JP5752937B2 - Copper-tin-nickel-phosphorus alloy with improved strength and formability - Google Patents

Description

  This application claims priority from US Provisional Application No. 60 / 979,064, filed Oct. 10, 2007, the entire disclosure of which is incorporated herein.

  The present invention relates to copper alloys, especially copper-tin-nickel-phosphorus alloys with improved strength and formability.

  There continues to be a need for high formability copper alloys of good formability and reasonable cost for use in electrical connectors, particularly for use in automotive electrical connectors. The current low cost Cu—Sn—Ni—P based connector alloy has practical strength (531 MPa (77 KSI)), moderate electrical conductivity (37% IACS), excellent formability, and moderate stress relaxation ( The combination of properties at 65% at 150 ° C. is lacking. Formability in this document is measured by strip formation by roll bending about 90 ° around a known radius die. This ratio is the ratio of the minimum die radius that can shape the strip without cracking to the strip thickness. Bending was measured both in the direction parallel to the rolling direction (bad direction, BW) and in the direction perpendicular (good direction, GW). Table 1 shows currently available Cu-Sn-Ni-P alloys.

  C19025 is likely to achieve the desired properties, but lacks strength with acceptable moldability. C40820 has strength and excellent moldability but does not have electrical conductivity.

  Embodiments of the present invention provide a copper-tin-nickel-phosphorus alloy having an improved combination of properties, particularly an improved combination of yield strength and formability.

According to a preferred embodiment, the alloy is
About 1% to about 2% Sn,
About 0.3% to about 1% Ni,
About 0.05% to about 0.15% P;
At least one of about 0.01% to about 0.20% Mg and about 0.02% to about 0.4% Fe, and the balance copper. The addition of iron can be used as a low-cost alternative to Mg if good stress relaxation is not required for the application.
More preferably, the alloy comprises about 1.1% to about 1.8% Sn, about 0.4% to about 0.9% Ni, about 0.05% to about 0.14% P, And about 0.05% to about 0.15% Mg. Fe can replace a part of Mg.
Most preferably, the alloy comprises about 1.2% to about 1.5% Sn, about 0.5% to about 0.7% Ni, about 0.09% to about 0.13% P, about Contains 0.02% to about 0.06% Mg, and the balance copper. The alloy is treated to have a yield strength of at least about 531 MPa (about 77 KSI), an electrical conductivity of at least about 37% IACS, and a formability of 1.0 / 1.0 (90 ° GW / BW). Is preferred. The alloy preferably also has 65% stress relaxation at 150 ° C.

  The alloy strengthens the solid solution by Sn. Ni and Mg are added to form phosphorus precipitates, and the addition of Mg has the advantage that the strength increases without lowering the conductivity. The ratio of metal (Ni + Mg) to P (M / P ratio) is preferably controlled in the range of 4 to 8.5. If this ratio is less than 4, no strength is obtained, and if it is greater than 8.5, this material does not achieve 40% IACS.

  According to a preferred embodiment of the present invention, the alloy is melted and cast, hot rolled at about 850 to about 1000 ° C., cold rolled to about 75%, and annealed at about 450 ° C. to about 600 ° C. And cold rolling up to about 60% reduction, followed by annealing at 425 ° C. to about 600 ° C., followed by cold rolling up to about 50% and subsequent final annealing at about 400 ° C. to 550 ° C. The The final cold rolling reduction is given to achieve the desired thickness and mechanical strength prior to the thermal stress relief process. In another preferred embodiment, this treatment includes two final annealing treatments, eliminating the upper step annealing, thereby improving formability and strength, respectively.

2 is a micrograph of the alloy of Example 1. The graph which shows the relationship between YS and M / P ratio, and illustrates the preferable M / P ratio with respect to a Cu-Sn-Ni-P-Mg alloy. A graph illustrating the relationship between% IACS and M / P ratio and illustrating a preferred M / P ratio of a ratio of 4 to 8.5 for a Cu-Sn-Ni-P-Mg alloy. 2 is a flow diagram of a preferred embodiment of a method for treating an alloy in accordance with the principles of the present invention. 3 is a flow diagram of an alternative preferred embodiment for processing an alloy in accordance with the principles of the present invention. 3 is a flow diagram of an alternative preferred embodiment for processing an alloy in accordance with the principles of the present invention. Photomicrograph of Alloy 4 after two annealing showing a grain size of 6-7 μm with some regions appearing to have grains that have not completely recrystallised. Micrograph of alloy 4 of step 3 after strip annealing showing a grain size of 4-5 μm.

The embodiments of the present invention provide a copper-tin-nickel-phosphorus alloy having an improved combination of properties, particularly an improved combination of yield strength and formability. In a preferred embodiment, the alloy is
About 1% to about 2% Sn,
About 0.3% to about 1% Ni,
About 0.05% to about 0.15% P;
At least one of about 0.01% to about 0.20% Mg and about 0.02% to about 0.4% Fe, and the balance copper. The addition of iron can be used as a low cost alternative to Mg if good stress relaxation is not required in the application.

  More preferably, the alloy comprises about 1.2% to about 1.5% Sn, about 0.5% to about 0.7% Ni, about 0.09% to about 0.13% P, About 0.02% to about 0.06% Mg, and the balance copper. Preferably, the alloy is processed to have a yield strength of at least about 531 MPa (about 77 KSI), a conductivity of at least about 37% IACS, and a formability of 1.0 / 1.0 (90 ° GW / BW). . Preferably the alloy also has a 65% stress relaxation at 150 ° C.

  The alloy strengthens the solid solution by Sn. Ni and Mg are added to form phosphorus precipitates, and the addition of Mg is accompanied by the benefit of increasing strength without reducing conductivity. The M / P ratio is preferably controlled in the range of 4 to 8.5. If this ratio is less than 4, no strength is obtained, and if it is greater than 8.5, the material does not achieve 40% IACS.

  According to a preferred embodiment of the present invention, the alloy is melted and cast, hot rolled at 850-1000 ° C., cold rolled up to about 75%, annealed at 450-600 ° C., and about 60%. Processed by cold rolling followed by annealing at 425-600 ° C. and approximately 50% cold rolling followed by final annealing at 400-550 ° C. The final cold rolling reduction is given to achieve the desired thickness and mechanical strength prior to the thermal stress relief process. In another preferred embodiment, this process includes a two-time final annealing process that eliminates the upper annealing, thereby improving formability and strength, respectively.

Example 1
A series of 4.54 kg (10 pounds) research ingots having the ingredients listed in Table 2 were melted in a silica crucible and 101.6 mm × 101.6 mm × 44.45 mm (4 inches × 4 inches × 1.75 inch) steel mold. After soaking for 2 hours at 900 ° C., they were 27.94 mm (40.64 mm / 34.29 mm / 27.94 mm) (1.1 inch (1.6 inch / 1.35 inch / 1.1) in 3 passes. Inch)), reheated at 900 ° C. for 10 minutes, and 12.70 mm (22.86 mm / 17.78 mm / 12.70 mm) (0.50 inch (0.9 inch / 0.00 mm) in 3 passes. 7 inches / 0.5 inches))) and further reduced by hot rolling, followed by water quenching. After trimming and milling to remove surface oxide, the alloy was cold rolled to 3.048 mm (0.120 inch) and annealed at 570 ° C. for 2 hours. The alloy was washed, cold rolled to 1.219 mm (0.048 inch) and annealed at 525 ° C. for 2 hours. The alloy was cold rolled to 0.762 mm (0.030 inches) and annealed at 500 ° C. for 2 hours. The final cold rolling was 60% to 0.305 mm (0.012 inch) and a stress relief heat treatment was performed at 250 ° C. for 2 hours.

＊この表およびこの文書全体を通じて、ＹＳは耐力を表し、ＭＰａ（ＫＳＩ）単位で示される。

* Throughout this table and throughout this document, YS represents yield strength and is expressed in units of MPa (KSI).

  From the data of Example 2, the amount of Ni is preferably at least 0.5, and the best overall alloy was determined to have a Ni / P ratio of 7-9. All bends were inferior due to the presence of sulfur contaminants forming long filaments as shown in FIG.

Example 2
A series of 4.54 kg (10 pounds) research ingots having the ingredients listed in Table 3 were melted in a silica crucible and 101.6 mm × 101.6 mm × 44.45 mm (4 inches × 4 inches × 1.75 inch) steel mold. After soaking for 2 hours at 900 ° C., they were 27.94 mm (40.64 mm / 34.29 mm / 27.94 mm) (1.1 inch (1.6 inch / 1.35 inch / 1.1) in 3 passes. Inch)), reheated at 900 ° C. for 10 minutes, and 12.70 mm (22.86 mm / 17.78 mm / 12.70 mm) (0.50 inch (0.9 inch / 0.00 mm) in 3 passes. 7 inches / 0.5 inches))) and further reduced by hot rolling, followed by water quenching. After trimming and milling to remove surface oxide, the alloy was cold rolled to 3.048 mm (0.120 inch) and annealed at 570 ° C. for 2 hours. The alloy was washed, cold rolled to 1.219 mm (0.048 inch) and annealed at 525 ° C. for 2 hours. The alloy was cold rolled to 0.610 mm (0.024 inch) and annealed at 450 ° C. for 8 hours. The final cold rolling was 50% to 0.305 mm (0.012 inch) and a stress relief heat treatment was performed at 250 ° C. for 2 hours.

  Overall, the strength is low except for alloys K293 and K294. Both of these alloys contain about 0.5% more Sn than any other, with higher Sn content associated with greater strength. The strengths of K286, K287 and K288 show the benefits of Mg in contrast to alloys K282 and K284 which are very close components but do not contain Mg. It is noteworthy that there is no decrease in conductivity (% IACS) with increasing proof stress. In both cases, strength was increased by adding iron to K291 containing no Ni and Mg to K289. The conductivity for the alloy containing iron was about 4% IACS lower than the alloy containing Mg. Both of these alloys are almost balanced, the Mg / P ratio is 1.81, which is close to the ideal value of K289 of 1.2, and the Fe / P ratio of K291 is still at the ideal value of 3.6. It is close to 4.00. Iron is a more effective strengthener, but lowers conductivity.

Example 3
A series of 4.54 kg (10 pounds) research ingots having the ingredients listed in Table 4 were melted in a silica crucible and 101.6 mm × 101.6 mm × 44.45 mm (4 inches × 4 inches × 1.75 inches). After soaking for 2 hours at 900 ° C., they were 27.94 mm (40.64 mm / 34.29 mm / 27.94 mm) (1.1 inch (1.6 inch / 1.35 inch / 1.1) in 3 passes. Inch)), reheated at 900 ° C. for 10 minutes, and 12.70 mm (22.86 mm / 17.78 mm / 12.70 mm) (0.50 inch (0.9 inch / 0.00 mm) in 3 passes. 7 inches / 0.5 inches))) and further reduced by hot rolling, followed by water quenching. After trimming and milling to remove surface oxide, the alloy was cold rolled to 3.048 mm (0.120 inch) and annealed at 570 ° C. for 2 hours. The alloy was washed, cold rolled to 1.219 mm (0.048 inch) and annealed at 525 ° C. for 2 hours. The alloy is cold rolled to 0.610 mm (0.024 inches) and 450 ° C. for 4 hours only for single annealing conditions, 4 hours at 450 ° C. to constitute double annealing conditions, an additional 375 Annealing was further performed at 4 ° C. for 4 hours. The final cold rolling was 50% to 0.305 mm (0.012 inch) and the stress relief heat treatment was performed at 250 ° C. for 2 hours for both conditions.

  Higher Sn content increases the strength considerably but lowers the conductivity. Comparing alloys K320 and K319, there is a difference of 3% IACS in conductivity, 48 MPa (7 KSI) in YS. This trend has less impact on strength than alloys without any other additives, but for those alloys with iron (K312 and K313) and those with magnesium (K314 and K315) Held. The overall advantage of K311 containing zinc as opposed to K310 does not exist because it increases strength but lowers conductivity. Double annealing showed an increase in formability (ie, 90 ° bend radius reduction that can be achieved). Note also the slight increase in conductivity.

Example 4
A series of 4.54 kg (10 pounds) research ingots having the ingredients listed in Table 4 were melted in a silica crucible and 101.6 mm × 101.6 mm × 44.45 mm (4 inches × 4 inches × 1.75 inches). After soaking at 900 ° C. for 2 hours, they were 27.94 mm (40.64 mm / 34.29 mm / 27.94 mm) (1.1 inch (1.6 inch / 1.35 inch / 1.1) in 3 passes. Inch)), reheated at 900 ° C. for 10 minutes, and 12.70 mm (22.86 mm / 17.78 mm / 12.70 mm) (0.50 inch (0.9 inch / 0.00 mm) in 3 passes. 7 inches / 0.5 inches))) and further reduced by hot rolling, followed by water quenching. After trimming and milling to remove surface oxide, the alloy was cold rolled to 3.048 mm (0.120 inch) and annealed at 570 ° C. for 2 hours. The alloy was washed, cold rolled to 1.219 mm (0.048 inch) and annealed at 525 ° C. for 2 hours. The alloy was cold rolled to 0.610 mm (0.024 inches) and annealed at 450 ° C. for 4 hours and an additional 375 ° C. for an additional 4 hours. The final cold rolling was 50% to 0.305 mm (0.012 inch) and a stress relief heat treatment was performed at 250 ° C. for 2 hours.

  Thirteen of the 22 alloys in this group had a yield strength of 517 MPa (75 KSI) or higher. The six containing iron (K338, K339, K345, K346, K355 and K361) were closest to K338 at 38% IACS, but none of them obtained 40% IACS conductivity . Four (K350, K351, K352 and K356) contained Mg, and three of these four exceeded 40% IACS. Note that K350, which did not achieve 40% IACS, had a metal-to-phosphorus ratio of 9 greater than the recommended 8.5. Three of the alloys with a yield strength of 517 MPa (75 ksi) or more (K343, K345, and K348) contained neither iron nor Mg, but none of these alloys had a conductivity of 40% IACS. It was.

Example 5
All data for Mg containing alloys and non-Mg containing alloys are summarized in Tables 6 and 7. These data are for Example 2 (alloys of Table 3 annealed twice and included in Tables 6 and 7), Example 3 (Table 4), and Example 4 (Table 5). Includes data from 3. The process used for all alloys is the same for the process used in the final two anneals at 450 ° C. for 4 hours (or 8 hours, see note) + 375 ° C. for 4 hours.

  Overall, the YS in Table 6 with Mg is larger than the YS in Table 7 without Mg. Only some Mg-free alloys K293, K294, K310, K326, K343, K345, and K348 reach the minimum YS of 517 MPa (75 KSI), 42.2, 38.5, 38.5, 38.5, respectively. , 38.4, 38.6 and 32.8% IACS with corresponding conductivity. Note that no alloy, except K293, achieves 40% IACS. Alloys K293, K294, and K326 all have YS and conductivity properties close to C19025, but have better bends. In contrast to the Mg alloys in Table 6, all have a YS of at least 517 MPa (75 KSI) except K289 and K290 (which do not have Ni and have an M / P ratio less than 4). The conductivity of all alloys is 40% IACS except for K318 (38.7% IACS) with a M / P of 7.66 and K350 (38.1% IACS) with a M / P ratio of 9.02. That's it. As the metal to phosphorus ratio increases, the conductivity decreases, making it more difficult to achieve the desired combination of properties. The addition of Mg makes it possible to achieve a combination of proof stress over 517 MPa (75 KSI) and conductivity of at least 40% IACS when using appropriate processing and maintaining a M / P ratio of 4 to 8.5. be able to. 2 and 3 illustrate the relationship between this ratio and YS and% IACS. The vertical line in FIG. 2 shows a preferred M / P ratio of 4 to 8.5.

Example 7
A series of 4.54 kg (10 pounds) research ingots having the ingredients listed in Table 8 were melted in a silica crucible and 101.6 mm × 101.6 mm × 44.45 mm (4 inches × 4 inches × 1.75 inch) steel mold. After soaking at 900 ° C. for 2 hours, they were 27.94 mm (40.64 mm / 34.29 mm / 27.94 mm) (1.1 inch (1.6 inch / 1.35 inch / 1.1) in 3 passes. Inch)), reheated at 900 ° C. for 10 minutes, and 12.70 mm (22.86 mm / 17.78 mm / 12.70 mm) (0.50 inch (0.9 inch / 0.00 mm) in 3 passes. 7 inches / 0.5 inches))) and further reduced by hot rolling, followed by water quenching. After trimming and milling to remove surface oxide, the alloy was cold rolled to 2.032 mm (0.080 inch) and annealed at 550 ° C. for 2 hours. The alloy was washed and cold rolled to 0.914 mm (0.036 inches) and annealed at 450 ° C. for 4 hours and an additional 375 ° C. for an additional 4 hours. The final cold rolling was 60% to 0.305 mm (0.012 inch) and a stress relief heat treatment was performed at 250 ° C. for 2 hours.

  The increase in cold work improved the strength for all alloys. However, the Mg-containing alloy (K352) having an M / P ratio of less than 9 was the only one that improved YS while maintaining or improving conductivity.

Example 8
A series of 4.54 kg (10 pounds) research ingots having the ingredients listed in Table 3 were melted in a silica crucible and 101.6 mm × 101.6 mm × 44.45 mm (4 inches × 4 inches × 1.75 inches). After soaking for 2 hours at 900 ° C., they were 27.94 mm (40.64 mm / 34.29 mm / 27.94 mm) (1.1 inch (1.6 inch / 1.35 inch / 1.1) in 3 passes. Inch)), reheated at 900 ° C. for 10 minutes, and 12.70 mm (22.86 mm / 17.78 mm / 12.70 mm) (0.50 inch (0.9 inch / 0.00 mm) in 3 passes. 7 inches / 0.5 inches))) and further reduced by hot rolling, followed by water quenching. After trimming and milling to remove surface oxide, the alloy was cold rolled to 3.048 mm (0.120 inch) and annealed at 570 ° C. for 2 hours. The alloy was washed, cold rolled to 1.219 mm (0.048 inch) and annealed at 525 ° C. for 2 hours. The alloy was cold rolled to 0.610 mm (0.024 inch) and annealed at 450 ° C. for a minimum of 4 hours. The final cold rolling was 50% to 0.305 mm (0.012 inch) and a stress relief heat treatment was performed at 250 ° C. for 2 hours. This sample was subjected to a stress relaxation test at 150 ° C. for 1000 hours. The results are shown in Table 9 below.

  Alloys K291 and K312 containing iron did not maintain 60% of the original stress. This result was similar between the two despite the presence of Ni in K312. K314 with the combination of Ni and Mg maintained over 65% of the initial stress.

Example 9
One set of Mg-containing and non-Mg-containing alloys was processed using the schedule shown. Tables 10 and 11 summarize the results. Both sets of alloys achieved yield strengths in excess of 552 MPa (80 KSI). All Mg-containing alloys exceeded the target conductivity of 38% IACS, but no Mg-containing alloys except K412. Moreover, the overall formability of the Mg-containing alloy was better.

Example 10
Factory processing was performed on six alloys with nominal components listed in Table 12. This process is described in detail in Table 13, where process 1 is a research process for comparison, and processes 2, 3, and 4 are factory processes.

  The chemical components shown in Table 12 are chemical components obtained by analyzing cast bars. Alloy 6 is in the C19025 CDA range and is present as a comparative example. All alloys were processed in the same way, they were all hot rolled from 900 ° C., formed into coils and then cooled to dimensions of 3.175 mm (0.125 inches) or 2.54 mm (0.100 inches). It was rolled for a while.

  The resulting properties at the final dimensions are shown in Table 14. Alloy 6 treated using Step 3 and Step 4 has the expected properties for this alloy, and in contrast to Step 3, Step 4 is more proof and inferior in bending. When alloy 5 was processed in step 2 as opposed to the metal in step 3, alloy 5 had a lower yield strength (YS) and was inferior in the direction of poor bending. Alloy 3 had comparable proof stress and electrical conductivity to both Step 2 and Step 3 treatments, but the metal treated in Step 3 was excellent in bending in the wrong direction.

  Steps 3 and 4 gave the best overall results. The results for Steps 1 and 2 for Alloy 1 and Alloy 4 show that, if this step was performed in the factory (Step 2) rather than the laboratory (Step 1), there was a slight chance of causing grain growth. Shows different results. Table 15 shows that the double annealing step (Step 2) gives good bending when simulated in the laboratory.

  Only the results for the horizontal direction are shown in Table 16 below. All alloys except Alloy 2 had at least 65% stress remaining after 1000 hours at 150 ° C.

Claims (13)

A copper-based alloy,
1% to 2% Sn,
0.3% to 1% Ni,
0.05% to 0.15% P,
Up to 0.20% Mg ,
The balance is copper
, And the while maintaining less than 1.0 /1.0 following bend formability (90 ° GW / BW) and conductivity of at least 37% IACS, have a yield strength of at least 531MPa, copper-based alloys.   The copper-based alloy of claim 1 containing up to 0.06% Mg. That having a conductivity of at least 40% IACS, copper-based alloy according to claim 1.   The copper-based alloy according to claim 1, wherein the Ni: P ratio is less than 9.   The copper-based alloy according to claim 1, wherein the (Ni + Mg): P ratio is 4 to 8.5.   The copper according to claim 1, wherein Sn is 1.2% to 1.5%, Ni is 0.5% to 0.7%, and P is 0.09% to 0.13%. Base alloy. The copper-based alloy of claim 6 , wherein the ratio of Ni: P is less than 9. The copper-based alloy according to claim 6 , wherein the ratio of (Ni + Mg): P is 4 to 8.5. It said copper base alloy that have a conductivity of at least 40% IACS, copper-based alloy according to claim 8. 1.2% to 1.5% Sn,
0.5% to 0.7% Ni,
0.09% to 0.13% P,
Up to 0.20% Mg ,
The balance is copper
A copper-based alloy is, that have a conductivity of strength of at least 531MPa and at least 37% IACS, copper-based alloys. That having a conductivity at least 40% IACS, copper-based alloy according to claim 10. 1.0 /1.0 that Yusuke following bend formability (90 ° GW / BW), copper-based alloy according to claim 10. The copper-based alloy according to claim 6 , wherein the ratio of (Ni + Mg): P is 4 to 8.5.

Images