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CN-122013605-A - Pearlitic steel rail and welding method of joint thereof

CN122013605ACN 122013605 ACN122013605 ACN 122013605ACN-122013605-A

Abstract

The invention discloses a pearlitic steel rail and a welding method of a joint thereof, wherein the pearlitic steel rail is characterized in that a specific amount of Ce element is added, and the size of a push convex crack at the bottom of the obtained steel rail joint rail is reduced from more than 156 mu m to less than 25 mu m by a specific joint welding method, the average size of the push convex crack is reduced by more than 80%, other tissue performances of the joint meet the requirement of TB/T1632, the performance is obviously improved, the average impact performance is more than 12.6J, and the average hardness of the joint with the section hardness of the welded joint reaches 94% -98% of the average hardness of a base metal.

Inventors

  • WANG XIAOQIANG
  • BAI WEI
  • LU XIN
  • WANG RUOYU

Assignees

  • 攀钢集团攀枝花钢铁研究院有限公司

Dates

Publication Date
20260512
Application Date
20260407

Claims (10)

  1. 1. The pearlitic steel rail is characterized in that the weight fraction of each element of the pearlitic steel rail is 0.61% -0.81%, the weight fraction of Si element is 0.11% -0.81%, the weight fraction of Mn element is 0.60% -1.20%, the weight fraction of Ce element is more than or equal to 0.005% -0.05%, the weight fraction of V element is less than or equal to 0.20%, the weight fraction of S element is less than or equal to 0.008%, the weight fraction of Al element is less than or equal to 0.004%, the weight fraction of O element is less than or equal to 0.003%, and the balance is Fe and unavoidable impurities.
  2. 2. A method of welding a pearlitic rail joint according to claim 1, characterized in that it comprises the steps of: The molten steel is smelted by a converter, LF refined, RH vacuum refined and continuously cast to obtain a pearlitic steel rail, wherein metal Ce is added in the RH vacuum refined stage; and (2) carrying out movable flash welding on the pearlitic steel rail to obtain a welded steel rail.
  3. 3. The welding method of a pearlitic steel rail joint according to claim 2, wherein in the step (2), the movable flash welding comprises five stages of flash leveling, preheating, burning, upsetting and pushing, wherein the voltage of the flash leveling stage is 350-450 v, and the flash time is controlled to be 10-30 s.
  4. 4. The welding method of the pearlitic steel rail joint according to claim 3, wherein in the step (2), the voltage in the preheating stage of the moving flash welding is 300 to 400v, and the preheating time is 40 to 90s.
  5. 5. The welding method of a pearlitic steel rail joint according to claim 4, wherein in the step (2), the voltage of the burning stage of the moving flash welding is 360-450 v, and the burning time is 15-40 s.
  6. 6. The welding method of a pearlitic steel rail joint according to claim 5, wherein in the step (2), the mobile flash welding further comprises an upsetting step, and the upsetting amount is 10-16 mm.
  7. 7. The welding method of a pearlitic rail joint according to claim 6, wherein in the step (2), the moving flash welding further includes a step of pushing the pearlitic rail after the upsetting, and the weld flash generated in the upsetting step is removed.
  8. 8. A method of welding a pearlitic rail joint as in claim 1 wherein the pearlitic rail is a 60kg/m heat treated pearlitic rail.
  9. 9. The welding method of the pearlitic steel rail joint according to claim 2, further comprising the step of (3) naturally cooling the welded rail to room temperature, and then induction heating the full section of the welded joint by an electric induction coil to perform post-welding heat treatment.
  10. 10. The welding method of a pearlitic steel rail joint according to claim 9, wherein the heating is stopped after the induction heating to 900-980 ℃, and then the cooling is performed by air blowing.

Description

Pearlitic steel rail and welding method of joint thereof Technical Field The invention relates to the technical field of pearlite steel rail smelting, in particular to a welding method of a pearlite steel rail and a joint thereof. Background With the rapid development of the world, rail traffic is also moving toward higher speeds, heavier loads and more comfortable and safer. Pearlitic rails are widely used in railway track due to their good wear resistance, strength and toughness. Flash welding is the most widely used rail welding method at present. However, in the process of flash welding of steel rails, the welded joint inevitably causes the occurrence of welding defects, and a push-out crack is one of common welding defects, which is commonly found at the lower surface of the rail bottom of the welded joint. On the one hand, the existence of the push-out crack can possibly lead to flaw detection alarm, influence the production progress, and on the other hand, the existence of the push-out crack can reduce the mechanical property of the steel rail welded joint, and seriously influence the service life of the steel rail and the safety of railway operation. The so-called push-out crack is a micro-crack generated in the push-out process of the end of flash welding, and research shows that the rail bottom crack is ubiquitous, and the rail bottom lower surface of most joints can be observed whether reflected waves or no reflected waves exist in flaw detection, but only a part of small micro-cracks do not necessarily cause flaw detection alarm. The occurrence of push-out cracks is related to various causes, and studies by scholars have shown that crack defects are related to MnS inclusions in the steel rail parent metal band structure. The MnS inclusions are distributed in a layered manner along the longitudinal direction of the strip-shaped tissue, the strength of the strip-shaped tissue in the vertical direction is weakened, meanwhile, the strength is reduced due to the fact that the MnS can fracture the continuity of the steel rail matrix, the strength is further reduced due to welding heating, the strip-shaped tissue is subjected to stronger shearing stress along the vertical direction due to upsetting and push-out at the end of welding, and tiny cracks can appear when the shearing stress value exceeds the strength of the strip-shaped tissue in the vertical direction. Secondly, the enrichment of alloy elements has a certain effect, firstly, the partial segregation of harmful elements and the enrichment of the harmful elements in grain boundaries can reduce the local strength and performance, and secondly, the enrichment of Mn and S elements can provide favorable conditions for the formation of MnS. Therefore, the degree of severity of microcracks at the rail bottom can be effectively reduced by improving the purity and the homogenization degree of the base metal. Moreover, the welding process has the influence that the post-welding protrusion allowance can influence the generation of the protrusion crack, the protrusion crack can be reduced to a certain extent by increasing the protrusion crack, but the protrusion allowance is limited, the follow-up procedure is seriously influenced by the excessively high protrusion allowance, and the temperature during protrusion also has influence on the protrusion crack. Therefore, development of a welding method for a pearlitic steel rail and a joint thereof is needed, which can effectively reduce the crack size of the pearlitic steel rail and improve the comprehensive performance. Disclosure of Invention The invention aims to provide a pearlitic steel rail and a welding method of a joint thereof, wherein the pearlitic steel rail is prepared by adding rare earth Ce element and adopting a specific joint welding method, the size of a push convex crack at the rail bottom of a flash welding joint of a steel rail is reduced from more than 156 mu m to less than 25 mu m, the average size of the push convex crack is reduced by more than 80%, other tissue properties of the joint meet TB/T1632 and the properties are obviously improved, the average impact property is more than 12.6J and is far more than 6.5J specified by a standard, and the average hardness H J of the joint with the section hardness of the welding joint reaches 94% -98% of the average hardness H p of a base metal. In order to achieve the aim of the invention, the invention provides a pearlitic steel rail, wherein the mass fraction of each element of the pearlitic steel rail is that the mass fraction of C element is 0.61% -0.81%, the mass fraction of Si element is 0.11% -0.81%, the mass fraction of Mn element is 0.60% -1.20%, the mass fraction of Ce element is 0.005% -0.05%, the mass fraction of V element is 0.20%, the mass fraction of S element is 0.008%, the mass fraction of Al element is 0.004%, and the mass fraction of O element is 0.003%. The rare earth Ce element is added in the pearlitic steel rail, so tha