JIS G is standard which specified the spring steel mainly used for the hot formed springs such as the laminated springs, coiled springs. The symbols which denote the degree of correspondence in the contents between the relevant International Standard and JIS are IDT (identical), MOD. See the chemical composition and physical properties of JIS G Grade SUP9A, find alternative materials, and connect with suppliers.
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The present invention relates to a piston ring for automobile engines, particularly to a compression ring used in a high-thermal-load environment in high-compression-ratio engines, and its production method. For environmental protection, automobile engines are recently designed to have improved fuel efficiency, low emission and high power, so that engines tend to have high compression ratios and high load.
However, higher compression ratios generally elevate combustion chamber temperatures, so that knocking easily occurs. A usual measure against knocking is the delaying of ignition timing spark advancebut it makes h impossible to keep high thermal efficiency.
Accordingly, investigation is conducted to lower the 48001 of combustion chamber walls. To lower the temperature of combustion chamber walls, it is effective to lower the temperature of piston crown surfaces. To this end, it is most effective to dissipate the heat of pistons to cooled cylinder walls via compression rings. Thus, among the three basic functions of piston rings, a gas-sealing function, a thermal conduction function and an oil control function, the thermal conduction function is utilized.
Because the thermal 8401 function is affected by ring substrates, the thermal conductivity of surface treatment layers, ring shapes, etc. In addition, when pistons are made of aluminum, aluminum softens as the combustion chamber temperature is elevated, so that fatigue failure occurs in ring grooves of pistons due to the high-temperature impingement and sliding of compression rings, making likely the wearing of ring grooves and microwelding to compression rings.
In view of this, the temperature of ring grooves should be lowered by using high-thermal-conductivity compression rings. To meet the above uis, for example, JP A proposes a proper composition comprising C, Si, Mn and Cr, which is defined by parameters in predetermined ranges, for piston rings having excellent thermal conductivity and thermal sag resistance, which are usable as compression rings.
Further, not only excellent characteristics but also price competitiveness are required on automobile parts such as piston rings. Thus, cost reduction is an important object. An object of the present invention is to provide a compression ring having excellent thermal conductivity and thermal sag resistance as well as good price competitiveness, which can be used in a high-thermal-load environment in high-compression-ratio engines, and a method for producing such a compression ring. The relation between the thermal conductivity of the steel and jiz total amount of alloying elements is shown in FIG.
Materials with smaller amounts of alloying elements have higher thermal conductivities. However, the thermal sag resistance is actually deteriorated as the amounts of alloying elements decrease, making impossible use for compression rings in a high-thermal-load environment.
Steel is generally more inexpensive as the amounts of alloying elements are smaller. Also, from the economic point of view, steel used in a large amount, namely, mass-produced like materials defined by JIS Japanese Industrial Standards is inexpensive.
Thus, the compression ring of the present invention has a composition comprising by mass 0. The spheroidal cementite preferably has an average particle size of 0.
SUP9A Spring Steel-JIS G4801 Alloy Structure Steel Material Grade
The method of the present invention for producing a compression ring having a composition comprising by mass 0. The compression ring of the present invention has a composition comprising by mass 0. The above composition is basically a steel composition identified by the material number of SUP10 according to JIS Ghaving high jid conductivity because of a small jiis amount of alloying elements, though it comprises small amounts of Cr and V.
However, it does not have sufficient thermal sag resistance. In the present invention, relatively large spheroidized cementite is dispersed in a tempered martensite matrix. This spheroidal cementite is known as residual cementite in spring steel subject to an oil-tempering treatment. Because stress is concentrated on the spheroidal cementite, it is considered as a factor iis decreasing the mechanical properties of steel wires.
In the present invention, the spheroidal cementite has an average particle size of 0. Because the residual cementite of about 0. If the average particle size exceeds 1.
The preferred average particle size is 0. Because the thermal conductivity is mainly determined by the movement of free electrons in crystal grains of metals, higher thermal conductivity is obtained with fewer solid solution elements.
The facts that the 4810 of Si, a solution-strengthening element, is particularly smaller in SUP10 used in the present invention than in Si—Cr steel, and that spheroidal cementite is formed, appear to contribute to the improvement of thermal conductivity by reducing the solid solution of C.
From the aspect of wear resistance and microwelding resistance, sliding peripheral surfaces of compression steel rings are usually subject to various surface treatments.
When good thermal conductivity is predominantly needed, a chromium plating is preferable, but when wear resistance and microwelding resistance are important, ion-plated CrN coatings are preferable, and DLC coatings are suitable for aluminum cylinders. Thus, for the same compression rings, proper surface treatments may be selected jiis on sliding mate members, use environment, etc. Of course, a nitriding treatment is also usable.
A wire used for the production of the compression ring of the present invention is produced by melting steel SUP10 having a composition comprising by mass 0. Because spheroidal cementite having a predetermined particle size, which is formed by the spheroidizing annealing, is influenced by subsequent heat treatments and affects subsequent drawing, the spheroidizing annealing is preferably conducted immediately before the last oil-tempering treatment.
Accordingly, the spheroidizing annealing is conducted preferably in place of the second patenting treatment. In this case, the spheroidizing annealing is inevitably a batch treatment. The batch treatment is inserted between continuous treatments in f conventional 48801 line, inevitably resulting in lower productivity. Though the spheroidizing annealing may be conducted in place of the first patenting treatment for higher productivity, attention should be paid to provide the spheroidal cementite with particle sizes in a predetermined range.
The temperature and time period of the oil-tempering treatment comprising nis oil quenching step uis a tempering treatment step should be set such that all spheroidal carbides are not dissolved, namely, the spheroidal carbides have a preferred area ratio. Because the heat treatment temperature and time differ depending on the size of a heat treatment furnace and the cross section areas of items to be treated, they should be adjusted such that the spheroidal jiis has preferred particle size and area ratio.
The compression ring of the present invention is obtained from the above wire drawn to have a predetermined cross section shape, usually by forming the wire to a free 401 ring by a cam machine, conducting a strain-removing heat treatment, and grinding the side surfaces, peripheral surface, gap, etc. Of course, surface treatments such as plating, PVD, etc.
Each wire of SUP10 steel rolled to 8 mm in diameter was formed into a rectangular cross-sectioned wire of 1. Image analysis on an enlarged photomicrograph of this structure revealed that the spheroidal cementite had an average particle v of 0.
JIS G – Spring steels (Foreign Standard)
Each rectangular cross-sectioned wire of 1. Image analysis conducted in the same manner as in Example 1 on scanning electron photomicrographs of the wire structures revealed that the spheroidal cementites in Examples 4 and 5 had average particle sizes of 0. Namely, a gg surface of the compression ring was provided with a CrN coating by ion plating, and side surfaces of the compression ring were provided with a zinc phosphate coating Example 2 and a manganese phosphate coating Example 3.
In Comparative Example 1, a rectangular cross-sectioned wire of 1. All peripheral surfaces in Comparative Examples were coated with CrN, side surfaces in Comparative Example 3 were coated with zinc phosphate, iis side surfaces in Comparative Example 4 were coated with manganese phosphate.
In a scanning electron photomicrograph of FIG. The test was conducted 5 times in each of Examples 1, 4 and 5, and Comparative Examples 1, 2 and 5, and the measured results were averaged.
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The averaged values of the thermal sag resistance were shown in Table 2. In Examples 1, jos and 5, and Comparative Examples 1, 2 and 5, the thermal conductivity was measured by a laser flash method. The results are shown in Table 2. Example 1 was higher than the Si—Cr steel of Comparative Example 2 but lower than the hard steel wire of Comparative Example 5 in thermal conductivity, confirming that the thermal conductivity depends on the amounts h alloying elements.
A higher thermal conductivity provided a higher thermal sag ratio in Comparative Examples 1, 2 and 5, but the thermal sag ratios of Examples 1 and 5 were lower than a line connecting three Comparative Examples, confirming that the thermal sag ratio decreased at the same thermal conductivity, namely improvement in the thermal sag resistance.
When the microwelding occurs, the torque of a rotating shaft 2 changes, accompanied by temperature elevation.
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The number of cycles at that time was used to evaluate the life of the ring. The results are shown in Table 2 and FIG. In Example 3 with a manganese phosphate coating, the difference of a substrate did not change the microwelding resistance life. This appears to be due to influence by the surface roughness of the manganese phosphate coating. Because the compression ring of the present invention has both high thermal conductivity and high thermal sag resistance, even when used in a high-thermal-load environment such as high-compression-ratio engines, the ring can efficiently dissipate heat from a piston head to a cooled cylinder wall without losing a spring force.
Accordingly, knocking can be suppressed without needing such control as to delay ignition timing, keeping high thermal efficiency.
Also, the temperature of ring grooves of an aluminum piston can be lowered, suppressing microwelding and wearing of the ring grooves. The production method of the present invention using mass-produced steel defined by JIS contributes to cost reduction. A SumoBrain Solutions Company.
Search Expert Search Quick Search. Compression ring and its production method. United States Patent To provide a price-competitive compression ring having excellent thermal conductivity and thermal sag resistance, which can be used in a high-thermal-load environment of high-compression-ratio engines, steel identified by the material number of SUP10 in JIS Gwhich contains small amounts of alloying elements, is used, and a piston ring wire is annealed before an oil-tempering treatment such that spheroidal cementite having an average particle size of 0.
Click for automatic bibliography generation. The Formation of Martensite. Japanese Office Action, dated Feb.
The extended European search report, dated Mar. What is claimed is: A compression ring consisting of a composition consisting of by mass 0. A method for producing a compression ring consisting of a composition consisting of by mass 0. Measurement of Thermal Conductivity In Examples 1, 4 and 5, and Comparative Examples 1, 2 and 5, the thermal conductivity was measured by a laser flash method.
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