JP6879133B2 - Austenitic stainless steel welded member - Google Patents
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- 229910000963 austenitic stainless steel Inorganic materials 0.000 title claims description 21
- 238000003466 welding Methods 0.000 claims description 74
- 239000002131 composite material Substances 0.000 claims description 22
- 239000011324 bead Substances 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 12
- 239000010953 base metal Substances 0.000 claims description 10
- 229910052748 manganese Inorganic materials 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 5
- 229910052799 carbon Inorganic materials 0.000 claims description 4
- 229910052804 chromium Inorganic materials 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- 239000012535 impurity Substances 0.000 claims description 2
- 229910052750 molybdenum Inorganic materials 0.000 claims description 2
- 229910052758 niobium Inorganic materials 0.000 claims 1
- 239000012071 phase Substances 0.000 description 16
- 229910000859 α-Fe Inorganic materials 0.000 description 13
- 229910000831 Steel Inorganic materials 0.000 description 11
- 239000010959 steel Substances 0.000 description 11
- 230000000694 effects Effects 0.000 description 8
- 238000000034 method Methods 0.000 description 8
- 229910001566 austenite Inorganic materials 0.000 description 7
- 230000007797 corrosion Effects 0.000 description 7
- 238000005260 corrosion Methods 0.000 description 7
- 230000005389 magnetism Effects 0.000 description 7
- 229910000734 martensite Inorganic materials 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 238000005097 cold rolling Methods 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 239000007791 liquid phase Substances 0.000 description 4
- 229910001220 stainless steel Inorganic materials 0.000 description 4
- 239000010935 stainless steel Substances 0.000 description 4
- 239000007789 gas Substances 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 230000032683 aging Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 238000005482 strain hardening Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 238000004040 coloring Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 238000007542 hardness measurement Methods 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 229910001105 martensitic stainless steel Inorganic materials 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000004021 metal welding Methods 0.000 description 1
- 229910052755 nonmetal Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 238000010587 phase diagram Methods 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
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Description
本発明は、レーザ溶接とTIG溶接を組み合わせたレーザ・TIG複合溶接オーステナイト系ステンレス溶接部材および溶接方法に関するものである。 The present invention relates to a laser / TIG composite welding austenitic stainless steel welding member and a welding method in which laser welding and TIG welding are combined.
レーザ溶接では、集光された高エネルギー密度の熱源を利用するため、TIG溶接に代表されるアーク溶接に比べ、1)高速深溶込み溶接が可能、2)溶接熱影響が非常に少ない、3)溶接変形が少ない、という特長がある。 Laser welding uses a concentrated heat source with high energy density, so compared to arc welding represented by TIG welding, 1) high-speed deep penetration welding is possible, 2) the effect of welding heat is very small, 3) ) It has the feature that there is little welding deformation.
ただ、レーザ溶接は冷却速度がはやく、溶接部の硬度が母材部に比べ上昇し靭性低下が課題である。レーザ溶接部の加工性を確保するための従来の公知技術は、以下のとおりである。 However, in laser welding, the cooling rate is fast, the hardness of the welded portion is higher than that of the base metal portion, and the problem is that the toughness is lowered. Conventionally known techniques for ensuring the workability of the laser welded portion are as follows.
非特許文献1では、マルテンサイト系ステンレス鋼では、高温域でオーステナイト相が生成し、常温ではマルテンサイト組織が形成される。このため、溶接金属部は著しく硬化し、割れの発生が懸念される。この、溶接後の急冷を避けるために、マルテンサイト変態が開始する温度より上の200℃以上で予熱して、徐々にマルテンサイトを生成させマルテンサイトの自己焼き戻しの効果も加味したうえで、靭性低下を回避している。ただ、オーステナイト系ステンレス鋼は元々延性に優れる材料であるために溶接後の後熱処理は実施されないとなっている。
In
本発明で着眼したレーザ・TIG複合溶接でステンレス鋼板の限った品質改善に着眼した例はない。特許文献1で金属材料全般の溶接においてスパッタ低減でステンレス鋼も使用できると言及している程度である。
There is no example of focusing on the limited quality improvement of stainless steel sheets by the laser / TIG composite welding that was focused on in the present invention.
オーステナイト系ステンレス鋼は溶接を施すことで、母材部に比べ硬度が上昇する。SUS304に代表されるオーステナイト系ステンレス鋼は液相からδフェライトが生成するδ凝固が起こる。δフェライトはオーステナイト相より硬度が高い。その溶接部の硬度が高いことは、言い換えれば延性が低下していることであり、延性に優れるオーステナイト相でもこの溶接部硬度低減が重要である。 By welding, austenitic stainless steel has a higher hardness than the base metal. In austenitic stainless steel represented by SUS304, δ solidification occurs in which δ ferritic is formed from the liquid phase. δ-ferrite has a higher hardness than the austenite phase. The high hardness of the welded portion means that the ductility is lowered, and it is important to reduce the hardness of the welded portion even in the austenite phase having excellent ductility.
上記の課題を解決するために、溶接直後からの冷却過程に本発明は着眼した。液相からδフェライト相が生成しても、その相はあくまで準安定相であり、状態図的にはオーステナイト相が最終安定相である。オーステナイト相がでる領域を緩冷却することで、δフェライト相→オーステナイト相に変態を促進させることで溶接部硬度上昇を抑えることを本発明の特徴としている。
すなわち、本発明は、オーステナイト系ステンレス鋼からなる母材にレーザ・TIG複合溶接を施したオーステナイト系ステンレス溶接部材であって、
溶接部のビード中央部におけるビッカース硬度が母材のビッカース硬度よりも大きく、その差が50以下であり、
母材のオーステナイト系ステンレス鋼の化学組成が、質量%において、C:0.20%以下、Si:1.87%以下、Mn:6.0%以下、Ni:6.0%以上、Cu:4.0%以下、Cr:12.0〜30.0%、N:0.30%以下、Mo:5.0%以下を含有し、残部がFeおよび不可避的不純物であり、式(1)に表されるδFの値が0以上20.0未満であるオーステナイト系ステンレス溶接部材である。
δF=−36C−0.13Mn−1.3Ni−30N−0.39Cu+1.3Cr+1.3Mo+0.67Si−5 ・・・(1)
ただし、C、Mn等の元素記号の位置には、元素記号に対応する成分の含有量(質量%)の値を代入する。ただし、当該成分が含有されない場合は式に算入しない。
In order to solve the above problems, the present invention focused on the cooling process immediately after welding. Even if a δ ferrite phase is generated from the liquid phase, that phase is a metastable phase to the last, and the austenite phase is the final stable phase in the phase diagram. A feature of the present invention is that the region where the austenite phase appears is slowly cooled to promote the transformation from the δ ferrite phase to the austenite phase, thereby suppressing the increase in the hardness of the welded portion.
That is, the present invention is an austenitic stainless steel welded member obtained by subjecting a base material made of austenitic stainless steel to laser / TIG composite welding.
The Vickers hardness at the center of the bead of the weld is larger than the Vickers hardness of the base metal, and the difference is 50 or less.
The chemical composition of the base material austenitic stainless steel is C: 0.20% or less, Si: 1.87 % or less, Mn: 6.0% or less, Ni: 6.0% or more, Cu: It contains 4.0% or less, Cr: 12.0 to 30.0%, N: 0.30% or less, Mo: 5.0% or less, and the balance is Fe and unavoidable impurities, according to the formula (1). It is an austenitic stainless steel welded member in which the value of δF represented by is 0 or more and less than 20.0.
δF = -36C-0.13Mn-1.3Ni-30N-0.39Cu + 1.3Cr + 1.3Mo + 0.67Si-5 ... (1)
However, the value of the content (mass%) of the component corresponding to the element symbol is substituted for the position of the element symbol such as C and Mn. However, if the component is not included, it is not included in the formula.
本発明の一態様におけるレーザ・TIG複合溶接オーステナイト系ステンレスを用いることで、レーザ造管前の予備加熱やレーザ溶接後の後熱処理等がなくとも、溶接部ビード中央部ビッカース硬度と母材部ビッカース硬さの差が小さく、溶接部靭性に優れたオーステナイト系ステンレス溶接部材を提供することができる。 By using the laser / TIG composite welded austenitic stainless steel in one aspect of the present invention, the Vickers hardness at the center of the weld bead and the Vickers at the base metal are not required for preheating before laser tube making or post-heat treatment after laser welding. It is possible to provide an austenitic stainless steel welded member having a small difference in hardness and excellent weld toughness.
以下、実施例に基づき本発明を更に詳細に説明するが、本発明はこれらの実施例に限定されることなく、特許請求の範囲に記載した発明の範囲内で種々の組合せが可能であり、それらも本発明の範囲に含まれる。 Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples, and various combinations are possible within the scope of the invention described in the claims. They are also included in the scope of the present invention.
<レーザ・TIG複合溶接方法の概要>
本発明に係るレーザ・TIG複合溶接方法について図に基づいて説明する。図1は、本発明に係るレーザ・TIG複合溶接方法についてTIG先行溶接を説明する図である。
図1において符号1はレーザ溶接を行うレーザ光のビームであり、符号2はTIG溶接トーチである。また、符号3は、素材であるオーステナイト系ステンレス鋼材である。この溶接方法によってレーザ・TIG複合溶接する場合、TIG溶接トーチ2によるTIG溶接が先行して行われ、続いてレーザ光のビーム1によるレーザ溶接が行われる。
<Outline of laser / TIG combined welding method>
The laser / TIG composite welding method according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating TIG advance welding for the laser / TIG composite welding method according to the present invention.
In FIG. 1,
図2、図3にレーザ・TIG複合溶接を施したオーステナイト系ステンレス鋼のビード外観とビード断面の一例を示す。図2に示すようにスパッタは少なく、図3に示すようにアンダーカットも0.1mmと小さい特徴もある。 2 and 3 show an example of the bead appearance and bead cross section of austenitic stainless steel subjected to laser / TIG composite welding. As shown in FIG. 2, the amount of sputtering is small, and as shown in FIG. 3, the undercut is as small as 0.1 mm.
以下、本発明を特定する事項について説明する。なお、各元素の含有量を示す「%」は特に示さない限り「質量%」を意味する。 Hereinafter, matters specifying the present invention will be described. In addition, "%" indicating the content of each element means "mass%" unless otherwise specified.
Cは強力なオーステナイト形成元素であり、かつ強度の向上に有効な元素であるが、過度の添加は再結晶処理で粗大なCr炭化物が析出し、耐粒界腐食や溶接性低下の原因となるので、Cは0.20%以下(0%を含まず)が望ましい。 C is a strong austenite-forming element and an element effective for improving the strength, but excessive addition causes coarse Cr carbides to precipitate in the recrystallization treatment, which causes intergranular corrosion resistance and deterioration of weldability. Therefore, C is preferably 0.20% or less (not including 0%).
Siは通常脱酸の目的のために使用するが、本発明鋼ではSi添加による固溶強化の目的がある。しかし、Si量が高くなると冷間加工の際、マルテンサイト相の生成を著しく促進させる効果がある。またSiは5.0%を越えると高温割れを誘発しやすくなり、製造上種々の問題も生じる。このため5.0%以下が望ましい。 Si is usually used for the purpose of deoxidation, but the steel of the present invention has the purpose of solid solution strengthening by adding Si. However, when the amount of Si is high, there is an effect of remarkably promoting the formation of the martensite phase during cold working. Further, if Si exceeds 5.0%, high temperature cracking is likely to be induced, which causes various problems in manufacturing. Therefore, 5.0% or less is desirable.
Mnは冷間圧延後の非磁性を確保するための元素である。さらにMnはNの固溶度を高める元素である。冷間加工後の非磁性を保つためにも必要である。ただ多量の添加は窒素加圧溶解をしてもブローホール発生に起因した表面欠陥や光輝焼鈍時の着色発生をもたらす。そのため上限は6.0%以下(0%を含まず)が望ましい。 Mn is an element for ensuring non-magnetism after cold rolling. Further, Mn is an element that increases the solid solubility of N. It is also necessary to maintain non-magnetism after cold working. However, even if a large amount of nitrogen is added under pressure, surface defects due to the occurrence of blow holes and coloring during bright quenching occur. Therefore, the upper limit is preferably 6.0% or less (excluding 0%).
NiはMnと同様に冷間圧延後の非磁性を確保するための元素である。冷間圧延後の非磁性を保つためには、6.0%以上必要であり、さらにSi,Mnの含有量に応じて、Ni量を調整する必要がある。 Like Mn, Ni is an element for ensuring non-magnetism after cold rolling. In order to maintain non-magnetism after cold rolling, 6.0% or more is required, and it is necessary to adjust the amount of Ni according to the contents of Si and Mn.
Cuも冷間圧延後の非磁性を確保するための元素である。ただ、過剰の添加は熱間加工性を劣化させ割れ発生の原因となるので成分範囲は4.0%以下が望ましい。 Cu is also an element for ensuring non-magnetism after cold rolling. However, since excessive addition deteriorates hot workability and causes cracks, the component range is preferably 4.0% or less.
Crは耐食性上必須の成分である。意図する耐食性を賦与するのには少なくとも12.0%のCrを必要とする。しかし、Crはフェライト形成元素でもあるので、高くしすぎると高温でδフェライト相が多量に生成してしまう。そこでδフェライト相抑制のためにオーステナイト形成元素(C、N、Ni、Mn、Cu等)を添加しなければならない。ただ、多量に含有されると、オーステナイト形成元素添加による調整だけでのδフェライト抑制はできなく、非磁性を確保できなくなるため上限を30%とした。 Cr is an essential component in terms of corrosion resistance. At least 12.0% Cr is required to provide the intended corrosion resistance. However, since Cr is also a ferrite forming element, if it is made too high, a large amount of δ ferrite phase will be generated at high temperature. Therefore, austenite-forming elements (C, N, Ni, Mn, Cu, etc.) must be added to suppress the δ ferrite phase. However, if it is contained in a large amount, δ ferrite cannot be suppressed only by adjusting by adding an austenite-forming element, and non-magnetism cannot be secured. Therefore, the upper limit is set to 30%.
Nは本発明の主要な特徴である非磁性を維持し、かつ高強度を得るための有効な元素である。なお、Nの過剰添加は鋳造時のブローホールの原因となるので、窒素加圧溶製等の工夫は必要であり、それを考慮しても上限は0.30%以下が望ましい。 N is an effective element for maintaining non-magnetism, which is a main feature of the present invention, and obtaining high strength. Since excessive addition of N causes blowholes during casting, it is necessary to devise measures such as nitrogen pressure melting, and even considering this, the upper limit is preferably 0.30% or less.
溶接後、液相からδフェライト凝固するδフェライト量の指標として、次の式(1)のようにδFを定義した。CやNに代表されるオーステナイト形成元素は正の係数、CrやSiに代表されるフェライト形成元素は負の係数である。
δF=−36C−0.13Mn−1.3Ni−30N−0.39Cu+1.3Cr+1.3Mo+0.67Si−5 ・・・(1)
δFの値が0以上で溶接後、液相からまずはδフェライトが生成する。δFが20.0を越えると熱間加工性に割れが発生するので上限を20.0とした。
ΔF was defined as the following equation (1) as an index of the amount of δ ferrite solidified from the liquid phase after welding. The austenite-forming element represented by C and N has a positive coefficient, and the ferrite-forming element represented by Cr and Si has a negative coefficient.
δF = -36C-0.13Mn-1.3Ni-30N-0.39Cu + 1.3Cr + 1.3Mo + 0.67Si-5 ... (1)
After welding when the value of δF is 0 or more, δ ferrite is first generated from the liquid phase. If δF exceeds 20.0, cracks occur in hot workability, so the upper limit was set to 20.0.
Moは耐食性を向上させ、時効処理で炭窒化物を微細に分布させる効果がある。ただ、Moを多量に添加すると高温でδフェライトが多量に形成されてしまうのでMoの成分範囲は5.0%以下が望ましい。 Mo has the effect of improving corrosion resistance and finely distributing the carbonitride by aging treatment. However, if a large amount of Mo is added, a large amount of δ ferrite is formed at a high temperature, so the component range of Mo is preferably 5.0% or less.
Tiは炭窒化物を形成して、溶接後の耐食性維持に有効な元素であるが、0.50%以上では製鋼スラブの表面キズが生成しやすくなり、製造面で問題がある。従って、上限を0.50%とした。 Ti is an element that forms a carbonitride and is effective in maintaining corrosion resistance after welding, but if it is 0.50% or more, surface scratches on the steelmaking slab are likely to occur, which poses a problem in terms of production. Therefore, the upper limit is set to 0.50%.
Nbも炭窒化物を形成して、溶接後の耐食性維持に有効な元素であり、探時効処理時の強度上昇に有効であるが、高温強度上昇による熱間加工性の低下をもたらすので上限を0.50%とした。 Nb is also an element that forms carbonitride and is effective in maintaining corrosion resistance after welding, and is effective in increasing the strength during aging treatment, but it causes a decrease in hot workability due to an increase in high-temperature strength, so the upper limit is set. It was set to 0.50%.
Bは熱間圧延温度域でのδフェライト相とオーステナイト相の変形抵抗の差異により生じる熱延鋼帯でのエッジクラックの発生防止に有効な元素であるが、過度の添加は低融点ほう化物を形成しやすくなり、逆に熱間加工性を劣化させるので、0.010%以下とした。 B is an element effective in preventing the occurrence of edge cracks in the hot-rolled steel strip caused by the difference in deformation resistance between the δ ferrite phase and the austenite phase in the hot rolling temperature range, but excessive addition causes a low melting point boulder. Since it becomes easy to form and conversely deteriorates hot workability, it was set to 0.010% or less.
Alは脱酸や耐酸化性のために有効な元素であるが、過剰な添加は表面欠陥の原因となるため上限を4.0%とした。 Al is an element effective for deoxidation and oxidation resistance, but the upper limit is set to 4.0% because excessive addition causes surface defects.
以下の元素は請求項の中では記載していないが、含有してもさしつかえない。
P:熱間加工性に有害な元素である。とくに0.050%を超えるとその影響は顕著になるので 望ましくは0.050%以下である。
S:結晶粒界に偏析しやすく、粒界脆化により熱間加工性の低下等を促進する元素である。0.020%を超えるとその影響は顕著になるので望ましくは0.020%以下である。
V、Zr:Vは固溶Cを炭化物として析出させる効果による加工性向上、Zrは鋼中の酸素を酸化物として捕えることによる加工性や靭性向上の面から有用な元素である。しかしながら、多量に添加すると製造性が低下するので、V、Zrの適正含有量は0.01〜0.30%である。
Oは酸化物系の非金属介在物を形成して鋼の清浄度を低下させるため、プレス成形性や曲げ性に悪影響を与えるため、0.02%以下とした。
これら以外にもCa、Mg、Co、REMなどは、溶製中に原料であるスクラップ中より含まれることもあるが、とりたてて多量に含まれる場合を除き、レーザ・TIG複合溶接オーステナイト系ステンレス溶接部特性には影響ない。
The following elements are not described in the claims, but may be contained.
P: An element harmful to hot workability. In particular, if it exceeds 0.050%, the effect becomes remarkable, so it is preferably 0.050% or less.
S: An element that easily segregates at grain boundaries and promotes deterioration of hot workability due to embrittlement at grain boundaries. If it exceeds 0.020%, the effect becomes remarkable, so it is preferably 0.020% or less.
V and Zr: V are useful elements in terms of improving workability due to the effect of precipitating solid solution C as a carbide, and Zr is a useful element in terms of improving workability and toughness by capturing oxygen in steel as an oxide. However, since the manufacturability is lowered when a large amount is added, the appropriate contents of V and Zr are 0.01 to 0.30%.
O is 0.02% or less because it forms oxide-based non-metal inclusions and lowers the cleanliness of steel, which adversely affects press formability and bendability.
In addition to these, Ca, Mg, Co, REM, etc. may be contained in the scrap that is the raw material during melting, but unless it is contained in a large amount, laser / TIG composite welding austenitic stainless steel welding It does not affect the characteristics of the parts.
表1の成分・組成をもつ板厚3.0mmのステンレス鋼板(焼鈍材)を素材とし、レーザ・TIG複合溶接もしくはレーザ単独溶接を実施した。表1中の鋼No.A〜Fは化学成分値が本発明の範囲内にある本発明例、鋼No.G〜Iはそれ以外の鋼(比較例)である。溶加材は用いなかった。 A stainless steel plate (annealed material) having a thickness of 3.0 mm having the components and compositions shown in Table 1 was used as a material, and laser / TIG composite welding or laser single welding was performed. Steel No. in Table 1 A to F are examples of the present invention in which the chemical composition values are within the range of the present invention, Steel No. GI are other steels (comparative examples). No filler metal was used.
溶接は突合せ溶接で端面は機械加工仕上したものを用いた。溶接条件は以下のとおりである。レーザ・TIG複合溶接を行う場合、TIG溶接を行うトーチとレーザ溶接を行うトーチの間隔は、3mmとした。また、レーザ溶接のアシストガスは、レーザ単独溶接を行う場合のみ使用し、レーザ・TIG複合溶接を行う場合は用いなかった。
配置: TIG先行、またはレーザ先行
レーザ溶接:出力 4kW、
スポット直径φ0.6mm、
傾斜0°、
アシストガス Ar100%、40L/min
Welding was butt welding and the end face was machined. Welding conditions are as follows. When laser / TIG composite welding is performed, the distance between the torch for TIG welding and the torch for laser welding is set to 3 mm. Further, the assist gas for laser welding was used only when performing laser single welding, and was not used when performing laser / TIG composite welding.
Arrangement: TIG precedent or laser precedent Laser welding: Output 4 kW,
Spot diameter φ0.6 mm,
Assist gas Ar100%, 40L / min
TIG溶接:後退角度30°、
電流300A、
アーク長 1.5mm、
シールドガス Ar100%、15L/min
TIG welding: receding angle 30 °,
Current 300A,
Arc length 1.5 mm,
Shield gas Ar100%, 15L / min
溶接速度: レーザ・TIG複合溶接 8.0m/min、
レーザ単独溶接 4.0m/min
Welding speed: Laser / TIG composite welding 8.0 m / min,
Laser single welding 4.0 m / min
レーザ・TIG複合溶接を行った溶接部材とレーザ単独溶接を行った溶接部材の、ビード中央部のビッカース硬度、母材部のビッカース硬度ならびにそれら二つの差を表2にまとめた。ビッカース硬度測定は板厚中心t/2、板厚t/4(表裏)の計3点の平均から求めた。なお、母材部の硬度とは溶接前のビード中央から1.5mm、1.75mmならびに2.0mmの3点平均値で定義している。 Table 2 summarizes the Vickers hardness at the center of the bead, the Vickers hardness at the base metal, and the difference between the two, between the welded member subjected to laser / TIG composite welding and the welded member subjected to laser single welding. The Vickers hardness measurement was obtained from the average of a total of three points, the plate thickness center t / 2 and the plate thickness t / 4 (front and back). The hardness of the base metal portion is defined as a three-point average value of 1.5 mm, 1.75 mm, and 2.0 mm from the center of the bead before welding.
表2に示したように、本発明例の溶接部材は、溶接部のビード中央部のビッカース硬度が母材部のビッカース硬さよりも上昇しているが、その差が50以下を満足している。特に、レーザ・TIG複合溶接を施した場合、TIG溶接先行のほうがレーザ溶接先行よりもビッカース硬度差が小さくなる。 As shown in Table 2, in the welded member of the example of the present invention, the Vickers hardness of the bead center portion of the welded portion is higher than the Vickers hardness of the base metal portion, but the difference satisfies the difference of 50 or less. .. In particular, when laser / TIG composite welding is performed, the difference in Vickers hardness is smaller in the TIG welding precedent than in the laser welding precedent.
具体例を図4に示す。図4は、素材として表1のA鋼のオーステナイト系ステンレス鋼を用い、レーザ・TIG複合溶接(TIG先行)を施したNo.1と、レーザ単独溶接を施したNo.16の溶接部材について、溶接部材のビード中央部からの距離と断面ビッカース硬度の関係を示すグラフである。ビード部中央部が最もビッカース硬度が高いが、ビード部中央部と母材部とのビッカース硬度差を比較すると、レーザ・TIG複合溶接を施したNo.1は、明らかにレーザ単独溶接を施したNo.16よりも硬度上昇が抑制されている。 A specific example is shown in FIG. In FIG. 4, the austenitic stainless steel of the A steel shown in Table 1 was used as the material, and the No. 1 was subjected to laser / TIG composite welding (TIG precedent). No. 1 and No. 1 with laser single welding. It is a graph which shows the relationship between the distance from the bead center part of the welding member, and the cross-sectional Vickers hardness about 16 welding members. The Vickers hardness is highest in the central part of the bead part, but when comparing the Vickers hardness difference between the central part of the bead part and the base metal part, No. No. 1 was clearly laser-only welded No. 1. Hardness increase is suppressed more than 16.
No.13はビッカース硬度差50以下であるが、G鋼におけるδFの値は−1.6でδフェライトは生成していない。No.14はH鋼でC量が請求範囲を超えており溶接冷却中に炭化物が生成し、耐食性が著しく低下している。No.15はI鋼のδFの値が25.3でδフェライト生成量が多すぎて、レーザ・TIG複合溶接による硬度低下効果でも、ビッカース硬度差50以下を満足できなかった。 No. No. 13 has a Vickers hardness difference of 50 or less, but the value of δF in G steel is −1.6 and δ ferrite is not formed. No. No. 14 is H steel, the amount of C exceeds the claimed range, carbides are generated during welding cooling, and the corrosion resistance is significantly reduced. No. In No. 15, the δF value of the I steel was 25.3, and the amount of δ ferrite produced was too large, and even with the hardness lowering effect of laser / TIG composite welding, the Vickers hardness difference of 50 or less could not be satisfied.
1 レーザ溶接を行うレーザ光のビーム
2 TIG溶接を行うトーチ
3 素材
1 Laser beam for
Claims (3)
溶接部のビード中央部におけるビッカース硬度が母材のビッカース硬度よりも大きく、その差が50以下であり、
母材のオーステナイト系ステンレス鋼の化学組成が、質量%において、C:0.20%以下、Si:1.87%以下、Mn:6.0%以下、Ni:6.0%以上、Cu:4.0%以下、Cr:12.0〜30.0%、N:0.30%以下、Mo:5.0%以下を含有し、残部がFeおよび不可避的不純物であり、式(1)に表されるδFの値が0以上20.0未満であるオーステナイト系ステンレス溶接部材。
δF=−36C−0.13Mn−1.3Ni−30N−0.39Cu+1.3Cr+1.3Mo+0.67Si−5 ・・・(1)
ただし、C、Mn等の元素記号の位置には、元素記号に対応する成分の含有量(質量%)の値を代入する。ただし、当該成分が含有されない場合は式に算入しない。 An austenitic stainless steel welded member in which a base metal made of austenitic stainless steel is subjected to laser / TIG composite welding.
The Vickers hardness at the center of the bead of the weld is larger than the Vickers hardness of the base metal, and the difference is 50 or less.
The chemical composition of the base material austenitic stainless steel is C: 0.20% or less, Si: 1.87 % or less, Mn: 6.0% or less, Ni: 6.0% or more, Cu: It contains 4.0% or less, Cr: 12.0 to 30.0%, N: 0.30% or less, Mo: 5.0% or less, and the balance is Fe and unavoidable impurities, according to the formula (1). An austenitic stainless steel welded member in which the value of δF represented by is 0 or more and less than 20.0.
δF = -36C-0.13Mn-1.3Ni-30N-0.39Cu + 1.3Cr + 1.3Mo + 0.67Si-5 ... (1)
However, the value of the content (mass%) of the component corresponding to the element symbol is substituted for the position of the element symbol such as C and Mn. However, if the component is not included, it is not included in the formula.
請求項1又は2に記載のオーステナイト系ステンレス溶接部材。 The chemical composition of the base material further contains Al: 0.78 to 4.0 % in mass%.
The austenitic stainless steel welding member according to claim 1 or 2.
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