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Method for improving hook-like crack of cold-drawn straight-slit welded pipe

A technology of straight seam welded pipe and straight seam welding, applied in the direction of metal rolling, etc., can solve the problems affecting product quality and prone to hook cracks in cold drawing of straight seam welded pipes, and achieve the goal of improving hook crack defects and organizing coordinated deformation Power-enhancing, easy-to-achieve effects

Inactive Publication Date: 2020-07-31
BENGANG STEEL PLATES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Longitudinal welded pipe is prone to hook cracks in cold drawing, which affects the product quality after cold drawing

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Embodiment 1: Take the production of SPHT3 as an example to illustrate the production method of the present invention.

[0016] (1) smelting according to conventional methods, and pouring into billets;

[0017] (2) Heat the billet in a walking heating furnace, and keep it warm for 60 minutes in a high temperature environment of 1220 ° C. After the billet is released from the furnace, it will be descaled in the descaling box and then rolled in the rough rolling mill. The rolling temperature is set to 1140 ℃, then enter the finishing rolling mill for rolling, the final rolling temperature is 870℃, the strip thickness is 6.0mm, coiled after laminar flow cooling, and the coiling temperature is set at 400℃;

[0018] (3) Straight seam welding into steel pipes, non-destructive testing after cold drawing, no hook cracks.

Embodiment 2

[0019] Embodiment 2: Take the production of SPHT3 as an example to illustrate the production method of the present invention.

[0020] (1) smelting according to conventional methods, and pouring into billets;

[0021] (2) Heat the billet in a walking heating furnace and keep it warm for 60 minutes in a high-temperature environment of 1210 ° C. After the billet is released from the furnace, it is descaled in a descaling box and then rolled in a rough rolling mill. The starting temperature is set to 1130 ℃, and then enter the finishing rolling unit for rolling, the final rolling temperature is 870℃, the strip thickness is 8.0mm, coiled after laminar flow cooling, and the coiling temperature is set at 380℃;

[0022] (3) Straight seam welding into steel pipes, non-destructive testing after cold drawing, no hook cracks.

Embodiment 3

[0023] Embodiment 3: Take the production of SPHT52.3 as an example to illustrate the production method of the present invention.

[0024] (1) smelting according to conventional methods, and pouring into billets;

[0025] (2) Heat the billet in a walking heating furnace and keep it warm for 60 minutes in a high-temperature environment of 1240 ° C. After the billet is released from the furnace, it is descaled in a descaling box and then rolled in a rough rolling mill. The starting temperature is set to 1150 ℃, and then enter the finishing rolling unit for rolling, the final rolling temperature is 870℃, the strip thickness is 8.0mm, coiled after laminar cooling, and the coiling temperature is set at 350℃;

[0026] (3) Straight seam welding into steel pipes, non-destructive testing after cold drawing, no hook cracks.

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PUM

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Abstract

The invention provides a method for improving a hook-like crack of a cold-drawn straight-slit welded pipe. The method for improving the hook-like crack of the cold-drawn straight-slit welded pipe includes the steps that step 1, smelting is carried out according to a conventional method to pour into a casting blank; step 2, the casting blank is placed in a step heating furnace for heating, heat preservation is carried out in the high temperature environment for 60 min, the casting blank is removed from the furnace, after descaling box descaling, the casting blank is rolled into a rough mill andthen rolled into a finishing mill, the final rolling temperature is 870 DEG C, and rolling is carried out after laminar cooling; and step 3, a steel pipe with straight seam welding has no destructiveflaw detection and no hook crack after cold-drawn, the method can be more stably applied to hot rolled steel coils for the cold-drawn straight-slit welded pipe in industrial mass production, comparedwith hot rolled steel coils produced in the past, and no hook crack defect can be realized.

Description

technical field [0001] The invention relates to the field of heat treatment of metal materials, in particular to a method for improving hook cracks in cold drawn straight seam welded pipes. Background technique [0002] Cold-drawn steel pipe is a kind of steel pipe. It is welded by hot-rolled steel coils and then cold-drawn. It has excellent performance and low cost. The production process path of cold drawn longitudinal welded pipe: hot rolled coil, slitting, ERW pipe making, annealing, surface treatment, cold drawing, pressure test, annealing, flaw detection, oiled packaging. [0003] Longitudinal welded pipes are prone to hook cracks in cold drawing, which affects the product quality after cold drawing. A lot of work has been carried out at home and abroad around such hook cracks, but the work is all around the steelmaking process, controlling the non-metallic inclusions in molten steel to improve the purity of molten steel, controlling chemical composition segregation, ...

Claims

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Application Information

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IPC IPC(8): B21C37/08B21B1/46C21D8/02
CPCB21B1/463B21C37/08C21D8/0226C21D8/0263C21D2211/002
Inventor 康海军王旭生张楠于立伟闵洪刚姜艳菲王文澜董宝权杨得草
Owner BENGANG STEEL PLATES