JPS5947326A - Production of rail having excellent resistance to edge rupture - Google Patents

Abstract

PURPOSE:To obtain a rail having excellent resistance to edge rupture in the fastened parts of rails by cooling the top and upper neck or body of the fastened parts of the rails in a prescribed temp. region from right above the A1 transformation point or the surface over the entire length thereof with a gas or moist gas kept under high pressure. CONSTITUTION:The fastened parts of rails having the temp. right above the A1 transformation point -1,300 deg.C after hot rolling or the fastened parts of the rails which are heated to said temp. by a heat medium such as gas heating or high frequency heating are cooled in the following way: The top 1 and upper neck 2 or body 3 of the fastened parts of said rails or the surfaces over the entire length from the top 1 through the upper neck 2 to the body 3 are selected as desired in accordance with the service conditions such as the passage frequencies of trains, the magnitude of load and the places to be laid with rails, etc., and are cooled with a high pressure gas or moist gas such as air. As a result the resistance to edge rupture of the rails is improved and the service life is prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a rail having excellent properties such as opening and tearing of a rail fastening portion.

Among the rail IJ1 damage, damage to the 4i1 rail joint is the most common, accounting for approximately 100% of the total number of rails, and has become a major maintenance problem. This 1. The rails are dark blue, and the joints are structurally discontinuous, and in addition to generating large static stress, there is also a large equity impact that passes through the train. Effect 11-
I'm confused as to what's going on.

Various Jj4 fg n in the fastening section are collectively referred to as "
The most common types of damage are horizontal cracks from the upper rail neck (clacks and cracks) and star-shaped cracks from the bolt holes (Stark cracks). As shown in Figure 1(a), a crack occurs from the fl root (upper l'!'1 part) of the rail head and abdomen, and the rail This is an extremely serious damage that propagates in the longitudinal direction and eventually breaks the rail head.

On the other hand, as shown in Fig. 1 (1)), a star-shaped crack from the pol I hole is generated from the pol I hole, and a part of it propagates, resulting in the ultimate VC. is rail head 7r, (S is missing JJi
This is a serious injury similar to a ``double'' cut.

Conventionally, no countermeasures have been taken for these injuries in the case of double neck cuts. -For star-shaped cracks originating from force and bolt holes, methods have been used to reduce stress concentration by reducing the diameter of the hole and by sealing the surface of the corner of the bolt hole. However, no effect has been obtained.Also, as an idea, by locally plastically deforming the area around the Holt hole,
Although there is a method of applying compressive residual stress (-1), it has not been put to practical use because it does not have a sufficient compressive residual ratio and force of 14 t and has various problems in implementation.

Therefore, the inventors asked whether 4-11 Jino and bolt holes or 1. ) Occurrence - Leero crack Kinpo Ichida - Ru] From 1, f Zukono'1. Elucidating the cause of 411 scars:. As a result, from the upper neck cut and O bolt hole) 1! The reason for the occurrence of cracks in the form 17 is the excessive force of the bolt tightening of the seam ν, τJ force, cam and 0' If＞! Shikoku also has an effect on the secondary θ (or bolt tightening): Even if the force is positive, depending on the trackbed conditions, the occurrence of JJT scratches may be avoided (there are cases where it is not possible). However, the fundamental factor is the train passing (external force (repetitive load IF) and the resistance force (fatigue/j) limit of the rail itself)
It turns out that it is used in a rounded state. However, in order to prevent the occurrence of scratches, it is necessary to increase the resistance (fatigue limit) of the vermilion itself.

Non-invention is based on this knowledge.
＋：A、Temperature V of 1300°C
The entire length of 1 is made of high pressure gas, 1 is water gas, and 1 is convex.
No way, no way! It is a two-track construction method with 1M characteristics.

8Y Tsumugi 17C Explanation of the present invention) L.

Before explaining the present invention, FIG. 2 describes the names of the various parts of the rail cross section. l is Qc Article 1”j capital, 2i1
71: "Double degree part, 3 is abdomen, 4 is 1 - curved part, 5 is 1
Base>r, IH.

After hot rolling, A1 transformation point irj: -1;
The rail fastening part 11, which is at a temperature of ~1300°C, is heated to that temperature by a heat medium such as gas power [1 heat, i'; P is abdomen 3,
Or 1. The entire length from the bright part 1 to the neck and the full length V to the abdominal part 3 can be adjusted according to the conditions of use, such as the frequency of train passage, the size of the load, the place of laying, etc. A selected high-pressure gas (eg, air) is cooled with a water-containing gas.

Directly at the A1 transformation point of the cooling start humidity, 1 to 1300°C is the temperature range where fine grains are obtained, resulting in high strength and improved total needle fatigue strength. If it becomes oxidized, cracks are likely to occur and the ductility decreases, and if it has a low A, transformation point, or C, transformation will occur and a fine pearlite structure cannot be obtained. In addition, the high-pressure gas or water-containing gas used as the refrigerant in this case prevents the coarsening of the pearlite formed during cooling and reduces the compressive residual stress k (; The cooling rate of water/111 is much faster than that of water/111, which produces a martenzite structure and crack-susceptible gold, t-:ji.
I really like it and it's 4.

Mafko, cooling V. On this occasion, what about the 14th ward of Hijodani? '1 To make all possible speeds uniform, track type 211S
Refrigerant ejection: Is it necessary to increase 1+ the most?

As mentioned above, H! with the method of the present invention! The fastening part of the rail is made of a fine pearlite structure, which has high strength and large compressive residual stress.

Therefore, by increasing the strength, the residual LrL force, which is smaller than the fatigue limit, is created as a force. As a result, IDt article (ii1 breakage! I
It has a long service life and has a long service life.

Next, embodiments of the present invention will be explained.

! <C1-Rail head i41< and JI A' jζIS Further, the abdomen was heated to 95°C (by 1℃V), b and then cooled with water-containing air at an effective pressure, and f2 the rail of the present invention and the rail l
/J'1 part is treated under the same conditions for the opening and tearing gloss of a normal rail; the results of the test show gold.

As is clear from the results in 1-1, the 4\invention 1 (the rib strip is '+14 rail tic :l, (a) 4 pile strength) and the large fi-residual 1 center force is N'- Ljsai%
No cracks were observed.

q, 1-z) and 0) fiili explanation No. 11 IC [Rail F1 6 farts, 3rd grade Jii (easy 1st grade upper l) Reno (1) and jp, 4 people crack ()) ) is shown. Figure 2 shows the name of 4Q (article hγIll).

1...Rail head, 2...LI'''1 part,;3...
belly) 11;, 4...11'l': lbe 5...bottom.

Patent applicant agent Patent Attorney J (6U)) 1 person)

Claims (1)

[Claims] A, Rail Tsumugi yarn j at 7111'1 degree just above the transformation point ~ 1300℃;
113, or C10, these full length surfaces,
4 break ψ: l, i 4 pieces 1 with 1 cooling with high pressure gas 1. Noah, the man who made the rails 1゜