JP2008093725A - Erosion preventive method and member with erosion preventive section - Google Patents
Erosion preventive method and member with erosion preventive section Download PDFInfo
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本発明は、浸食環境下で使用されるタービン翼などの部材の浸食防止技術に係り、特に、硬質材料をレーザや電子ビームなどの高密度エネルギー照射で肉盛溶接する浸食防止方法および浸食防止部を備えた部材に関するものである。 The present invention relates to a technique for preventing erosion of a member such as a turbine blade used in an erosion environment, and in particular, an erosion prevention method and an erosion prevention unit for overlay welding a hard material by high-density energy irradiation such as a laser or an electron beam. It is related with the member provided with.
一般に、タービン機器内にはタービン回転翼などの部材が使用されている。図４は蒸気タービンの構造を示す断面図であり、図４中の符号１は主蒸気管、２は再熱蒸気管、３はタービンロータ、４は低圧外部ケーシング、６はクロスオーバー管である。低圧外部ケーシング４内部には低圧内部ケーシング５が収納され、この低圧内部ケーシング５の内側にタービン動翼７およびタービン静翼８が配置されている。 Generally, members such as turbine rotor blades are used in turbine equipment. 4 is a cross-sectional view showing the structure of the steam turbine. In FIG. 4, reference numeral 1 is a main steam pipe, 2 is a reheat steam pipe, 3 is a turbine rotor, 4 is a low-pressure outer casing, and 6 is a crossover pipe. . A low pressure internal casing 5 is accommodated in the low pressure external casing 4, and a turbine blade 7 and a turbine stationary blade 8 are disposed inside the low pressure internal casing 5.
タービン動翼７およびタービン静翼８は、蒸気中に含まれる水滴や酸化スケールの微粉によって浸食を受ける浸食環境下にある。特に、タービン駆動用の蒸気に水滴が混じる後方段階では、その水滴により多大な浸食が発生する。また、タービン後方の翼列では、翼長の大きな部材が用いられるので、周速が大きくなり、厳しい浸食環境となる。このようなタービン翼の浸食は、浸食による減肉化はもちろん問題であるが、浸食部位を起点としたタービン翼の疲労破壊が過去の蒸気タービンの事故原因にもなっているため、疲労破壊を起こすリスクが最も危惧されている。 The turbine rotor blade 7 and the turbine stationary blade 8 are in an erosion environment that is eroded by water droplets contained in the steam and fine oxide particles. In particular, at the rear stage where water droplets are mixed with steam for driving the turbine, the water droplets cause a great erosion. Further, since the blade row behind the turbine uses a member having a large blade length, the peripheral speed increases and a severe erosion environment is created. Such turbine blade erosion is, of course, a problem of thinning due to erosion, but since fatigue failure of the turbine blade starting from the erosion site has also caused accidents in past steam turbines, The risk of waking up is most worrisome.
そこでタービン翼など浸食を受け易い部材に関しては、その耐久性を高めて安全性を確保するために、従来、様々な浸食防止対策がなされてきた。すなわち、浸食の発生が予想される部位に局部的に火炎もしくは高周波を用いた焼入れを施す手法、翼形状に整形したステライトなどの鍛造品をろう付けや溶接によって取り付ける手法、プラズマ溶接を用いて部材自体に直接肉盛溶接する手法などが提案されている。 Therefore, various measures for preventing erosion have been taken for members that are susceptible to erosion, such as turbine blades, in order to increase their durability and ensure safety. That is, a method of locally quenching a portion where erosion is expected using a flame or high frequency, a method of attaching a forged product such as stellite shaped into a blade shape by brazing or welding, a member using plasma welding A technique for direct overlay welding to itself has been proposed.
また近年では、電子ビームやレーザといった１０5Ｗ・ｃｍ2以上の高エネルギー密度熱源を用いた低入熱の肉盛溶接方法が提案されている（例えば、特許文献１参照）。このうち、電子ビームを用いた溶接方法は、タービン翼の浸食防止に数多くの実績があり、鍛造のステライトをタービン回転翼に溶接する方法は１９７０年代から盛んに適用されている。また、レーザを用いた溶接方法は、９０年代から試験研究が行われており、１−２ｍｍ程度のステライト層を翼面に肉盛する方式が適用されている。 In recent years, a low heat input overlay welding method using a high energy density heat source of 10 5 W · cm 2 or more such as an electron beam or a laser has been proposed (for example, see Patent Document 1). Among these, the welding method using an electron beam has many achievements in preventing the erosion of the turbine blade, and the method of welding forged stellite to the turbine rotor blade has been actively applied since the 1970s. In addition, a laser-based welding method has been studied since the 1990s, and a method of overlaying a stellite layer of about 1-2 mm on the blade surface is applied.
このような電子ビームやレーザを用いた肉盛溶接方法によれば、低入熱であるため、部材の劣化や変形を最小限に抑えることができ、しかも部材上に肉盛部のみを形成するだけで済む。したがって、部材への負荷が少なく、部材に対し浸食防止機能を安価に付与できる手法として有効である。具体的には、特許文献１に記載されているように、コバルト基の硬質材料であるステライトを翼形状の母材上に直接肉盛溶接することが既に実用化されている。
以上述べたように、浸食を受け易い部材の浸食防止方法は、部材の耐久性向上と、部材を組み込んだ機器の安定性・安全性を確保する上で不可欠な技術であり、常にその改善が望まれている。特に、厳しい浸食環境下にあるタービン翼においては、その先端部近傍の周速の大きな部分や、周縁部などの体積当たりの表面積が大きな部分、あるいは部材厚さが薄い部分などに発生する浸食に対しては、十分な対策をとることが要請されている。 As described above, erosion prevention methods for members that are susceptible to erosion are indispensable technologies for improving the durability of the members and ensuring the stability and safety of the devices incorporating the members. It is desired. In particular, in turbine blades under severe erosion environments, erosion occurs in parts with a large peripheral speed near the tip, parts with a large surface area per volume such as the peripheral part, or parts with a thin member thickness. For this, it is required to take sufficient measures.
中でも、翼長の大きなタービン翼は、部材の軽量化を図るべく翼の肉厚を薄くする傾向にあり、部材を薄くする分、高強度の材料を用いることが多い。高強度の材料は部材を薄くして軽量化には寄与するが、溶接加工は難しいという難点がある。例えば、高強度の鋼種を用いて厚さを１０ｍｍ以下とした薄いタービン回転翼を製造した場合、このような薄い部材に対し大きな入熱を与える焼入れや焼き戻しといった手法では、材料特性を低下させる懸念がある。また、タービン翼の厚さが薄ければ、僅かな変形が生じただけでも、タービンの性能に与える影響も大きくなる。そのため、浸食の防止に関してはいっそう注意が必要となっている。 Among them, turbine blades with large blade lengths tend to reduce the thickness of the blades in order to reduce the weight of the members, and high strength materials are often used as the members are thinned. A high-strength material contributes to weight reduction by thinning the member, but has a drawback that welding is difficult. For example, when a thin turbine rotor blade having a thickness of 10 mm or less is manufactured using a high-strength steel type, a technique such as quenching or tempering that gives a large heat input to such a thin member reduces the material characteristics. There are concerns. Further, if the thickness of the turbine blade is thin, even if a slight deformation occurs, the influence on the performance of the turbine becomes large. Therefore, more caution is required regarding prevention of erosion.
ところで、高強度の材料を得るために、焼き入れや焼き戻しで強度を調整する鋼以外にも、析出強化型の１７−４ＰＨのような鋼を用いる場合もある。しかし、析出強化型の鋼を用いたタービン回転翼では、焼き入れによる硬さの改善は期待できない。これは、ろう付けのように８００度以上の温度で処理した場合、広範囲で部材の強度が低下してしまい、本来の材料特性を発揮できないためである。 By the way, in order to obtain a high-strength material, in addition to steel whose strength is adjusted by quenching or tempering, steel such as precipitation-strengthened 17-4PH may be used. However, a turbine rotor blade using precipitation strengthened steel cannot be expected to improve hardness by quenching. This is because when the treatment is performed at a temperature of 800 ° C. or more as in brazing, the strength of the member is lowered in a wide range and the original material characteristics cannot be exhibited.
また、翼形状に整形したステライトなどの鍛造硬質材料を、ろう付けや溶接によって浸食対策の必要な部位に取り付ける手法は、浸食防止手法として広く認知されているが、硬質材料となるコバルト基のステライト鍛造品が非常に高価である点が問題となっている。その上、ステライトの開先加工が難しく、加工コストが高いので、タービン翼製造コストの上昇要因となっていた。 In addition, the method of attaching a forged hard material such as stellite shaped into a wing shape to a part that requires erosion countermeasures by brazing or welding is widely recognized as an erosion prevention method, but it is a cobalt-based stellite that becomes a hard material. The problem is that forged products are very expensive. In addition, since the stellite groove processing is difficult and the processing cost is high, it has been a factor in increasing the turbine blade manufacturing cost.
入熱量の大きな溶接方法が持つ上記の課題、すなわち材料の劣化や変形、さらにはコストの増大といった課題を解消する方法としては、前記特許文献１などのように、電子ビームやレーザといった高密度エネルギーを用いた肉盛溶接方法が有効であると考えられている。しかしながら、従来の肉盛溶接方法には次のような課題が指摘されていた。すなわち、ステライトは通常、１．０ｗｔ％程度の多くの炭素を含むため、低入熱であっても溶接によって母材とステライト層が混ざり合うことで複雑な炭素の希釈層が形成される。この炭素希釈層は、肉盛溶接部分に高温割れを招きやすく、溶接施工上、好ましくなかった。 As a method for solving the above-mentioned problems of the welding method having a large heat input, that is, the deterioration and deformation of the material, and the increase in cost, as described in Patent Document 1, high density energy such as an electron beam or a laser is used. It is considered that the overlay welding method using the steel is effective. However, the following problems have been pointed out in conventional overlay welding methods. That is, since stellite usually contains a large amount of carbon of about 1.0 wt%, even if the heat input is low, a complicated carbon dilution layer is formed by mixing the base material and the stellite layer by welding. This carbon dilution layer is liable to cause high temperature cracking in the build-up welded portion, which is not preferable in terms of welding construction.
また、炭素の希釈層形成といった問題以外にも、ステライトの肉盛量が大きくなると、肉盛溶接による収縮の残留応力（引張残留応力）が増大するが、この残留応力は溶接後の熱処理で大きく改善することが難しく、タービンの運転環境下で、残留応力に起因して肉盛部分の端部が剥れるような割れや、溶接金属部での割れが発生することがある。 In addition to the problem of carbon dilute layer formation, when the build-up amount of stellite increases, the residual stress of shrinkage due to build-up welding (tensile residual stress) increases, but this residual stress is increased by heat treatment after welding. It is difficult to improve, and cracks in the end portion of the build-up part due to residual stress or cracks in the weld metal part may occur in the turbine operating environment.
しかも、レーザを用いてステライトの肉盛溶接を実施すると、ステライト溶接金属部の硬さが通常の鍛造品に比べて非常に大きな値になる。例えば、ステライトＮｏ．６を用いた場合、鍛造品がロックウェルＣスケールで３５から４０前後であるのに対し、レーザを用いた肉盛溶接部では５０以上の高い値を示す。つまりレーザを用いた肉盛溶接部は極めて硬いため、溶接部の割れ感受性も高い状態となる。このような肉盛溶接部の硬さの上昇は、強度が高くなる反面、延靭性の低下を伴うことになる。つまり、肉盛溶接部の硬さが、かえって肉盛部分の端部が剥れるような割れや溶接金属部での割れの発生を助長させている。 In addition, when overlay welding of stellite is performed using a laser, the hardness of the stellite weld metal part becomes a very large value as compared with a normal forged product. For example, Stellite No. When No. 6 is used, the forged product has a Rockwell C scale of around 35 to 40, whereas the built-up weld using a laser shows a high value of 50 or more. That is, since the weld overlay using a laser is extremely hard, the crack sensitivity of the weld is also high. Such an increase in the hardness of the build-up welded portion increases the strength but is accompanied by a decrease in ductility. That is, the hardness of the build-up welded part promotes the occurrence of cracks that peel off the end of the built-up part and cracks in the weld metal part.
以上のように、従来技術においては、タービン翼など浸食が発生し易い部位を有する部材に対し、低コストで浸食を防止可能であり、しかも浸食防止部分に割れなどが生じることなく施工効率が良好な浸食防止技術の開発が待たれていた。 As described above, in the conventional technology, it is possible to prevent erosion at a low cost with respect to a member having a portion where erosion is likely to occur, such as a turbine blade, and the construction efficiency is good without causing cracks in the erosion prevention portion. Development of a new anti-erosion technology was awaited.
本発明は、上記の事情に鑑みて提案されたものであり、浸食が発生し易い部位を有する部材に対し、浸食防止機能を安価且つ確実に付与することができ、製造時および使用時にかけて浸食防止機能を安定して発揮できる経済性・信頼性に優れた浸食防止方法を提供し、さらに、そのような方法を用いることにより安価で安定した浸食防止部を備えた部材を提供することを目的としている。 The present invention has been proposed in view of the above circumstances, and can provide an erosion prevention function inexpensively and reliably to a member having a portion where erosion is likely to occur. An object of the present invention is to provide an economical and reliable erosion prevention method capable of stably exhibiting a prevention function, and to provide a member having an inexpensive and stable erosion prevention portion by using such a method. It is said.
上記の目的を達成するために、本発明の浸食防止方法は、浸食環境下で使用される部材の浸食防止方法において、硬質材料の粉末を高密度エネルギー照射で溶融させ肉盛溶接して硬質層を形成し、前記部材の一部を局部的に前記硬質層に置き換えて浸食防止部を設けることを特徴としている。 In order to achieve the above object, the erosion prevention method of the present invention is a method for preventing erosion of a member used in an erosion environment, in which a hard material powder is melted by high-density energy irradiation and overlay welding is performed. And a portion of the member is locally replaced with the hard layer to provide an erosion preventing portion.
また、本発明の浸食防止部を備えた部材は、以上のような浸食防止方法により浸食防止部を設けた点に特徴がある。 Moreover, the member provided with the erosion preventing part of the present invention is characterized in that the erosion preventing part is provided by the above erosion preventing method.
本発明によれば、浸食環境下で使用される部材の一部に、硬質材料の粉末を高密度エネルギー照射で溶融させ肉盛溶接して硬質層を形成することで、局部的に部材の材料を硬質層に置き換えることができ、浸食防止部を所望の領域に容易に設けられるので、高価な硬質材料の鍛造品を溶接する場合に比べて、大幅に製造コストを低減することが可能である。 According to the present invention, a material of a member is locally formed by melting a hard material powder by high-density energy irradiation and overlay welding to a part of the member used in an erosion environment, and forming a hard layer. Can be replaced with a hard layer, and the erosion prevention part can be easily provided in a desired region, so that the manufacturing cost can be greatly reduced as compared with the case where a forged product of an expensive hard material is welded. .
［代表的な実施形態］
（構成）
以下、本発明を適用した浸食防止方法の代表的な実施形態について、図１〜図３を参照して具体的に説明する。
[Typical embodiment]
(Constitution)
Hereinafter, a typical embodiment of an erosion prevention method to which the present invention is applied will be specifically described with reference to FIGS.
図１は本実施形態に係る浸食防止方法の一例を示しており、図１中の（ａ）はタービン回転翼４１を示す斜視図、（ｂ）は（ａ）に示すタービン回転翼４１の先端部を示す拡大図、（ｃ）はタービン回転翼４１の先端部の対象部位４２（点線で囲んだ部分）に代えて浸食防止部４３を設けた状態を示す斜視図である。 FIG. 1 shows an example of an erosion prevention method according to the present embodiment, in which (a) in FIG. 1 is a perspective view showing a turbine rotor blade 41, and (b) is a tip of the turbine rotor blade 41 shown in (a). FIG. 4C is a perspective view showing a state in which an erosion preventing portion 43 is provided in place of the target portion 42 (portion surrounded by a dotted line) at the tip of the turbine rotor blade 41.
図１に示すように、本実施形態の浸食防止方法は、浸食環境下で使用されるタービン回転翼４１を対象部材とした浸食防止方法であって、その翼リーディングエッジ部を浸食対策が必要な対象部位４２として、ここに硬質材料の粉末をレーザで溶融させ肉盛溶接し、翼形状の一部を局部的に硬質材料に置き換えることで浸食防止部４３を設けたことを特徴としている。なお、前述した特許文献１では翼形状をなす母材の上に肉盛溶接するバタリング方式であったが、本実施形態はこの方式ではなく、翼形状の一部だけを肉盛溶接で形成して置き換える翼形状の成形方式を採用している。 As shown in FIG. 1, the erosion prevention method according to the present embodiment is an erosion prevention method using a turbine rotor blade 41 used in an erosion environment as a target member, and requires countermeasures against erosion at the blade leading edge portion. The target portion 42 is characterized in that a hard material powder is melted with a laser and welded on the target portion 42, and a part of the blade shape is locally replaced with the hard material to provide an erosion preventing portion 43. In Patent Document 1 described above, a buttering method in which overlay welding is performed on a base material having a blade shape, but this embodiment is not this method, and only a part of the blade shape is formed by overlay welding. The wing shape molding method is used.
すなわち、図１の（ｂ）に示すように、タービン回転翼４１における浸食対策が必要な対象部位４２を切り取って、切り取った部分に粉末の硬質材料を肉盛溶接して浸食防止部４３を設けている。つまり、対象部位４２を、図１の（ｃ）に示すように浸食防止部４３にて復元形成させている。 That is, as shown in FIG. 1B, the target portion 42 of the turbine rotor blade 41 that needs to be eroded is cut out, and the hard portion of powder is welded to the cut portion to provide an erosion preventing portion 43. ing. That is, the target part 42 is restored and formed by the erosion preventing part 43 as shown in FIG.
浸食対策が必要な対象部位４２とは、使用環境下で液滴および固体粒子による浸食が発生し易い部位であって、ここでは、タービン回転翼４１における先端部近傍の周速の大きな部位などの、対象部材１における動作速度が局部的に大きな部位、対象部材１における周縁部などの体積あたりの表面積が局部的に大きな部位、あるいは局部的に厚さが薄い部位などである。 The target portion 42 that requires countermeasures against erosion is a portion where erosion due to droplets and solid particles is likely to occur in the use environment. Here, a portion having a large peripheral speed near the tip of the turbine rotor blade 41 is used. A region where the operation speed of the target member 1 is locally large, a region where the surface area per volume of the target member 1 such as a peripheral portion is locally large, or a region where the thickness is locally thin.
続いて、図２を用いて本実施形態の施工方法の概略について説明する。図２は、本実施形態の施工方法の概略について説明するための図であり、図２中の（ａ）は、本実施形態に係る浸食防止方法を示すイメージ図、（ｂ）は（ａ）の模式的なＡ矢視断面図である。図２に示すように、タービン回転翼４１などの対象部材１において、タービン回転翼４１運転時での液滴および固体粒子による浸食が発生し易い部位に対し、中間層２および硬質層３の材料となる粉末材料７を溶接材料供給手段５により供給しながら、レーザ光源６からレーザ照射して、レーザによる肉盛溶接を実施し、上下２層構造の浸食防止部４を形成する。 Then, the outline of the construction method of this embodiment is demonstrated using FIG. FIG. 2 is a diagram for explaining the outline of the construction method of the present embodiment, (a) in FIG. 2 is an image diagram showing an erosion prevention method according to the present embodiment, and (b) is a diagram of (a). It is typical A arrow sectional drawing. As shown in FIG. 2, in the target member 1 such as the turbine rotor blade 41, the material of the intermediate layer 2 and the hard layer 3 with respect to a portion that is easily eroded by droplets and solid particles during the operation of the turbine rotor blade 41. While the powder material 7 is supplied by the welding material supply means 5, laser irradiation is performed from the laser light source 6, and build-up welding by laser is performed to form the upper and lower two-layer structure erosion preventing portion 4.
中間層２は、延靭性に優れた材料の粉末をレーザで溶融させ肉盛溶接して形成した部分であり、硬質層３と対象部材１の母材との中間部分に０．５〜３．０ｍｍの厚さで形成される。また、中間層２を構成する材料としては、ステライトなどの硬質材料に比べて強度と硬さの低いオーステナイト系ステンレスあるいはオーステナイト組織で特に炭素を固溶しない固溶強化型のＮｉ基合金が用いられている。 The intermediate layer 2 is a portion formed by melting a powder of a material excellent in ductility with a laser and overlay welding, and 0.5 to 3 .5 in the intermediate portion between the hard layer 3 and the base material of the target member 1. It is formed with a thickness of 0 mm. Further, as the material constituting the intermediate layer 2, an austenitic stainless steel having a lower strength and hardness than a hard material such as stellite or a solid solution strengthened Ni-based alloy that does not particularly dissolve carbon in an austenitic structure is used. ing.
硬質層３はステライトなどの硬質材料の粉末をレーザで溶融させ肉盛溶接して形成した部分であり、次の表１に示すような材料が使用されている。 The hard layer 3 is a portion formed by melting a hard material powder such as stellite with a laser and overlay welding, and a material as shown in the following Table 1 is used.
（作用効果）
以上のような本実施形態の作用効果は、次の通りである。すなわち、本実施形態では、タービン回転翼４１の翼形状の一部である翼リーディングエッジ部を浸食対策が必要な対象部位４２とし、これをいったん切り取り、ここにレーザによる肉盛溶接を用いた浸食防止部４３を復元形成することにより、タービン回転翼４１における浸食が発生し易い部位に対して優れた浸食防止機能を持たせることが可能であり、信頼性の向上を図ることができる。特に、翼長が大きく、翼の肉厚の薄い高強度材を用いたタービン回転翼４１の浸食防止に大きな効果を発揮する。
(Function and effect)
The operational effects of the present embodiment as described above are as follows. That is, in the present embodiment, the blade leading edge portion, which is a part of the blade shape of the turbine rotor blade 41, is used as the target portion 42 that requires countermeasures against erosion. By reconstructing the prevention portion 43, it is possible to give an excellent erosion prevention function to a portion where erosion is likely to occur in the turbine rotor blade 41, thereby improving reliability. In particular, it has a great effect on preventing erosion of the turbine rotor blade 41 using a high strength material having a large blade length and a thin blade thickness.
しかも、浸食対策が必要な対象部位４２を切り取って、切り取った形状と同じ形状の鍛造品を溶接接合する方式は従来存在するが、前述したように、この方式はコストが高く、経済的に不利であった。このような従来方式に比べて、硬質材料の粉末をレーザにて肉盛溶接することにより切り取った部分だけを復元する本実施形態の方式は、製作コストの削減に大きな効果をもたらすことが期待できる。 In addition, there is a conventional method of cutting out the target portion 42 that requires countermeasures against erosion and welding the forged product having the same shape as the cut shape. However, as described above, this method is costly and economically disadvantageous. Met. Compared to such a conventional method, the method of the present embodiment that restores only the portion cut by overlay welding of a hard material powder with a laser can be expected to have a great effect on the reduction of the manufacturing cost. .
さらに、本実施形態では、対象部材１の母材の上に硬質層３を直接形成するのではなく、母材と硬質層３との間に０．５ｍｍ以上の中間層２を介在させているので、次のような利点がある。まず、対象部材１の母材と硬質層３の硬質材料が混ざり合うことがない。このため、中間層２として炭素含有量の少ない材料を使用することで、炭素含有量の多い材料を母材上に直接肉盛溶接した場合に生じていた炭素希釈層の形成を回避可能である。したがって、対象部材１の母材が鉄基である場合に炭素を固溶しないＮｉ基合金を中間層２とすれば、硬質層３における炭素希釈層の形成を極めて効果的に防止でき、溶接施工上の信頼性を大幅に改善することができる。 Further, in the present embodiment, the hard layer 3 is not directly formed on the base material of the target member 1, but an intermediate layer 2 of 0.5 mm or more is interposed between the base material and the hard layer 3. So there are the following advantages. First, the base material of the target member 1 and the hard material of the hard layer 3 are not mixed. For this reason, by using a material with a low carbon content as the intermediate layer 2, it is possible to avoid the formation of a carbon dilution layer that occurs when a material with a high carbon content is directly welded on the base material. . Therefore, when the base material of the target member 1 is iron-based, if the Ni-based alloy that does not dissolve carbon in the intermediate layer 2 is used, the formation of a carbon dilution layer in the hard layer 3 can be extremely effectively prevented, and welding work is performed. The above reliability can be greatly improved.
また、中間層２の存在は、製造時の収縮の残留応力（引張残留応力）に起因する肉盛部分の端部が剥れるような割れや溶接金属部での割れ発生に対しても大きな効果がある。この点について図３を参照して説明する。図３の（ａ）は、中間層２による残留応力の軽減効果を説明するためのグラフであって、中間層２を設けない場合（従来例）の最大残留応力と、中間層２を設けた場合（本実施形態）の最大残留応力の計測結果を示している。 In addition, the presence of the intermediate layer 2 has a great effect on cracks in which the end of the built-up part is peeled off due to shrinkage residual stress (tensile residual stress) at the time of manufacture or cracks in the weld metal part. There is. This point will be described with reference to FIG. FIG. 3A is a graph for explaining the effect of reducing the residual stress by the intermediate layer 2. The maximum residual stress when the intermediate layer 2 is not provided (conventional example) and the intermediate layer 2 are provided. The measurement result of the maximum residual stress in the case (this embodiment) is shown.
このグラフからも明らかなように、中間層２を有する本実施形態の最大残留応力は低い値となっており、応力腐食割れの発生するリスクを軽減させることが可能であり、残留応力に起因する肉盛部分端部や溶接金属部の割れを確実に防ぐことができる。なお、図４の（ｂ）は、残留応力の計測に使用した試験片２１とその計測位置２２を示す模式的な斜視図である。 As is clear from this graph, the maximum residual stress of the present embodiment having the intermediate layer 2 is a low value, and the risk of stress corrosion cracking can be reduced, resulting from the residual stress. It is possible to reliably prevent cracks at the end of the built-up part and the weld metal part. FIG. 4B is a schematic perspective view showing the test piece 21 used for measuring the residual stress and the measurement position 22 thereof.
また、中間層２の介在していることで、万が一硬質層３で割れが生じたとしても、硬質層３から伸展してきた割れの伝播を遅らせるかまたは阻止することができるといった効果もある。さらに、中間層２の厚さは、３ｍｍを上限としたので、溶接継手部の高サイクル疲労強度や、翼面に露出する中間層の耐浸食性も確保することができる。 In addition, since the intermediate layer 2 is interposed, even if a crack occurs in the hard layer 3, there is an effect that the propagation of the crack extending from the hard layer 3 can be delayed or prevented. Furthermore, since the upper limit of the thickness of the intermediate layer 2 is 3 mm, the high cycle fatigue strength of the welded joint and the erosion resistance of the intermediate layer exposed on the blade surface can be ensured.
さらに、本実施形態は粉末材料７を用いたレーザ溶接で中間層２を形成させることにより、低入熱の条件で肉盛溶接を実施しており、溶接入熱による対象部材１の母材における材料特性の低下を回避することができる。一般に用いられるＥＢＷやＴＩＧによる溶接施工では母材の熱影響部が１ｍｍ以上となるのに対し、本実施形態によれば、熱影響部を１ｍｍ以下に抑えることが可能となる。 Further, in the present embodiment, the intermediate layer 2 is formed by laser welding using the powder material 7, thereby performing overlay welding under conditions of low heat input, and in the base material of the target member 1 by welding heat input It is possible to avoid deterioration of material properties. In the welding construction by EBW or TIG generally used, the heat affected zone of the base material is 1 mm or more, but according to this embodiment, the heat affected zone can be suppressed to 1 mm or less.
［他の実施形態］
なお、本発明は、前述した実施形態に限定されるものではなく、本発明の範囲内で他にも多種多様な変形例が実施可能である。例えば、実施形態中で記載した材料は一例にすぎず、本発明において、硬質材料や中間層を構成する材料としては、他にも各種の材料を適宜選択可能である。
[Other Embodiments]
It should be noted that the present invention is not limited to the above-described embodiments, and various other variations can be implemented within the scope of the present invention. For example, the materials described in the embodiments are merely examples, and in the present invention, various other materials can be appropriately selected as the hard material and the material constituting the intermediate layer.
また、上記実施形態では浸食防止部４を２層構造としているが、硬さの異なる３種類以上の材料を肉盛溶接することで、浸食防止部４の硬さを段階的に変化させる実施形態も包含する。このような実施形態によれば、母材から硬質層に至る断面の硬さをより滑らかにすることができ、残留応力はいっそう低減する。 Moreover, in the said embodiment, although the erosion prevention part 4 is made into 2 layer structure, Embodiment which changes the hardness of the erosion prevention part 4 in steps by carrying out overlay welding of 3 or more types of materials from which hardness differs. Is also included. According to such an embodiment, the hardness of the cross section from the base material to the hard layer can be made smoother, and the residual stress is further reduced.
さらに、本発明は、タービン回転翼を対象部材とした浸食防止手法として好適であるが、タービン静翼などの他のタービン部品に対しても同様に適用可能であり、同様に優れた効果が得られるものである。さらに、タービン以外の各種の機器についても、浸食環境下で使用される各種の部材に対して同様に適用可能であり、同様に優れた効果が得られるものである。 Furthermore, the present invention is suitable as an erosion prevention method using turbine rotor blades as target members, but it can be similarly applied to other turbine parts such as turbine stationary blades, and similarly excellent effects are obtained. It is what Furthermore, various devices other than the turbine can be similarly applied to various members used in an eroding environment, and similarly excellent effects can be obtained.
硬質層３を構成する硬質材料としては、ステライトだけでなく、コバルト基合金を用いてもよい。耐浸食性に優れるコバルト基合金の積層高さは、部材の経年的な損傷状態に直接影響するので、鉄基合金からなる部材を母材とする場合、鉄基合金の母材に比べてコバルト基合金の浸食速度は半分以下に改善できる。タービン回転翼４１にコバルト基合金の硬質層３を適用する場合、翼リーディングエッジ部の浸食は、エッジ部分付近から始まるため、積層高さ５ｍｍ以上のコバルト基合金を用いることで、浸食防止効果をより高めることができる。 As a hard material constituting the hard layer 3, not only stellite but also a cobalt-based alloy may be used. The stacking height of the cobalt-based alloy, which has excellent corrosion resistance, directly affects the aging damage of the member. The erosion rate of the base alloy can be improved to less than half. When the hard layer 3 of the cobalt-based alloy is applied to the turbine rotor blade 41, the erosion of the blade leading edge portion starts from the vicinity of the edge portion. Therefore, by using a cobalt-based alloy having a stacking height of 5 mm or more, the erosion preventing effect is obtained. Can be increased.
また、粉末材料をレーザで溶融させ肉盛溶接する際、１バスあたりの積層高さが１ｍｍ以下の小入熱の溶接ビードを多層で積層した方法も包含する。このような浸食防止方法を用いて、タービン回転翼４１のリーディングエッジ先端部分を翼形状に形成した場合、中間層２、硬質層３に関わらず、１パスあたりの積層高さが１ｍｍ以下とする小入熱の溶接ビードを多層で積層させる。この実施形態によれば、溶接入熱による母材の材料特性の低下や翼の変形が生じるおそれがない。特に、１パスあたりの積層高さを１ｍｍ以下としたことで、溶接施工時に発生する融合不良を確実に防ぐことができる。 In addition, a method of laminating multiple layers of small heat input weld beads having a laminating height of 1 mm or less per bath when the powder material is melted by laser and overlay welding is included. When the leading edge tip portion of the turbine rotor blade 41 is formed into a blade shape using such an erosion prevention method, the stacking height per pass is 1 mm or less regardless of the intermediate layer 2 and the hard layer 3. Laminate multiple weld beads with low heat input. According to this embodiment, there is no possibility that the material characteristics of the base material are deteriorated or the blade is deformed due to welding heat input. In particular, by setting the stacking height per pass to 1 mm or less, it is possible to reliably prevent poor fusion that occurs during welding.
レーザを用いた肉盛溶接で、溶接中１５０℃以上に予熱した状態で、中間層２としては線膨張係数の大きなオーステナイト系ステンレスを、硬質層３としてはステライトを用いて多層盛させて、浸食防止部４を設けるようにしてもよい。すなわち、硬質層３にステライトの粉末を用いる場合、溶接による収縮が大きいため残留応力が大きくなる傾向がある。そこで、１５０℃の予熱状態で線膨張係数の大きな中間層２を設けることにより残留応力の低減化を図っている。これにより、製造時の収縮の残留応力（引張残留応力）に起因する肉盛部分端部が剥れや溶接金属部の割れを、いっそそう確実に抑える効果があり、製造時および運転時での信頼性が向上する。 In overlay welding using laser, in a state preheated to 150 ° C. or higher during welding, the austenitic stainless steel having a large linear expansion coefficient is used as the intermediate layer 2 and the stellite is used as the hard layer 3 to form a multi-layered erosion. The prevention unit 4 may be provided. That is, when stellite powder is used for the hard layer 3, the residual stress tends to increase due to large shrinkage due to welding. Therefore, the residual stress is reduced by providing the intermediate layer 2 having a large linear expansion coefficient in a preheated state at 150 ° C. As a result, there is an effect to more surely suppress peeling of the built-up part end due to shrinkage residual stress (tensile residual stress) and cracking of the weld metal part at the time of manufacture. Reliability is improved.
また、レーザで溶融させ肉盛溶接した後、溶接部を研磨仕上げする浸食防止方法も含まれる。この方法によれば、溶接部を研磨して表面を滑らかな表面に仕上げることができるため、溶接ビード端部のノッチ効果による疲労強度の低下やタービン翼の性能への悪影響がない。 Also included is an erosion prevention method in which the welded portion is polished after being melted with a laser and subjected to overlay welding. According to this method, since the welded portion can be polished and the surface can be finished to have a smooth surface, there is no adverse effect on the fatigue strength reduction or turbine blade performance due to the notch effect at the weld bead end.
さらに、部材の材質が析出強化型の鋼である場合、溶体化時効状態でレーザを用いた肉盛溶接を行い、溶接後、再度、時効熱処理を行っても良い。一般的に析出強化型の鋼を材料とした部材では、時効熱処理後は母材の強度が増して溶接性が悪くなる。そのため、溶体化状態で溶接している。本手法では、レーザにより溶接入熱を小さく抑えていることから、時効熱処理後の状態でも溶接可能なのが特徴である。また、溶接後に母材の熱影響部で溶体化状態になる部位が生じるため、溶接後、再度、時効熱処理を行うことで母材強度を回復させ、継手強度を回復させることが可能である。 Furthermore, when the material of the member is precipitation strengthened steel, build-up welding using a laser may be performed in a solution aging state, and aging heat treatment may be performed again after welding. In general, in a member made of precipitation-strengthened steel, the strength of the base material is increased and the weldability is deteriorated after the aging heat treatment. Therefore, welding is performed in a solution state. This technique is characterized in that welding is possible even in a state after aging heat treatment because the welding heat input is suppressed to a low level by a laser. Moreover, since the part which will be in solution state in the heat affected zone of a base material arises after welding, it is possible to recover a base material strength and to recover joint strength by performing an aging heat treatment again after welding.
また、前記実施形態においては、高密度エネルギー照射としてレーザを用いた場合について説明したが、本発明においては、レーザに限らず、電子ビームなどの他の高密度エネルギー照射を適用することも可能であり、同様に優れた効果が得られるものである。 In the embodiment, the case where a laser is used for high-density energy irradiation has been described. However, in the present invention, not only a laser but also other high-density energy irradiation such as an electron beam can be applied. In the same way, excellent effects can be obtained.
１…対象部材
２…中間層
３…硬質層
４…浸食防止部
５…溶接材料供給手段
６…レーザ光源
７…粉末材料
２１…試験片
２２…計測位置
４１…タービン回転翼
４２…対象部位
４３…浸食防止部
DESCRIPTION OF SYMBOLS 1 ... Target member 2 ... Intermediate | middle layer 3 ... Hard layer 4 ... Erosion prevention part 5 ... Welding material supply means 6 ... Laser light source 7 ... Powder material 21 ... Test piece 22 ... Measurement position 41 ... Turbine rotor blade 42 ... Target part 43 ... Erosion prevention part
Claims (12)
硬質材料の粉末を高密度エネルギー照射で溶融させ肉盛溶接して硬質層を形成し、前記部材の一部を局部的に前記硬質層に置き換えて浸食防止部を設けることを特徴とする浸食防止方法。 In a method for preventing erosion of members used in an erosion environment,
Erosion prevention characterized in that hard material powder is melted by high density energy irradiation and overlay welding is performed to form a hard layer, and part of the member is locally replaced with the hard layer to provide an erosion prevention portion Method.
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| JP2006280711A JP4901413B2 (en) | 2006-10-13 | 2006-10-13 | Erosion prevention method and member with erosion prevention part |
| KR1020097002094A KR101147719B1 (en) | 2006-08-02 | 2007-08-02 | Erosion preventive method and member with erosion preventive section |
| EP07790323A EP2047939A4 (en) | 2006-08-02 | 2007-08-02 | Erosion preventive method and member with erosion preventive section |
| PCT/JP2007/000834 WO2008015795A1 (en) | 2006-08-02 | 2007-08-02 | Erosion preventive method and member with erosion preventive section |
| CN2007800281431A CN101495265B (en) | 2006-08-02 | 2007-08-02 | Erosion preventive method and member with erosion preventive section |
| US12/375,948 US20090308847A1 (en) | 2006-08-02 | 2007-08-02 | Erosion prevention method and member with erosion preventive section |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2009185814A (en) * | 2008-02-04 | 2009-08-20 | General Electric Co <Ge> | Steam turbine bucket having erosion durability |
| JP2010000540A (en) * | 2008-06-19 | 2010-01-07 | General Electric Co <Ge> | Process for treating metal article and product manufactured by the same |
| JP2010190128A (en) * | 2009-02-18 | 2010-09-02 | Toshiba Corp | Method for preventing erosion of turbine blade, and turbine blade |
| EP2444190A1 (en) | 2010-10-19 | 2012-04-25 | Kabushiki Kaisha Toshiba | Build-up welding method and structural material |
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| JP2014205912A (en) * | 2013-04-10 | 2014-10-30 | ゼネラル・エレクトリック・カンパニイ | Erosion-resistant coating system and processing method therefor |
| JP2015078686A (en) * | 2013-09-25 | 2015-04-23 | ゼネラル・エレクトリック・カンパニイ | Erosion shield, method of fabricating shield, and method of fabricating article having shield |
| WO2015068227A1 (en) * | 2013-11-06 | 2015-05-14 | 川崎重工業株式会社 | Turbine blade and manufacturing method therefor |
| WO2015156182A1 (en) * | 2014-04-07 | 2015-10-15 | 三菱日立パワーシステムズ株式会社 | Rotor blade, erosion shield forming method and rotor blade manufacturing method |
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| DE112013004639T5 (en) | 2012-09-21 | 2015-06-25 | Mitsubishi Hitachi Power Systems, Ltd. | Method for welding erosion-resistant metal material and turbine blade |
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| JP2009185814A (en) * | 2008-02-04 | 2009-08-20 | General Electric Co <Ge> | Steam turbine bucket having erosion durability |
| JP2010000540A (en) * | 2008-06-19 | 2010-01-07 | General Electric Co <Ge> | Process for treating metal article and product manufactured by the same |
| JP2010190128A (en) * | 2009-02-18 | 2010-09-02 | Toshiba Corp | Method for preventing erosion of turbine blade, and turbine blade |
| EP2444190A1 (en) | 2010-10-19 | 2012-04-25 | Kabushiki Kaisha Toshiba | Build-up welding method and structural material |
| JP2012086241A (en) * | 2010-10-19 | 2012-05-10 | Toshiba Corp | Build-up welding method and structural material |
| JP2013170543A (en) * | 2012-02-22 | 2013-09-02 | Toshiba Corp | Repairing method for turbine blade, and turbine blade |
| US9903207B2 (en) | 2012-02-23 | 2018-02-27 | Nuovo Pignone Srl | Turbo-machine impeller manufacturing |
| JP2014205912A (en) * | 2013-04-10 | 2014-10-30 | ゼネラル・エレクトリック・カンパニイ | Erosion-resistant coating system and processing method therefor |
| JP2015078686A (en) * | 2013-09-25 | 2015-04-23 | ゼネラル・エレクトリック・カンパニイ | Erosion shield, method of fabricating shield, and method of fabricating article having shield |
| WO2015068227A1 (en) * | 2013-11-06 | 2015-05-14 | 川崎重工業株式会社 | Turbine blade and manufacturing method therefor |
| JPWO2015068227A1 (en) * | 2013-11-06 | 2017-03-09 | 川崎重工業株式会社 | Turbine blade and method for manufacturing the same |
| WO2015156182A1 (en) * | 2014-04-07 | 2015-10-15 | 三菱日立パワーシステムズ株式会社 | Rotor blade, erosion shield forming method and rotor blade manufacturing method |
| JP2015200218A (en) * | 2014-04-07 | 2015-11-12 | 三菱日立パワーシステムズ株式会社 | Rotor blade, method for forming erosion shield, rotor blade manufacturing method |
| US10907483B2 (en) | 2014-04-07 | 2021-02-02 | Mitsubishi Power, Ltd. | Turbine blade, erosion shield forming method, and turbine blade manufacturing method |
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