobium 0.04 to 0.06 weight %
vanadium 0.035 to 0.05 weight %
molybdenum 0.30 to 0.50 weight %
aluminum 0.04 to 0.06 weight %
nitrogen 0.015 to 0.02 weight %
phosphorus < 0.03 weight %
sulfur < 0.02 weight %
the rest being iron and accidentally accompanying elements, produced by alloying with alloying elements and subjected to treatment including the following steps:
a) heating to a reheating temperature of 1000°C-1080°C;
b) cooling to approximately 850°C at least partly with rolling;
c) slow and/or delayed cooling to room temperature.
2. Method according to Claim 1, characterized by the fact that the reheating temperature is 1050°C-1080°C.
3. Method according to Claim 1 or 2, characterized by the fact that the heating in step a) is done in two steps, first normally to approximately 850°C and then by slow-down heating to the reheating temperature.
4. Method according to one of Claims 1 to 3, characterized by the fact that after step a) and before step b), the steel is kept at the reheating temperature until complete dissolution of the microalloying elements.
5. Method according to one of Claims 1 to 4, characterized by the fact that the rolling in step b) is done in the temperature range starting from the reheating temperature, especially from 1065°C ~ 15°C to about 900°C.
6. Method according to Claim 5, characterized by the fact that the rolling is done from 1065°C ~ 15°C to about 900°C.
7, Method according to one of Claims 1 to 4, characterized by the fact that the rolling is carried out in the temperature range from about 950°C to about 850°C.
8. Method according to one of Claims 1 to 6, characterized by the fact that the slow and/or delayed cooling to room temperature according to step c) is done starting from 850°C.
9 Method according to one of Claims 1 to 6, characterized by the fact that the steel is quenched directly after rolling in step b), from 850°C, rapidly to a temperature of about 550°C and that then slow cooling begins according to step c) starting from about 550°C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/CH1994/000228 WO1995015405A1 (en) | 1993-12-01 | 1994-11-28 | Fine-grain steels with a stable corrosion-protection coating for reinforcement, mechanical-engineering, equipment-manufacture and construction purposes |
| WOPCT/CH94/00228 | 1994-11-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2206349A1 true CA2206349A1 (en) | 1996-06-06 |
Family
ID=4549356
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2206349 Abandoned CA2206349A1 (en) | 1994-11-28 | 1995-11-28 | Process for producing high quality, fine-grained structural steel with a stable anticorrosive layer for concrete-reinforcing mechanical apparatus and metal constructions engineering |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0795040A1 (en) |
| AU (1) | AU3920995A (en) |
| BR (1) | BR9509829A (en) |
| CA (1) | CA2206349A1 (en) |
| MX (1) | MX9703857A (en) |
| WO (1) | WO1996017099A1 (en) |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4279647A (en) * | 1979-06-18 | 1981-07-21 | Henrik Giflo | Construction steel exhibiting high fatigue strength |
| US4299621A (en) * | 1979-07-03 | 1981-11-10 | Henrik Giflo | High mechanical strength reinforcement steel |
| CA1207639A (en) * | 1983-03-17 | 1986-07-15 | Rodney J. Jesseman | Low alloy steel plate and process for production therefor |
| EP0198024B1 (en) * | 1984-10-30 | 1990-04-11 | TISCHHAUSER, Max Willy | Method for producing prestressed steel |
| CH687879A5 (en) * | 1993-12-01 | 1997-03-14 | Met Cnam Paris Max Willy Tisch | Reinforcement, machine, apparatus and Metallbaustaehle in fines Dumaguete with stable anticorrosive coating. |
-
1995
- 1995-11-28 AU AU39209/95A patent/AU3920995A/en not_active Abandoned
- 1995-11-28 BR BR9509829A patent/BR9509829A/en not_active Application Discontinuation
- 1995-11-28 EP EP95936921A patent/EP0795040A1/en not_active Withdrawn
- 1995-11-28 WO PCT/CH1995/000278 patent/WO1996017099A1/en not_active Application Discontinuation
- 1995-11-28 CA CA 2206349 patent/CA2206349A1/en not_active Abandoned
- 1995-11-28 MX MX9703857A patent/MX9703857A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| MX9703857A (en) | 1998-02-28 |
| EP0795040A1 (en) | 1997-09-17 |
| WO1996017099A1 (en) | 1996-06-06 |
| AU3920995A (en) | 1996-06-19 |
| BR9509829A (en) | 1997-09-30 |
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