DE60222595T2 - STEEL MATERIAL FOR MECHANICAL CONSTRUCTIONS WITH EXCELLENT ROLLING PERFORMANCE, DETERLECTIVE RAKING STRENGTH AND TORSION PROPERTIES AND DRIVE SHAFT - Google Patents

Description

Technical area

The The present invention relates to engineering steel products. Especially the present invention relates to a mechanical engineering steel product, excellent formability in rotational forming, resistance to harsher and torsion properties. A steel product is provided this being a engineering steel product using an electric furnace instead of a blast furnace was made and that different properties, even if an accompanying element as Cu or Ni is incorporated, maintains.

Technical background

For machine components, such as drive shafts for use in motor vehicles and constant velocity joints It is required that they have torsional strength on a required Level. To ensure torsional strength was So far, a hot-rolled steel rod generally through the steps of Hot forging, Normalizing, if necessary is, cutting, cold forging and the like, so that a given Form and subsequent induction hardening and Tempered.

In In recent years, attempts have been made to protect the environment, to reduce the weight of motor vehicle bodies to the gas mileage from motor vehicles to ver. To reduce weight of automotive components has been an improvement in torsional strength desired by motor vehicle elements. Further, in a manufacturing process for automotive components also machinability and hardness resistance of steel products required.

to Improvement of torsional strength was considered that Quenching and hardness penetration depth by induction hardening elevated become. However, the quenching hardness and the hardness penetration depth too increase, must be either a change the high frequency curing conditions or an increase the amount of alloying elements in a steel product. In the two cases described above, the manufacturing costs inevitably increased. To simultaneously torsional strength, machinability and machinability Quenching-crack resistance of automotive components, for example according to the disclosure in Patent Document 1, a technique proposed that the amount of Alloy elements specified.

however can only be done by specifying chemical components accordingly the above technique the problem occur that the compositional area, at the same time the properties of the machinability, Quenching-crack resistance and torsion properties, is very small. Furthermore, the problem of unstable quality is always not yet solved.

• Patentdokument 1: Ungeprüfte veröffentlichte japanische Patentanmeldung Nr. 4-218641 (Ansprüche)
• Patentdokument 2: Patent JP 3-288563 (Ansprüche).

Therefore, in order to solve the above-described problems, the present inventors proposed a engineering steel product having excellent machinability, resistance to corrosion and torsional properties as disclosed in, for example, Patent Document 2, wherein the steel texture is controlled simultaneously with a corresponding adjustment of the components of the steel product.

• Patent Document 1: Unexamined Published Japanese Patent Application No. Hei. 4-218641 (Claims)
• Patent Document 2: Patent JP 3-288563 (Claims).

however For example, it has been found that when the engineering steel product disclosed in Patent Document 2 is omitted Using an electric furnace is produced, desired properties can not be obtained and in particular the deterioration in terms of formability is significant in rotary forming. Compared to an under Use of a blast furnace furnace produced steel product is an accompanying element such as Cu or Ni inevitably in use built of an electric furnace produced steel product. It will assumed that the accompanying elements the formability of rotary forming affect.

The JP-A-9 111401 discloses a steel for use in engineering with a composition comprising, by mass, 0.35-0.60% C, ≤ 0.05% Si, 0.65-1.70% Mn, ≤ 0.020% P , 0.005-0.035% S, ≤ 0.15% Cr, 0.05-0.50% Mo, 0.01-0.05% Ti, 0.01-0.05% Al, ≤ 0.01% N , 0.0005-0.0050% B and the remainder Fe, and further having a structure containing 5-30% by area of bainite phase, and further, the above torsional strength in this steel is controlled to ≥ 1400 MPa. The hardness resistance of this steel can to a greater extent be controlled by the Ms value given by the equation Ms = 538 - 317 (% C) - 33 (% Mn) - 28 (% Cr) - 17 (% Ni) - 11 (% Si) - 11 (% Mo) is defined to be improved to ≥ 360. Moreover, one or more kinds of ≦ 1.0% Cu, ≦ 3.5% Ni, 0.01-0.30% V and 0.005-0.050% Nb may further be incorporated into this steel.

A The main object of the present invention is the solution of problems described above. That is, task of the present The invention is the provision of a mechanical engineering steel product the excellent hardness resistance and torsional properties, and which is effective in deterioration in the Regarding the formability in rotary forming even in production using an electric furnace instead of a blast furnace prevented. Further, also formed from this steel product Drive shaft proposed.

Disclosure of the invention

• (1) Um die nachteiligen Einflüsse von Begleitelementen zu unterdrücken, ist es wirksam, die Menge an Cr zu erhöhen;
• (2) jedoch verursacht eine Erhöhung der Menge an Cr eine Verschlechterung im Hinblick auf die Umformbarkeit bei Rotationsumformung und sie bewirkt auch eine Verschlechterung im Hinblick auf Torsionseigenschaften und spanende Verarbeitbarkeit;
• (3) die Verschlechterung der Torsionseigenschaften und spanenden Bearbeitbarkeit gleichzeitig mit einer Erhöhung der Menge an Cr kann durch eine Erhöhung der Menge an Si und zusätzlich durch eine Verringerung der Menge von Mn gelöst werden; und
• (4) die Verschlechterung im Hinblick auf die Umformbarkeit bei Rotationsumformung kann überwunden werden, wenn ein LD-Wert, der ein Index für die Textur und die Härte durch die Härtbarkeit ist, in einem vorgegebenen Bereich kontrolliert wird.

Through long and intensive research conducted by the inventors of the present invention to solve the above objects, the findings given below have been obtained.

• (1) In order to suppress the adverse influences of accompanying elements, it is effective to increase the amount of Cr;
• (2) however, an increase in the amount of Cr causes a deterioration in workability in rotary forming and also causes deterioration in torsion properties and machinability;
• (3) the deterioration of the torsional properties and machinability simultaneously with an increase in the amount of Cr can be solved by increasing the amount of Si and additionally by decreasing the amount of Mn; and
• (4) The deterioration with respect to workability in rotary forming can be overcome when an LD value which is an index of the texture and the hardness by the hardenability is controlled in a predetermined range.

• 1. Ein Maschinenbaustahlprodukt, das mit hervorragender Umformbarkeit bei Rotationsumformung, Härterissbeständigkeit und Torsionseigenschaften ausgestattet ist, das – auf Masseprozentbasis – umfasst: C: 0,35 % bis 0,50 %, Si: 0,05 % bis 0,15 %, Mn: 0,20 % bis 1,1 %, P: 0,02 % oder weniger, S: 0,005 % bis 0,035 %, Cr: mehr als 0,1 % bis 0,2 %; Mo: 0,05 % bis 0,5 %, Ti: 0,01 % bis 0,05 %, Al: 0,01 % bis 0,05 %, N: 0,01 % oder weniger, B: 0,0005 % bis 0,0050 %, Cu: 0,06 % bis 0,25 %, Ni: 0,05 % bis 0,2 %, optional V: 0,01 % bis 0,30 % und optional Nb: 0,005 % bis 0,05 %, wobei ein LD-Wert, der durch die im folgenden angegebene Gleichung (1) dargestellt wird, von 120 oder weniger erfüllt ist und der Rest der Zusammensetzung Fe und beiläufige Verunreinigungen umfasst; wobei gilt: LD = 0,569x{7,98x(C)}1/2x(1 + 4,1 Mn)·(1 + 2,83 P)(1 – 0,62 S)·(1 + 0,64 Si)·(1 + 2,33 Cr)·(1 + 0,52 Ni)·(1 + 3,14 Mo)·(1 + 0,27 Cu)·(1 + 1,5(0,9 – C))} + 52,6 (1) In der obigen Gleichung geben C, Mn, P, S, Si, Cr, Ni, Mo und Cu in der Gleichung jeweils den Gehalt (Masseprozent) an den jeweiligen Elementen an.
• 2. Das Maschinenbaustahlprodukt mit hervorragender Umformbarkeit bei Rotationsumformung, Härterissbeständigkeit und Torsionseigenschaften nach obigem 1, das ferner – auf Masseprozentbasis – V: 0,01 % bis 0,30 % und Nb: 0,005% bis 0,05 % umfasst.
• 3. Eine Antriebswelle, die das Maschinenbaustahlprodukt nach obigem 1 oder 2 umfasst, wobei auf dieser eine gehärtete Schicht durch Durchführen von Induktionshärten und Anlassen bereitgestellt wird.

The present invention has been accomplished on the basis of the above findings, and the specific aspects of the present invention are as follows.

• 1. A machined steel product provided with excellent formability in rotary forming, hardening resistance and torsional properties, which comprises, by mass percentage, C: 0.35% to 0.50%, Si: 0.05% to 0.15%, Mn : 0.20% to 1.1%, P: 0.02% or less, S: 0.005% to 0.035%, Cr: more than 0.1% to 0.2%; Mo: 0.05% to 0.5%, Ti: 0.01% to 0.05%, Al: 0.01% to 0.05%, N: 0.01% or less, B: 0.0005 % to 0.0050%, Cu: 0.06% to 0.25%, Ni: 0.05% to 0.2%, optional V: 0.01% to 0.30%, and optional Nb: 0.005% to 0.05%, wherein an LD value represented by the following equation (1) is satisfied by 120 or less, and the rest of the composition comprises Fe and incidental impurities; where: LD = 0.569x {7.98x (C)} 1.2 x (1 + 4.1 Mn) × (1 + 2.83 P) (1 - 0.62 S) · (1 + 0.64 Si) · (1 + 2.33 Cr) · (1 + 0, 52 Ni) · (1 + 3.14 Mo) · (1 + 0.27 Cu) · (1 + 1.5 (0.9 - C))} + 52.6 (1) In the above equation, C, Mn, P, S, Si, Cr, Ni, Mo and Cu in the equation respectively indicate the content (mass%) of the respective elements.
• 2. The engineering grade steel product having excellent formability in rotary forming, hardening resistance and torsional properties according to the above 1, further comprising - by mass percentage basis - V: 0.01% to 0.30% and Nb: 0.005% to 0.05% includes.
• 3. A drive shaft comprising the engineering steel product according to the above 1 or 2, on which a hardened layer is provided by performing induction hardening and tempering.

Brief description of the drawings

1 is a diagram showing the influence of the LD value on the formability in rotary forming.

2 shows the result of measuring the static strength of a drive shaft, which was determined by a static strength test.

3 shows the result of measurement of the fatigue strength of a drive shaft of an example and that of a comparative example.

Best way to carry out the invention

in the Next, the present invention will be described in detail. The reasons for the Specification of the composition of a steel product of the present Invention in the above range will be described. In the present Invention gives "%" for components Unless otherwise specified, "mass percent" is used.

C: 0.35% or more, 0.50% or less

C is an element that has the biggest impact on high-frequency hardenability and it is an effective element for increasing the Hardness and the depth of a hardened Layer by quenching and to ensure torsional strength of 1400 MPa or more after induction hardening and tempering. If the Content is less than 0.35%, is the effect of the carbon component not sufficient, and if the content is more than 0.50%, are machinability and resistance to harshness deteriorated. Therefore, the C content is in the range of 0.35 % to 0.50%.

Si: 0.15% or less, 0.05 or more

In addition to Function as a deoxidizing element, Si is an element that performs the function the reinforcement of Steel, when dissolved in ferrite, thereby increasing the torsional strength is improved. The salary is 0.05% or more. However, if the Si content is more than 0.15% the machinability significantly affected and therefore is the content set to 0.15% or less.

Mn: 0.2% or more, 1.1% or less

Mn is an effective element for improving the hardenability and increasing the Härteeindringtiefe during induction hardening, thereby contributing to the improvement of torsional strength. However, when the content is less than 0.2%, the effect of the Mn component is unsatisfactory. On the other hand, if the content is more than 1.1 %, additionally for formability in rotational forming, the machinability and the torsional strength also deteriorates. Therefore, the Content of Mn set to the range of 0.2% to 1.1%. Preferably the content is in the range of 0.2% to 0.8%.

P: 0.020% or less

There for P the There is a tendency for segregation to occur in austenite grain boundaries Quenching occurs and hardening takes place, the content of P is preferably reduced as much as possible. in the In view of this, the content is reduced to 0.020% or less.

S: 0.005% or more, 0.035% or less

S forms in steel MnS and it has the function of improving the machinability and therefore the content is 0.005% or more fixed. However, because MnS tends to cause cracking and one Reduction of strength and toughness causes is the maximum Content of S fixed at 0.035%. Preferably, the content is in the range of 0.010% to 0.035%.

Cr: more than 0.1%, 0.2% or less

Cr is a particularly important element in the present invention and if Cr is included, can the adverse influence of accompanying elements as Cu and Ni are advantageously removed, the disadvantageous Influence a deterioration of the formability during rotary forming, Torsion properties, machinability and the like is. However, when the content of Cr is 0.1% or less, it is the effect of a Cr component is insufficient. on the other hand is because the formability of rotary forming, machinability and torsional strength are deteriorated when the content is more than 0.2%, the content of Cr is set to more than 0.1% to 0.2%.

Mo: 0.05% or more, 0.5% or less

Not a word Not only is it effective in improving hardenability, but it also has the function of facilitating the growth of bainite, so that the machinability is improved. Therefore, the salary must 0.05% or more; however, if the salary exceeds 0.5% is, the machinability is adversely affected. Therefore, the content of Mo is in the range of 0.05% to 0.5% established. Preferably, the content is in the range of 0.1% to 0.5%.

Ti: 0.01% or more, 0.05% or less

Ti forms a nitride with N and it reduces the grain size of austenite at high temperature heating. This element is essential to ensure dissolved B that to improve the hardenability is effective. Therefore, the content must be 0.01% or more; if however, the content is more than 0.05%, is the toughness deteriorated. Therefore, the content of Ti is in the range of 0.01 % to 0.05%.

Al: 0.01% or more, 0.05% or less

al is an effective element as a deoxidizer and this effect the content of it must be at least 0.01%. However, when the content is more than 0.05%, huge alumina grains grow and becomes a fatigue injury fires whereby the fatigue strength is reduced. Therefore, the salary Al is set to the range of 0.01% to 0.05%.

N: 0.01% or less

N is an effective element for forming a nitride with Al or Ti and to reduce the grain size of austenite at high frequency heating and therefore fatigue resistance can be improved. But when the content thereof is more than 0.01%, the nitride grows coarsely and the fatigue strength is adversely deteriorated. Furthermore, if an excessive amount At N, BN is formed and as a result the amount becomes a solved one B component, which is effective for improving the hardenability, in disadvantageous Way reduced. Therefore, the content of Ni is 0.01% or less established.

B: 0.0005% or more, 0.0050% or less

B has the effect of improving torsional strength Improve the hardenability and by raising the hardness penetration depth at high frequency hardening. In order to obtain the above effect, the content of the same must be 0.0005 % or more; however, if the content is more than 0.0050%, the toughness reduced. Therefore, the content of B is in the range of 0.0005 % to 0.0050%.

Cu: 0.06% or more, 0.25% or less

Cu is an element that is inevitably included as a companion element is. If the content is more than 0.25%, deterioration may occur formability in rotary forming and the like occur in some cases and therefore, the content is set to 0.25% or less. on the other hand when the content is reduced to less than 0.06%, the Production costs increased and as a result, the content is set to 0.06% or more.

Ni: 0.05% or more, 0.2% or less

Ni is an element that is inevitably included as a companion element. When the content is more than 0.2%, in some cases, a deterioration of the formability in rotary forming and the occur and therefore the content is set to 0.2% or less. On the other hand, if the content is reduced to less than 0.05%, the manufacturing cost is increased and, as a result, the content is set to 0.05% or more.

The Main components are described above and according to the present invention Invention can additionally to these components also the elements given below optionally used.

V: 0.01% or more, 0.30% or less, and Nb: 0.005% or more, 0.050% or less

Either V and Nb form carbonitrides and they reduce the grain size of austenite, thereby effectively contributing to the improvement of strength. However, if the content of V and Nb is less than 0.01% or less is 0.005%, the effects of these are insufficient. On the other hand, if the contents of V and Nb are more than 0.30% and more than 0.050% respectively, a big and coarse material precipitated and the tenacity thereby reduced. Therefore, the content of V is in the range of 0.01% to 0.30%, the content of Nb to the range of 0.005% to 0.050%.

Even though the appropriate portions of the components are described above it according to the present Invention is insufficient that the individual components just meet the above ranges, and the individual components need be controlled so that the LD value by the below given equation (1) is 120 or less.

The following applies: LD = 0.569x {7.98x (C)} 1.2 x (1 + 4.1 Mn) · (1 + 2.83 P) · (1 - 0.62 S) · (1 + 0.64 Si) · (1 + 2.33 Cr) · (1 + 0 , 52 Ni) · (1 + 3.14 Mo) · (1 + 0.27 Cu) (1 + 1.5 (0.9 - C))} + 52.6 (1)

In In the above equation, C, Mn, P, S, Si, Cr, Ni, Mo and Cu respectively the content (mass percentage) of the respective elements.

This LD value is the index of texture and hardness due to hardenability.

1 Fig. 10 shows the results of measurement of the influence of the LD value on the formability in rotary forming of high Cr steel and high Si steel. Further, in the above-described figure, the results of measurement of low-Cr and low-Si steel according to the disclosure in Patent Document 2 described above are also given for comparison.

In this embodiment is the formability of rotary forming by in one Form Roll Test Evaluated Mold Life Evaluated.

As In the figure, in both cases, when the LD value is more than 120, rapidly reducing die life; however, if the LD value 120 or less, is the mold life, i. the formability of rotary forming of the high Cr content, high Si content steel according to the present invention Invention much higher quality.

Accordingly, become in the present invention, the components are controlled so that an LD value of 120 or less is obtained.

In In the present invention, the steel texture is not specifically specified; however, a structure consisting of ferrite as the main component and is about 5 to 30 on a bainite phase on area percent basis, preferably used.

The steel product described above is preferably used for energy transmission devices, especially for Motor vehicle drive shafts and constant velocity joints used. In addition to Excellent machinability can, since the load carrying capacity elevated is a significant advantage, i. a weight reduction, to be obtained.

When next are preferred manufacturing conditions according to the present invention described.

One Steel melting process for The steel product of the present invention can be prepared by a known method carried out and it is not specifically limited. The engineering steel The present invention provides excellent formability Rotationsumformung, even if Cu or Ni are included in the Melting of steel carried out using an electric furnace difficult to remove, and therefore the melting of Steel preferably carried out using an electric furnace. vacuum degassing, such as RH degassing, refining using pans, and the like can additionally carried out become. A molten steel is produced by a continuous casting process or a slab-making process and then solidified into materials with predetermined shapes by hot rolling or hot forging shaped. After processing by an intermediate heat treatment, if this is necessary, such as normalizing, spheroidizing or glowing Soft annealing, be the materials obtained in this way to a desired Cold forming, such as cutting, forging or forming, completed.

In The present invention provides the product with a predetermined Mold by hot rolling or hot forging shaped or then by normalizing further edited. A cooling after the formation of austenite by this hot rolling or hot forging and subsequent normalizing or the like is preferably at a rate of about 0.2 to 2.0 ° C / s carried out, to produce a suitable amount of bainite. In particular, will for one Steel bar with a big one Diameter an accelerated cooling, the cooling is controlled, preferably carried out.

Further may be the last induction hardening and tempering by heating during about 0.2 to 1.0 s with a power of about 120 kW using an induction hardening device with a frequency of about 15 kHz and a subsequent tempering at a temperature of 170 ° C while carried out for about 30 minutes become.

Examples

stole with the composition given in Table 1 was in a Steel converters melted, whereupon continuous casting under Formation of a billet with a size of 400 × 540 mm followed and then became made from it a billet of 150 mm square formed by hot rolling. Was next this ingot to a straight rod of a diameter of 25 mm by heating to 1030 ° C and subsequent Hot rolling and then air cooling with a cooling rate of 0.7 ° C / s shaped.

The Results of a measurement of texture, formability in rotational forming, Torsion properties and hardness resistance of the steel rod thus formed are shown in Table 2.

The Measuring method of steel texture and various properties are given below.

(1) texture

After this a photograph of the microtexture of the straight bar after cooling Using an optical microscope was recorded, the Texture of the steel identified from this photograph and further the area percentage a bainite phase determined by an image analyzer.

(2) Formability in rotary forming

The Formability in rotary forming has been determined by the tool life according to one Form roll test assessed. The mold life was through the number of materials that were rolled up until the form rolling due to the tilting of teeth, of detachment a fracture surface, tooth wear and the like could not continue, determined.

• Zahnform: Involutenform, Modul: 1,27, Druckwinkel: 30°, Zahl der Zähne: 21, Schraubengangdurchmesser: 26,27 mm, großer Durchmesser: 28,1 mm, kleiner Durchmesser: 24,88 mm, Durchmesser über Stiften (Stift mit 2,5 mm Durchmesser): 30,49 mm.

The material of the mold was SKD 11 and the grooving data were the following.

• Tooth shape: involute, module: 1.27, pressure angle: 30 °, number of teeth: 21, screw diameter: 26.27 mm, large diameter: 28.1 mm, small diameter: 24.88 mm, diameter over pins (pin with 2.5 mm diameter): 30.49 mm.

(3) torsion properties

After a Torsionsteststück in the form of a smooth round rod with a parallel region ei 20 mm in diameter was formed from a straight bar and then quenched at a frequency of 15 kHz using an induction hardening device, annealing was performed at 170 ° C for 30 minutes, and then the torsion test was performed. The hardness penetration depth after induction hardening and tempering was set at about 4 mm. The torsion test was carried out using a 4900 J (500 kgf · m) torsion tester, and the maximum torsional shear strength was found to be torsional strength.

(4) Tear resistance

to Determination of hardness resistance was a round rod (20 mm diameter) with a V-shaped notch on the surface the same along the axis direction from the above straight bar of a diameter of 25 mm and then by an equivalent to that described above induction hardening processed. Having 10 digits on a C-section of the round rod polished and looked at, the assessment was based on the number generated cracks performed.

(5) Machinability

For the test of the machinability, an opening of a length of 12 mm using a made of SKH 4 drill was formed with a diameter of 4 mm at a rotation speed of 1500 rpm ^-1 and the process described above was repeated until the formation of the opening could not be continued, whereby the total length (mm) of the openings was obtained. This total length of openings formed in this way was judged as tool life.

As from Table 2 is clearly shown, according to the lying before Invention obtained steel products excellent formability at Rotational deformation, torsion properties, resistance to tempering and machinability on.

The static strength and fatigue strength of a drive shaft formed from the steel product of the present invention equipped with an induction hardening and tempering-hardened layer will be described with reference to FIG 2 or 3 described. The drive shaft of the example according to the present invention was formed from the steel product No. 2 shown in Table 1. The drive shaft of the comparative example was formed from the steel product No. 18 shown in Table 1. 2 Fig. 11 is a graph showing the results of determination of the static strength of the drive shafts by a static strength test. The static strength test (static strength test) is used to assess the static strength by determining the maximum torque that is obtained when the drive shaft breaks. The number of drive shafts used for the test was 1 for the comparative example and 2 for the examples. The results for Comparative Example, Example 1 and Example 2 are in 2 shown. The maximum torque obtained when the drive shaft of the comparative example broke is set to 1, and the maximum torque obtained when the drive shaft of the example broke is represented by the ratio thereto. It is clear that the static strength of the drive shaft of the example was improved to about 1.17 times that of the drive shaft of the comparative example.

3 FIG. 15 is a graph showing the results of the endurance strengths of the drive shaft of the example and the drive shaft of the comparative example obtained by fatigue test. The fatigue strength test is a fatigue strength test obtained when a torque is repeatedly applied. A predetermined load torque is repetitively applied to the drive shaft, and the number of cycles N of load exertion causing the drive shaft to break is obtained. The vertical axis indicates a value obtained by dividing the load torque by the static strength of the drive shaft of the comparative example, and the value thus obtained is dimensionless. The horizontal axis indicates the number of cycles of load application that causes the drive shaft to break. For example, based on the test results obtained in this way, when the number of cycles was 10,000, the value along the vertical axis for the drive shaft of the comparative example was about 0.49 and the value along the vertical axis for the drive shaft of the example was about 0.55 , Therefore, it is clear that the fatigue strength of the drive shaft of the example was improved by about 10% as compared with that of the comparative example.

Industrial Applicability

According to the present invention, adverse effects of a companion element also from egg A mechanical engineering steel product made using an electric furnace, wherein the sliding elements are inevitably contained in the steel product, are removed. A steel product having excellent formability in rotary forming, torsion properties, resistance to tearing and hardenability can be obtained. In particular, when the steel product according to the present invention is used for forming energy transmission devices such as automobile drive shafts and constant velocity joints, in addition to excellent machinability, a significant advantage, ie, weight reduction, due to the high strength can be obtained.

Claims (3)

Engineering steel product provided with excellent formability in rotary forming, hardening resistance and torsional properties, comprising - on a weight percentage basis: C: 0.35% to 0.50%, Si: 0.05% to 0.15%, Mn: 0, 20% to 1.1%, P: 0.02% or less, S: 0.005% to 0.035%, Cr: more than 0.1% to 0.2%; Mo: 0.05% to 0.5%, Ti: 0.01% to 0.05%, Al: 0.01% to 0.05%, N: 0.01% or less, B: 0.0005 % to 0.0050%, Cu: 0.06% to 0.25%, Ni: 0.05% to 0.2%, optional V: 0.01% to 0.30%, and optional Nb: 0.005% to 0.05%, wherein an LD value represented by the following equation (1) is satisfied by 120 or less, and the rest of the composition comprises Fe and incidental impurities; where: LD = 0.569x {7.98x (C)} 1.2 × (1 + 4.1 Mn) × (1 + 2.83 P) · (1 - 0.62 S) (1 + 0.64 Si) · (1 + 2.33 Cr) · (1 + 0, 52 Ni) · (1 + 3.14 Mo) · (1 + 0.27 Cu) (1 + 1.5 (0.9 - C))} + 52.6 (1) wherein C, Mn, P, S, Si, Cr, Ni, Mo and Cu in the equation indicate the content (mass%) of the respective elements, respectively. Engineering steel product with excellent formability in rotary forming, resistance to harsher and torsional properties according to claim 1, further comprising - on a percentage by mass basis - V: 0.01% to 0.30% and Nb: 0.005% to 0.05% includes. Drive shaft following the engineering steel product Claim 1 or 2, wherein on this a hardened layer by performing of induction hardening and starting is provided.