Contact Carrier Materials - Revision history

Doduco Admin: /* High Cu Content Copper Alloys */

2023-01-04T08:49:05Z

‎High Cu Content Copper Alloys

Doduco Admin: /* Triple-Layer Carrier Materials */

2023-01-03T12:20:45Z

‎Triple-Layer Carrier Materials

Doduco Admin: /* Selection Criteria for Copper-Based Materials */

2023-01-03T12:19:20Z

‎Selection Criteria for Copper-Based Materials

Doduco Admin: /* Pure Copper */

2023-01-03T12:16:58Z

‎Pure Copper

Doduco Admin: /* High Cu Content Copper Alloys */

2022-12-05T12:27:08Z

‎High Cu Content Copper Alloys

Doduco Admin: /* Nickel-Beryllium Alloys */

2022-12-05T12:26:13Z

‎Nickel-Beryllium Alloys

Doduco Admin at 12:24, 5 December 2022

2022-12-05T12:24:31Z

Doduco Admin at 08:43, 5 December 2022

2022-12-05T08:43:27Z

Doduco Admin at 08:20, 5 December 2022

2022-12-05T08:20:59Z

Doduco Admin at 08:00, 5 December 2022

2022-12-05T08:00:16Z

← Older revision		Revision as of 08:49, 4 January 2023
Line 225:		Line 225:
	CuNi1Co1Si also belongs into this family and has properties similar to the low alloyed CuBe materials.		CuNi1Co1Si also belongs into this family and has properties similar to the low alloyed CuBe materials.

		+	<br style="clear:both;"/>

	<figtable id="tab:Physical Properties of Selected High Cu Content Copper Alloys">		<figtable id="tab:Physical Properties of Selected High Cu Content Copper Alloys">

@@ Line 676: / Line 676: @@
 ==<!--5.3-->Triple-Layer Carrier Materials==
-Manufacturing of triple-layer carrier materials is usually performed by cold rollcladding. The three materials cover each other completely. The advantage of this composite material group is, that the different mechanical and physical properties of the individual components can be combined with each other.
+Manufacturing of triple-layer carrier materials is usually performed by cold rollcladding. The three materials cover each other completely. The advantage of this composite material group is that the different mechanical and physical properties of the individual components can be combined with each other.
 Depending on the intended application, the following layer systems are utilized:

@@ Line 491: / Line 491: @@
 If current carrying capability is the key requirement, mechanical strength may have to be sacrificed as for example in carrier parts for stationary contacts. In this case, depending on the current level, pure copper or low alloyed copper materials such as CuSn0.15, or for economic reasons CuZn30, may be suitable.
-For spring contact components, the interdependent relations between electrical conductivity and fatigue strength, or electrical conductivity and relaxation behavior are of main importance. The first case is critical for higher load relay springs. CuAg2 plays an important role for these applications. The latter is critical for components that are exposed to continuing high mechanical stresses like for example in connectors. The spring force must stay close to constant over the expected life time of the parts, even at elevated temperatures from the environment or current carrying. In this case, the relaxation behavior of the copper materials, which may cause a decrease in spring force over time, must be considered. Besides this, easy forming during manufacturing must be possible; this means, that bending operations can also be performed at high mechanical strength values.
+For spring contact components, the interdependent relations between electrical conductivity and fatigue strength, or electrical conductivity and relaxation behavior are of main importance. The first case is critical for higher load relay springs. CuAg2 plays an important role for these applications. The latter is critical for components that are exposed to continuing high mechanical stresses like for example in connectors. The spring force must stay close to constant over the expected life time of the parts, even at elevated temperatures from the environment or current carrying. In this case, the relaxation behavior of the copper materials, which may cause a decrease in spring force over time, must be considered. Besides this, easy forming during manufacturing must be possible; this means that bending operations can also be performed at high mechanical strength values.
 The increasing requirements on spring components in connectors, especially for use in automotive applications, such as higher surrounding temperatures, increased reliability and the trend towards miniaturization led to a change of materials from traditionally CuZn30 and CuSn4 to CuNiSi alloys, for example. These CuNiSi alloys and the newer heavy duty copper alloys like CuNi1Co1, are significantly improved with regards to mechanical strength, relaxation behavior and electrical conductivity.

@@ Line 54: / Line 54: @@
 The purity of technically pure and un-alloyed copper used for electrical applications depends on the type used and ranges between > 99.90 and 99.95
 wt%. The copper types are designated mainly by their oxygen content as oxygen containing, oxygen-free, and de-oxidized with phosphorus as
-described in DIN EN 1652 (<xr id="tab:MaterialDesignations"/>  and <xr id="tab:Composition of Some Pure Copper Types"/><!--5.2-->). (<xr id="tab:Physical Properties of Some Copper Types"/><!--Tables 5.3.--> and <xr id="tab:Mechanical Properties of Some Copper Types"/><!--5.4-->) show the physical and mechanical properties of these copper materials. According to these, Cu-ETP, Cu-OFE and Cu-HCP are the types of copper for which minimum values for the electrical conductivity are guaranteed.
+described in DIN EN 1652 (<xr id="tab:MaterialDesignations"/>  and <xr id="tab:Composition of Some Pure Copper Types"/><!--5.2-->). <xr id="tab:Physical Properties of Some Copper Types"/><!--Tables 5.3.--> and <xr id="tab:Mechanical Properties of Some Copper Types"/><!--5.4--> show the physical and mechanical properties of these copper materials. According to these, Cu-ETP, Cu-OFE and Cu-HCP are the types of copper for which minimum values for the electrical conductivity are guaranteed.
 Cu-ETP is less suitable for welding or for brazing in reducing atmosphere because of the oxygen content (danger of hydrogen embrittlement).

@@ Line 209: / Line 209: @@
 <figure id="fig:Influence of small additions on the electrical conductivity of copper">
-[[File:Influence of small additions on the electrical conductivity of copper.jpg|right|thumb|Influence of small additions on the electrical conductivity of copper]]
+[[File:Influence of small additions on the electrical conductivity of copper.jpg|right|thumb|Figure 4: Influence of small additions on the electrical conductivity of copper]]
 </figure>

@@ Line 658: / Line 658: @@
 <figure id="fig:Phase diagram of nickel beryllium">
-[[File:Phase diagram of nickel beryllium.jpg|right|thumb|Phase diagram of nickel-beryllium]]
+[[File:Phase diagram of nickel beryllium.jpg|right|thumb|Figure 9: Phase diagram of nickel-beryllium]]
 </figure>
@@ Line 664: / Line 664: @@
 <figure id="fig:Precipitation hardening of NiBe2 soft at 480C">
-[[File:Precipitation hardening of NiBe2 soft at 480C.jpg|right|thumb|Precipitation hardening of NiBe2 (soft) at 480°C]]
+[[File:Precipitation hardening of NiBe2 soft at 480C.jpg|right|thumb|Figure 10: Precipitation hardening of NiBe2 (soft) at 480°C]]
 </figure>

@@ Line 520: / Line 520: @@
 ===<!--5.2.2-->Nickel Alloys===
-Because of its low electrical conductivity NiCu30Fe is besides pure Ni and CuNi alloys the most widely used backing material for weldable contact components. With 1 – 2 wt% additives of Fe as well as 0.5 – 1 wt% Mn and Co, the mechanical strength of the binary alloy NiCu30 can be increased.
+Because of its low electrical conductivity, NiCu30Fe is besides pure Ni and CuNi alloys the most widely used backing material for weldable contact components. With 1 – 2 wt% additives of Fe as well as 0.5 – 1 wt% Mn and Co, the mechanical strength of the binary alloy NiCu30 can be increased.
 The strength values of NiCu30Fe are significantly higher than those of the copper rich CuNi alloys [[#figures12|(Figs. 7 – 8)]]<!--(Figs. 5.47 and 5.48)-->. The good spring properties and thermal stability of NiCu30Fe make it a suitable material for the use as thermally stressed contact springs.
 <div class="multiple-images">
 <figure id="fig:Strain hardening of NiCu30Fe by cold working">
-[[File:Strain hardening of NiCu30Fe by cold working.jpg|right|thumb|Strain hardening of NiCu30Fe by cold working]]
+[[File:Strain hardening of NiCu30Fe by cold working.jpg|right|thumb|Figure 7: Strain hardening of NiCu30Fe by cold working]]
 </figure>
 <figure id="fig:Softening of NiCu30Fe after annealing for 0.5 hrs">
-[[File:Softening of NiCu30Fe after annealing for 0.5 hrs.jpg|right|thumb|Softening of NiCu30Fe after annealing for 0.5 hrs and after 80% cold working]]
+[[File:Softening of NiCu30Fe after annealing for 0.5 hrs.jpg|right|thumb|Figure 8: Softening of NiCu30Fe after annealing for 0.5 hrs and after 80% cold working]]
 </figure>
 </div>
@@ Line 661: / Line 655: @@
 ===<!--5.2.3-->Nickel-Beryllium Alloys===
-Because of decreasing solubility of beryllium in nickel with decreasing temperature, NiBe can be precipitation hardened similar to CuBe <xr id="fig:Phase diagram of nickel beryllium"/><!--(Fig. 5.49)-->. The maximum soluble amount of Be in Ni is 2.7 wt% at the eutectic temperature of 1150°C. To achieve a high hardness by precipitation hardening, NiBe similar to CuBe, is annealed at 970 - 1030°C and rapidly quenched to room temperature. Soft annealed material is easily cold formed and after stamping and forming a hardening anneal is performed at 480 to 500°C for 1 to 2 hours.
+Because of decreasing solubility of beryllium in nickel with decreasing temperature, NiBe can be precipitation hardened similar to CuBe (<xr id="fig:Phase diagram of nickel beryllium"/><!--(Fig. 5.49)-->). The maximum soluble amount of Be in Ni is 2.7 wt% at the eutectic temperature of 1150°C. To achieve a high hardness by precipitation hardening, NiBe similar to CuBe, is annealed at 970 - 1030°C and rapidly quenched to room temperature. Soft annealed material is easily cold formed and after stamping and forming a hardening anneal is performed at 480 to 500°C for 1 to 2 hours.
 <figure id="fig:Phase diagram of nickel beryllium">
@@ Line 667: / Line 661: @@
 </figure>
-Commercial nickel-beryllium alloys contain 2 wt% Be. Compared to CuBe2 the NiBe2 materials have a significantly higher modulus of elasticity but a much lower electrical conductivity. The mechanical strength is higher than that of CuBe2 <xr id="fig:Precipitation hardening of NiBe2 soft at 480C"/><!--(Fig. 5.50)-->, the spring bending force limit can exceed values of over 1400 MPa and the fatigue strength reaches approximately 400 MPa.
+Commercial nickel-beryllium alloys contain 2 wt% Be. Compared to CuBe2 the NiBe2 materials have a significantly higher modulus of elasticity but a much lower electrical conductivity. The mechanical strength is higher than that of CuBe2 (<xr id="fig:Precipitation hardening of NiBe2 soft at 480C"/><!--(Fig. 5.50)-->), the spring bending force limit can exceed values of over 1400 MPa and the fatigue strength reaches approximately 400 MPa.
 <figure id="fig:Precipitation hardening of NiBe2 soft at 480C">
@@ Line 673: / Line 667: @@
 </figure>
-A further advantage of NiBe2 is its high temperature stability. Cold worked and subsequently precipitation hardened NiBe2 can withstand sustained
+A further advantage of NiBe2 is its high temperature stability. Cold worked and subsequently precipitation hardened, NiBe2 can withstand sustained
 temperatures of 400 - 650°C, depending on ist pre-treatment.
@@ Line 702: / Line 696: @@
 ==<!--5.4-->Thermostatic Bimetals==
-Thermostatic bimetals are composite materials consisting of two or three layers of materials, with different coefficients of thermal expansion. They are usually bonded together by cladding. If such a material part is heated, either directly through current flow or indirectly through heat conduction or radiation, the different expansion between the active (strong expansion) and passive (low expansion) layer causes bending of the component part.
+Thermostatic bimetals are composite materials, consisting of two or three layers of materials, with different coefficients of thermal expansion. They are usually bonded together by cladding. If such a material part is heated, either directly through current flow or indirectly through heat conduction or radiation, the different expansion between the active (strong expansion) and passive (low expansion) layer causes bending of the component part.
 Directional or force effects on the free end of the thermostatic bimetal part is then used as a trigger or control mechanism in thermostats, protective switches or in control circuits. Depending on the required function of the thermostatic bimetal component different design shapes are used:
@@ Line 711: / Line 705: @@
 *'''Stamped and formed parts''' for special designs and applications
-The wide variety of thermostatic bimetal types is specified mostly through DIN 1715 and/or applicable ASTM standards <xr id="tab:Partial Selection from the Wide Range of Available Thermo-Bimetals"/><!--(Table 5.23)-->. The different types have varying material compositions for the active and passive side of the materials. The mostly used alloys are iron-nickel and manganese-copper-nickel. Mainly used in circuit protection switches (i.e. circuit breakers) some thermo-bimetals include an intermediate layer of copper or nickel which allows to design parts with a closely controlled electrical resistance.
+The wide variety of thermostatic bimetal types is specified mostly through DIN 1715 and/or applicable ASTM standards (<xr id="tab:Partial Selection from the Wide Range of Available Thermo-Bimetals"/><!--(Table 5.23)-->). The different types have varying material compositions for the active and passive side of the materials. The mostly used alloys are iron-nickel and manganese-copper-nickel. Mainly used in circuit protection switches (i.e. circuit breakers), some thermo-bimetals include an intermediate layer of copper or nickel which allows to design parts with a closely controlled electrical resistance.
@@ Line 755: / Line 749: @@
 ===<!--5.4.1-->Design Formulas===
-For the design and calculation of the most important thermostatic-bimetal parts, formulas are given in <xr id="tab:Design Formulas for Thermostatic Bimetal Components"/><!--Table 5.24-->. The necessary properties can be extracted for the most common materials from <xr id="tab:Partial Selection from the Wide Range of Available Thermo-Bimetals"/><!--Table 5.23-->. The values given are valid only for a temperature range up to approximately 150°C. For higher temperatures data can be obtained from the materials manufacturer.
+For the design and calculation of the most important thermostatic-bimetal parts, formulas are given in (<xr id="tab:Design Formulas for Thermostatic Bimetal Components"/><!--Table 5.24-->). The necessary properties can be extracted for the most common materials from (<xr id="tab:Partial Selection from the Wide Range of Available Thermo-Bimetals"/><!--Table 5.23-->). The values given are valid only for a temperature range up to approximately 150°C. For higher temperatures; data can be obtained from the materials manufacturer.
@@ Line 859: / Line 853: @@
 ===<!--5.4.2-->Stress Force Limitations===
-For all calculations according to the formulas in <xr id="tab:Design Formulas for Thermostatic Bimetal Components"/><!--Table 5.24--> one should check if the thermally or mechanically induced stress forces stay below the allowed bending force limit. The following formulas are applicable for calculating the allowable load (Force P<sub>max</sub> or momentum M<sub>max</sub>):
+For all calculations according to the formulas in (<xr id="tab:Design Formulas for Thermostatic Bimetal Components"/><!--Table 5.24-->) one should check if the thermally or mechanically induced stress forces stay below the allowed bending force limit. The following formulas are applicable for calculating the allowable load (Force P<sub>max</sub> or momentum M<sub>max</sub>):

@@ Line 206: / Line 206: @@
 ===<!--5.1.3-->High Cu Content Copper Alloys===
-The high Cu content alloy materials are closest in their properties to pure copper materials. By defined addition of small amounts of alloying elements, it is possible to increase the mechanical strength and especially the softening temperature of copper and at the same time decrease the electrical conductivity only insignificantly <xr id="fig:Influence of small additions on the electrical conductivity of copper"/><!--(Fig. 5.4)-->. Silver, iron, tin, zinc, nickel, chromium, zirconium, silicon, and titanium are used. Usually the additive amounts are significantly below 3 wt%. This group of materials consists of mixed crystal as well as precipitation hardening alloys. The precipiytion hardening copper-beryllium and copper-chromium-zirconium materials are decribed later in a separate section.
+The high Cu content alloy materials are closest in their properties to pure copper materials. By defined addition of small amounts of alloying elements, it is possible to increase the mechanical strength and especially the softening temperature of copper and at the same time decrease the electrical conductivity only insignificantly (<xr id="fig:Influence of small additions on the electrical conductivity of copper"/><!--(Fig. 5.4)-->). Silver, iron, tin, zinc, nickel, chromium, zirconium, silicon and titanium are used. Usually, the additive amounts are significantly below 3 wt%. This group of materials consists of mixed crystal as well as precipitation hardening alloys. The precipitation hardening copper-beryllium and copper-chromium-zirconium materials are decribed later in a separate section.
 <figure id="fig:Influence of small additions on the electrical conductivity of copper">
@@ Line 212: / Line 212: @@
 </figure>
-From the large number of high-Cu alloys, only the properties of selected ones are covered here <xr id="tab:Physical Properties of Selected High Cu Content Copper Alloys"/><!--(Tab. 5.5)--> and <xr id="tab:Mechanical Properties of Selected High Cu Content Copper Alloys"/><!--(Tab. 5.6)-->. Some of these materials are not included in the EN standards system.
+From the large number of high-Cu alloys, only the properties of selected ones are covered here (<xr id="tab:Physical Properties of Selected High Cu Content Copper Alloys"/><!--(Tab. 5.5)--> and <xr id="tab:Mechanical Properties of Selected High Cu Content Copper Alloys"/><!--(Tab. 5.6)-->). Some of these materials are not included in the EN standards system.
-The low alloyed materials CuAg0.1 and CuCd1 are mostly used as overhead drive cables where they have to meet sustained loads at elevated temperatures without softening.
+The low alloyed materials CuAg0.1 and CuCd1 are mostly used as overhead drive cables, where they have to meet sustained loads at elevated temperatures without softening.
-The materials CuFe0.1 and CuSn0.15 have a high electrical conductivity. The mechanical strength of both is relatively low but stays almost constant at temperatures up to 400°C. The are used as substrates for power semiconductors and also as carriers for stationary contacts in higher energy switchgear.
+The materials CuFe0.1 and CuSn0.15 have a high electrical conductivity. The mechanical strength of both is relatively low but stays almost constant at temperatures up to 400°C. They are used as substrates for power semiconductors and also as carriers for stationary contacts in higher energy switchgear.
-CuFe2 is a material exhibiting high electrical conductivity and good formability. During an annealing process Fe-rich precipitations are formed in the " -Cu matrix which change the mechanical properties very little but increase the electrical conductivity significantly. Besides being used as a contact carrier material in switching devices, this material has broader applications in automotive connectors and as a substrate in the semiconductor technology.
+CuFe2 is a material exhibiting high electrical conductivity and good formability. During an annealing process, Fe-rich precipitations are formed in the Cu matrix, which changes the mechanical properties very little but increases the electrical conductivity significantly. Besides being used as a contact carrier material in switching devices, this material has broader applications in automotive connectors and as a substrate in the semiconductor technology.
-CuNi2Si has high mechanical strength, good formability, and at the same time high electrical conductivity. This combination of advantageous properties is achieved by a defined finely dispersed precipitation of nickel silicides. CuNi2Si is used mainly in the form of stamped and formed parts in thermally stressed electromechanical components for automotive applications.
+CuNi2Si has high mechanical strength, good formability and at the same time high electrical conductivity. This combination of advantageous properties is achieved by a defined finely dispersed precipitation of nickel silicides. CuNi2Si is used mainly in the form of stamped and formed parts in thermally stressed electromechanical components for automotive applications.
 CuSn1CrNiTi and CuCrSiTi are advanced developments of the Cu-Cr-Ti precipitation materials with fine intermetallic dispersions. The material
@@ Line 465: / Line 465: @@
 ===<!--5.1.4-->Naturally Hard Copper Alloys===
-Alloys like brasses (CuZn), tin bronzes (CuSN), and German silver (CuNiZn), for which the required hardness is achieved by cold working, are defined as naturally hard alloys. Included in this group are also the silver bronzes (CuAg) with 2 – 6 wt% of Ag.
+Alloys like brasses (CuZn), tin bronzes (CuSN) and German silver (CuNiZn), for which the required hardness is achieved by cold working, are defined as naturally hard alloys. Included in this group are also the silver bronzes (CuAg) with 2 – 6 wt% of Ag.
 Main Articel: [[Naturally Hard Copper Alloys| Naturally Hard Copper Alloys]]
@@ Line 475: / Line 475: @@
 ===<!--5.1.6-->Precipitation Hardening Copper Alloys===
-Besides the naturally hard copper materials precipitation hardening, copper alloys play also an important role as carrier materials for electrical contacts. By means of a suitable heat treatment, finely dispersed precipitations of a second phase can be achieved, which increases the mechanical strength of these copper alloys significantly.
+Besides the naturally hard copper materials, precipitation hardening copper alloys play also an important role as carrier materials for electrical contacts. By means of a suitable heat treatment, finely dispersed precipitations of a second phase can be achieved, which increases the mechanical strength of these copper alloys significantly.
 Main Articel: [[Precipitation Hardening Copper Alloys| Precipitation Hardening Copper Alloys]]
@@ Line 491: / Line 491: @@
 If current carrying capability is the key requirement, mechanical strength may have to be sacrificed as for example in carrier parts for stationary contacts. In this case, depending on the current level, pure copper or low alloyed copper materials such as CuSn0.15, or for economic reasons CuZn30, may be suitable.
-For spring contact components the interdependent relations between electrical conductivity and fatigue strength, or electrical conductivity and relaxation behavior are of main importance. The first case is critical for higher load relay springs. CuAg2 plays an important role for these applications. The latter is critical for components that are exposed to continuing high mechanical stresses like for example in connectors. The spring force must stay close to constant over the expected life time of the parts, even at elevated temperatures from the environment or current carrying. In this case the relaxation behavior of the copper materials, which may cause a decrease in spring force over time, must be considered. Besides this easy forming during manufacturing must be possible; this means that bending operations can also be performed at high mechanical strength values.
+For spring contact components, the interdependent relations between electrical conductivity and fatigue strength, or electrical conductivity and relaxation behavior are of main importance. The first case is critical for higher load relay springs. CuAg2 plays an important role for these applications. The latter is critical for components that are exposed to continuing high mechanical stresses like for example in connectors. The spring force must stay close to constant over the expected life time of the parts, even at elevated temperatures from the environment or current carrying. In this case, the relaxation behavior of the copper materials, which may cause a decrease in spring force over time, must be considered. Besides this, easy forming during manufacturing must be possible; this means, that bending operations can also be performed at high mechanical strength values.
-The increasing requirements on spring components in connectors, especially for use in automotive applications, such as higher surrounding temperatures, increased reliability, and the trend towards miniaturization led to a change of materials from traditionally CuZn30 and CuSn4 to CuNiSi alloys, for example. These CuNiSi alloys and the newer heavy duty copper alloys like CuNi1Co1 are significantly improved with regards to mechanical strength, relaxation behavior and electrical conductivity.
+The increasing requirements on spring components in connectors, especially for use in automotive applications, such as higher surrounding temperatures, increased reliability and the trend towards miniaturization led to a change of materials from traditionally CuZn30 and CuSn4 to CuNiSi alloys, for example. These CuNiSi alloys and the newer heavy duty copper alloys like CuNi1Co1, are significantly improved with regards to mechanical strength, relaxation behavior and electrical conductivity.
 ==<!--5.2-->Nickel and Nickel Alloys==
@@ Line 499: / Line 499: @@
 ===<!--5.2.1-->Technical Grade Pure Nickel===
-Technical grade pure nickel commonly contains 99.0 to 99.8 wt% Ni and up to 1 wt% Co. Other ingredients are iron and manganese <xr id="tab:Physical Properties of Nickel and Nickel Alloys"/><!--(Tab. 5.21)--> and <xr id="tab:Mechanical Properties of Nickel and Nickel Alloys"/><!--(Tab. 5.22)-->. Work hardening and softening behavior of nickel are shown in [[#figures11|(Figs. 5 – 6)]]<!--Figs. 5.45 and 5.46-->.
+Technical grade pure nickel commonly contains 99.0 to 99.8 wt% Ni and up to 1 wt% Co. Other ingredients are iron and manganese (<xr id="tab:Physical Properties of Nickel and Nickel Alloys"/><!--(Tab. 5.21)--> and <xr id="tab:Mechanical Properties of Nickel and Nickel Alloys"/><!--(Tab. 5.22)-->). Work hardening and softening behavior of nickel are shown in [[#figures11|(Figs. 5 – 6)]]<!--Figs. 5.45 and 5.46-->.
 One of the significant properties of nickel is its modulus of elasticity, which is almost twice as high as that of copper. At temperatures up to 345°C nickel is ferro-magnetic.
@@ Line 506: / Line 506: @@
 Because of the always present thin oxide layer on its surface, nickel is not suitable as a contact material for switching contacts.
 <div class="multiple-images">
 <figure id="fig:Strain hardening of technical pure nickel by cold working">
-[[File:Strain hardening of technical pure nickel by cold working.jpg|right|thumb|Strain hardening of technical pure nickel by cold working]]
+[[File:Strain hardening of technical pure nickel by cold working.jpg|right|thumb|Figure 5: Strain hardening of technical pure nickel by cold working]]
 </figure>
 <figure id="fig:Softening of technical grad nickel after annealing for 3 hrs">
-[[File:Softening of technical grad nickel after annealing for 3 hrs.jpg|right|thumb|Softening of technical grad nickel after annealing for 3 hrs after 50% cold working]]
+[[File:Softening of technical grad nickel after annealing for 3 hrs.jpg|right|thumb|Figure 6: Softening of technical grad nickel after annealing for 3 hrs after 50% cold working]]
 </figure>
 </div>

@@ Line 187: / Line 187: @@
 </table>
 </figtable>
 <div class="multiple-images">