Patent Publication Number: US-2021181685-A1

Title: Housing And Device

Description:
The present application is based on, and claims priority from JP Application Serial Number 2019-225201, filed Dec. 13, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a housing and a device. 
     2. Related Art 
     JP 2013-101157 A discloses a watch housing using ferritic stainless steel in which a surfacing layer is austenitized by nitrogen absorption treatment, specifically, a case band and a case back. 
     In JP 2013-101157 A, austenitization of the surfacing layer of ferritic stainless steel results in hardness, corrosion resistance, and antimagnetic performance required as a watch housing. 
     When the housing of JP 2013-101157 A, for example, is dropped, an outer surface is impacted. In this case, particularly, a corner portion is easily subjected to strong impact, and a frequency of strong impact is high, thus such a corner portion needs to be reinforced, but JP 2013-101157 A does not describe any such reinforcing of a corner portion. Thus, there is a demand for a housing that is robust against impact by dropping or the like. 
     SUMMARY 
     A housing of the present disclosure is a housing formed of austenitized ferritic stainless steel including a base formed of a ferrite phase and a surfacing layer formed of an austenitized phase in which the ferrite phase is austenitized, the housing including a first surface exposed to an external space of the housing, and a second surface that is adjacent to the first surface with a corner portion interposed therebetween, and that is exposed to the external space, wherein a surfacing layer at the corner portion is thicker in thickness than a surfacing layer in the first surface and a surfacing layer in the second surface. 
     A device including the housing of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partial cross-sectional view schematically illustrating a watch of an exemplary embodiment. 
         FIG. 2  is an enlarged cross-sectional view illustrating a main part of a case main body. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Exemplary Embodiment 
     A watch  1  of an exemplary embodiment of the present disclosure will be described below with reference to the drawings. 
       FIG. 1  is a partial cross-sectional view schematically illustrating the watch  1  of the present exemplary embodiment. 
     As illustrated in  FIG. 1 , the watch  1  includes an outer packaging case  2 . The outer packaging case  2  includes a cylindrical case main body  21 , a case back  22  fixed to a back surface side of the case main body  21 , an annular bezel  23  fixed to a front surface side of the case main body  21 , and a glass plate  24  held by the bezel  23 . Furthermore, a movement (not illustrated) is housed in the case main body  21 . Note that, the case main body  21  is an example of a housing of the present disclosure, and the watch  1  is an example of a device of the present disclosure. 
     A winding stem pipe  25  fits into and is fixed to the case main body  21 , and a shaft portion  261  of a crown  26  is rotatably inserted into the winding stem pipe  25 . 
     The case main body  21  and the bezel  23  engage with each other via a plastic packing  27 , and the bezel  23  and the glass plate  24  are fixed to each other by a plastic packing  28 . 
     Furthermore, the case back  22  is engaged with the case main body  21 , and a ring-shaped rubber packing or case back packing  40  is interposed in a seal portion  50  in a compressed state. With this configuration, the seal portion  50  is liquid-tightly sealed, and a waterproof function is obtained. 
     A groove  262  is formed at an outer periphery halfway the shaft portion  261  of the crown  26 , and a ring-shaped rubber packing  30  is fitted into the groove  262 . The rubber packing  30  adheres to an inner circumferential surface of the winding stem pipe  25 , and is compressed between the inner circumferential surface and an inner surface of the groove  262 . According to this configuration, a gap between the crown  26  and the winding stem pipe  25  is liquid-tightly sealed and a waterproof function is obtained. Note that, when the crown  26  is rotated and operated, the rubber packing  30  rotates together with the shaft portion  261  and, slides in a circumferential direction while adhering to the inner circumferential surface of the winding stem pipe  25 . 
     Case Main Body 
       FIG. 2  is an enlarged cross-sectional view of a main part of the case main body  21 , specifically, a region II in  FIG. 1 . 
     As illustrated in  FIG. 2 , the case main body  21  is formed of ferritic stainless steel including a base  211  formed of a ferrite phase, a surfacing layer  212  formed of an austenite phase (hereinafter, an austenitized phase) in which the ferrite phase is austenitized, and a mixed layer  213  in which the ferrite phase and the austenitized phase are mixed with each other. 
     Further, in the present exemplary embodiment, the case main body  21  includes a first surface  21 A exposed to an external space of the case main body  21 , and a second surface  21 B that is adjacent to the first surface  21 A with a corner portion  21 C interposed therebetween, and is exposed to the external space. In other words, the corner portion  21 C is a location that couples the first surface  21 A with the second surface  21 B. 
     Then, the corner portion  21 C is configured such that an angle θ of an internal angle formed by the first surface  21 A and the second surface  21 B is greater than 0° and less than 180°. In other words, the first surface  21 A and the second surface  21 B are configured such that the corner portion  21 C protrudes toward the external space. 
     Note that, in the present exemplary embodiment, the first surface  21 A and the second surface  21 B are surfaces that are disposed closer to the case back  22  than the crown  26 . Also, the second surface  21 B is partially in contact with the case back  22 . 
     Base 
     The base  211  contains, in percent by mass, Cr: 18 to 22%, Mo: 1.3 to 2.8%, Nb: 0.05 to 0.50%, Cu: 0.1 to 0.8%, Ni: less than 0.5%, Mn: less than 0.8%, Si: less than 0.5%, P: less than 0.10%, S: less than 0.05%, N: less than 0.05%, and C: less than 0.05%, with a balance being formed of ferritic stainless steel formed of Fe and unavoidable impurities. 
     Cr is an element that increases a transfer rate of nitrogen to the ferrite phase, and a diffusion rate of nitrogen in the ferrite phase, in nitrogen absorption treatment. When Cr is less than 18%, the transfer rate and diffusion rate of nitrogen decrease. Furthermore, when Cr is less than 18%, corrosion resistance of the surfacing layer  212  deteriorates. On the other hand, when Cr exceeds 22%, hardening occurs, and workability as a material worsens. Furthermore, when Cr exceeds 22%, an aesthetic appearance is spoiled. Thus, Cr content may be 18 to 22%, may be 20 to 22%, and may be 19.5 to 20.5%. 
     Mo is an element that increases the transfer rate of nitrogen to the ferrite phase, and the diffusion rate of nitrogen in the ferrite phase, in the nitrogen absorption treatment. When Mo is less than 1.3%, the transfer rate and diffusion rate of nitrogen decrease. Furthermore, when Mo is less than 1.3%, corrosion resistance as a material deteriorates. On the other hand, when Mo exceeds 2.8%, hardening occurs, and the workability as the material worsens. Furthermore, when Mo exceeds 2.8%, a configuration organization of the surfacing layer  212  becomes significantly heterogeneous, and the aesthetic appearance is spoiled. Thus, Mo content may be 1.3 to 2.8%, may be 1.8 to 2.8%, and may be 2.25 to 2.35%. 
     Nb is an element that increases the transfer rate of nitrogen to the ferrite phase, and the diffusion rate of nitrogen in the ferrite phase, in the nitrogen absorption treatment. When Nb is less than 0.05%, the transfer rate and diffusion rate of nitrogen decrease. On the other hand, when Nb exceeds 0.50%, hardening occurs, and the workability as the material worsens. Furthermore, a deposition section is generated, and the aesthetic appearance is spoiled. Thus, Nb content may be 0.05 to 0.50%, may be 0.05 to 0.35%, and may be 0.15 to 0.25%. 
     Cu is an element that controls absorption of nitrogen in the ferrite phase in the nitrogen absorption treatment. When Cu is less than 0.1%, a variation in nitrogen content in the ferrite phase increases. On the other hand, when Cu exceeds 0.8%, the transfer rate of nitrogen to the ferrite phase decreases. Thus, the Cu content may be 0.1 to 0.8%, may be 0.1 to 0.2%, and may be 0.1 to 0.15%. 
     Ni is an element that inhibits the transfer of nitrogen to the ferrite phase, and the diffusion of nitrogen in the ferrite phase, in the nitrogen absorption treatment. When Ni is equal to or greater than 0.5%, the transfer rate and the diffusion rate of nitrogen decrease. Furthermore, it is possible that corrosion resistance worsens, and that it becomes difficult to prevent occurrence of a metal allergy and the like. Thus, Ni content may be less than 0.5%, may be less than 0.2%, and may be less than 0.1%. 
     Mn is an element that inhibits the transfer of nitrogen to the ferrite phase, and the diffusion of nitrogen in the ferrite phase, in the nitrogen absorption treatment. When Mn is equal to or greater than 0.8%, the transfer rate and the diffusion rate of nitrogen decrease. Thus, Mn content may be less than 0.8%, may be less than 0.5%, and may be less than 0.1%. 
     Si is an element that inhibits the transfer of nitrogen to the ferrite phase, and the diffusion of nitrogen in the ferrite phase, in the nitrogen absorption treatment. When Si is equal to or greater than 0.5%, the transfer rate and the diffusion rate of nitrogen decrease. Thus, Si content may be less than 0.5%, and may be less than 0.3%. 
     P is an element that inhibits the transfer of nitrogen to the ferrite phase, and the diffusion of nitrogen in the ferrite phase, in the nitrogen absorption treatment. When P is equal to or greater than 0.10%, the transfer rate and the diffusion rate of nitrogen decrease. Thus, P content may be less than 0.10%, and may be less than 0.03%. 
     S is an element that inhibits the transfer of nitrogen to the ferrite phase, and the diffusion of nitrogen in the ferrite phase, in the nitrogen absorption treatment. When S is equal to or greater than 0.05%, the transfer rate and the diffusion rate of nitrogen decrease. Thus, S content may be less than 0.05%, and may be less than 0.01%. 
     N is an element that inhibits the transfer of nitrogen to the ferrite phase, and the diffusion of nitrogen in the ferrite phase, in the nitrogen absorption treatment. When N is equal to or greater than 0.05%, the transfer rate and the diffusion rate of nitrogen decrease. Thus, N content may be less than 0.05%, and may be less than 0.01%. 
     C is an element that inhibits the transfer of nitrogen to the ferrite phase, and the diffusion of nitrogen in the ferrite phase, in the nitrogen absorption treatment. When C is equal to or greater than 0.05%, the transfer rate and the diffusion rate of nitrogen decrease. Thus, C content may be less than 0.05%, and may be less than 0.02%. 
     Note that, the base  211  is not limited to the configuration described above, and it is sufficient that the base  211  is formed of the ferrite phase. 
     Surfacing Layer 
     The surfacing layer  212  is provided by performing the nitrogen absorption treatment on the base material forming the base  211 , to austenitize the ferrite phase. In the present exemplary embodiment, nitrogen content in the surfacing layer  212  is set to 1.0 to 1.6% in percent by mass. In other words, nitrogen is contained at high concentrations in the surfacing layer  212 . Accordingly, anticorrosive performance in the surfacing layer  212  can be improved. 
     In addition, in the present exemplary embodiment, the surfacing layer  212  includes a first surfacing layer  212 A and a second surfacing layer  212 B. 
     The first surfacing layer  212 A is provided at a position corresponding to the first surface  21 A. In other words, the first surfacing layer  212 A is provided along a direction extending from the first surface  21 A and orthogonal to the first surface  21 A, or a normal line direction of the first surface  21 A. 
     In the present exemplary embodiment, a thickness t 1  of the first surfacing layer  212 A is 100 μm to 350 μm. In addition, the thicknesses t 1  is a thickness of a layer formed of the austenitized phase, and, for example, in a visual field when SEM observation is performed at a magnification of 500 to 1000, is a shortest distance from the first surface  21 A to a ferrite phase of a first mixed layer  213 A described below. Alternatively, the thickness t 1  is a shortest distance from the first surface  21 A to a shallowest location of the austenitized phase. Additionally, when a distance from the first surface  21 A to each of a plurality of points that is short in distance to the ferrite phase is measured, an average value thereof may be defined as the thickness t 1 . 
     The second surfacing layer  212 B is provided at a position corresponding to the second surface  21 B. In other words, the second surfacing layer  212 B is provided along a direction extending from the second surface  21 B and orthogonal to the second surface  21 B, or a normal line direction of the second surface  21 B. 
     In the present exemplary embodiment, a thickness t 2  of the second surfacing layer  212 B is, similar to the thickness t 1  of the first surfacing layer  212 A, 100 μm to 350 μm. In addition, the thicknesses t 2  is a thickness of a layer formed of the austenitized phase, and, for example, in a visual field when SEM observation is performed at a magnification of 500 to 1000, is a shortest distance from the second surface  21 B to a ferrite phase of a second mixed layer  213 B described below. Alternatively, the thickness t 2  is a shortest distance from the second surface  21 B to a shallowest location of the austenitized phase. Additionally, when a distance from the second surface  21 B to each of a plurality of points that is short in distance to the ferrite phase is measured, an average value thereof may be defined as the thickness t 2 . 
     Here, in the present exemplary embodiment, the surfacing layer  212  is provided such that a thickness t 3  of the surfacing layer  212  at the corner portion  21 C is larger than the thickness t 1  of the first surfacing layer  212 A and the thickness t 2  of the second surfacing layer  212 B. Specifically, the thickness t 3  is equal to or greater than 150 μm, and may be equal to or greater than 200 μm. 
     Accordingly, the thickness t 3  of the surfacing layer  212  at the corner portion  21 C can be increased, and impact resistance can be improved, thus for example, even when the watch  1  is dropped and the corner  21 C is impacted, damage to the corner portion  21 C can be suppressed. 
     In addition, in the present exemplary embodiment, the thickness t 3  is equal to or less than 550 μm, and may be equal to or less than 500 μm. Accordingly, it is possible to prevent a nitrogen absorption treatment time for providing the surfacing layer  212  from becoming too long. 
     Note that, in the present exemplary embodiment, the thickness of the surfacing layer  212  at the corner portion  21 C is set to t 3 , by adjusting a degree of entrance of nitrogen in the nitrogen absorption treatment, and a cut amount in cutting performed after the nitrogen absorption treatment. 
     Note that, the thicknesses t 3  is a thickness of a layer formed of the austenitized phase, and, for example, in a visual field when SEM observation is performed at a magnification of 500 to 1000, is a shortest distance from the corner portion  21 C to the ferrite phase of the first mixed layer  213 A, or to the ferrite phase of the second mixed layer  213 B. Alternatively, the thickness t 3  is a shortest distance from the corner portion  21 C to a shallowest location of the austenitized phase. Additionally, when a distance from the corner portion  21 C to each of a plurality of points that is short in distance to the ferrite phase is measured, an average value thereof may be defined as the thickness t 3 . 
     Mixed Layer 
     In a step of forming the surfacing layer  212 , the mixed layer  213  is generated by a variation in transfer rate of nitrogen entering the base  211  formed of the ferrite phase. In other words, at a location where the transfer rate of nitrogen is high, nitrogen enters into a deep location of the ferrite phase and the location is austenitized, and at a location where the transfer rate of nitrogen is low, the ferrite phase is austenitized only up to a shallow location, thus the mixed layer  213  is formed in which the ferrite phase and the austenitized phase are mixed with each other with respect to a depth direction. Note that, the mixed layer  213  is a layer including a shallowest site to a deepest site of the austenitized phase when viewed in a cross-section, and is a layer thinner than the surfacing layer  212 . 
     Here, in the present exemplary embodiment, the mixed layer  213  includes the first mixed layer  213 A and the second mixed layer  213 B. The first mixed layer  213 A is a layer formed between the base  211  and the first surfacing layer  212 A. The second mixed layer  213 B is a layer formed between the base  211  and the second surfacing layer  212 B. 
     Effect of Exemplary Embodiment 
     According to the present exemplary embodiment, the following advantageous effects can be produced. 
     The case main body  21  of the present exemplary embodiment is formed of austenitized ferritic stainless steel including the base  211  formed of the ferrite phase, and the surfacing layer  212  formed of the austenitized phase. Further, the case main body  21  includes the first surface  21 A exposed to the external space, and the second surface  21 B that is adjacent to the first surface  21 A with the corner portion  21 C interposed therebetween, and is exposed to the external space. Furthermore, the angle θ of the internal angle formed by the first surface  21 A and the second surface  21 B at the corner portion  21 C is greater than 0° and less than 180°. In other words, the first surface  21 A and the second surface  21 B are configured such that the corner portion  21 C protrudes toward the external space. Then, the surfacing layer  212  at the corner portion  21 C is thicker in thickness than the first surfacing layer  212 A in the first surface  21 A and the second surfacing layer  212 B in the second surface  21 B. 
     Accordingly, the thickness t 3  of the surfacing layer at the corner portion  21 C protruding toward the external space, that is, the corner portions  21 C that is easily subjected to strong impact and for which frequency of strong impact is high, can be increased, and impact resistance can be improved. Accordingly, for example, even when the watch  1  is dropped and the corner portion  21 C is impacted, damage to the corner portion  21 C can be suppressed. Accordingly, the case main body  21  that is robust against impact by dropping or the like can be implemented. 
     In the present exemplary embodiment, the thickness t 3  of the surfacing layer  212  at the corner portion  21 C is equal to or greater than 150 μm, and equal to or less than 550 μm, and may be equal to or greater than 200 μm, and equal to or less than 500 μm. 
     Accordingly, impact resistance at the corner portion  21 C can be sufficiently ensured, and it is possible to suppress that a nitrogen absorption treatment time becomes too long. 
     In the present exemplary embodiment, the base  211  contains, in percent by mass, Cr: 18 to 22%, Mo: 1.3 to 2.8%, Nb: 0.05 to 0.50%, Cu: 0.1 to 0.8%, Ni: less than 0.5%, Mn: less than 0.8%, Si: less than 0.5%, P: less than 0.10%, S: less than 0.05%, N: less than 0.05%, and C: less than 0.05%, with a balance being formed of Fe and unavoidable impurities. 
     This makes it possible to increase the transfer rate of nitrogen to the ferrite phase, and the diffusion rate of nitrogen in the ferrite phase, in the nitrogen absorption treatment. 
     In the present exemplary embodiment, the nitrogen content of the surfacing layer  212  is 1.0 to 1.6% in percent by mass. 
     Accordingly, anticorrosive performance in the surfacing layer  212  can be improved. 
     Evaluation Test 
     Next, an evaluation test was performed on a relationship between impact resistance performance and layer thickness of an austenitized surfacing layer. 
     Summary and a result of the evaluation test will be described below. 
     Impact Resistance Performance Test Method 
     First, a plurality of test pieces were produced each formed of ferritic stainless steel containing Cr: 20%, Mo: 2.1%, Nb: 0.2%, Cu: 0.1%, Ni: 0.05%, Mn: 0.5%, Si: 0.3%, p: 0.03%, S: 0.01%, N: 0.01%, and C: 0.02%, with a balance being formed of Fe and unavoidable impurities. 
     Next, by performing nitrogen absorption treatment on each of the test pieces, the plurality of test pieces each formed with an austenitized surfacing layer on a surface thereof were obtained. 
     Then, for each test piece, iron balls having weight of 10 g, 20 g, 30 g, 40 g, 50 g, 60 g, 70 g, and 80 g, respectively were dropped from a height of 1 m, and amounts of deformation in a vertical direction of the surfacing layer were measured. 
     Impact Resistance Performance Test Result 
     As shown in Table 1, for the iron ball having larger weight, the amount of deformation in the vertical direction of the surfacing layer was larger, and assumed load was increased. Note that, in the present test, the assumed load was determined by the following equation. Also, as a result of a separate test, Vickers hardness of the test piece of the present test was 380 Hv. 
         P= 13.22× H ×( D/ 1000)2  Assumed Load Calculation Equation
 
     P: assumed load [kg]
 
H: Vickers hardness of the test piece [Hv]
 
D: amount of deformation [μm]
 
     
       
         
           
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 IRON 
                   
                   
                 REQUIRED 
               
               
                 BALL 
                 AMOUNT OF 
                 ASSUMED 
                 LAYER 
               
               
                 WEIGHT 
                 DEFORMATION 
                 LOAD 
                 THICKNESS 
               
               
                 [g] 
                 [μm] 
                 [kg] 
                 [μm] 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 10 
                 10 
                 0.5 
                 70 
               
               
                 20 
                 20 
                 2.0 
                 140 
               
               
                 30 
                 30 
                 4.5 
                 210 
               
               
                 40 
                 40 
                 8.0 
                 280 
               
               
                 50 
                 50 
                 12.6 
                 350 
               
               
                 60 
                 60 
                 18.1 
                 420 
               
               
                 70 
                 70 
                 24.6 
                 490 
               
               
                 80 
                 80 
                 32.2 
                 560 
               
               
                   
               
            
           
         
       
     
     Here, when the test piece or the like is impacted, and the test piece deforms, a range of seven times the amount of deformation is said to be affected. Thus, in the present test, the layer thickness of the surfacing layer required for the assumed load was evaluated as seven times the amount of deformation. 
     As shown in Table 1, in general, the assumed load as impact on the watch, is approximately 2 kg, thus it was suggested that the layer thickness of the surfacing layer required for this assumed load is 140 μm. 
     In the exemplary embodiment described above, the thickness t 3  of the surfacing layer  212  at the corner portion  21 C is equal to or greater than 150 μm, thus it was suggested that the surfacing layer has sufficient impact resistance performance for the assumed load as the impact to the watch. 
     Modification Example 
     Note that the present disclosure is not limited to each of the exemplary embodiments described above, and variations, modifications, and the like within the scope in which the object of the present disclosure can be achieved are included in the present disclosure. 
     In the exemplary embodiment described above, the housing of the present disclosure is configured as the case main body  21  for the watch, but is not limited thereto. For example, the housing of the present disclosure may be configured as at least one of a case back and a bezel. Additionally, the watch may have a plurality of the components as described above. 
     In the exemplary embodiment described above, the corner portion  21 C is configured such that the angle θ of the internal angle formed by the first surface  21 A and the second surface  21 B is greater than 0° and less than 180°, but is not limited thereto. For example, the corner portion may be configured to have a curved shape (R shape), and may be configured such that an angle of an internal angle formed by a virtual extension line along the first surface and a virtual extension line along the second surface is greater than 0° and less than 180° in cross-sectional view. In this case, a thickest portion of a surfacing layer at the corner portion configured to have the curved shape may be configured to be thicker in thickness than a surfacing layer in the first surface and a surfacing layer in the second surface. 
     In the exemplary embodiment described above, the first surface  21 A and the second surface  21 B are disposed closer to the case back  22  than the crown  26 , but are not limited thereto. For example, the first surface and the second surface may be disposed closer to the glass plate than the crown. 
     In the exemplary embodiment described above, the corner portion  21 C is constituted by two surfaces, the first surface  21 A and the second surface  21 B, but is not limited thereto. For example, the corner portion may be constituted by three or more surfaces. That is, the corner portion may be a location that couples three or more surfaces with each other. 
     In the exemplary embodiment described above, the case main body  21  is configured as the watch component, but is not limited thereto. For example, the case main body  21  may be configured as a housing of an electronic device other than a watch, or the like. That is, a housing may be configured as a housing for an electronic device, and the device of the present disclosure may be configured as an electronic device. By including a housing configured in this way, an electronic device can have high impact resistance performance. 
     Summary of Present Disclosure 
     A housing of the present disclosure is a housing formed of austenitized ferritic stainless steel including a base formed of a ferrite phase, and a surfacing layer formed of an austenitized phase in which the ferrite phase is austenitized, that includes a first surface exposed to an external space of the housing, and a second surface adjacent to the first surface with a corner portion interposed therebetween, and exposed to the external space, wherein an angle of an internal angle formed by the first surface and the second surface at the corner portion is greater than 0°, and less than 180°, and a surfacing layer at the corner portion is thicker in thickness than a surfacing layer in the first surface and a surfacing layer in the second surface. 
     Accordingly, a thickness of the surfacing layer at the corner portion protruding toward the external space, that is, the corner portions that is easily subjected to strong impact and for which frequency of strong impact is high, can be increased, and impact resistance can be improved. Accordingly, for example, even when the housing is dropped and the corner portion is impacted, damage to the corner portion can be suppressed. Thus, a housing that is robust against impact by dropping or the like can be implemented. 
     In the housing of the present disclosure, the thickness of the surfacing layer at the corner portion may be equal to or greater than 150 μm, and equal to or less than 550 μm. 
     Accordingly, impact resistance at the corner portion can be ensured, and it is possible to suppress that a nitrogen absorption treatment time becomes too long. 
     In the housing of the present disclosure, the thickness of the surfacing layer at the corner portion may be equal to or greater than 200 μm, and equal to or less than 500 μm. 
     Accordingly, the impact resistance at the corner portion can be more sufficiently ensured, and it is possible to suppress that the nitrogen absorption treatment time becomes too long. 
     In the housing of the present disclosure, the base may contain, in percent by mass, Cr: 18 to 22%, Mo: 1.3 to 2.8%, Nb: 0.05 to 0.50%, Cu: 0.1 to 0.8%, Ni: less than 0.5%, Mn: less than 0.8%, Si: less than 0.5%, P: less than 0.10%, S: less than 0.05%, N: less than 0.05%, and C: less than 0.05%, with a balance being formed of Fe and unavoidable impurities. 
     This makes it possible to increase the transfer rate of nitrogen to the ferrite phase, and a diffusion rate of nitrogen in the ferrite phase, in the nitrogen absorption treatment. 
     In the housing of the present disclosure, nitrogen content of the surfacing layer may be 1.0 to 1.6% in percent by mass. 
     Accordingly, anticorrosive performance in the surfacing layer can be improved. 
     A device including the housing of the present disclosure.