CN103551812A - Cold bending processing method for austenitic stainless steel - Google Patents
Cold bending processing method for austenitic stainless steel Download PDFInfo
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- CN103551812A CN103551812A CN201310556239.2A CN201310556239A CN103551812A CN 103551812 A CN103551812 A CN 103551812A CN 201310556239 A CN201310556239 A CN 201310556239A CN 103551812 A CN103551812 A CN 103551812A
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- stainless steel
- austenitic stainless
- pipe
- solution treatment
- processing method
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- 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
- C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
Abstract
The invention provides a cold bending processing method for austenitic stainless steel. The method comprises the following steps of (1) measuring the nominal external radius r of an austenitic stainless steel pipe, and computing deformation according to the following formula: deformation (percent)=100r/R, wherein R is the nominal bending radius of the center line of the pipe; (2) performing solution treatment on the austenitic stainless steel pipe when the deformation is bigger than determined critical deformation at the temperature which is not lower than 1093 DEG C. According to the method provided by the invention, the goals that not only is the austenitic stainless steel pipe safe to use but also the manufacturing cost is saved can be achieved.
Description
Technical field
The present invention relates to metal manufacture field, specifically, relate to a kind of austenitic stainless steel clod wash processing method.
Background technology
Austenitic stainless steel pipe is widely used in the critical components such as station boiler high temperature superheater, high temperature reheater, and it need to be processed into according to designing requirement the bend pipe of required bending radius after manufacture completes.But the bending quality that ，Ge great manufactory processes is for various reasons uneven, occurs more leakage accident after installation and operation.Therefore, determine that a not only safe but also economic bent tube technique method seems particularly important.
Summary of the invention
The object of the present invention is to provide a kind of austenitic stainless steel clod wash processing method.This method first clod wash, to setting bending radius corresponding to different distortion amount, is then determined the heat treatment requirements after clod wash by various test datas, and then reaches Austenitic stainless steel pipe and both used safely, saves again the object of manufacturing cost.
For reaching above-mentioned purpose, the invention provides a kind of austenitic stainless steel clod wash processing method, described method comprises the steps:
(1) measure the nominal outer radius r of Austenitic stainless steel pipe, and calculate deflection according to following formula:
Deflection (%)=100r/R, wherein R is the nominal bending radius of pipe center line;
(2) when deflection is greater than determined critical strain amount, Austenitic stainless steel pipe is carried out to solution treatment, described solution treatment is for being more than or equal to and carrying out solution treatment at 1093 ℃ in temperature.
According to austenitic stainless steel clod wash processing method of the present invention, wherein the described solution treatment of preferred steps (2) is to be at 1155 ℃, to carry out solution treatment in temperature.
According to austenitic stainless steel clod wash processing method of the present invention, wherein the described solution treatment of preferred steps (2) is for processing 1.5h.
According to method of the present invention, described in step (1), critical strain amount is 15%.
The present invention has also investigated the solid solution treatment method of the bend pipe of multiple degree of crook:
Wherein, the present invention, when determining whether to carry out solution treatment, calculates as follows:
(1) measure the nominal outer radius r of Austenitic stainless steel pipe, according to following formula, calculate respectively and be less than critical strain amount, equal critical strain amount and be greater than the corresponding bending radius of critical strain amount, and between each adjacent flex radius, get respectively 5 numerical value that are spaced apart 10mm; According to resulting numerical value, adopt bending machine to carry out clod wash to Austenitic stainless steel pipe and obtain bend pipe: critical strain amount (%)=100r/R
(2) sampling of every group of bend pipe cross section border is carried out carrying out under Brinell hardness experiment, light microscope and surface sweeping Electronic Speculum metallographic structure analysis and carried out tensile tests at room and impact experiment;
(3) according to the experimental result of step (2), determine whether bend pipe needs to carry out solution treatment.
According to method of the present invention, described in step (1), critical strain amount is 15%.
According to method of the present invention, described in step (2), be sampled as at straight length and get an annular test block, at bend pipe and position, straight tube boundary, respectively get respectively an annular test block, and get an annular test block in bend pipe middle part.
Wherein further preferably test block is highly greater than 8 times of impression diameter of the Brinell hardness that will do.
According to method of the present invention, described in step (2), be sampled as in each annular test block and in inner arc side and outer arc side, evenly get respectively three points respectively.
After above-mentioned sample is detected, compare with the bend pipe after method of the present invention is processed, find that above-mentioned sample all makes moderate progress, specifically can be referring to embodiment.
In sum, the invention provides a kind of austenitic stainless steel clod wash processing method.Method tool of the present invention has the following advantages:
This method first clod wash, to setting bending radius corresponding to different distortion amount, is then determined the heat treatment requirements after clod wash by various test datas, and then reaches Austenitic stainless steel pipe and both used safely, saves again the object of manufacturing cost.
Accompanying drawing explanation
Fig. 1 is embodiment 1 leak position schematic diagram; Wherein 1 is to give a tongue-lashing quick-fried the 5th, 3 six roots of sensation for leakage for there being the 4th, 2 of crackle vestige;
Fig. 2 is three blow-by tube patterns of the 1st screen;
Fig. 3 is the 6th blow-by tube pattern of the 1st screen;
Fig. 4 is the 5th blow-by tube pattern of the 1st screen;
Fig. 5 is the 4th blow-by tube pattern of the 1st screen;
Fig. 6 is the 6th blow-by tube inwall pattern of the 1st screen;
Fig. 7 is two blow-by tube patterns of the 14th screen;
Fig. 8 is hardness test sampling and testing position signal;
Fig. 9 is that inner arc is along brilliant crack morphology;
Figure 10 is near metallographic structure inner arc crackle;
Figure 11 is outer arc metallographic structure;
Figure 12 is that pattern is amplified in outer arc metallographic structure.
The specific embodiment
By specific embodiment, describe below the beneficial effect of implementation process of the present invention and generation in detail, be intended to help reader to understand better essence of the present invention and feature, not as restriction that can practical range to this case.
Embodiment 1
On January 16th, 2012, Inner Mongol Shang Dou Power Generation Corporation Ltd. (hereinafter to be referred as: Shang Dou genco) 6# stove high temperature superheater leaks, this unit was stopped transport next day, while entering internal check, find: crackle appears in totally 3 lower bend pipes of 62 meters of absolute altitudes (8 two layers downstairs) left several the 1st screens of high temperature superheater entrance side, wherein from interior several the 4th curved arc inner arc sides outward, there is crackle, the 5th curved arc back of the body arc side given a tongue-lashing and collapsed, there is crackle in the 6th curved arc inner arc side, tentatively determines booster (leak position as shown in Figure 1) headed by the 6th elbow.
In ignition trigger on January 30, again there is booster on February 10 and shut down in 6# stove.On inspection for there is circumferential crack in the 4th lower bend pipe inner arc side of left several the 14th screen of high temperature superheater entrance side.The bend pipe material of twice leakage is SA213-TP347H, specification
.
Leakage line macro morphology:
Leak for the first time the macro morphology of bend pipe as shown in Figures 2 to 6.Visible, 4,5,6 bend pipes of the 1st screen are newer, and outer surface is without coking and oxide skin.The 6th pipe inner arc side has two circumferential cracks, is positioned at bend pipe bottom, is symmetric, and crack length is about 1/2 circumference, in the middle of two Cracks, has a place to give a tongue-lashing the vestige collapsing; The 5th bend pipe inner arc side discovery is water stain first, and water stain area is larger, accounts for the area of lower bend pipe inner arc 1/2, examine, the fine crack that mays be seen indistinctly at water stain inner ring edge, is about quarter turn, back of the body arc side has a place to give a tongue-lashing the vestige that collapses, and this position blow loss is larger, and tube wall attenuate is serious; The 4th bend pipe inner arc side also finds that there is the crackle of a long quarter turn.Cut the 6th pipe open and observe inwall, find that crackle is at the expansion of inner arc side ecto-entad, the genetic defects such as inner wall smooth non-scale and straight way.
Leak for the second time the macro morphology of bend pipe as shown in Figure 7.Shang Dou genco sends two bend pipes here, is respectively and exceeds the 4th, 5 of left several the 14th screens of entrance, and wherein the 4th is blow-by tube.Power plant aspect is sawed-off along crackle hoop by blow-by tube, censorship DianKeYuan.
Chemical composition:
Three bend pipes of the 1st screen and two bend pipes of the 14th screen are carried out to chemical composition analysis, analysis result (%) as shown in table 1.From table, the chemical element composition of pipe meets ASME SA-213-2010 standard (hereinafter to be referred as requirement standard).
Table 1, chemical composition contrast
| Elemental composition | Cr | Mn | Ni |
| Standard-required | 17.0～20.0 | ≦2.0 | 9.0～13.0 |
| 1-6# pipe | 17.64 | 1.60 | 11.28 |
| 1-5# pipe | 17.40 | 1.64 | 11.28 |
| 1-4# pipe | 17.38 | 1.57 | 11.30 |
| 14-4# pipe | 17.80 | 1.51 | 11.45 |
| 14-5# pipe | 17.39 | 1.56 | 11.42 |
Hoop hardness:
The bend pipe of twice leakage is carried out to Brinell hardness test, and sample position and test method are as shown in Figure 8.Under bend pipe, three annular test blocks are got at curved arc position, are designated as B, C, D test block, at straight length, get an annular test block, are designated as A test block.On each annular test block, carry out 6 brinelings, wherein 1～3 is inner arc side, and 4～6 is outer arc side.
Result of the test is as shown in table 2, and from table, the 4th bend pipe A test block hardness of the 1st screen is starkly lower than B, C, D test block hardness, average hardness value difference 70HB, and wherein B, C, D test block inner arc side hardness are higher than outer arc side hardness, about hardness value difference 10HB.The 5th bend pipe exists to the 4th hardness number that bend pipe is similar and distributes, and the hardness number difference that is inside and outside arc reduces to some extent.4,5 bend pipe Brinell hardness of the 14th screen have similar result of the test.Standard code, the pipe Brinell hardness of TP347H material should not surpass 192HB, as can be seen here, check bend pipe hardness number higher than standard code, and straight length and lower curved arc place hardness number difference excessive.
Table 2, two bend pipe different parts hoop hardness contrasts of the 1st screen
Mechanical property:
In view of raw material size is limit, only the straight sections sampling to the 6th bend pipe of the 1st screen, carries out room-temperature mechanical property test, and result is as shown in table 3.In four tensile test pieces, except a sample has yield strength, its excess-three root does not all have yield strength, and the tensile strength of four samples and elongation after fracture all meet standard-required.
Table 3, mechanical property test data
Metallographic structure:
Metallographic specimen is got in seam broken place at the 6th bend pipe of the 1st screen, observes metallographic structure.As shown in Fig. 9-12, at the main crackle of inner arc side, around exist along brilliant time crackle as seen, near main crackle, metallographic structure is normal austenite structure, and crystal grain is without distortion, and evenly, on crystal boundary, there is a small amount of granular carbide in size; The metallographic structure of outer arc side is also normal austenite structure, and grain boundaries carbide is less, on indivedual crystal boundaries, has granular carbide.
Analysis of experiments:
Bend pipe under high temperature superheater entrance side has been carried out to macro morphology, chemical composition, hoop hardness, mechanical property and metallographic structure analysis.Result of the test shows, exceeds bend pipe material under entrance side and meets standard; Circumferential crack happening part, pattern height are similar, and all in lower bend pipe inner arc side, penetration of cracks inner arc side pipe wall, expands to tube wall outer arc side.Elbow internal wall is comparatively bright and clean, and oxide skin is less.Leak, without attenuate, is brittle fracture; Pipe bent position metallographic structure is normal austenite structure, and homogeneous grain size, without distortion, is found along brilliant crackle at main crackle edge, and crack tip has branch, and direction of crack propagation is vertical with stress direction, illustrates that bend pipe exists action of pulling stress; The every data fit standard-required of mechanical property test, but in view of got tensile sample be straight length but not curved arc place, therefore mechanical property test only has reference significance; Hoop Brinell hardness test result shows, the ball hardness number at lower curved arc place is higher than the 70HB of straight length place, and wherein inner arc side hardness is higher than outer arc side hardness 10HB, and lower curved arc place ball hardness number is all between 200～225HB.ASME standard code, the hardness of TP347H should not surpass 192HB, and visible censorship exceeds lower bend pipe (comprising the lower bend pipe that there is no crackle) hardness number and all exceeds standard.
After aspect contact boiler for producing producer of power plant, learn, under this high temperature superheater entrance, bend pipe is cold roll forming during fabrication, does not take solid solution treatment process after bend pipe.First, the hardness number regulation that is above standard in lower curved arc place is more, and internal stress is excessive, may be that the top pier power that bend pipe inner arc side applies during due to clod wash is excessive, causes the deflection of bend pipe inner arc to be greater than the deflection of outer arc, and inner arc is under excessive stress state.Secondly, ASME boiler and pressure vessel standard I volume-power boiler is built in rules (2010 editions) and is clearly stipulated, the TP347H steel pipe of being on active service between 538～677 ℃, when deflection is greater than 15% after cold working, should carry out solution treatment (as shown in table 4).
Build a rules PG-19 piece of writing and also provided the strain computing formula of pipe bend after cold working:
Strain (%)=100r/R (7-1)
In formula: r is pipe nominal outer radius; R is the nominal bending radius of pipe center line.In conjunction with 6# stove, exceed bend pipe analysis under entrance, booster measured diameter is 51mm, draws r=25.5mm, and radius of curvature R=170mm is 15% thereby calculate bent pipe deformation.Solution treatment is carried out in the bend pipe suggestion of 15% deflection.In sum, because cold bending process is improper, also do not carry out solution treatment after clod wash, under the effect of residual stress, inner arc intergranular crack, produces circumferential crack.
Table 4, rear cold-formed range of strain and heat treatment requirements
This sample, after 1155 ℃ of solution treatment (temperature by with reference to ASME standard: SA213, then draw through great many of experiments), is carried out to the detection of hoop hardness again, and result is as shown in table 5 below.Can find out, except having indivedual point hardness values still higher than standard, most of measuring point hardness number has met standard.
Table 5, two bend pipe different parts hoop hardness contrasts of the 1st screen
Test example
The present invention also provides following test example, get with above-described embodiment in manage the on all four bend pipes of parameter such as radius, bending radius, carry out after solution treatment, detecting with above-described embodiment bend pipe same position sampling, wherein solid solubility temperature is 1120 ℃.
This sample, after 1120 ℃ of solution treatment (temperature by with reference to ASME standard: SA213, then draw through great many of experiments), is carried out to the detection of hoop hardness again, and result is as shown in table 6 below.Can find out, most of hardness measuring point and standard differ far away, are difficult to meet standard.
Table 6, two bend pipe different parts hoop hardness contrasts of the 1st screen
Claims (4)
1. an austenitic stainless steel clod wash processing method, is characterized in that, described method comprises the steps:
(1) measure the nominal outer radius r of Austenitic stainless steel pipe, and calculate deflection according to following formula:
Deflection (%)=100r/R, wherein R is the nominal bending radius of pipe center line;
(2) when deflection is greater than determined critical strain amount, Austenitic stainless steel pipe is carried out to solution treatment, described solution treatment is for being more than or equal to and carrying out solution treatment at 1093 ℃ in temperature.
2. austenitic stainless steel clod wash processing method according to claim 1, is characterized in that, the described solution treatment of step (2) is is at 1155 ℃, to carry out solution treatment in temperature.
3. austenitic stainless steel clod wash processing method according to claim 1 and 2, is characterized in that, the described solution treatment of step (2) is for processing 1.5h.
4. austenitic stainless steel clod wash processing method according to claim 1 and 2, is characterized in that, described in step (1), critical strain amount is 15%.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104946932A (en) * | 2014-03-25 | 2015-09-30 | 新日铁住金株式会社 | Method for manufacturing austenite series heat-resistant alloy pipe and austenite series heat-resistant alloy pipe manufactured by the method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS552773A (en) * | 1978-06-21 | 1980-01-10 | Sumitomo Metal Ind Ltd | Heat-treating method for heat resistant nickel base alloy pipe |
| DE10258941A1 (en) * | 2002-12-17 | 2004-07-01 | Kirchhoff Witte Gmbh & Co. Kg | U-section half-shell forming part of rigid driven or undriven axle for utility vehicle is made by bending flat sheet-metal blank and edges of two U-sections are welded together |
| CN1554892A (en) * | 2003-12-26 | 2004-12-15 | 庄建新 | U-shaped seamless stainless steel pipe and its preocessing process |
-
2013
- 2013-11-11 CN CN201310556239.2A patent/CN103551812A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS552773A (en) * | 1978-06-21 | 1980-01-10 | Sumitomo Metal Ind Ltd | Heat-treating method for heat resistant nickel base alloy pipe |
| DE10258941A1 (en) * | 2002-12-17 | 2004-07-01 | Kirchhoff Witte Gmbh & Co. Kg | U-section half-shell forming part of rigid driven or undriven axle for utility vehicle is made by bending flat sheet-metal blank and edges of two U-sections are welded together |
| CN1554892A (en) * | 2003-12-26 | 2004-12-15 | 庄建新 | U-shaped seamless stainless steel pipe and its preocessing process |
Non-Patent Citations (5)
| Title |
|---|
| ASME BOILER AND PRESSURE VESSEL COMMITTEE ON POWER BOILERS: "《ASME Boiler and Pressure Vessel Code Part 1 Rules for Construction of Power Boilers》", 1 July 2010, article "PG-19 COLD FORMING OF AUSTENITIC MATERIALS", pages: 10-12 * |
| ASME BOILER AND PRESSURE VESSEL COMMITTEE ON POWER BOILERS: "《ASME Boiler and Pressure Vessel Code Part 1 Rules for Construction of Power Boilers》", 1 July 2010, 中国石化出版社 * |
| 朱长春等: "TP347H钢管工艺及性能试验研究", 《第七届（2009）中国钢铁年会论文集》 * |
| 杨自新等: "固溶处理对TP347H钢性能的影响", 《锅炉制造》 * |
| 林瑾等: "奥氏体不锈钢管固溶处理试验研究", 《材料工程》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104946932A (en) * | 2014-03-25 | 2015-09-30 | 新日铁住金株式会社 | Method for manufacturing austenite series heat-resistant alloy pipe and austenite series heat-resistant alloy pipe manufactured by the method |
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Application publication date: 20140205 |