CN111659984B

CN111659984B - Titanium alloy anchor chain for ship and ocean engineering and welding production process thereof

Info

Publication number: CN111659984B
Application number: CN202010441250.4A
Authority: CN
Inventors: 宋德军; 高福洋; 孙奇; 孙建刚; 陶欢
Original assignee: 725th Research Institute of CSIC
Current assignee: 725th Research Institute of CSIC
Priority date: 2020-05-22
Filing date: 2020-05-22
Publication date: 2021-11-30
Anticipated expiration: 2040-05-22
Also published as: CN111659984A

Abstract

The invention relates to a titanium alloy anchor chain for ships and ocean engineering and a welding production process thereof, wherein a high-strength titanium alloy bar is used as a raw material, a special bending and welding process is adopted, and a crosspiece is placed before chain rings are welded.

Description

Titanium alloy anchor chain for ship and ocean engineering and welding production process thereof

Technical Field

The invention relates to the field of ship and ocean engineering, in particular to a titanium alloy anchor chain for ship and ocean engineering and a welding production process thereof.

Background

The anchor chain is a chain between the connecting anchor and the ship body or the ocean engineering equipment, the ocean engineering equipment is continuously developed along with the development requirement of ocean resources, and the requirement of ocean engineering on the anchor chain is continuously increased; anchor chains with higher specifications and strength levels are continuously developed and applied, the diameter of the cross section of a welded junction of a large-specification high-strength anchor chain is larger than 40mm, the tensile strength of the R4-level anchor chain is required to be larger than 860MPa, and the production quality of the large-specification high-strength anchor chain is also required to be higher and higher.

The anchor chain can be divided into a cast anchor chain, a forged anchor chain and a welded anchor chain according to the production mode of the anchor chain; welded anchor chains are widely used because of their good quality and moderate manufacturing costs; at present, a flash welding mode with high automation degree becomes a mainstream mode of modern high-strength welding anchor chain production, and the flash welding process mainly comprises the steps of blanking, heating, ring bending, welding, deburring and gear pressing.

In the prior art, most of steel anchor chains are adopted, however, with the development of ocean engineering equipment, titanium alloy is widely applied to ocean engineering due to the characteristics of light weight, high strength and corrosion resistance, and has urgent application requirements in the field of anchor chains; the existing steel anchor chain production process, particularly the molding welding and surface coating asphalt anti-corrosion treatment process is not suitable for the titanium alloy anchor chain; in the existing flash welding process, two ends of a titanium alloy are directly and horizontally opposite to each other and two end surfaces are parallel to each other when a ring is bent; in addition, the titanium alloy flash butt welding generates coarse primary alpha phase due to large heat input quantity of the core part, the strength of a joint is influenced, so that the service strength of the anchor chain is reduced, and the flash butt welding is not suitable for manufacturing the titanium alloy anchor chain.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a titanium alloy anchor chain for ship and ocean engineering and a welding production process thereof, wherein the process can ensure the welding quality and the dimensional accuracy of the titanium alloy anchor chain, simultaneously improves the production efficiency, reduces the dislocation and the welding deformation of the end part, reduces the stress concentration of the end part of the anchor chain ring, and can also improve the wear resistance of the titanium alloy anchor chain, and the manufactured anchor chain can meet the R4-grade requirement.

In order to achieve the purpose, the invention adopts the technical scheme that: a welding production process of a titanium alloy anchor chain for ship and ocean engineering comprises the following steps:

step one, blanking: selecting a high-strength titanium alloy bar as a raw material, wherein the titanium alloy bar has the properties that the yield strength is more than or equal to 740MPa, the tensile strength is more than or equal to 840MPa, the elongation is more than or equal to 10 percent, and the reduction of area is more than or equal to 30 percent;

step two, heating: heating the titanium alloy bar coated with the high-temperature anti-oxidation coating to 850-;

step three, ring bending: bending the heated titanium alloy bar on a bending mechanism, arranging a bending mandrel at two initial positions of the titanium alloy bar to be bent, bending the titanium alloy bar around the bending mandrel into a U shape with a horizontal bottom, bending two side edges of the U shape around the bending mandrel to the middle in the axial direction to enable two end surfaces of the titanium alloy bar to be close to each other, and stopping bending when the minimum gap at the bottoms of the two end surfaces is 2-3mm and the two end surfaces form a V-shaped opening with a non-contact bottom, so that a bending ring is formed; it should be noted that, because the titanium alloy has a large elastic resilience, the titanium alloy needs to be bent inwards by about 10-50% to ensure that the front face of the finally bent chain ring has a bending angle of about 0-10 degrees;

step four, assembling the crosspieces: assembling the crosspiece to the middle position of the chain ring, wherein the arc-shaped sections at the two ends of the crosspiece are well matched with the excircle of the chain ring, so that better fitting is realized;

step five, chain ring welding: grinding and cleaning two end faces to be connected of the chain link, processing a required welding groove, and realizing closed welding of the chain link by adopting arc welding or electron beam welding so as to form a welding anchor chain with reliable quality;

step six, welding a crosspiece: welding the crosspiece to ensure the connection strength and smooth transition between the crosspiece and the chain ring;

step seven, checking: and (5) inspecting the finished product to obtain the anchor chain without air holes and slag inclusion.

The production process further comprises the eighth step of thermal oxidation: and (3) carrying out high-temperature heating oxidation in an air furnace at the temperature of 500-900 ℃, forming a thermal oxidation layer on the surface of the anchor chain, increasing the surface hardness of the anchor chain and improving the wear resistance of the anchor chain.

The invention also provides a titanium alloy anchor chain, which is prepared by using the welding production process with the titanium alloy bar as the raw material, has the tensile strength of more than 860Mpa, and meets the requirement of the R4-level anchor chain.

Has the advantages that: 1. the titanium alloy is adopted to prepare the anchor chain, and the titanium alloy has the characteristics of light weight, high strength and good seawater corrosion resistance, so that the service life of the anchor chain is greatly prolonged, and the safety of the anchor chain in the using process is ensured; 2. the invention adopts special process to bend and weld the chain link, bending is carried out by combining the material characteristics during ring bending, the requirement of the angle after bending is fully ensured, arc welding or electron beam welding is adopted during welding, the forming precision and the welding quality are fully ensured, stress concentration is avoided, and the prepared anchor chain meets the requirement of R4 grade; 3. in the prior art, the crosspieces are pressed after the chain rings are welded, and in the welding production process, the crosspieces are placed after the ring is bent and before the chain rings are welded, the crosspieces are welded after the chain rings are welded, so that the connection quality of the crosspieces is greatly improved; 4. according to the invention, the surface of the anchor chain is hardened through thermal oxidation after welding, so that the wear resistance of the anchor chain is improved, and the service life of the titanium alloy anchor chain in the using process is further prolonged.

Drawings

FIG. 1 illustrates a conventional anchor chain bend angle in the prior art;

FIG. 2 is a schematic representation of the overbending of the present invention;

FIG. 3 is a schematic illustration of the assembly of the crosspiece of the present invention;

FIG. 4 is a schematic view of the finished welded chain link.

Detailed Description

The invention is described in further detail below with reference to the figures and specific examples.

The invention relates to a welding production process of a titanium alloy anchor chain for ship and ocean engineering, which comprises the following steps: the method is characterized in that a titanium alloy bar is selected as a raw material to prepare an R4-grade anchor chain, the tensile strength of the prepared anchor chain is greater than 860MPa, and the production process specifically comprises the following steps:

step three, ring bending: bending the heated titanium alloy bar on a bending mechanism, arranging a bending mandrel at two initial positions of the titanium alloy bar to be bent, bending the titanium alloy bar around the bending mandrel into a U shape with a horizontal bottom, bending two side edges of the U shape around the bending mandrel to the middle in the axial direction, enabling two end surfaces of the titanium alloy bar to be close to each other, and stopping bending when the minimum gap at the bottom is 2-3mm and the two end surfaces form a V-shaped opening with a non-contact bottom, so that the bending ring is formed; fig. 1 shows a bending angle of a conventional anchor chain, and particularly, because titanium alloy has large elastic resilience, the bending needs to be bent inwards by about 10-50% (relative to the width of a chain ring) too much, as shown in fig. 2, so as to ensure that a bending angle (which refers to an included angle between a downward bending position and a horizontal position) of about 0-10 ° exists on the front surface of the finally bent chain ring, and then the chain ring with the required dimensional accuracy is obtained through welding deformation control;

step four, assembling the crosspieces: as shown in fig. 3, the crosspiece is assembled in the middle of the chain ring, and the arc-shaped sections at the two ends of the crosspiece are well matched with the excircle of the chain ring, so that better fit is realized;

step six, welding a crosspiece: welding the crosspieces to ensure the connection strength and smooth transition of the crosspieces between the chain rings;

step seven, checking: inspecting the finished product to obtain the anchor chain without air holes and slag inclusion, wherein the chain ring of the finished product after welding is shown in figure 4;

step eight, thermal oxidation, namely performing high-temperature heating oxidation in an air furnace at the temperature of 500-900 ℃ to form a thermal oxidation layer on the surface of the anchor chain, so that the surface hardness of the anchor chain is increased, and the wear resistance of the anchor chain is improved; meanwhile, the machining stress and the welding residual stress generated in the processes of bending the bar and welding can be effectively removed by heating at the temperature of 500-900 ℃, so that the stability of the structure and the performance of the anchor chain is ensured.

In order to better illustrate the technical solution of the present invention and its effects, two specific examples are given below.

Example 1

Step one, blanking: selecting a high-strength titanium alloy bar with the diameter of 40mm as a raw material, wherein the properties of the titanium alloy bar comprise yield strength of 780MPa, tensile strength of 880MPa, elongation of 12% and reduction of area of 35%;

step two, heating: heating the titanium alloy bar coated with the high-temperature anti-oxidation coating to 850 ℃ by using a heating furnace, and preserving heat for 1 hour to ensure that the temperature of the core part of the titanium alloy bar is close to that of the surface of the titanium alloy bar, so as to realize complete heat penetration of the bar;

step three, ring bending: bending the heated titanium alloy bar on a bending mechanism, arranging a bending mandrel at two initial positions of the titanium alloy bar to be bent, bending the titanium alloy bar around the bending mandrel into a U shape with a horizontal bottom, bending two side edges of the U shape around the bending mandrel to the middle in the axial direction to enable two end surfaces of the titanium alloy bar to be close to each other, stopping bending when the minimum gap at the bottom is 2-3mm and the two end surfaces form a V-shaped opening with a non-contact bottom, so that the bending ring is formed, particularly, the titanium alloy has large elastic resilience, so that the bending needs to be inwards over-bent by about 30 percent, the finally bent chain ring is ensured to have a bending angle of about 10 degrees on the front surface, and the chain ring meeting the requirement of dimensional accuracy is obtained through welding deformation control subsequently;

step four, assembling the crosspieces: the crosspiece is assembled in the middle of the chain ring, the arc-shaped sections at the two ends of the crosspiece are well matched with the excircle of the chain ring, and good fitting is achieved.

Step five, chain ring welding: the two end faces to be connected of the chain ring are polished and cleaned, a required welding groove is processed, the closed welding of the chain ring is realized by adopting electric arc welding, the good matching of the chain ring and the crosspiece is realized by welding deformation control, the size precision of the chain ring is ensured, and finally the welding anchor chain with the size meeting the requirements and reliable quality is obtained.

Step six, welding a crosspiece: the crosspieces are welded, so that the connecting strength and smooth transition between the crosspieces and the chain rings are ensured.

And step eight, performing thermal oxidation, namely performing high-temperature heating oxidation in an air furnace at 900 ℃ to form a thermal oxidation layer on the surface of the anchor chain, so that the surface hardness of the anchor chain is increased, and the wear resistance of the anchor chain is improved.

The mechanical properties of the anchor chain prepared in example 1 are: yield strength 792MPa, tensile strength 878MPa, elongation 14% and reduction of area 38%;

example 2

Step one, blanking: selecting a high-strength titanium alloy bar with the diameter of 30mm as a raw material, wherein the properties of the titanium alloy bar comprise yield strength of 820MPa, tensile strength of 900MPa, elongation of 10% and reduction of area of 31%;

step two, heating: heating the titanium alloy bar coated with the high-temperature anti-oxidation coating to 940 ℃ by using an induction coil, and preserving heat for 30 minutes to ensure that the temperature of the core part of the titanium alloy bar is close to that of the surface of the titanium alloy bar, so as to realize complete heat penetration of the bar;

step three, ring bending: bending the heated titanium alloy bar on a bending mechanism, arranging a bending mandrel at two initial positions of the titanium alloy bar to be bent, bending the titanium alloy bar around the bending mandrel into a U shape with a horizontal bottom, bending two side edges of the U shape around the bending mandrel to the middle in the axial direction, enabling two end surfaces of the titanium alloy bar to be close to each other, stopping bending when the minimum gap at the bottom is 2-3mm and the two end surfaces form a V-shaped opening with a non-contact bottom, namely forming the bending ring, and particularly, because the titanium alloy has larger elastic resilience, bending needs to be inwards over-bent by about 10 percent when bending, thereby ensuring that the front face of the finally bent chain ring has a bending angle of about 0 degree and the two end surfaces are basically aligned;

Step five, chain ring welding: the two end faces to be connected of the chain ring are polished and cleaned, the welding end faces and the peripheral range are clean, electron beam welding is adopted to realize closed welding of the chain ring, and therefore the welding anchor chain with reliable quality is formed.

And step eight, performing thermal oxidation. And (3) carrying out high-temperature heating oxidation in an air furnace at 700 ℃ to form a thermal oxidation layer on the surface of the anchor chain, so that the surface hardness of the anchor chain is increased, and the wear resistance of the anchor chain is improved.

The mechanical properties of the anchor chain prepared in example 2 are: the yield strength is 797MPa, the tensile strength is 892MPa, the elongation is 15 percent, and the reduction of area is 34 percent.

The invention selects titanium alloy bar as material, adopts special process to bend and weld chain ring, and puts crosspiece before welding chain ring, unlike steel anchor chain and pressing and flash welding after welding chain ring in the prior art, the production process of the invention generally ensures the forming precision and welding quality of anchor chain, avoids stress concentration, and simultaneously, the wear resistance of anchor chain can be improved by hardening the surface of anchor chain through thermal oxidation after welding, the service life of titanium alloy anchor chain in use can be further improved, and the anchor chain prepared by the process of the invention can meet higher requirements of ocean engineering.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A welding production process of a titanium alloy anchor chain for ship and ocean engineering is characterized by comprising the following steps,

step three, ring bending: bending the heated titanium alloy bar on a bending mechanism, arranging a bending mandrel at two initial positions of the titanium alloy bar to be bent, bending the titanium alloy bar around the bending mandrel into a U shape with a horizontal bottom, bending two side edges of the U shape around the bending mandrel to the middle in the axial direction to enable two end surfaces of the titanium alloy bar to be close to each other, and stopping bending when the minimum gap at the bottoms of the two end surfaces is 2-3mm and the two end surfaces form a V-shaped opening with a non-contact bottom, so that a bending ring is formed; it should be noted that, because the titanium alloy has large elastic resilience, the titanium alloy needs to be bent inwards and over-bent during bending so as to ensure that the front face of the finally bent chain ring has a bending angle of about 0-10 degrees;

2. The welding production process of the titanium alloy anchor chain for the ship and ocean engineering as claimed in claim 1, wherein the production process further comprises the following steps of eight, thermal oxidation: and (3) carrying out high-temperature heating oxidation in an air furnace at the temperature of 500-900 ℃, forming a thermal oxidation layer on the surface of the anchor chain, increasing the surface hardness of the anchor chain and improving the wear resistance of the anchor chain.

3. The titanium alloy anchor chain is characterized in that the anchor chain is prepared by using a titanium alloy bar as a raw material and using the welding production process of any one of claims 1-2, has the tensile strength of more than 860Mpa and meets the requirement of an R4-grade anchor chain.