CA1038732A - Method for producing a killed steel wire rod - Google Patents
Method for producing a killed steel wire rodInfo
- Publication number
- CA1038732A CA1038732A CA208,726A CA208726A CA1038732A CA 1038732 A CA1038732 A CA 1038732A CA 208726 A CA208726 A CA 208726A CA 1038732 A CA1038732 A CA 1038732A
- Authority
- CA
- Canada
- Prior art keywords
- rolling
- temperature
- finish
- steel wire
- wire rod
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- 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
-
- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/525—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length for wire, for rods
Abstract
Abstract of the Disclosure:
A method for producing high tensile strength steel wire rods and bars having a basic composition comprising;
C 0.02 to 0.20%
Si 0.03 to 0.90%
Mn 1.00 to 1.85%
together with one or more selected from the group consisting of with the balance being the iron and unavoidable impurities, which comprises heating a steel having above composition at a temperature not lower than 1150°C, conducting intermediate rolling and/or finish rolling at a temperature between 700 and 1050°C, controlling the cooling rate from finish of the hot rolling to a coiling to 40 to 350°C/sec., and controlling the cooling rate from the coiling to gathering to 1 to 15°C/sec.
to obtain hot rolled steel wire rods and bars having excellent workability and spot weldability and having a tensile strength not lower than 50 kg/mm2 and a reduction of area not lower than 50%.
A method for producing high tensile strength steel wire rods and bars having a basic composition comprising;
C 0.02 to 0.20%
Si 0.03 to 0.90%
Mn 1.00 to 1.85%
together with one or more selected from the group consisting of with the balance being the iron and unavoidable impurities, which comprises heating a steel having above composition at a temperature not lower than 1150°C, conducting intermediate rolling and/or finish rolling at a temperature between 700 and 1050°C, controlling the cooling rate from finish of the hot rolling to a coiling to 40 to 350°C/sec., and controlling the cooling rate from the coiling to gathering to 1 to 15°C/sec.
to obtain hot rolled steel wire rods and bars having excellent workability and spot weldability and having a tensile strength not lower than 50 kg/mm2 and a reduction of area not lower than 50%.
Description
~1~3~732 ~ ~ ~
The present invention relates to a method for produc~
ing a killed steel wire rod ~including bar) having a tensile strength of 50 kg/mm2 to 70 kg/mm2 as hot rolled and having excellent workability especially cold-working cold-forging and ~;
drawability and spot weldability. Descriptions will be made for steel wire rods and bars all together.
Up to now, various trials have been made and proposed ;
for development of a steel wire rod having high strength and excellent toughness as hot rolled. However, strength is gene-rally incompatible with toughness and weldability, and a steel material having both high strength and excellent toughness is ;
hard to obtain by an ordinary rolling. Meanwhile a low carbon steel wire rod as rolled shows a tensile strength of 30 to 45 kg/mm2, and a high carbon steel wire rod having 70 to 110 kg/mm2 tensile strength is poor in workability and weldability. Pro--posals have been made for lmprovement of the as-rolled structure ~of steel materials as for means~for improving these incompatible .
properties. Among these proposals in~the field of a high~
carbon s;teel wire rod, the development of technics of obtaining ;~
a sor~ite structure having excellent wire~drawability by adjust-ment of the cooling rate after hot rolling is very important for the~production technics ~or steel wire rods. In case of a low-carbon steel material, addition of alloylng elements is essential for increasing the strength, and various trials have `
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been made such that elements such as Si, Mn and Cr are added for improving hardenability, and special elements such as Nb, Ti and V are utilized so as to improve both strength and toughness. However, it has never been proposed or tried to `~
control the cooling of a low-carbon alloy steel wire rod contain- ~
ing the above elements after hot rolling. Much less, it has ~ -never been tried to control the rolling temperature in addition `~
.
The present invention relates to a method for produc~
ing a killed steel wire rod ~including bar) having a tensile strength of 50 kg/mm2 to 70 kg/mm2 as hot rolled and having excellent workability especially cold-working cold-forging and ~;
drawability and spot weldability. Descriptions will be made for steel wire rods and bars all together.
Up to now, various trials have been made and proposed ;
for development of a steel wire rod having high strength and excellent toughness as hot rolled. However, strength is gene-rally incompatible with toughness and weldability, and a steel material having both high strength and excellent toughness is ;
hard to obtain by an ordinary rolling. Meanwhile a low carbon steel wire rod as rolled shows a tensile strength of 30 to 45 kg/mm2, and a high carbon steel wire rod having 70 to 110 kg/mm2 tensile strength is poor in workability and weldability. Pro--posals have been made for lmprovement of the as-rolled structure ~of steel materials as for means~for improving these incompatible .
properties. Among these proposals in~the field of a high~
carbon s;teel wire rod, the development of technics of obtaining ;~
a sor~ite structure having excellent wire~drawability by adjust-ment of the cooling rate after hot rolling is very important for the~production technics ~or steel wire rods. In case of a low-carbon steel material, addition of alloylng elements is essential for increasing the strength, and various trials have `
-:.. . . .
been made such that elements such as Si, Mn and Cr are added for improving hardenability, and special elements such as Nb, Ti and V are utilized so as to improve both strength and toughness. However, it has never been proposed or tried to `~
control the cooling of a low-carbon alloy steel wire rod contain- ~
ing the above elements after hot rolling. Much less, it has ~ -never been tried to control the rolling temperature in addition `~
.
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~r ~93~ 2 so to develop a steel wire rod of good structure having desir-able workability.
One of the objects of ~he present invention is to provide a method for producing a high-strength steel wire rod having a structure of good wor~ahility by controlling the temperature of the rolled steel material and also controlling the cooling rate after the finish rolling, and the steel material obtained by the present invention is useful for high-strength bolts PC wire, metal networks, umbrella ribs, spring 10 washers and springs. ~
Another object of the invention is to provide a ,~ ~ -method for producing high tensile strength steel wire rods and ~,~; - -bars having a basic composition comprising~
C ~ 0.02 to 0~20% -Si 0.03 to 0.90% -~, .
- Mn 1.00 to 1.85%
together with one or more selected from the group consisting of : - .:
~b ~ 0~05%
V c 0.08%
Tis 0.25%
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~ Zr0.30% ~;~
';;
Cr 5 0~40%
B ~ 0.005%
with the balance being the iron and unavoidable impurities, ~-which comprises heatlng a steel having above composition at a temperature not lower than 1150 C, conducting at least one of an intermediate rolling and a finish rolling at a temperature between 700 and 1050 C, controlling the cooling rate from :~
~inish of the hot rolling to a coiling to 40 to 350C/sec, and controlling the cooling rate from the coiling to gethering to 1 to 15 C/sec. to obtain hot rolled steel wire rods and bars ~ -3-~,~ ,. .
.
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~L~3~32 having excellent workability and spot weldability and having a tensile strength not lower than 50 kg/m~ and a reduction of area not lower than 50%.
The steel wire rod according to the present invention shows both high strength and excellent toughness, so that it -~
is possible to obtain a product having a similar or better .
quality than that of a conventional product obtained by a ~
secondary working (mainly o~ heat treatment) even when the ~ -secondary working of the wire rod is considerably omitted. .;~
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This gives very significant advantages. For example, in case .;~
of producing hlgh-strength bolts of 80kg/mm2, the conventional practice is as follows. A high-carbon steel wire rod, such as a plain carbon steel containing 0.45% C is subjected to cold .
: wire drawing to a required size, then to a spheroidizing ~
::~ : , ' `' : ~ annealing so as to facilitate cold-forgingability to skin-pass ; : : working to heading ;, ~
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and threading works into bolt shape, to water or oil quenching and lastly to tempering to obtain 80 to 110 kg/mm strength.
Whereas, in case of the wire rod according to the present invention, the wire rod as hot rolled is subjected only to slight skin-pass drawing into a required size, and then to heading and threading works, thereby a bolt having 80 to 100 kg/
mm2 of tensile strength without any defect can be obtained, and heat treatments such as spheroidizing annealing, quenching and `~
~ tempering can be omitted and thus high level of economy is assured.
Further, when the present invention is applied to pro-duction of PC wires (prestressed concrete wires) it is sufficient ~ -: . , that~the wire rod of the present invention is subjected only to slight skin-pass drawing and shape working including indent work for application in prestressed concrete products for example, and `~
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thus the patenting heat treatment which is conventionally done ---;
can be omitted. Yet a wire having high tensile strength and very excellent spot weldability can be obtained.
Detailed descriptions will be made on the method of the ~ present lnvention First, regarding the chemical composition of the wire rod according to the present invention, it contains as basic elements 0.02 to 0.20% C~ 0.03 to 0.90/O Si and l.00 to 1~85% Mn ;
together with one or more of not more than 0.05% Nb, not more than 0 . 08% V~ not more than 0.25% Ti, not more than 0.30/O Zr, not more than 0,005% B and not more than 0.40% Cr, and contains A~
in an amount as contained in an ordinary killed-steel with the -balance being iron and unavoidable impurities.
The lower limit of 0.02% for carbon has been set for -the reason that if the carbon content is less than 0. 02% strength is lowered and desired results can not be obtained, while if the carbon content is beyond 0. 200/o workability and spot weldability lower and thus the upper limit set at 0. 20~/o.
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Si is a deoxidizing element and also is effective to increase strength by soLid solution hardening. For this purpose it ls added up to 0.90/O, beyond which workability lowers and uneconom-ical. The lower limit is set at 0~03% which is necessary for ~, deoxidation. ~ i Mn is an element effective to improve hardenability ~ .
and contributes to facilitate the bainite hardening during cool-ing after the finish rolling and to convert and refine a bainite { -~
structure of the steel matrix, and to improve toughness. The .., 10~ lower limit of Mn is set at 1.00% because below this limit the above effects can not be obtained and the upper limit is set at 1.85% from the consideration for minimizing adverse effect by the ; ~ manganese segregation as well as economy.
Nb, V, Ti and Zr, as described hereinafter, are added for the purpose of forming their carbldes and nitrides and preci~
; pltating them finely during the rolling to suppress recrystalliza-tion~of austenite~grains of the wlre rod durlng the hot rolling ~so as to refine the ferrite-pearlité or bainite structure produ-ced during the cooling step, as well as for the purpose of increas-20 ~ ing strength by precipitatlng the carbides and nitrides super- , flnely. ;The carbides and nitrides of~these elements must be dis-solved in solid solution into the steel matrix during the blllet heating prior to the rolling of the wire rod and for this purpose, it is necessary to heat the slab at a temperature hlgher than ~;
11SOC. The upper limits of these elements are set in view of the contents of C and N in the steel and from the economical point.
Cr is added in a small amount for improving hardenability, ~ ,~
but as shown in the examples Cr nee~ not be added in case of a wire rod of ~imall diameter. However, it is desirable to add Cr in an amount not more than 0.40~/O in case of a wire rod of diameter more than about 8 mm. The upper limit of 0.40% in this case is 2t from the reason that Cr addition beyond this limit will not pro-, .. . . .
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duce any remarkable effect and result only in uneconomy.
B is also added for the purpose of improving harden-ability, and its addition ls defined to -the minimum amount nec- -essary for this purpose.
Ti is necessary to attain fully the effect of B, but Ti is added in the present invention for attaining precipitation ~;
hardening by precipitation of fine titanium carbide and nitride, ~;
increasing strength through refinement of the grains and improv~
ing weldability, The upper limit of Ti is set at 0.25% from the ~-limitation in the heating temperature prior to the wire rod roll-ing as well as from the economical point. ;;
Also in the present invention, it lS desirable to main- ~-tain Ceq not higher than 0,55 so as to assure excellent spot weld~
ability. ~ -Next, descriptions will be made below on the rolling method of the present invention `~
In general, the billet heating temperature for the wire~
rod rolling lS ~lower than that for the rolling of other products, and i5 usuaLly between 1050 and lI50C However, in the present ~ inventlon, the billet heating temperature;should be not lower than~1150C,~preferably not lower than l200C in order to assure ~complete~solld solut1on of the precipitates so as to~fully atta1n ;~
the precipitation hardening due to the carbides and nltrides of Nb, ; --V, Ti, Zr and B
In the present invention the rolllng temperature is con-trolled as under.
;
In case of a wire rod rolling, a cooling device is not `
generally used during the rolling and the rolled material is cool- ;
ed gradually by a small amount of cooling water in the air, but in the step of finish rolling, the temperature of the rolled rnater- `
ial is raised by the heat of plastic working due to increased ;~
rolling speed, (This ordinary rolling method is called as OR here-,. ... . . . . . . ..
.: ~ ,. . ., . ~ :
,' ;
inafter). One of the features of the presen-t invention lies in ,~
that the temperature of the steel material during the rolling is `~
controlled by a suitable cooling device. (This method is called as CR hereinafter). In this case, the cooling device must have ~ ~
a cooling capacity large enough to cool the s-teel to a prescribed '~ -temperature in a short time because the rolling speed is high, ~
and must be capable to adjust cooling in association with a ther- `; ;
mometer. , .
The present invention will be described in more details ~l0 ~ referring to the attached drawings. ,~
Fig l shows the temperature control during the wlre rod (8 mm diameter) rolling, Fig, 2 shows relations between tensile strength and reduction of area of the wire rod as rolled.
Flg, 3 shows relations between the~finish outlet temper~
-ature and tensile~strength yi~eld point and drawabllityO
Fig 4 shows similarly relations between yleld point and re1axatlon-loss.
Pig, S is a microphotograph ( x200) of the wire rod 20~ ~ obtained by the present invention.
FlgO 6 lS a graph showing transition curves of impact ~values.~
Fig. 7 is also a graph showing transition curves of ~ `' .
impact values.
Now referring to Fig. l which shows one embodiment of the continuous rolling apparatus for conducting the controlled - rolling according to the present invention, the rolling apparatus includes a rough rolling mill of 7 stands a first intermediate rolling mill of 6 stands, a second intermediate rolling mill of 2 stands and a finish rolling mill of l0 stands. In the finish rolling mill, 8 stands are used for production of wire rods of `
8 mm diameter, and four stands are used for production of wire -\ :
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rods of 13 mm diameter. The billet size is llS mm square, and 18 m length. The size of the intermecliate products is 24 mm diameter at the stand No. 13 and 20 mm diameter at the stand No. ~ ;
15. ;
No 3 shows the ordinary rolling (OR) in which the - `
heating temperature is set at 1200C, and the temperature of the rolled material gradually lowers from the rough rolling to the second intermediate rolling and gets about 930C at the finish ;- ~ -inlet, but increases when the rolled material enters the finish ;
10 rolling mill group and gets a finish temperature of about 1005C. .
No 21 is an example of OR in w~ich the heating temperature is 1085C, and relatively lower than in No. 3, but almost same ten~
dencies take place. No 2 lS an example~of the controlled roll- ;~
ing (CR) in which the heating temperature is 1150C and a cooling device is provided between the first intermediate rolling mill ;
stand group and the second intermediate rolling mill stand group and~between the~second intermedlate rolling mill stand group and the~finish rolling mill stand group to adjust the cooling and coo~l the rolled material to a prescribed temperature. Namely thé
20~ same procedures are taken untiI the rolled material passes the flrst~intermedi~ate rolling mill stand group as in case of OR, but after the~staDd No. 13, the rolled materlal is cooled to 910C i~
and rolled by the~second intermediate rolling mill, cooled to 810C after the stand No. 15, enters between the finish rolls and finished at 860C. ;~
No. 20 is an example of CR in which the temperature of l~ -the rolled material is further lowered and the material enters the -~ ~
:; , finish rolling mill stand group at 750C. The results obtained by the example will be described hereinafter.
For the object of the controlled rolling, the heating temperature should be not lower than il50C and is desirable as high as possible, but in view of limitations such as the capacity --8~
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and structure of a heating furnace, and from considera-tions for oxidation and decarburization, the upper limit of the heating tem~
perature ls set at 1200C ln this example, because excesslvely hlgh temperature is not economlcal. During the rolling, the above mentloned nltrldes and carbides begln to preclpltate as the temp-" . . , erature lowers but not so much around 1000C. The austenite phase ;of the steel material is converted into a worked structure by the rolllng, but immediately recrystallizes because the temperature lS high enough and is converted l* worked structure by the next ; lO rolling and then recrystalllzes. Thls procedure lS repeated at each of the rolllng mill stands and ln this way the rolling is proceeded. The present inventors have studied the above structu- ~;
ral changes by investlgating the intermedlate material having~a freed~structure~caused by quenchlng ln the course of a rolllng, and~have found~that the~carblde and nltrlde formlng~ elements such as~Nb delays the recryatalllzation, and that the recrystalllzatlon~
proceeds lmmediately at a rolllng~temperature above about 910C, but~the~structure~remalns as nan-recrystalllzed phase below~9lOC.
It is predlcted~that this temperature va~rles dependlng on the 20~ rolllng speed, namely passlng time between the stands, but the recrystallizatlon;is n~ot caused during the pass~tlme (;about 6 seconds)~between the stand No. 13 and;the stand No. 14 and between the stand No.;15~and the~stand No, 16, and the boundry temperature~
for the recrystallization and~the non-rearystallization at the ,~
pass time of 6 to 6.5 m/sec. over the~stand No. 15 is about 910C. ;~
It is very important to know what temperature would be thls boundary temperature ln the flnish rolllng mlll stand group where the rolling speed ls larger. Slnce the rolling tlme (pass tlme between stands) is short, namely because the strain rate is high, this boundary temperature is considered to be higher than 910C, but it is difficult to confirm by experiments whethér the recrystallized austenite grains are formed or not. Therefore, _g~
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the present inventors classified'the finish rolled wire rods in- `
to the structure in which the worked structure remains and the '' structure in which the worked structure is not retained through ;~
observation of their micro-structures, and investigated them ln ;~
connection with -the finish inlet t~mperature, and found the work- '~
ed structure retains when the finish inlet temperature is not "' higher than 910C even if the finish temperature higher than ~-910C, and thus discovered that if adjustment is rnade in the ' preceding stands so as to maintain the temperature at the stand ~' ~o. l~, namely the finish inlet temperature not higher than 910C, , ' the rolling is regarded to be within the non-recrystallization zone, This technical thought provides means applicable to other `~
type of rolling mills, For this purpose, the rolling degrees in '~
this example are shown as under. The rolling degree from the slab of 115 mm diameter to the intermediate rod of 20 mm diameter' '~
finlsh inlet) is about 97% in the recLuction of area, the rolling degree from the intermediate rod of 20 mm diameter to the final ' product of 8 mm diameter is 84%, and the degreé from the inter-medlate rod of 20 mm diameter to the final product of 13 mm ''''~
diameter is 60%, and the pass times in the finish rplling mill '~ ' ~stand group is 8 passes for the rolling from the 20 mm diameter i''~
to the 8 mm diameter, and 4 passes for the rolling from the 20 mm diameter to the 13 mm diameter.
Descriptions will be made on the method of cooling -' .: - :
aftex the rolling.
The cooling of the wire rod after the finish rolling -~
is divided into two steps, in the first step the surface temper-ature is cooled by about 100 to 300C within a few seconds using a leading and cooling device equipped with pipes filled'with water as used in the wire rolling mill and the wire rod is coiled to a desired temperature between 850 and 600C, and in the second step t'he cooling is done at an adequate rate between 1 and 15C/sec.
, ,., . . . ;
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~;931~32 using a uniform cooling device such as disclosed in the Japanese -~
patenk publica-tions Sho 42-15463 and Sho 42-18894 and the coil is gathered. Thus, the cooling rate after the finish rolliny is 2 to 15C/sec. in average through the first and second steps.
The effects of the above cooling procedure are des~
cribed hereinunder.
The fine austenite grains are obtained by the control-led rolling as above, and yet in the course of transformation of the austenite into a ferrite-pearlite or bainite structure, the structure gets finer if the cooling rate is increased, thus impro~
ving strength and toughness, Meanwhile the nitrides and carbides ;~
precipitated on the dislocation, which is induced in the hot roll~
ing are coherent with the ferritic matrix and these precipitates ~ ;
;~ harden the ferrlte phase remarkably. This precipitation varies depending on the cooling rate and thus it~ ls~very important to ad]ust the cooling~rate. Namely, the adjustment of cooling has two distinctive metallurglcal slgnificances as above.
Mechanlcal properties and metallurgical features of the ~ .
~ ~ hot rolled wire rod obtained by the above method are explained 20 ~ ~ hereinunder.
Table l~shows chemical compositions, the relation bet-. .:
ween the rolling method and temperature and mechanical properties.
Figs. 2, 3 and 4 show respectively the relation between tensile strength and reduction of area, ~etween tensile strength and yield :~
point, and between tensile strength and the finish outlet temper- -ature.
A11 of the steels of the present invention were prepared in LD convertor, but there is no special limitation in the steel- `~
maki~g method.
From the relation between tensile strength and drawing shown in Yig. 2, it is understood the steel of the present inven-tion has considerably high strength and high ductility even when ":
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rolled by the ordinary rolling method. Namelyt the steels No. 1, No. 2, No. 25 and No. 27 show tensile strength of about 55 to 90 kg/mm and drawability of 77 to 70% as compared with tensile , '~
strength of S5 to 70 kg/mm and drawability of 65 to 55% of an ,~ -ordinary carbon steel and thus these steels show relatively high drawability in comparison with the tensile strength. sy compari- ~" -~
son of the steel No. 1 with the steel No.3,and comparison of the steel No~ 21 wlth the steel No.18, it is clear that the increased , ,~
heating temperature increases strength even in case of the ,; ,' ordinary rolling material~
In Fig, 2, the CR materials are related by the arrow -' mark to the OR materials. T'he steel No, 2 shows only slight ~ ~- ,' effect or CR due to the low heating temperature of 1150C, but '~
shows improvement of yield point as shown in~Fig. 3. Steels No. `' ;~
4 and No. 5 show remarkable increase of drawability, and these '~
steels show remarkable improvement of workability instead of slight increase of yield point (see Table 3). This is due to the '~
fact that the intermediate rolling temperature was set in the !'~'' ~'`'.~'' order of 700C and the finish temperature was lowered as shown in ~ Fig. 4.
2~ Steels No. 19 and No. 20 are exanples in which the in~
termedlate rolling temperature was set in the order of 800C so ~ as to increase strength without lowering drawability. The impro~
; ~ vement of strenght of drawability of the steels No. 26 and No.
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28 attained by CR is remarkable.
Fig. 4 shows effects by the finish outlet temperature. `- , The finish outlet temperature of the OR material is about 1000C ', and that of the CR material is about,950 to 780C. In case of the CR material, it is clear that tensile strength and yield point lower and drawability increases when the finish ou-tlet temperature is below 850C. It is between about 850 and 950C that tensile strength and yield point increase while reduction of area does not chan~eO Thus there is difference in the effect by the -12~
i ! ; ' ` i'~ ' '' ,, ' ', : '.'. ' ' intermediate rolling temperature between the order of 700C and the order of 800C (including 910C). Similar tendencies are seen even when the rolling size is 13 mm diameter , but it is generally noticed that the heat due to the plastic working varies depending on th~ reduction amount and the rolling speed in the finish rolling line.
The fact that the steel of the present invention has always higher reduction of area than the ordinary material hav~g the same level of strength is mainly due to the effect by the re~
finement of the ferrite-pearlite structure as shown in Fig. 5.
The ferrite grain size obtained by the controlled rolling temper~
~; ature is a very fine grain having a grain size number larger than ;
; No, 10.
; Fig~ 6~shows the transition cur~es of Charpy impact -`
values, and lt~iS clearly shown-by thls~flgure that the transition temperature is lowered remarkably by the controlled rolling temp-~
erature.
Examples of application of the present lnVention for hexagonal bolts are shown in Table 3 and Table 4. `.
~:20;~ The bolt strength is just t~e .same or higher than the -~
tensile strength of the wire, and completely no breaking of head ;~
was caused in the wedge~test ~angle: 10). Also the~fatigue limit under pulsating stress is very high, Further, ~torque tests were conducted using nute and the results were that rupture was caused at the tllread and thus the bolt~strength was satisfactory. ;
From the above various tests, it has been found the bolts made by the steel wire rod o the present invention have similar or better quality than the conventional quenched-tempered bolts, and thus the excellent quality of the wire rod of the present in-vention has been confirmedO
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0~ ~ pl;.: 0 ~ 0~ 0 0 0 ~0 0 O 11 ~ ~ c,) ~ 0 0 0 0 0 0 0 O ~:
: ': ~ : ' ~ ~ t~
~ ~ ~ 0~ ~ 0 ~ ~ 0 ~ ~ ~ Lr~
X '~: ~ ~ LO u) ~I
~ : r ~ ~I r-¦r--I r--¦ r--I ~ ~ x; ~ :
l In ~) ~ OU~ U~~ U~ :-' ~r-l 0 ~r~ 0 lO~ ~) ~I
a) , ~n . ~ .. . . . . . ~u . :;~: ; . .-r--¦ 0 00 0 0 0 0 O
(~ ~
Dr-l10 r-ldr t~ ~ i;,~ :
O Or Ir l r-lr--l r~l O : . ::
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~38~32 Table_1 - (21 con-t ' d .. ~ . .
Steel Ser-Chemical Composition (W-t %) Deslg- lal .__ . .
nation No. C Si Mn P S Al Ti Nb V
A 1 1 0.06 0.73 1.61 0.021 0.018 0.004 0.19 - -2 ll ll . ._ _ . - : " . .
A 2 3 0.07 0.78 1.52 0.021 0.004 0.004 0.23 - -~ . _ ,' '~
B 160.16 0.86 1.58 0.024 0.019 0.030 0.18 - -17 ll ll . __ ~ . -, 18 0.13 0.26 1.33 0.024 0.004 0.028 - 0.037 -,C 1 19 ~ ~ , . '~
" "
21 " "
~ . -- ~ ~
22 1.33 0.024 ~4 " "
. : ~ ,_ .. .. _._. ~ . .
D 1 25 ~ 0.13 0.26 1.28 0.023 0.005 0.025 - 0.010 0.020 26 ~ ~
. . . _ , _,, _ _ _ :~
D 2 27 0.11 0.20 1.20 0.025 0.003 0.010 - 0.010 0.020 ~ ~ -28 ll ll `
~:._. . _ - ---- ~--- ---- ~--D 3 29 0.12 0.22 1.26 0.024 0.018 0.015 ~ - 0.010 0.025 ~ ~
- . __ ,, _ , _ . ,, _ ,,. ~ . ~ , E 30 0.10 0.25 1.25 0.024 0.015 0.010 0015 0.015 -.. , : _ ._ _ , . ~ : ~
F 31 0.11 0.23 1.24 0.023 0.013 0.015 - 0.015 - ~ ~
. _ . . __ , _ ........... _ ._ . . _ ,~
G 32 0.12 0.24 1.26 0.018 0.018 0.018 - - 0.05 ..... _ . ,;
I 34 0.15 0.23 1.28 0.024 0.020 0.018 - - -. .
, . . . . .
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, . . .
- ~3~,'~2 :
Table 1 - (2) (cont'd from page 15) cont'd --..... ... . _._ . . .... _ _ _ . . . . . . ~
Steel Ser- Chemical Comp- Rolling Roll- Rolling Rolling Tempera- ~ :
Desig- ial osition (Wt %) Size ing Speed ture (CL_ _ l nation No. Zr N (mm ~) Method (M/S) Heating 13~--~ _ . ..... .. ..
: A 1 1 _ 0.0047 8 OR 20 11501000 :
2 " CR 910 ~ ;~
. ~.. _._._ - . _ ._ _ .: ~ .
A 2 3 - 0.0040 8 OR 201135 1020 : 4 " CR. 1190920 .~ CR 1190870 , ., _ ~ , _ ;~' l B 16:_ 0.0045 8 OR 34 1200980 i~ ~
: ~ 17 " CR "~ 970 ~ ~ :
. . ''~
18: - 0.0046 8 OR 34 1200980 : I
C 1 )L9 1l CR " 990 : 20 " CR 20 930 i :¦ 21 ll OR 34 1085 960 -- :
: ~C 2 :23 : ~ I CR ~ ,i 990 24 " ~; CR ;~10 930 :: : ;~~ ~: ~ , --D 1 25 -0.0084 8 OR ~20 1170 950 26 ~ " ~CR ~;: 1200 850 , ~: ~ .-, ~ ~ : : - : : .
~D 2 27 - 0.0068 8 OR 20 1160 960 : ~ :: 28 " CR 1200 : 880 ~ , :
: : ~ ~ ~ - ~ ~ :
: - D 3 29 - 0.0045 I 8: : CR 20 1200 880 ~;
E ~ 30 - 0.0055 ¦ 8 CR 20 1200 890 ; '' i i F 31 0.300.0050 I 8 OR 20¦ 1200 885 . .~' :
G 32 _ 0.0075 I 8 CR : 201 1200 850 , :
I 34 0.180.0050 , 8 CR 201200 885 .:.-~
Remarks OR : Ordinary Rolling ~.
CR : Temperature-Controlled Rolling - , .
. .
Table 1 - (2) (cont'd from page 16) r Rolling Coil- Tensile Properties = I
Temperature ing --~ ~ Reduc-Iser (C) Temp Yield Tensile Elonga- tion ¦ial Fin-~h--Flnlsh era~r~ Point 2 Streng~h tion of Area Yield ~o. 15# Inlet Outlet (C) (Kg/mm )(Kg/mm ) (%) (%) Ratio :
. ........ . _ 1 920920 g80 750 48.6 70.0 24.0 69,8 0.69 l `
2 810800 860 700 60.3 72.0 26.7 70.4 0.84 , .. , ~ _ '' .~ ,,
~r ~93~ 2 so to develop a steel wire rod of good structure having desir-able workability.
One of the objects of ~he present invention is to provide a method for producing a high-strength steel wire rod having a structure of good wor~ahility by controlling the temperature of the rolled steel material and also controlling the cooling rate after the finish rolling, and the steel material obtained by the present invention is useful for high-strength bolts PC wire, metal networks, umbrella ribs, spring 10 washers and springs. ~
Another object of the invention is to provide a ,~ ~ -method for producing high tensile strength steel wire rods and ~,~; - -bars having a basic composition comprising~
C ~ 0.02 to 0~20% -Si 0.03 to 0.90% -~, .
- Mn 1.00 to 1.85%
together with one or more selected from the group consisting of : - .:
~b ~ 0~05%
V c 0.08%
Tis 0.25%
: :. ~ .
~ Zr0.30% ~;~
';;
Cr 5 0~40%
B ~ 0.005%
with the balance being the iron and unavoidable impurities, ~-which comprises heatlng a steel having above composition at a temperature not lower than 1150 C, conducting at least one of an intermediate rolling and a finish rolling at a temperature between 700 and 1050 C, controlling the cooling rate from :~
~inish of the hot rolling to a coiling to 40 to 350C/sec, and controlling the cooling rate from the coiling to gethering to 1 to 15 C/sec. to obtain hot rolled steel wire rods and bars ~ -3-~,~ ,. .
.
,: ';
,, , , , : ~
~L~3~32 having excellent workability and spot weldability and having a tensile strength not lower than 50 kg/m~ and a reduction of area not lower than 50%.
The steel wire rod according to the present invention shows both high strength and excellent toughness, so that it -~
is possible to obtain a product having a similar or better .
quality than that of a conventional product obtained by a ~
secondary working (mainly o~ heat treatment) even when the ~ -secondary working of the wire rod is considerably omitted. .;~
,,:~ . .
This gives very significant advantages. For example, in case .;~
of producing hlgh-strength bolts of 80kg/mm2, the conventional practice is as follows. A high-carbon steel wire rod, such as a plain carbon steel containing 0.45% C is subjected to cold .
: wire drawing to a required size, then to a spheroidizing ~
::~ : , ' `' : ~ annealing so as to facilitate cold-forgingability to skin-pass ; : : working to heading ;, ~
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and threading works into bolt shape, to water or oil quenching and lastly to tempering to obtain 80 to 110 kg/mm strength.
Whereas, in case of the wire rod according to the present invention, the wire rod as hot rolled is subjected only to slight skin-pass drawing into a required size, and then to heading and threading works, thereby a bolt having 80 to 100 kg/
mm2 of tensile strength without any defect can be obtained, and heat treatments such as spheroidizing annealing, quenching and `~
~ tempering can be omitted and thus high level of economy is assured.
Further, when the present invention is applied to pro-duction of PC wires (prestressed concrete wires) it is sufficient ~ -: . , that~the wire rod of the present invention is subjected only to slight skin-pass drawing and shape working including indent work for application in prestressed concrete products for example, and `~
.. ~ ~ , .
thus the patenting heat treatment which is conventionally done ---;
can be omitted. Yet a wire having high tensile strength and very excellent spot weldability can be obtained.
Detailed descriptions will be made on the method of the ~ present lnvention First, regarding the chemical composition of the wire rod according to the present invention, it contains as basic elements 0.02 to 0.20% C~ 0.03 to 0.90/O Si and l.00 to 1~85% Mn ;
together with one or more of not more than 0.05% Nb, not more than 0 . 08% V~ not more than 0.25% Ti, not more than 0.30/O Zr, not more than 0,005% B and not more than 0.40% Cr, and contains A~
in an amount as contained in an ordinary killed-steel with the -balance being iron and unavoidable impurities.
The lower limit of 0.02% for carbon has been set for -the reason that if the carbon content is less than 0. 02% strength is lowered and desired results can not be obtained, while if the carbon content is beyond 0. 200/o workability and spot weldability lower and thus the upper limit set at 0. 20~/o.
:, ~, ~ ' . ', . , ~3~73~
Si is a deoxidizing element and also is effective to increase strength by soLid solution hardening. For this purpose it ls added up to 0.90/O, beyond which workability lowers and uneconom-ical. The lower limit is set at 0~03% which is necessary for ~, deoxidation. ~ i Mn is an element effective to improve hardenability ~ .
and contributes to facilitate the bainite hardening during cool-ing after the finish rolling and to convert and refine a bainite { -~
structure of the steel matrix, and to improve toughness. The .., 10~ lower limit of Mn is set at 1.00% because below this limit the above effects can not be obtained and the upper limit is set at 1.85% from the consideration for minimizing adverse effect by the ; ~ manganese segregation as well as economy.
Nb, V, Ti and Zr, as described hereinafter, are added for the purpose of forming their carbldes and nitrides and preci~
; pltating them finely during the rolling to suppress recrystalliza-tion~of austenite~grains of the wlre rod durlng the hot rolling ~so as to refine the ferrite-pearlité or bainite structure produ-ced during the cooling step, as well as for the purpose of increas-20 ~ ing strength by precipitatlng the carbides and nitrides super- , flnely. ;The carbides and nitrides of~these elements must be dis-solved in solid solution into the steel matrix during the blllet heating prior to the rolling of the wire rod and for this purpose, it is necessary to heat the slab at a temperature hlgher than ~;
11SOC. The upper limits of these elements are set in view of the contents of C and N in the steel and from the economical point.
Cr is added in a small amount for improving hardenability, ~ ,~
but as shown in the examples Cr nee~ not be added in case of a wire rod of ~imall diameter. However, it is desirable to add Cr in an amount not more than 0.40~/O in case of a wire rod of diameter more than about 8 mm. The upper limit of 0.40% in this case is 2t from the reason that Cr addition beyond this limit will not pro-, .. . . .
' ~3~73~
duce any remarkable effect and result only in uneconomy.
B is also added for the purpose of improving harden-ability, and its addition ls defined to -the minimum amount nec- -essary for this purpose.
Ti is necessary to attain fully the effect of B, but Ti is added in the present invention for attaining precipitation ~;
hardening by precipitation of fine titanium carbide and nitride, ~;
increasing strength through refinement of the grains and improv~
ing weldability, The upper limit of Ti is set at 0.25% from the ~-limitation in the heating temperature prior to the wire rod roll-ing as well as from the economical point. ;;
Also in the present invention, it lS desirable to main- ~-tain Ceq not higher than 0,55 so as to assure excellent spot weld~
ability. ~ -Next, descriptions will be made below on the rolling method of the present invention `~
In general, the billet heating temperature for the wire~
rod rolling lS ~lower than that for the rolling of other products, and i5 usuaLly between 1050 and lI50C However, in the present ~ inventlon, the billet heating temperature;should be not lower than~1150C,~preferably not lower than l200C in order to assure ~complete~solld solut1on of the precipitates so as to~fully atta1n ;~
the precipitation hardening due to the carbides and nltrides of Nb, ; --V, Ti, Zr and B
In the present invention the rolllng temperature is con-trolled as under.
;
In case of a wire rod rolling, a cooling device is not `
generally used during the rolling and the rolled material is cool- ;
ed gradually by a small amount of cooling water in the air, but in the step of finish rolling, the temperature of the rolled rnater- `
ial is raised by the heat of plastic working due to increased ;~
rolling speed, (This ordinary rolling method is called as OR here-,. ... . . . . . . ..
.: ~ ,. . ., . ~ :
,' ;
inafter). One of the features of the presen-t invention lies in ,~
that the temperature of the steel material during the rolling is `~
controlled by a suitable cooling device. (This method is called as CR hereinafter). In this case, the cooling device must have ~ ~
a cooling capacity large enough to cool the s-teel to a prescribed '~ -temperature in a short time because the rolling speed is high, ~
and must be capable to adjust cooling in association with a ther- `; ;
mometer. , .
The present invention will be described in more details ~l0 ~ referring to the attached drawings. ,~
Fig l shows the temperature control during the wlre rod (8 mm diameter) rolling, Fig, 2 shows relations between tensile strength and reduction of area of the wire rod as rolled.
Flg, 3 shows relations between the~finish outlet temper~
-ature and tensile~strength yi~eld point and drawabllityO
Fig 4 shows similarly relations between yleld point and re1axatlon-loss.
Pig, S is a microphotograph ( x200) of the wire rod 20~ ~ obtained by the present invention.
FlgO 6 lS a graph showing transition curves of impact ~values.~
Fig. 7 is also a graph showing transition curves of ~ `' .
impact values.
Now referring to Fig. l which shows one embodiment of the continuous rolling apparatus for conducting the controlled - rolling according to the present invention, the rolling apparatus includes a rough rolling mill of 7 stands a first intermediate rolling mill of 6 stands, a second intermediate rolling mill of 2 stands and a finish rolling mill of l0 stands. In the finish rolling mill, 8 stands are used for production of wire rods of `
8 mm diameter, and four stands are used for production of wire -\ :
1~3i!~
rods of 13 mm diameter. The billet size is llS mm square, and 18 m length. The size of the intermecliate products is 24 mm diameter at the stand No. 13 and 20 mm diameter at the stand No. ~ ;
15. ;
No 3 shows the ordinary rolling (OR) in which the - `
heating temperature is set at 1200C, and the temperature of the rolled material gradually lowers from the rough rolling to the second intermediate rolling and gets about 930C at the finish ;- ~ -inlet, but increases when the rolled material enters the finish ;
10 rolling mill group and gets a finish temperature of about 1005C. .
No 21 is an example of OR in w~ich the heating temperature is 1085C, and relatively lower than in No. 3, but almost same ten~
dencies take place. No 2 lS an example~of the controlled roll- ;~
ing (CR) in which the heating temperature is 1150C and a cooling device is provided between the first intermediate rolling mill ;
stand group and the second intermediate rolling mill stand group and~between the~second intermedlate rolling mill stand group and the~finish rolling mill stand group to adjust the cooling and coo~l the rolled material to a prescribed temperature. Namely thé
20~ same procedures are taken untiI the rolled material passes the flrst~intermedi~ate rolling mill stand group as in case of OR, but after the~staDd No. 13, the rolled materlal is cooled to 910C i~
and rolled by the~second intermediate rolling mill, cooled to 810C after the stand No. 15, enters between the finish rolls and finished at 860C. ;~
No. 20 is an example of CR in which the temperature of l~ -the rolled material is further lowered and the material enters the -~ ~
:; , finish rolling mill stand group at 750C. The results obtained by the example will be described hereinafter.
For the object of the controlled rolling, the heating temperature should be not lower than il50C and is desirable as high as possible, but in view of limitations such as the capacity --8~
.. . . . .
.. .
;
, . ~ , ' ? ' `
. .
~0;~73~
and structure of a heating furnace, and from considera-tions for oxidation and decarburization, the upper limit of the heating tem~
perature ls set at 1200C ln this example, because excesslvely hlgh temperature is not economlcal. During the rolling, the above mentloned nltrldes and carbides begln to preclpltate as the temp-" . . , erature lowers but not so much around 1000C. The austenite phase ;of the steel material is converted into a worked structure by the rolllng, but immediately recrystallizes because the temperature lS high enough and is converted l* worked structure by the next ; lO rolling and then recrystalllzes. Thls procedure lS repeated at each of the rolllng mill stands and ln this way the rolling is proceeded. The present inventors have studied the above structu- ~;
ral changes by investlgating the intermedlate material having~a freed~structure~caused by quenchlng ln the course of a rolllng, and~have found~that the~carblde and nltrlde formlng~ elements such as~Nb delays the recryatalllzation, and that the recrystalllzatlon~
proceeds lmmediately at a rolllng~temperature above about 910C, but~the~structure~remalns as nan-recrystalllzed phase below~9lOC.
It is predlcted~that this temperature va~rles dependlng on the 20~ rolllng speed, namely passlng time between the stands, but the recrystallizatlon;is n~ot caused during the pass~tlme (;about 6 seconds)~between the stand No. 13 and;the stand No. 14 and between the stand No.;15~and the~stand No, 16, and the boundry temperature~
for the recrystallization and~the non-rearystallization at the ,~
pass time of 6 to 6.5 m/sec. over the~stand No. 15 is about 910C. ;~
It is very important to know what temperature would be thls boundary temperature ln the flnish rolllng mlll stand group where the rolling speed ls larger. Slnce the rolling tlme (pass tlme between stands) is short, namely because the strain rate is high, this boundary temperature is considered to be higher than 910C, but it is difficult to confirm by experiments whethér the recrystallized austenite grains are formed or not. Therefore, _g~
~ . ' ''' " ' .: : ,~
,'~ ,. ' ' ':
-~C~3~
the present inventors classified'the finish rolled wire rods in- `
to the structure in which the worked structure remains and the '' structure in which the worked structure is not retained through ;~
observation of their micro-structures, and investigated them ln ;~
connection with -the finish inlet t~mperature, and found the work- '~
ed structure retains when the finish inlet temperature is not "' higher than 910C even if the finish temperature higher than ~-910C, and thus discovered that if adjustment is rnade in the ' preceding stands so as to maintain the temperature at the stand ~' ~o. l~, namely the finish inlet temperature not higher than 910C, , ' the rolling is regarded to be within the non-recrystallization zone, This technical thought provides means applicable to other `~
type of rolling mills, For this purpose, the rolling degrees in '~
this example are shown as under. The rolling degree from the slab of 115 mm diameter to the intermediate rod of 20 mm diameter' '~
finlsh inlet) is about 97% in the recLuction of area, the rolling degree from the intermediate rod of 20 mm diameter to the final ' product of 8 mm diameter is 84%, and the degreé from the inter-medlate rod of 20 mm diameter to the final product of 13 mm ''''~
diameter is 60%, and the pass times in the finish rplling mill '~ ' ~stand group is 8 passes for the rolling from the 20 mm diameter i''~
to the 8 mm diameter, and 4 passes for the rolling from the 20 mm diameter to the 13 mm diameter.
Descriptions will be made on the method of cooling -' .: - :
aftex the rolling.
The cooling of the wire rod after the finish rolling -~
is divided into two steps, in the first step the surface temper-ature is cooled by about 100 to 300C within a few seconds using a leading and cooling device equipped with pipes filled'with water as used in the wire rolling mill and the wire rod is coiled to a desired temperature between 850 and 600C, and in the second step t'he cooling is done at an adequate rate between 1 and 15C/sec.
, ,., . . . ;
., .
~;931~32 using a uniform cooling device such as disclosed in the Japanese -~
patenk publica-tions Sho 42-15463 and Sho 42-18894 and the coil is gathered. Thus, the cooling rate after the finish rolliny is 2 to 15C/sec. in average through the first and second steps.
The effects of the above cooling procedure are des~
cribed hereinunder.
The fine austenite grains are obtained by the control-led rolling as above, and yet in the course of transformation of the austenite into a ferrite-pearlite or bainite structure, the structure gets finer if the cooling rate is increased, thus impro~
ving strength and toughness, Meanwhile the nitrides and carbides ;~
precipitated on the dislocation, which is induced in the hot roll~
ing are coherent with the ferritic matrix and these precipitates ~ ;
;~ harden the ferrlte phase remarkably. This precipitation varies depending on the cooling rate and thus it~ ls~very important to ad]ust the cooling~rate. Namely, the adjustment of cooling has two distinctive metallurglcal slgnificances as above.
Mechanlcal properties and metallurgical features of the ~ .
~ ~ hot rolled wire rod obtained by the above method are explained 20 ~ ~ hereinunder.
Table l~shows chemical compositions, the relation bet-. .:
ween the rolling method and temperature and mechanical properties.
Figs. 2, 3 and 4 show respectively the relation between tensile strength and reduction of area, ~etween tensile strength and yield :~
point, and between tensile strength and the finish outlet temper- -ature.
A11 of the steels of the present invention were prepared in LD convertor, but there is no special limitation in the steel- `~
maki~g method.
From the relation between tensile strength and drawing shown in Yig. 2, it is understood the steel of the present inven-tion has considerably high strength and high ductility even when ":
:, ~ , ' ' .
~3~3~ :
rolled by the ordinary rolling method. Namelyt the steels No. 1, No. 2, No. 25 and No. 27 show tensile strength of about 55 to 90 kg/mm and drawability of 77 to 70% as compared with tensile , '~
strength of S5 to 70 kg/mm and drawability of 65 to 55% of an ,~ -ordinary carbon steel and thus these steels show relatively high drawability in comparison with the tensile strength. sy compari- ~" -~
son of the steel No. 1 with the steel No.3,and comparison of the steel No~ 21 wlth the steel No.18, it is clear that the increased , ,~
heating temperature increases strength even in case of the ,; ,' ordinary rolling material~
In Fig, 2, the CR materials are related by the arrow -' mark to the OR materials. T'he steel No, 2 shows only slight ~ ~- ,' effect or CR due to the low heating temperature of 1150C, but '~
shows improvement of yield point as shown in~Fig. 3. Steels No. `' ;~
4 and No. 5 show remarkable increase of drawability, and these '~
steels show remarkable improvement of workability instead of slight increase of yield point (see Table 3). This is due to the '~
fact that the intermediate rolling temperature was set in the !'~'' ~'`'.~'' order of 700C and the finish temperature was lowered as shown in ~ Fig. 4.
2~ Steels No. 19 and No. 20 are exanples in which the in~
termedlate rolling temperature was set in the order of 800C so ~ as to increase strength without lowering drawability. The impro~
; ~ vement of strenght of drawability of the steels No. 26 and No.
..
28 attained by CR is remarkable.
Fig. 4 shows effects by the finish outlet temperature. `- , The finish outlet temperature of the OR material is about 1000C ', and that of the CR material is about,950 to 780C. In case of the CR material, it is clear that tensile strength and yield point lower and drawability increases when the finish ou-tlet temperature is below 850C. It is between about 850 and 950C that tensile strength and yield point increase while reduction of area does not chan~eO Thus there is difference in the effect by the -12~
i ! ; ' ` i'~ ' '' ,, ' ', : '.'. ' ' intermediate rolling temperature between the order of 700C and the order of 800C (including 910C). Similar tendencies are seen even when the rolling size is 13 mm diameter , but it is generally noticed that the heat due to the plastic working varies depending on th~ reduction amount and the rolling speed in the finish rolling line.
The fact that the steel of the present invention has always higher reduction of area than the ordinary material hav~g the same level of strength is mainly due to the effect by the re~
finement of the ferrite-pearlite structure as shown in Fig. 5.
The ferrite grain size obtained by the controlled rolling temper~
~; ature is a very fine grain having a grain size number larger than ;
; No, 10.
; Fig~ 6~shows the transition cur~es of Charpy impact -`
values, and lt~iS clearly shown-by thls~flgure that the transition temperature is lowered remarkably by the controlled rolling temp-~
erature.
Examples of application of the present lnVention for hexagonal bolts are shown in Table 3 and Table 4. `.
~:20;~ The bolt strength is just t~e .same or higher than the -~
tensile strength of the wire, and completely no breaking of head ;~
was caused in the wedge~test ~angle: 10). Also the~fatigue limit under pulsating stress is very high, Further, ~torque tests were conducted using nute and the results were that rupture was caused at the tllread and thus the bolt~strength was satisfactory. ;
From the above various tests, it has been found the bolts made by the steel wire rod o the present invention have similar or better quality than the conventional quenched-tempered bolts, and thus the excellent quality of the wire rod of the present in-vention has been confirmedO
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~38~32 Table_1 - (21 con-t ' d .. ~ . .
Steel Ser-Chemical Composition (W-t %) Deslg- lal .__ . .
nation No. C Si Mn P S Al Ti Nb V
A 1 1 0.06 0.73 1.61 0.021 0.018 0.004 0.19 - -2 ll ll . ._ _ . - : " . .
A 2 3 0.07 0.78 1.52 0.021 0.004 0.004 0.23 - -~ . _ ,' '~
B 160.16 0.86 1.58 0.024 0.019 0.030 0.18 - -17 ll ll . __ ~ . -, 18 0.13 0.26 1.33 0.024 0.004 0.028 - 0.037 -,C 1 19 ~ ~ , . '~
" "
21 " "
~ . -- ~ ~
22 1.33 0.024 ~4 " "
. : ~ ,_ .. .. _._. ~ . .
D 1 25 ~ 0.13 0.26 1.28 0.023 0.005 0.025 - 0.010 0.020 26 ~ ~
. . . _ , _,, _ _ _ :~
D 2 27 0.11 0.20 1.20 0.025 0.003 0.010 - 0.010 0.020 ~ ~ -28 ll ll `
~:._. . _ - ---- ~--- ---- ~--D 3 29 0.12 0.22 1.26 0.024 0.018 0.015 ~ - 0.010 0.025 ~ ~
- . __ ,, _ , _ . ,, _ ,,. ~ . ~ , E 30 0.10 0.25 1.25 0.024 0.015 0.010 0015 0.015 -.. , : _ ._ _ , . ~ : ~
F 31 0.11 0.23 1.24 0.023 0.013 0.015 - 0.015 - ~ ~
. _ . . __ , _ ........... _ ._ . . _ ,~
G 32 0.12 0.24 1.26 0.018 0.018 0.018 - - 0.05 ..... _ . ,;
I 34 0.15 0.23 1.28 0.024 0.020 0.018 - - -. .
, . . . . .
, ,, , . , . .: :.
, . . .
- ~3~,'~2 :
Table 1 - (2) (cont'd from page 15) cont'd --..... ... . _._ . . .... _ _ _ . . . . . . ~
Steel Ser- Chemical Comp- Rolling Roll- Rolling Rolling Tempera- ~ :
Desig- ial osition (Wt %) Size ing Speed ture (CL_ _ l nation No. Zr N (mm ~) Method (M/S) Heating 13~--~ _ . ..... .. ..
: A 1 1 _ 0.0047 8 OR 20 11501000 :
2 " CR 910 ~ ;~
. ~.. _._._ - . _ ._ _ .: ~ .
A 2 3 - 0.0040 8 OR 201135 1020 : 4 " CR. 1190920 .~ CR 1190870 , ., _ ~ , _ ;~' l B 16:_ 0.0045 8 OR 34 1200980 i~ ~
: ~ 17 " CR "~ 970 ~ ~ :
. . ''~
18: - 0.0046 8 OR 34 1200980 : I
C 1 )L9 1l CR " 990 : 20 " CR 20 930 i :¦ 21 ll OR 34 1085 960 -- :
: ~C 2 :23 : ~ I CR ~ ,i 990 24 " ~; CR ;~10 930 :: : ;~~ ~: ~ , --D 1 25 -0.0084 8 OR ~20 1170 950 26 ~ " ~CR ~;: 1200 850 , ~: ~ .-, ~ ~ : : - : : .
~D 2 27 - 0.0068 8 OR 20 1160 960 : ~ :: 28 " CR 1200 : 880 ~ , :
: : ~ ~ ~ - ~ ~ :
: - D 3 29 - 0.0045 I 8: : CR 20 1200 880 ~;
E ~ 30 - 0.0055 ¦ 8 CR 20 1200 890 ; '' i i F 31 0.300.0050 I 8 OR 20¦ 1200 885 . .~' :
G 32 _ 0.0075 I 8 CR : 201 1200 850 , :
I 34 0.180.0050 , 8 CR 201200 885 .:.-~
Remarks OR : Ordinary Rolling ~.
CR : Temperature-Controlled Rolling - , .
. .
Table 1 - (2) (cont'd from page 16) r Rolling Coil- Tensile Properties = I
Temperature ing --~ ~ Reduc-Iser (C) Temp Yield Tensile Elonga- tion ¦ial Fin-~h--Flnlsh era~r~ Point 2 Streng~h tion of Area Yield ~o. 15# Inlet Outlet (C) (Kg/mm )(Kg/mm ) (%) (%) Ratio :
. ........ . _ 1 920920 g80 750 48.6 70.0 24.0 69,8 0.69 l `
2 810800 860 700 60.3 72.0 26.7 70.4 0.84 , .. , ~ _ '' .~ ,,
3 930 920 1885 700 62.8 82.1 21.1 72.6 0.76
4 710700 800 700 65.0 70.7 25.9 79.0 0.92 ~ -120710 780 700 44.1 61.3 28.6 80.2 0.72 _ . .~
16 9609301010 750 74.0 90.0 15.0 63.5 0.82 17 890810 950 700 82.0 103.015.5 65.0 0.85 `~
_ ., 18 9709701020 800 46.2 68.6 23.9 68.9 0.67 19 910810 940 ll 46.9 71.2 21.9 66 9 0 66 810750 820 ll 45.3 69.8 25.5 71 5 0 69 21 910920 985 ll 40~0 30~3 27.6 76.6 0.66 _ ~ _ _ ~ .. .
22 940 940 950 ll 47.3 60.3 22.7 67.7 0.71 23 910 800 865 ll 47.6 62.6 24.3 74.8 0.76 24 800 750 840 ll 47.9 60.3 25.3 75.2 0.80 ~
_ . ''' :,.. .
950 940 1010 ? 42.7 57.7 30.7 71.6 0.74 26 780 770 860 " 53.6 63.6 26.3 75.2 0.83 ; -~
~ " ~
27 960 9501020 710 39.4 55.3 30.0 75.8 0.71 ~
28 710 700 800 700 46.7 56.4 29.7 78.7 0.83 1 ~-_ ~_ __ _ _. ~
29 710 700 800 700 45.9 56.6 30.0 79.0 0.81 . _ . ~ . - ~ - . ':; ' 720 715 830 700 48.0 59.0 29.5 76.0 -0.81 -; -. ~,... . .
31 710 710- 805 750 48.5 60.0 27.0 73.0 0.81 1 _, _ , 32 780 770 860~700 51.562.027.0 74.5 0.83 34 7~0 ilO 810~750 49.061.026.8 74.0 0.80 . .
-~73~
Table 2: Mechanical Properties of Wire Rod As Hot Rolled cont'd , ~~~~ ^~~~~ ~~ ~Finish~~~ ~~~~~ ~~~~~ ~~ ~~ . ~ ~ .
Wlre Heating Inlet Finish Coiling :~
Steel Ser= Dia Roll- Roll- Temper- Tempera- Outlet Tempera-Desig- ial meter ing ing ature ture Tempera- tu,re .
nation No~ (mm) Method Speed (C) (C) ture(C) (C) -,: :
_ . ..... __. .. . . .. ..
A 1 8 ~ OR 34 1200 945 . 1020 810 :
" 2 " CR " 1190 810 930 800 .
, ._ _ -:
" 4 " " " 1200 920 ~1010 650 ~ 5 " CR " 1190 700 810 660 :
_ _ ',~
C 6 8~ OR 34 1200 945 1005 800 , 7 " CR " " 870 960 "
~ 8 " ~ 810 940~ " .~
~ 9 ~" " 20 " 720 840 " :~ :
" ~10 13 OR 14 1200 950 : 970 " :~
" 11 " ~ CR ~ 750 835 "
12 " " 10 " 800 860 "
~ : : -- '' D ~13 8 OR 34 1200 945 1010 750 " 14 " CR "~ " 810 950 700 . ~ ~ - - - - .. :''~
E : 15 8 ~ OR 34 1180 945 103:0 730 -"~16 " CR* . " ~" 900 990 800 "17 ": " " " 780 895 "
` 18 " " * " : " 790 9lg 820 : :~
., . - :- .. ~.. ::
F19 8 ~ OR 34 1180; 950 1040 750 ~ :
"20 " CR " " 770 900 780 ~ :
. _ .. :. _ . . ', ~ ," ~ ' . ' " 22 " " " " 760 900 "
_ .__ _ " 24 " CR " " 790 860 "
, ... ' I
Remark: * Air Cooled after Rolling ::
.~.
' , - 18 -.
,.. . .
, ~:.: . ' :
~13&~73;~ -Table 2 (cont'd from page 18) _ _ _ ................. _ . ............. _ .. . __ Ten~ile Properties teel Ser- Yield Tensile Elonga-Desig- ial Point 2 Streng~h tion Drawing nation No~ (ICq~mm ) (Kq/mm ) (%) (%) Yield Ratio A 158.1 71.5 20.3 74.1 0.81 " 262.7 75.4 19.4 73.8 0.83 . ....................... _ - ., B 366.3 87.8 16.1 70.3 0.76 " 476.1 92.6 15.4 69.1 0.82 " 565.5 77.6 23.2 75.3 0.84 ~ . ?~
C 671.4 89.0 15.5 64.9 0.80 " 779.5 96.4 14.0 64.9 0.83 " 878.4 96.9 14.5 64.2 0.81 " 963.9 92.5 17.8 66.6 0.69 " 1066.6 91.0 16.4 61.2 0.73 " 1170.9 84.9 14.9 63.7 0.83 i~ 1261.8 85.4 17.5 61.9 0.72 .
D 1374.0 90.0 15.0 63.5 0.82 " 1482.0 103.0 15.5 65.0 0.85 E 1577.5 ga.5 Il.0 53.0 0.79 " 1673.0 95.~0 12.0 50.0 0.77 " ~ 17 82.5 95.1 13.5 56.0 0.87 "1880.0 93.0 13.1 55.0 0.86 ~ _ F19~ 73.0 92.5 11.0 60.2 0.79 ~i2078.0 88.5 13.5 65.1 0.88 G2193.6 118.5 10.1 55.3 0.79 "2293.2 115.3 11.5 58.4 0.81 H2344.5 62.5 20.0 78.0 0.71 "2447.2 59.0 22.0 81.0 0.80 . .
, ., . ,, , ~
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.
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fdrl ~ ~ ; ,, ~ ~1) ~ ' : ~.
' ~ : - _, ~ ~ ~
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O (s~ r-l ~ r-r ~ ~ ~ ~ 0~ 0 r r-l r-i ~ ; .r~
' rC ~ , ~ ~ ' ~ i I I I I I
~ ~ '' ~ ~; ~ ~ ~ ~ ; ~ ~ ~ r~ ~ ~;
~D . ~ o ~ ~D ~ CO r-l ~1 a r~ ~ ~ ~ r~ ~. ~ ~ ~
(d :: ~ ~ : ~ ~ : : l rc; ~I
;~:~ ~ ~ ~ : ~ ~ ~ ~ E~ ~ ~ ~ ~ ~ : ~ ~ ~
~' ': ~ , ~ ~ ~ ~ :
.. ~ rl ~) ~;
~ ~~ ~-1 10 ~ co E; u~ ~_ . .
~i o ~; a~ c> ~ t~ ~) o o : ~ . ~
S~ . ~ ~ .. I , ~
~ ~ ~ : ~ ~ ~ I (~ ~I r-J .~
(D E~ O O O O O ~
. ~ ~ ~ ~
:~ ` . '~ t~ , : ~`
. r-i rll rl .~ ~ ~ co a) o ~ ~ C
. ~ ~0 ~i N . ~
0 ~ i r~ 1 ~-1 ~ O r J ~ l r-l ~1 D 0 ~ ~~) a) ~ ~
~n n ~ __~ ~ _ 2~ `~
.. . . .
,,, : . , . . ~.
16 9609301010 750 74.0 90.0 15.0 63.5 0.82 17 890810 950 700 82.0 103.015.5 65.0 0.85 `~
_ ., 18 9709701020 800 46.2 68.6 23.9 68.9 0.67 19 910810 940 ll 46.9 71.2 21.9 66 9 0 66 810750 820 ll 45.3 69.8 25.5 71 5 0 69 21 910920 985 ll 40~0 30~3 27.6 76.6 0.66 _ ~ _ _ ~ .. .
22 940 940 950 ll 47.3 60.3 22.7 67.7 0.71 23 910 800 865 ll 47.6 62.6 24.3 74.8 0.76 24 800 750 840 ll 47.9 60.3 25.3 75.2 0.80 ~
_ . ''' :,.. .
950 940 1010 ? 42.7 57.7 30.7 71.6 0.74 26 780 770 860 " 53.6 63.6 26.3 75.2 0.83 ; -~
~ " ~
27 960 9501020 710 39.4 55.3 30.0 75.8 0.71 ~
28 710 700 800 700 46.7 56.4 29.7 78.7 0.83 1 ~-_ ~_ __ _ _. ~
29 710 700 800 700 45.9 56.6 30.0 79.0 0.81 . _ . ~ . - ~ - . ':; ' 720 715 830 700 48.0 59.0 29.5 76.0 -0.81 -; -. ~,... . .
31 710 710- 805 750 48.5 60.0 27.0 73.0 0.81 1 _, _ , 32 780 770 860~700 51.562.027.0 74.5 0.83 34 7~0 ilO 810~750 49.061.026.8 74.0 0.80 . .
-~73~
Table 2: Mechanical Properties of Wire Rod As Hot Rolled cont'd , ~~~~ ^~~~~ ~~ ~Finish~~~ ~~~~~ ~~~~~ ~~ ~~ . ~ ~ .
Wlre Heating Inlet Finish Coiling :~
Steel Ser= Dia Roll- Roll- Temper- Tempera- Outlet Tempera-Desig- ial meter ing ing ature ture Tempera- tu,re .
nation No~ (mm) Method Speed (C) (C) ture(C) (C) -,: :
_ . ..... __. .. . . .. ..
A 1 8 ~ OR 34 1200 945 . 1020 810 :
" 2 " CR " 1190 810 930 800 .
, ._ _ -:
" 4 " " " 1200 920 ~1010 650 ~ 5 " CR " 1190 700 810 660 :
_ _ ',~
C 6 8~ OR 34 1200 945 1005 800 , 7 " CR " " 870 960 "
~ 8 " ~ 810 940~ " .~
~ 9 ~" " 20 " 720 840 " :~ :
" ~10 13 OR 14 1200 950 : 970 " :~
" 11 " ~ CR ~ 750 835 "
12 " " 10 " 800 860 "
~ : : -- '' D ~13 8 OR 34 1200 945 1010 750 " 14 " CR "~ " 810 950 700 . ~ ~ - - - - .. :''~
E : 15 8 ~ OR 34 1180 945 103:0 730 -"~16 " CR* . " ~" 900 990 800 "17 ": " " " 780 895 "
` 18 " " * " : " 790 9lg 820 : :~
., . - :- .. ~.. ::
F19 8 ~ OR 34 1180; 950 1040 750 ~ :
"20 " CR " " 770 900 780 ~ :
. _ .. :. _ . . ', ~ ," ~ ' . ' " 22 " " " " 760 900 "
_ .__ _ " 24 " CR " " 790 860 "
, ... ' I
Remark: * Air Cooled after Rolling ::
.~.
' , - 18 -.
,.. . .
, ~:.: . ' :
~13&~73;~ -Table 2 (cont'd from page 18) _ _ _ ................. _ . ............. _ .. . __ Ten~ile Properties teel Ser- Yield Tensile Elonga-Desig- ial Point 2 Streng~h tion Drawing nation No~ (ICq~mm ) (Kq/mm ) (%) (%) Yield Ratio A 158.1 71.5 20.3 74.1 0.81 " 262.7 75.4 19.4 73.8 0.83 . ....................... _ - ., B 366.3 87.8 16.1 70.3 0.76 " 476.1 92.6 15.4 69.1 0.82 " 565.5 77.6 23.2 75.3 0.84 ~ . ?~
C 671.4 89.0 15.5 64.9 0.80 " 779.5 96.4 14.0 64.9 0.83 " 878.4 96.9 14.5 64.2 0.81 " 963.9 92.5 17.8 66.6 0.69 " 1066.6 91.0 16.4 61.2 0.73 " 1170.9 84.9 14.9 63.7 0.83 i~ 1261.8 85.4 17.5 61.9 0.72 .
D 1374.0 90.0 15.0 63.5 0.82 " 1482.0 103.0 15.5 65.0 0.85 E 1577.5 ga.5 Il.0 53.0 0.79 " 1673.0 95.~0 12.0 50.0 0.77 " ~ 17 82.5 95.1 13.5 56.0 0.87 "1880.0 93.0 13.1 55.0 0.86 ~ _ F19~ 73.0 92.5 11.0 60.2 0.79 ~i2078.0 88.5 13.5 65.1 0.88 G2193.6 118.5 10.1 55.3 0.79 "2293.2 115.3 11.5 58.4 0.81 H2344.5 62.5 20.0 78.0 0.71 "2447.2 59.0 22.0 81.0 0.80 . .
, ., . ,, , ~
.. . . . .
.. . . ..
'!
r~
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~ o ~ o o o u:~ o ~
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~, ~ a) o ~Q ~ o ~. ' O u~ r~ r~
.
h ~ t~ ~) U ::1 ~ U
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fdrl ~ ~ ; ,, ~ ~1) ~ ' : ~.
' ~ : - _, ~ ~ ~
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' rC ~ , ~ ~ ' ~ i I I I I I
~ ~ '' ~ ~; ~ ~ ~ ~ ; ~ ~ ~ r~ ~ ~;
~D . ~ o ~ ~D ~ CO r-l ~1 a r~ ~ ~ ~ r~ ~. ~ ~ ~
(d :: ~ ~ : ~ ~ : : l rc; ~I
;~:~ ~ ~ ~ : ~ ~ ~ ~ E~ ~ ~ ~ ~ ~ : ~ ~ ~
~' ': ~ , ~ ~ ~ ~ :
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. r-i rll rl .~ ~ ~ co a) o ~ ~ C
. ~ ~0 ~i N . ~
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.. . . .
,,, : . , . . ~.
Claims (4)
1. A method for producing high tensile strength steel wire rods and bars having a basic composition comprising:
C 0.02 to 0.20%
Si 0.03 to 0.90%
Mn 1.00 to 1.85%
together with one or more selected from the group consisting of Nb ? 0.05%
V ? 0.08%
Ti ? 0.25%
Zr ? 0.30%
Cr ? 0.40%
B ? 0.005%
with the balance being the iron and unavoidable impurities, which comprises heating a steel having above composition at a temperature not lower than 1150°C, conducting at least one of an intermediate rolling and a finish rolling at a temperature between 700 and 1050°C, controlling the cooling rate from finish of the hot rolling to a coiling to 40 to 350°C/sec., and controlling the cooling rate from the coiling to gethering to 1 to 15°C/sec. to obtain hot rolled steel wire rods and bars having excellent workability and spot weldability and having a tensile strength not lower than 50 kg/mm and a reduction of area not lower than 50%.
C 0.02 to 0.20%
Si 0.03 to 0.90%
Mn 1.00 to 1.85%
together with one or more selected from the group consisting of Nb ? 0.05%
V ? 0.08%
Ti ? 0.25%
Zr ? 0.30%
Cr ? 0.40%
B ? 0.005%
with the balance being the iron and unavoidable impurities, which comprises heating a steel having above composition at a temperature not lower than 1150°C, conducting at least one of an intermediate rolling and a finish rolling at a temperature between 700 and 1050°C, controlling the cooling rate from finish of the hot rolling to a coiling to 40 to 350°C/sec., and controlling the cooling rate from the coiling to gethering to 1 to 15°C/sec. to obtain hot rolled steel wire rods and bars having excellent workability and spot weldability and having a tensile strength not lower than 50 kg/mm and a reduction of area not lower than 50%.
2. The method according to claim 1, in which the steel wire rods and bars contain one or more of not more than 0.05%
Nb, not more than 0.08% V, not more than 1.25% Ti and not more than 0.30% Zr, in addition to the basic composition.
Nb, not more than 0.08% V, not more than 1.25% Ti and not more than 0.30% Zr, in addition to the basic composition.
3. The method according to claim 1, in which the steel wire rods and bars contain one or more of not more than 0.25%
Ti, not more than 0.005% .beta. and not more than 0.40% Cr in addition to the basic composition.
Ti, not more than 0.005% .beta. and not more than 0.40% Cr in addition to the basic composition.
4. The method according to any of claims 1 to 3 in which the cooling rate from the finish of the hot rolling to the cooling is 150 to 250°C/sec.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10187573A JPS5420931B2 (en) | 1973-09-10 | 1973-09-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1038732A true CA1038732A (en) | 1978-09-19 |
Family
ID=14312131
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA208,726A Expired CA1038732A (en) | 1973-09-10 | 1974-09-09 | Method for producing a killed steel wire rod |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US3926687A (en) |
| JP (1) | JPS5420931B2 (en) |
| CA (1) | CA1038732A (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5734333B2 (en) * | 1974-06-21 | 1982-07-22 | ||
| JPS5215407A (en) * | 1975-07-29 | 1977-02-05 | Nippon Steel Corp | Continuous heat treatment method for wire rods |
| JPS5286919A (en) * | 1976-01-13 | 1977-07-20 | Kobe Steel Ltd | High strength steel superior in workability and weldability and its pr eparation |
| JPS5921369B2 (en) * | 1976-10-25 | 1984-05-19 | 新日本製鐵株式会社 | Manufacturing method for high-tensile, high-carbon steel wire with excellent wire drawability |
| JPS5476421A (en) * | 1977-12-01 | 1979-06-19 | Nippon Steel Welding Prod Eng | Intermediate annealing method for welding steel wire |
| JPS54132421A (en) * | 1978-04-05 | 1979-10-15 | Nippon Steel Corp | Manufacture of high toughness bainite high tensile steel plate with superior weldability |
| JPS5585658A (en) * | 1978-12-25 | 1980-06-27 | Daido Steel Co Ltd | Free cutting steel |
| JPS5910415B2 (en) * | 1978-12-27 | 1984-03-08 | 新日本製鐵株式会社 | Manufacturing method for high-tensile wire rods and steel bars with excellent stress corrosion cracking resistance |
| GB2088257B (en) * | 1980-11-08 | 1984-07-18 | Sumitomo Metal Ind | Making rod or wire |
| JPS57126913A (en) * | 1981-01-27 | 1982-08-06 | Kobe Steel Ltd | Production of high-toughness high-strength wire or rod steel |
| US4605449A (en) * | 1981-05-19 | 1986-08-12 | Arbed S.A. | Process for producing a rolled steel product having high weldability, a high yield strength and a good notch impact toughness at very low temperatures |
| FR2525503B1 (en) * | 1982-04-22 | 1984-07-13 | Ugine Aciers | |
| JPS59107063A (en) * | 1982-12-10 | 1984-06-21 | Daido Steel Co Ltd | Wire rod for bolt and its production |
| US4604145A (en) * | 1984-01-13 | 1986-08-05 | Sumitomo Metal Industries, Ltd. | Process for production of steel bar or steel wire having an improved spheroidal structure of cementite |
| CH681603A5 (en) * | 1984-05-30 | 1993-04-30 | Von Roll Ag | |
| US4619714A (en) * | 1984-08-06 | 1986-10-28 | The Regents Of The University Of California | Controlled rolling process for dual phase steels and application to rod, wire, sheet and other shapes |
| JP2802155B2 (en) * | 1990-09-21 | 1998-09-24 | 株式会社神戸製鋼所 | Method for producing high-strength steel wire without heat treatment and excellent in fatigue resistance and wear resistance |
| JP3215891B2 (en) * | 1991-06-14 | 2001-10-09 | 新日本製鐵株式会社 | Manufacturing method of steel rod for cold working |
| CA2135255C (en) * | 1994-05-26 | 2000-05-16 | William E. Heitmann | Cold deformable, high strength, hot rolled bar and method for producing same |
| US6017274A (en) * | 1997-09-02 | 2000-01-25 | Automotive Racing Products, Inc. | Method of forming a fastener |
| KR100435468B1 (en) * | 1999-12-21 | 2004-06-10 | 주식회사 포스코 | A method for manufacturing wire rod for armouring cable |
| CA2378934C (en) | 2002-03-26 | 2005-11-15 | Ipsco Inc. | High-strength micro-alloy steel and process for making same |
| US7220325B2 (en) * | 2002-04-03 | 2007-05-22 | Ipsco Enterprises, Inc. | High-strength micro-alloy steel |
| CN102978362B (en) * | 2012-11-27 | 2014-07-30 | 南京钢铁股份有限公司 | Thermal control and cold control process of ultralow-carbon fiber steel |
| PL424691A1 (en) * | 2018-02-27 | 2019-09-09 | Solvera Gawel Technology Spółka Akcyjna | Method for producing drawn wire, preferably to be applied as the charge material for cold forging of fasteners |
| CN111235466B (en) * | 2020-02-26 | 2022-02-25 | 江苏省沙钢钢铁研究院有限公司 | TiC dispersion strengthening complex phase reinforcing steel bar and production method thereof |
| CN113151653A (en) * | 2021-02-26 | 2021-07-23 | 邢台钢铁有限责任公司 | Production method of large-size medium-carbon steel wire rod |
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|---|---|---|---|---|
| US3231432A (en) * | 1964-10-08 | 1966-01-25 | Morgan Construction Co | Process for the quenching of hot rolled rods in direct sequence with rod mill |
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| DE1758380B1 (en) * | 1968-05-21 | 1973-07-12 | Thyssen Niederrhein Ag | METHOD FOR MANUFACTURING ROLLED WIRE |
| US3711338A (en) * | 1970-10-16 | 1973-01-16 | Morgan Construction Co | Method for cooling and spheroidizing steel rod |
| DE2133744B2 (en) * | 1971-07-07 | 1973-07-12 | August Thyssen-Hütte AG, 4100 Duisburg | THE USE OF A FULLY KILLED STEEL FOR ARTICLES FROM HOT-ROLLED STRIP |
-
1973
- 1973-09-10 JP JP10187573A patent/JPS5420931B2/ja not_active Expired
-
1974
- 1974-09-09 US US504270A patent/US3926687A/en not_active Expired - Lifetime
- 1974-09-09 CA CA208,726A patent/CA1038732A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5420931B2 (en) | 1979-07-26 |
| JPS5051920A (en) | 1975-05-09 |
| US3926687A (en) | 1975-12-16 |
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