JPS60114553A - Alloy steel for piston ring - Google Patents

Abstract

PURPOSE:To improve the durability of a piston ring made of an alloy steel by adding prescribed percentages of C, Si, Cr, Mo, V and W and forming a nitrided layer on the outside. CONSTITUTION:This alloy steel for a piston ring consists of, by weight, 0.3- 0.5% C, 0.8-1.5% Si, 4.5-5.5% Cr, 1-1.5% Mo, 0.3-2.1% V and/or W and the balance Fe and has a nitrided layer on the outside as required. The alloy steel has wear resistance, scuffing resistance and heat resistance, and a piston ring made of the alloy steel has superior durability.

Description

[Detailed description of the invention] The present invention relates to an improved steel alloy for piston rings.

In recent years, with the lighter weight and higher output of internal combustion engines, the quality required for piston rings has become higher.Currently, spring steel is used as the steel, but the quality required for piston ring materials has increased. characteristics are not necessarily satisfied. Furthermore, many of today's piston rings are plated with Pf7 chromium to improve wear resistance, but the plating process takes a long time and waste liquid treatment is a cause of high costs, so plating is not recommended. There is a demand for a piston ring net that has sufficient wear resistance to withstand use when applied, has good workability, and has excellent heat resistance and toughness.

The present invention has been made in view of the above, and the t4
/ invention has carbon 0.3 to 0. j ffi amount%, silicon 0
, r ~ /, J - weight %, chromium 41 - ~yoj weight %, molybdenum i, o - i, s weight %, one or both of vanadium and tungsten in a total of 0.3 to 2.7 weight %
, the remainder of the invention relates to an alloy steel for piston rings, the remainder of which is substantially iron, and the λth invention is a nitriding treatment of the alloy steel according to the first invention to form a nitrided layer on at least the sliding surface (outer peripheral surface). This relates to an alloy steel for piston rings that has further improved scuff resistance and wear resistance.

First, the seventh invention will be explained.

Carbon forms carbides with iron, lithium, molybdenum, vanadium, and tungsten and contributes to wear resistance. If this is less than 0.3% by weight (hereinafter, weight% is simply expressed as "%"), the amount of carbide formed is small and the above effect is insufficient, and if it exceeds 0.5%, the toughness decreases. Therefore, the range is 0.3 to 0. j%.

Silicon improves heat resistance, but if it is less than 0.1 g%, this effect is insufficient, and if it exceeds 2%, it becomes brittle, so the range is set to 0.1 g to 7.2%.

Chromium forms carbides and contributes to wear resistance.

Further, in the second invention, the hardness of the nitrided layer is increased to improve scuff resistance. If this is less than lAt%, the amount of carbide formed will be small and the above effect will be insufficient, and if it exceeds soil j%, the toughness will be impaired, so lA! The range shall be ~yoj%.

Molybdenum forms carbides and contributes to wear resistance, and is a secondary
In the invention, embrittlement due to chromium is prevented, and the hardness of the nitrided layer is increased to improve scuff resistance. This is /, 0
If the content is less than %, the above effect is insufficient, and even if it is contained in a large amount exceeding /,j%, the effect will not increase significantly, so the content is set in the range of 0 to 7.5%.

Vanadium and tungsten together form carbides to improve wear resistance and also provide resistance to temper softening. Since the effects are the same for both, one or both of these are included, but if the total amount is less than 0.3%, the above effects are insufficient, and if it exceeds 1.13%, toughness will be impaired. So, the range is 0.3~! , 7%.

Next, the first invention will be explained. No.! The invention improves scuff resistance and wear resistance by nitriding the copper alloy according to the first invention and forming a nitride layer on at least the sliding surface (the outer peripheral surface of the piston ring). This invention relates to an improved alloy steel for piston rings. As the nitriding treatment, any nitriding method such as gas nitriding, gas soft nitriding, salt bath nitriding, ion nitriding, etc. can be used.

Next, an example will be described.

As a sample of the first invention, 0.3g%0%/, 4to%
Si, 1 Arr% a r s /, /-2% No, 0
．． 93%V.

An alloy steel with the remainder substantially made of iron was used as the sample of the first invention, which was obtained by subjecting the above alloy steel to the usual gas nitriding treatment, and a copper sw for valve springs subjected to austempering was used as a comparative material.
OSO-V was used as a comparative material, and cast iron with hard chrome plating was prepared, and the following tests were conducted.

(1) The main parts of the wear test equipment rR are schematically shown in Fig. 1, and the test equipment rR has a diameter of 10 m that is removably attached to the stator holder.
Lubricating oil is applied to the center of the disk m from the back side through the injection hole 3. A pressing force is applied to the stator holder by a hydraulic device (not shown) with a predetermined pressure toward the right in the figure. A rotor is provided opposite to the disc 2, and is rotated at a predetermined speed by a drive device (not shown). The rotor is removably removed (= J-shaped specimen holder.
Test pieces t of 0 mm are placed on a concentric circle at equal intervals fj. In such a device, a predetermined pressing force is applied to the stator holder so that the disc (mate material) 2 and the test piece B come into contact with each other with a predetermined surface pressure. Rotate the low tag while lubricating the surface at a predetermined lubricating speed. Tests are conducted using such test equipment, and after trial driving,
Test piece B was removed and the reduction in height due to wear was measured. Among the test pieces B, the surface-treated one "C" had its surface layer in contact with the disk!

The test conditions are as follows. Mating disc IA'1 cast iron 'ya2s for cylinder liner, friction speed: 3m/s
ec,, fm/sθC1 Oil and refueling conditions: Mail mixed with a considerable amount of sludge from the 50-hour durability test of a diesel engine, oil temperature ♂θ, 3pm 0~≠oo
co/m soil n5 contact pressure: 700 kg/cm”,
Friction pressure N: 1100k.

The test results are shown in Figure 3. As can be seen from the figure, the amount of wear is much lower than that of the alloy cage according to the second invention compared to swosa-v, and it is equivalent to a single layer of aluminum alloy, which has traditionally been said to have excellent wear resistance. The alloy steel according to the invention of No. 1152 having a nitrided layer has less wear than the chromium plating layer, and has further improved wear resistance.

(2) Scuff test The test was conducted in the following manner using the test equipment used in the abrasion test. That is, as in o11 abrasion test, the test piece O is a disk! The pressure acting on the stator holder is increased stepwise at regular intervals.
The torque (frictional force) T generated on the stator holder/ due to the friction between the test piece B and the disk J is calculated using the spindle 7 shown in FIG. 2, which is a side view taken along the line u-n in FIG. It acts on the load cell g through the dynamic strain meter, and the change is read by a dynamic strain meter and recorded in the record 8110. It is assumed that scuffing occurs when the torque T suddenly increases, and the contact surface pressure at that time is used as the scuffing surface pressure, and the quality of the scuffing resistance is judged based on the magnitude of the scuffing surface pressure.

The test conditions are as follows. Friction speed: I m/
6 ec %i? #j+f+: Motor oil #30
, the contact surface pressure 24t Q ]<p/am" was increased by 10 kg/Ct for every 3 minutes of red vortex, and the other conditions were the same as in the above wear test.

The fourth test result is shown in the figure. As can be seen from the figure, alloy ii! according to the present invention! 1 has a higher scuffing surface pressure than the comparative H size and has excellent scuffing resistance.

In particular, the alloy W according to the invention of S+2, in which the nitrided layer is formed, has improved scuff resistance even more than that according to the first invention.

(3) Tension Reduction Test A tension reduction test specified in ``J Engineering SBI IO3, 21 Piston Ring'' was carried out using a plain pressure ring measuring 76.0 mm x 7.2 mm x 3.7 mm.

The heating temperature was set to 30θ0a as per the standard, but the heating time was also 5 hours and 70 hours instead of the standard 7 hours.

The test results are shown in FIG. From the same figure, it can be seen that compared to the comparative swosc+-v, the piston ring manufactured by the present invention ψ71 (') has a significantly lower tension reduction rate and has excellent heat resistance.(JIs standard) 300'
It is specified to be 10% or less after heating for 0.7 hours. ) As explained above, Alloy 11 according to the first invention has extremely excellent wear resistance and scuff resistance, and Alloy M according to the first invention has even better resistance to scratches and is pure. Improved properties and scuff resistance. In addition, the copper alloys of the present invention also have excellent heat resistance, and piston rings made of these alloy steels have extremely low tensile strength loss. Therefore, the copper alloy of the present invention can be used as a material for piston rings. When this is done, the durability of the piston ring is significantly improved, and the so-called release period for the next overhaul salt from the engine's main hole is greatly extended, which is of great utility in the M industry.

[Brief explanation of the drawing]

Part 1 is a partial cross-sectional view showing the main parts of the test equipment used for the wear test and scuff test, and Figures 2 and 2 are n-na of Figure 1.
FIG. Figure m3 is a graph showing the results of the Fi wear test, Figure ≠ is a graph showing the results of the H scuff test, and Figure 3 is a graph showing the results of the tension reduction test. /- stator holder, 2-1- disc (mating material), 3-
Lubrication hole, ≠-rotor, j-test piece holder, 2-test piece,
g~ p-docel, tar dynamic distortion reduction h1 person Rikenha Co., Ltd. 114 I''32 shi1 Figure 4 No. 5 (α1 addition #!-closed, br Procedural amendment (voluntary) January 1988 6 "1 Kazuo Wakasugi, Commissioner of the Japan Patent Office 1. Indication of the case: Patent Application No. 221428 of 1982 2. Title of the invention: Alloy steel for piston rings 3. Name of the person making the amendment: Riken Co., Ltd. 4. Date of the amendment order. (Voluntary) 5. Number of inventions increased by amendment 06. Target of amendment: Detailed explanation of the invention in Ming #TI book 7. Contents of amendment (1) Ming II book 1, page 3, line 13 “1.2 %"of[
1.5%” [corrected. (2) Change “1.2%” to “1.5” on page 3, line 15 of the specification.
%”. Procedural amendment measure (method) March 7, 1956 Director-General of the Patent Office Kazuo Wakasugi Dear Mr. and Mrs. Indication of the case 1955 Wakafl'F*I No. 22/Mud! 1. Name of the invention: Alloy steel for piston rings Date of amendment order: February 1, 1925 Target of amendment: Full text of the specification

Claims (1)

[Claims] / Carbon 0.3 to O, S weight %, silicon o, gi, s weight %, Tarom 44rs, s weight %, molybdenum 1.0
~7.5% by weight, vanadium and/or tungsten for table use 0.3~2. /Claw" Alloy steel for piston rings, the remainder of which is essentially iron. ! Carbon 0.3~O, S weight%, silicon o, g~i, s weight%, chromium 4', j--left j nail h (%, molybdenum 7
．． 0~/,! ;7ff, amount %, one or both of vanadium and tungsten in total 0.3 ~ j, /Iltm
%, the remainder being substantially iron, and having a nitrided layer on at least the outer peripheral surface.