JPS5835259B2 - Manufacturing method for high-strength, high-corrosion-resistant link chain - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a high-strength, high-corrosion-resistant member, and particularly to a method of manufacturing a high-strength, high-corrosion-resistant member that allows link chains with excellent corrosion resistance to be manufactured at low cost.

The link chain used in the chain block of lifting equipment is a key component that determines the quality of the equipment.

Therefore, link chains are required to have high strength, high toughness, and high wear resistance.

In other words, due to the chain hoist's mission as a lifting machine, the link chains used in it are loaded with a large load, but depending on the operating condition of the equipment, when the maximum load is applied, the link chain may Under normal use,
When the vehicle leaves the ground, an impact load stress greater than the maximum load is applied.

Therefore, it is necessary that the link chain does not fail due to fatigue even if the impact stress of the maximum capacity of the equipment is repeatedly applied to the link chain.

On the other hand, if the lifting hook accidentally gets caught on a structure and someone tries to lift it, the tensile strength must be greater than the impact load when suspended from the ground. The tensile strength is defined as 5 times or more the rated load.

Therefore, in the case of a single chain block with a rated load of 1 ton, the link chain must have an O tensile strength of 5 tons or more.

Next, in order to extend the life of the link chain, it is necessary to have excellent wear resistance, but in this case, the wear limit of the crane structure standard is 5 of the inner length pitch of the link chain.
% is the limit.

Therefore, the conditions required for link chains can be roughly divided into (I) repeated impact loads when leaving the ground, that is, high impact fatigue strength, and (2) tensile rupture strength equal to the rated capacity. (3) It is desirable that the wear resistance is 5 times or more.

Conventionally, in order to satisfy these conditions, low manganese steel was tempered and carburized, or nickel-chromium molybdenum low alloy steel developed by the applicant was carburized and quenched, or carbon content was reduced. 0.15-0.26
% by weight, silicon content 0.1-0.35% by weight, manganese content 0.9-2% by weight, molybdenum content 0.1
~0.6% by weight, phosphorus and sulfur content of 0.035% by weight or less, the balance being substantially iron, a surface carbon concentration of 0.5-0.8% by weight, an effective carburizing depth of Link chains that are carburized and quenched to have a diameter of 1/70 to 1/30 of the link chain diameter, and carbon content of 0.15 to 0.2.
6% by weight, silicon content 0.1-0.35% by weight, manganese content 0.4-0.9% by weight, chromium content 0.
4 to 0.9% by weight, molybdenum content 0.1 to 0.6% by weight, phosphorus and sulfur content not more than 0.035% by weight,
Surface carbon concentration of 0.5 to 0 for steel where the remainder is essentially iron
．． 8% by weight, effective carburizing depth is 1/70 of link chain.
Link chains that have been carburized and quenched to a ratio of ~1/30 are used as link chains.

These conventional link chains fully meet the above requirements in terms of strength, toughness and wear resistance.

However, in recent years, the uses of chain blocks have expanded, and they are now used in food, medical, and fishing industries.In addition to the above-mentioned high strength, toughness, and high abrasion resistance, the characteristics of chain blocks include weather resistance and Corrosion resistance is increasingly required.

However, it is difficult to impart corrosion resistance to the conventional link chain without sacrificing high strength and high wear resistance.

On the other hand, link chains with excellent corrosion resistance have conventionally been made of stainless steel or have been subjected to various plating treatments.

However, link chains made of stainless steel have poor wear resistance, so they not only cannot provide sufficient performance required in the market, but also have the disadvantage of being expensive.

In addition, for link chains that have been plated,
In conventional plating methods, when a load is applied, bending stress is generated in the chain, which causes a difference in elastic strain between the plating layer and the base metal layer, causing the plating to peel off and reduce corrosion resistance. effectiveness is significantly reduced.

In addition, the manufacturing process for link chains manufactured by conventional plating treatment is as shown in Figure 1, but since carburizing heat treatment and plating treatment are performed in separate processes, the number of steps is large and the manufacturing cost is low. It had the disadvantage of being expensive.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and has high strength and high corrosion resistance, which makes it possible to easily and quickly manufacture a member that has high strength and excellent corrosion resistance and is suitable for use as a link chain. The purpose of the present invention is to provide a method for manufacturing a member.

The present invention provides a method for manufacturing a link chain with high strength and high corrosion resistance, in which an element different from the main component of the link chain is diffused into the surface of the link chain made of iron-based material, and then the link chain, which is in a high temperature state, is brought to a low temperature. The above object is achieved by directly immersing it in a matting solution that is held at a temperature of 100 mL and rapidly cooling it.

In addition, in the same method for manufacturing high-strength, high-corrosion-resistant link chains, on the surface of link chains made of iron-based materials,
After diffusing and penetrating an element different from the main component of the link chain, the link chain, which is in a high temperature state, is directly immersed in a plating solution kept at a low temperature to quench it, and then further immersed in a plating solution to increase the temperature. By holding the steel for a certain period of time, tempering is also performed, thereby achieving the above object.

Hereinafter, a manufacturing method for manufacturing a link chain will be specifically described.

That is, as shown in Fig. 2, a link chain made of steel is treated with water-soluble nickel salt such as nickel chloride and hypophosphorous acid l-IJ, which is maintained at 40 to 150°C after carburizing or carbonitriding. It is directly inserted into an aqueous solution (so-called chemical nickel plating solution) containing a reducing phosphorus compound salt such as aluminum, quenched and cooled, and kept in the aqueous solution for 10 to 120 minutes.

Through such treatment, a link chain that is strong, has excellent wear resistance, and has high corrosion resistance can be obtained.

Here, the reason why the temperature of the chemical nickel solution is set to 40 to 150° C. is based on the hardening of these aqueous solutions by quenching and cooling hardening in the carburizing heat treatment of the link chain and imparting corrosion resistance.

At temperatures below 40°C, sufficient strength can be obtained through quenching and cooling hardening of the link chain, but in order to form a corrosion-resistant film in this aqueous solution (related to the holding time described below), temperatures above 40°C are preferable. After the carbonitriding treatment, the temperature is preferably 150° C. or lower in order to obtain hardening, hardening, and corrosion-resistant coating that does not easily peel off.

Next, the holding time is preferably 10 to 120 minutes in order to form a sufficiently corrosion-resistant film.

Examples will be described below.

A link chain with a wire diameter of 7.1φ consisting of 0.21% carbon, 0.21% silicon, 1.39% manganese, 0.013% phosphorus, 0.011% sulfur, and the balance substantially iron by weight, It was manufactured using the manufacturing process shown in FIG.

That is, in a gas carburizing atmosphere (carbon content 0.6 to 0.7%) heated to 850 to 880'C, the immersion depth was 0.
Carburized to a temperature of 2 mm, directly inserted into an aqueous solution of nickel chloride and sodium hypophosphite held at 60°C, quenched and cooled, held for 120 minutes, then heated to 180°C.
G. Tempering was performed for 1 hour.

The microstructure near the surface of the link chain obtained by this treatment is shown in FIG.

The magnification of FIG. 3 is 400x.

As is clear from FIG. 3, the link chain obtained by the above treatment has a carburized layer on the surface of the tempered martensitic structure, and further has a nickel-based layer which is effective for corrosion resistance on top of the carburized layer. is formed with a thickness of 17 μm.

The composition of the chemical nickel plating solution used in the production of this example was as follows: 1 ton of water, 30 g of nickel chloride as a water-soluble salt, 50 g of sodium gluconate as a complexing agent.
10g of sodium hypophosphite is melted as a g1 reducing agent, and the pH is adjusted to be in the range of 4 to 6.

The characteristics of the link chain made in this way are that the plating layer is less likely to peel off and cracks are less likely to occur, compared to the corrosion resistance of conventional carburized link chains that have been given wear resistance.
, was significantly better.

In addition, the rated load of a chain block equipped with a 7.1φ link chain is 1 ton, but for safety reasons, crane standards require it to have a tensile strength of at least 5 times the rated load, that is, 5 tons or more. However, the tensile strength of the link chain made by the method of the present invention is 7.2 to 8.
3 tons, elongation at break is 13-17%, and tensile strength is 6.5-7.5 tons compared to conventional carburized link chains.
Both are excellent compared to the elongation at break of 6 to 14%.

In addition, regarding wear resistance, as a result of conducting an actual machine wear test on a chain block with a rated load of 1 ton, the wear amount when hoisting 5x103 times was 0.09 maK compared to the inner length pitch wear amount of a conventional carburized link chain. Whereas,
The link chain made according to the present invention has a hardness of 0.06 mm and also has excellent wear resistance.

Further, in the above embodiments, nickel plating was applied to the iron-based material, but the type of plating is not limited to nickel plating. For example, the same effect can be obtained by applying copper plating using a known steel chemical plating method. Can be done.

Further, in the above embodiments, carburizing treatment was performed when heating to a temperature above the transformation point in a non-oxidizing atmosphere, but pretreatment is not limited to carburizing treatment, and may include vacuum heating, heating in hydrogen, Similar effects can be obtained by performing pretreatment using methods such as nitriding, heating in argon, and heating in nitrogen.

As explained above, the present invention provides a method for manufacturing a link chain with high strength and high corrosion resistance, in which an element different from the main component of the link chain is diffused into the surface of the link chain made of iron-based material, and then the link chain is heated to a high temperature. The link chain is quenched by being directly immersed in a tamping liquid kept at a low temperature, and if necessary, tempered by being held in a tamping liquid at a higher temperature for a certain period of time. High-strength link chains can be created with short processing steps.
It has the excellent effect of easily imparting high corrosion resistance.

[Brief Description of the Drawings] Fig. 1 is a process diagram showing a conventional link chain manufacturing method, Fig. 2 is a process diagram showing a manufacturing method of a high strength and highly corrosion resistant link chain according to the present invention, and Fig. 3 is a process diagram showing a manufacturing method of a high strength and highly corrosion resistant link chain according to the present invention. 2 is a micrograph at a magnification of 400 times showing the cross-sectional microstructure of the link chain produced by the method shown in FIG.

Claims (1)

[Claims] 1. After diffusing and penetrating the surface of a link chain made of iron-based material with an element different from the main component of the link chain,
A method for producing a high-strength, high-corrosion-resistant link chain, which comprises quenching the link chain in a high-temperature state by directly immersing it in a plating solution kept at a low temperature. 2. The method of manufacturing a high-strength, high-corrosion-resistant link chain according to claim 1, wherein the link chain is made of an iron-based material that undergoes quench hardening, and the rapid cooling is a quenching treatment. 3. The high-strength, high-corrosion-resistant plating solution according to claim 1 or 2, wherein the plating solution is a chemical nickel plating solution containing a water-soluble nickel salt and a reducing phosphorus compound salt, maintained at 40 to 150°C. How to make link chains. 4 The iron-based material contains 0.15 to 0.26% carbon by weight.
, silicon 0.1-0.35%, manganese 0.9-2%
, molybdenum 0.1-0.6%, phosphorus and sulfur 0.0
4. The method for manufacturing a high-strength, high-corrosion-resistant link chain according to any one of claims 1 to 3, wherein 35% or less and the remainder are substantially iron. 5 The iron-based material contains 0.15 to 0.26% carbon by weight.
, silicon 0.1-0.35%, manganese 0.4-0.
9%, chromium 0.4-0.9%, molybdenum 0.1-0
．． 6%, phosphorus and sulfur are 0.035% or less, and the balance is substantially iron. 6 After diffusing and penetrating the surface of a link chain made of iron-based material with an element different from the main component of the link chain,
The link chain, which is in a high temperature state, is directly immersed in a plating solution kept at a low temperature to rapidly cool it, and then tempered by holding it in the plating solution at an elevated temperature for a certain period of time. A method for producing a link chain with high strength and high corrosion resistance. 7. The method of manufacturing a high-strength, high-corrosion-resistant link chain according to claim 6, wherein the link chain is made of an iron-based material that undergoes quench hardening, and the rapid cooling is a quenching treatment. 8. The plating solution was maintained at 40 to 150°C.
The method for manufacturing a high-strength, high-corrosion-resistant link chain according to claim 6 or 7, wherein the chemical nickel plating solution contains a water-soluble nickel salt and a reducing phosphorus compound salt. 9 The iron-based material contains 0.15 to 0.26% carbon by weight.
, silicon 0.1-0.35%, manganese 0.9-2%
, molybdenum 0.1-0.6%, phosphorus and sulfur 0.0
9. The method for manufacturing a high-strength, high-corrosion-resistant link chain according to any one of claims 6 to 8, wherein 35% or less and the remainder are substantially iron. 10 The iron-based material contains 0.15 to 0.26 carbon by weight.
%, silicon 0.1-0.35%, manganese 0.4-0
．． 9%, chromium 0.4~0.9%, molybdenum 0.1~
0.6%, phosphorus and sulfur are 0.035% or less, and the balance is substantially iron. Method.