CN104889705A - Stainless steel tube production method for heat exchanger - Google Patents

Abstract

The invention relates to an improvement of a stainless steel production process, in particular to a production method of a stainless steel tube used in a heat exchanger. It includes steps in turn: round steel raw material—peeling—perforation—barren pipe—polishing—inspection—cold rolling—cold drawing—deoiling—annealing—pickling—finished product; the piercing temperature is 1100-1190°C; the cold drawing The lubricating oil used is a mixture of 35-45wt% paraffin and 55-65wt% engine oil; the annealing is carried out in stages, and the temperature is 700-800°C in the first stage, 930-970°C in the second stage, and 930-970°C in the third stage. 1010-1050°C, the fourth stage 1030-1080°C, the fifth stage 1030-1080°C, the fourth stage and the fifth stage are heat preservation stages for a total of 6-10 minutes of heat preservation; the pickling adopts mixed acid pickling, mixed acid It includes 5-8wt% hydrofluoric acid and 10-15wt% nitric acid, and the pickling temperature is 40-60°C. The invention makes the manufactured stainless steel pipe suitable for use in heat exchangers, and has a high yield.

Description

A kind of production method of stainless steel tube for heat exchanger

technical field

The invention relates to an improvement of a stainless steel production process, in particular to a production method of a stainless steel tube used in a heat exchanger.

Background technique

Existing product implementation standards are becoming more and more stringent. Whether the product is qualified or unqualified until the final product is inspected results, resulting in waste of production costs, and the quality is not guaranteed. In some cases, it cannot be remanufactured, especially when unqualified products are found in the fixed-length tubes, and the production can only be refilled.

Chinese patent CN1563772A (2005-1-12) discloses a fully wrapped stainless steel pipe and its manufacturing method, but it is not suitable for preparing heat exchangers.

Contents of the invention

The purpose of the present invention is to provide a production method for stainless steel tubes for heat exchangers that is suitable for high yield.

Above-mentioned technical purpose of the present invention is achieved through the following technical solutions:

A method for producing stainless steel tubes for heat exchangers, which is characterized in that it includes steps in sequence: round steel raw material—peeling—perforation—blank pipe—polishing—inspection—cold rolling—cold drawing—degreasing—annealing—pickling— finished product;

The piercing temperature is 1100-1190°C;

The lubricating oil that adopts when described cold drawing is the paraffin of 35-45wt% and the machine oil mixture of 55-65wt%;

The annealing is carried out in stages, the temperature is 700-800°C, 930-970°C, 1010-1050°C, 1030-1080°C, 1030-1080°C, and the temperature is kept for 6-10 minutes;

The pickling adopts mixed acid pickling, the mixed acid includes hydrofluoric acid at a ratio of 5-8wt% and nitric acid at 10-15wt%, and the pickling temperature is 40-60°C.

The invention controls raw materials, and through material and process control of special content ratio, the stainless steel tube made is suitable for use in heat exchangers. The original standard stipulated that the outer diameter tolerance requirement of 6-30mm outer diameter is (-0.2mm)-(+0.15)mm, and now the outer diameter tolerance of outer diameter less than or equal to 25mm is -0.1-(+0.1)mm, and the size requirements are strict . The finished product rate of adopting the process of the invention is increased from the original finished product rate of 85% to more than 88%, and the cost is reduced.

As a preference, for finished 06Cr19Ni10 or 00Cr17Ni14Mo2 stainless steel pipes with specifications of (19.01-19.08)*(1.61-1.69) mm: the blank pipe is (66-68)*(4.2-4.8);

The first cold rolling to (37-39)*(2.31-2.38) mm, the cold deformation coefficient is 3.31-3.38;

The second cold rolling to (19.01-19.08) * (1.61-1.69) mm, the cold deformation coefficient is 2.88-2.95.

Through a specific production process, while the finished product obtains the required specific specifications, it can meet the standards required in the field of heat exchangers and improve the finished product rate.

As a preference, for finished 06Cr19Ni10 or 00Cr17Ni14Mo2 stainless steel pipes with a specification of 19.05*1.65mm: the empty pipe is 67*4.5mm;

The first cold rolling to 38*2.35mm, the cold deformation coefficient is 3.35;

The second cold rolling to 19.05*1.65mm, the cold deformation coefficient is 2.92.

As a preference, for the 06Cr19Ni10 material, the perforation temperature is 1150-1190°C; the annealing is carried out in stages, and the temperatures are 780°C, 950°C, 1020°C, 1050°C, 1050°C; the temperature is kept for 8 minutes.

As a preference, for 00Cr17Ni14Mo2 material, the piercing temperature is 1100-1150°C; the annealing is carried out in stages, and the temperature is 700-720°C, 930-970°C, 1010-1050°C, 1045-1065°C, 1045-1065°C ; Keep warm for 6-10 minutes.

As a preference, for the 00Cr17Ni14Mo2 material, the piercing temperature is 1100-1150°C; the annealing is carried out in stages, and the temperatures are 700°C, 950°C, 1030°C, 1050°C, 1050°C; The lubricating oil that adopts is the paraffin of 40wt% and the engine oil mixture of 60wt%.

As a preference, as a preference, the peeling thickness in the peeling step is 1.2-1.5mm; the polishing includes rough polishing and fine polishing, and the number of polishing points is 2.1-2.3%; the diameter of the eddy current flaw detection through hole is 0.8mmB level during the finished product inspection Standard samples are tested.

In some stainless steel pipe production processes, in order to control production costs, the billet factory reduces the quality of the round steel surface, resulting in more cracks and cracks. The present invention determines the peeling quantity according to different quality surfaces during peeling, controls the annealing process in the production stage, and at the same time adjusts the polishing of the outer surface through the control of the polishing quality of the outer surface of the blank tube to control the quality of the outer surface of the intermediate product , Compared with previous products, the quality of stainless steel pipes can be controlled step by step from the source, fine cracks on the surface can be eliminated, and the surface quality of stainless steel pipes is high. The quality inspection of the finished product is carried out by tightening non-destructive flaw detection on the outer surface to detect the outer surface defects of the finished product. The eddy current flaw detection grade of the sample tube is adjusted from grade A to grade B, and the surface quality of the stainless steel pipe is high.

Preferably, the method further includes welding after the finished product inspection, the welding includes welding torch current control, inner bead leveling, outer bead grinding and heat treatment; the welding torch current control includes the use of two welding torch argon arc Welding, the current of the two welding torches is the same during welding, controlled at 100-150A; the outer bead grinding adopts an automatic grinding device, and the grinding pressure is controlled by the contact current between the emery cloth wheel and the steel pipe surface; the heat treatment is carried out in an inert gas environment , rapid cooling after heat treatment at 1010-1050°C.

The existing welding bead treatment method in the stainless steel pipe is likely to cause scratches on the inner wall of the pipe and reduce the qualified rate of the product. The welding method of the invention can improve the stability of the product quality and the surface quality is good.

Preferably, the outer ring of the guide wheel supporting the welded stainless steel pipe in the welding is made of brass.

The friction between brass and steel pipe is small, which can avoid scratches on the outer surface of the welded stainless steel by the guide wheel, and further improve the surface quality of the stainless steel pipe for heat exchangers.

In summary, the present invention has the following beneficial effects:

1. Suitable for heat exchangers, high product qualification rate;

2. Eliminate fine cracks on the surface of the steel pipe, and the surface quality is good.

Detailed ways

Embodiment one

The production method of the stainless steel tube used in the heat exchanger includes the following steps: round steel raw material—peeling—perforation—barren pipe—polishing—inspection—cold rolling—cold drawing—degreasing—annealing—pickling—finished product;

For finished TP304L (06Cr19Ni10) stainless steel pipes with specifications of 19.01*1.61mm:

The perforation temperature is 1150°C; the blank tube is 66*4.2;

The lubricating oil that adopts during cold drawing is the paraffin of 35wt% and the machine oil mixture of 65wt%;

The first cold rolling to 37*2.31mm, the cold deformation coefficient is 3.31;

The second cold rolling to 19.01*1.61mm, the cold deformation coefficient is 2.88.

Annealing is carried out in stages, the temperature is 720°C, 930°C, 1010°C, 1045°C, 1045°C in sequence, and the temperature is kept for 6 minutes;

Pickling adopts mixed acid pickling, the mixed acid includes hydrofluoric acid with a ratio of 8wt% and nitric acid at 10wt%, and the pickling temperature is 50°C.

The final stainless steel tube is suitable for use in heat exchangers; the finished product rate is increased to 88%, and the cost is reduced.

Embodiment two

The production method of the stainless steel tube used in the heat exchanger includes the following steps: round steel raw material—peeling—perforation—barren pipe—polishing—inspection—cold rolling—cold drawing—degreasing—annealing—pickling—finished product;

For finished TP304L (06Cr19Ni10) stainless steel pipes with specifications of 19.08*1.69mm:

The perforation temperature is 1190°C; the blank tube is 68*4.8;

The lubricating oil that adopts during cold drawing is the paraffin of 45wt% and the machine oil mixture of 55wt%;

The first cold rolling to 39*2.38mm, the cold deformation coefficient is 3.38;

The second cold rolling to 19.08*1.69mm, the cold deformation coefficient is 2.95.

Annealing is carried out in stages, the temperature is 750°C, 970°C, 1050°C, 1065°C, 1065°C in sequence, and the temperature is kept for 10 minutes;

Pickling adopts mixed acid pickling, the mixed acid includes hydrofluoric acid with a ratio of 6wt% and nitric acid with a ratio of 15wt%, and the pickling temperature is 50°C.

The final stainless steel tube is suitable for use in heat exchangers; the finished product rate is increased to 88.5%, and the cost is reduced.

Embodiment Three

For finished TP304L (06Cr19Ni10) stainless steel pipes with specifications of 19.05*1.65mm:

The perforation temperature is 1160°C; the blank tube is 67*4.5mm;

The lubricating oil that adopts during cold drawing is the paraffin of 40wt% and the machine oil mixture of 60wt%;

The first cold rolling to 38*2.35mm, the cold deformation coefficient is 3.35;

The second cold rolling to 19.05*1.65mm, the cold deformation coefficient is 2.92.

The annealing is carried out in stages, the temperature is 780°C, 950°C, 1020°C, 1050°C, 1050°C in sequence; the temperature is kept for 8 minutes.

Pickling adopts mixed acid pickling, mixed acid includes 5-8wt% hydrofluoric acid and 10-15wt% nitric acid, and the pickling temperature is 40-60°C.

The final stainless steel tube is suitable for use in heat exchangers; the finished product rate is increased to 88.8%, and the cost is reduced.

Embodiment Four

Same as Example 1, the difference is that for the finished TP316L (00Cr17Ni14Mo2) stainless steel pipe with a specification of 19.01*1.61mm:

Piercing temperature 1100℃;

Annealing is carried out in stages, the temperature is 680°C, 930°C, 1010°C, 1045°C, 1045°C in sequence; keep warm for 6 minutes.

  The final stainless steel tube is suitable for use in heat exchangers; the finished product rate is increased to 88.1%, and the cost is reduced.

Embodiment five

Same as Example 2, except for the finished product of TP316L (00Cr17Ni14Mo2) stainless steel pipe with a specification of 19.08*1.69mm:

Piercing temperature 1150°C;

The annealing is carried out in stages, the temperature is 720°C, 970°C, 1050°C, 1065°C, 1065°C in sequence; keep warm for 10 minutes.

The final stainless steel tube is suitable for use in heat exchangers; the finished product rate is increased to 88.4%, and the cost is reduced.

Embodiment six

Same as Example 3, the difference is that for the finished TP316L (00Cr17Ni14Mo2) stainless steel pipe of 19.05*1.65mm, the piercing temperature is 1130°C; the annealing is carried out in stages, and the temperature is 700°C, 950°C, 1030°C, 1050°C, and 1050°C.

The final stainless steel tube is suitable for use in heat exchangers; the finished product rate is increased to 88.9%, and the cost is reduced.

Embodiment seven

Same as Embodiment 4, the difference is that the peeling thickness in the peeling step is 1.2mm.

Polishing includes rough polishing and fine polishing, and the number of polishing points is 2.1%.

During the finished product inspection, the diameter of the eddy current flaw detection through hole is tested with a 0.8mm B-level standard sample.

Welding is carried out after the finished product inspection. Welding includes torch current control, inner bead leveling, outer bead grinding and heat treatment; torch current control includes argon arc welding with two torches, and the current of the two torches is the same during welding. At 100A; the outer weld bead is polished using an automatic grinding device, and the grinding pressure is controlled by the contact current between the emery cloth wheel and the steel pipe surface; the heat treatment is in an inert gas environment, and it is cooled rapidly after heat treatment at 1010°C; the guide for supporting the welded stainless steel pipe during welding The outer ring of the wheel is brass.

The final stainless steel tube is suitable for use in heat exchangers; the finished product rate is increased to 88.1%, and the cost is reduced. Eddy current flaw detection, the pass rate is 90%.

Embodiment Eight

Same as the fifth embodiment, the difference is that the peeling thickness in the peeling step is 1.5 mm.

Polishing includes rough polishing and fine polishing, and the number of polishing points is 2.3%.

During the finished product inspection, the diameter of the eddy current flaw detection through hole is tested with a 0.8mm B-level standard sample.

Welding is carried out after the finished product inspection. Welding includes torch current control, inner bead leveling, outer bead grinding and heat treatment; torch current control includes argon arc welding with two torches, and the current of the two torches is the same during welding. At 150A; the outer weld bead is polished using an automatic grinding device, and the grinding pressure is controlled by the contact current between the emery cloth wheel and the steel pipe surface; the heat treatment is rapid cooling after heat treatment at 1050°C in an inert gas environment; the guide for supporting the welded stainless steel pipe during welding The outer ring of the wheel is brass. The pass rate of eddy current flaw detection is 91%.

Embodiment nine

Same as Embodiment 6, the difference is that the peeling thickness in the peeling step is 1.3mm.

Polishing includes rough polishing and fine polishing, and the number of polishing points is 2.2%.

During the finished product inspection, the diameter of the eddy current flaw detection through hole is tested with a 0.8mm B-level standard sample.

Welding is carried out after the finished product inspection. Welding includes torch current control, inner bead leveling, outer bead grinding and heat treatment; torch current control includes argon arc welding with two torches, and the current of the two torches is the same during welding. At 130A; the outer weld bead is polished using an automatic grinding device, and the grinding pressure is controlled by the contact current between the emery cloth wheel and the steel pipe surface; the heat treatment is in an inert gas environment, and it is cooled rapidly after heat treatment at 1030°C; the guide for supporting the welded stainless steel pipe during welding The outer ring of the wheel is brass. The pass rate of eddy current flaw detection is 92%.

This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. Those skilled in the art can make modifications to this embodiment without creative contribution as required after reading this specification, but as long as they are within the rights of the present invention All claims are protected by patent law.

Claims (9)

1. for a stainless steel tube production method for heat exchanger, it is characterized in that it comprises step successively: raw material-peeling-perforation-hollow forging-polishing-inspection-cold rolling-cold-drawn-deoil-anneal round steel-pickling-finished product;

Described piercing temperature is 1100-1190 DEG C;

The lubricating oil adopted during described cold-drawn is the paraffin of 35-45wt% and the machine oil mixture of 55-65wt%;

Described annealing is carried out stage by stage, temperature be followed successively by first stage 700-800 DEG C, second stage 930-970 DEG C, phase III 1010-1050 DEG C, fourth stage 1030-1080 DEG C, five-stage 1030-1080 DEG C, described fourth stage and five-stage are that holding stage amounts to insulation 6-10 minute;

Described pickling adopts nitration mixture pickling, and it is the hydrofluoric acid of 5-8wt% and the nitric acid of 10-15wt% that nitration mixture comprises proportioning, and pickling temperature is 40-60 DEG C.

2. a kind of stainless steel tube production method for heat exchanger according to claim 1, is characterized in that: 06Cr19Ni10 or the 00Cr17Ni14Mo2 stainless steel tube finished product for specification being (19.01-19.08) * (1.61-1.69) mm: hollow forging is (66-68) * (4.2-4.8);

First time is cold-rolled to (37-39) * (2.31-2.38) mm, and cold deformation coefficient is 3.31-3.38;

Second time is cold-rolled to (19.01-19.08) * (1.61-1.69) mm, and cold deformation coefficient is 2.88-2.95.

3. a kind of stainless steel tube production method for heat exchanger according to claim 2, is characterized in that: 06Cr19Ni10 or the 00Cr17Ni14Mo2 stainless steel tube finished product for specification being 19.05*1.65mm: hollow forging is 67*4.5mm;

First time is cold-rolled to 38*2.35mm, and cold deformation coefficient is 3.35;

Second time is cold-rolled to 19.05*1.65mm, and cold deformation coefficient is 2.92.

4. a kind of stainless steel tube production method for heat exchanger according to claim 2, is characterized in that: for 06Cr19Ni10 material, described piercing temperature 1150-1190 DEG C; Described annealing is carried out stage by stage, and temperature is followed successively by 780 DEG C, 950 DEG C, 1020 DEG C, 1050 DEG C, 1050 DEG C; Be incubated 8 minutes.

5. a kind of stainless steel tube production method for heat exchanger according to claim 2, is characterized in that: for 00Cr17Ni14Mo2 material, described piercing temperature 1100-1150 DEG C; Described annealing is carried out stage by stage, and temperature is followed successively by 680-720 DEG C, 930-970 DEG C, 1010-1050 DEG C, 1045-1065 DEG C, 1045-1065 DEG C; Insulation 6-10 minute.

6. a kind of stainless steel tube production method for heat exchanger according to claim 5, is characterized in that: for 00Cr17Ni14Mo2 material, described piercing temperature 1100-1150 DEG C; Described annealing is carried out stage by stage, and temperature is followed successively by 700 DEG C, 950 DEG C, 1030 DEG C, 1050 DEG C, 1050 DEG C; Be incubated 8 minutes; The lubricating oil adopted during described cold-drawn is the paraffin of 40wt% and the machine oil mixture of 60wt%.

7. a kind of stainless steel tube production method for heat exchanger according to any one of claim 1-6, is characterized in that: the peeling thickness in described peeling step is 1.2-1.5mm; Described polishing comprises rough polishing and essence is thrown, and polishing is counted as 2.1-2.3%; During product inspection, eddy current inspection through-hole diameter adopts 0.8mmB level standard specimen to detect.

8. a kind of stainless steel tube production method for heat exchanger according to claim 7, it is characterized in that: described method is welded after being also included in product inspection, described welding comprises welding torch Current Control, the leveling of interior welding bead, the polishing of outer welding bead and heat treatment; Described welding torch Current Control comprises the argon arc welding of employing two welding torch, and during welding, the electric current of two welding torches is identical, controls at 100-150A; Described outer welding bead polishing adopts automatically grinding device, and polishing pressure is controlled by the pick-up current size of flap wheel and steel tube surface; Described heat treatment is in an inert atmosphere, cools rapidly after 1010-1050 DEG C of heat treatment.

9. a kind of stainless steel tube production method for heat exchanger according to claim 8, is characterized in that: the outer ring of supporting the directive wheel of welded stainless steel pipe in described welding is brass.