JPH029882B2 - - Google Patents
Info
- Publication number
- JPH029882B2 JPH029882B2 JP6437881A JP6437881A JPH029882B2 JP H029882 B2 JPH029882 B2 JP H029882B2 JP 6437881 A JP6437881 A JP 6437881A JP 6437881 A JP6437881 A JP 6437881A JP H029882 B2 JPH029882 B2 JP H029882B2
- Authority
- JP
- Japan
- Prior art keywords
- outer shell
- cast iron
- hardness
- molten metal
- casting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 229910001018 Cast iron Inorganic materials 0.000 claims description 33
- 239000002184 metal Substances 0.000 claims description 28
- 229910052751 metal Inorganic materials 0.000 claims description 28
- 239000000463 material Substances 0.000 claims description 26
- 238000005266 casting Methods 0.000 claims description 22
- 239000002131 composite material Substances 0.000 claims description 18
- 229910001566 austenite Inorganic materials 0.000 claims description 15
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 13
- 229910002804 graphite Inorganic materials 0.000 claims description 12
- 239000010439 graphite Substances 0.000 claims description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 10
- 229910000734 martensite Inorganic materials 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 7
- 239000011159 matrix material Substances 0.000 claims description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims description 6
- 229910052804 chromium Inorganic materials 0.000 claims description 5
- 229910052748 manganese Inorganic materials 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 3
- 239000011257 shell material Substances 0.000 description 58
- 150000001247 metal acetylides Chemical class 0.000 description 13
- 229910045601 alloy Inorganic materials 0.000 description 10
- 239000000956 alloy Substances 0.000 description 10
- 230000000694 effects Effects 0.000 description 9
- 238000010438 heat treatment Methods 0.000 description 9
- 229910052721 tungsten Inorganic materials 0.000 description 9
- 230000000717 retained effect Effects 0.000 description 7
- 238000002425 crystallisation Methods 0.000 description 6
- 230000008025 crystallization Effects 0.000 description 6
- 229910001563 bainite Inorganic materials 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 4
- 229910001080 W alloy Inorganic materials 0.000 description 4
- 238000005275 alloying Methods 0.000 description 4
- 229910001567 cementite Inorganic materials 0.000 description 4
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 238000005496 tempering Methods 0.000 description 3
- 229910001141 Ductile iron Inorganic materials 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000009750 centrifugal casting Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 229910001208 Crucible steel Inorganic materials 0.000 description 1
- 229910001145 Ferrotungsten Inorganic materials 0.000 description 1
- 229910001060 Gray iron Inorganic materials 0.000 description 1
- 229910001037 White iron Inorganic materials 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000005496 eutectics Effects 0.000 description 1
- -1 for example Inorganic materials 0.000 description 1
- 230000009931 harmful effect Effects 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 238000004881 precipitation hardening Methods 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
- 239000007787 solid Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Landscapes
- Reduction Rolling/Reduction Stand/Operation Of Reduction Machine (AREA)
Description
（産業上の利用分野）
本発明は、線材、棒鋼、平鋼等の中間あるいは
仕上圧延用に供される複合ロールの外殻の鋳造方
法に関する。
（従来の技術）
一般に複合ロールは、圧延材に接するロール外
殻と、外殻に固着されたロール軸部とで構成され
ており、前記固着手段としては、外殻と軸部とを
溶着一体化する方法、及び外殻を円筒状のスリー
ブとして製作し、別途準備された軸材とを焼嵌め
等によつて機械的に結合する方法がある。
線材や棒鋼・平鋼等の中間・仕上圧延用複合ロ
ールにおいて、外殻がスリーブの場合、被圧延材
と接する外殻外表面部は耐摩耗性確保のため高合
金チルド材や高合金グレン材等の高硬度炭化物が
晶出した高合金硬質鋳鉄材によつて形成され、一
方軸材に固着される内表面部は鋳造時の割れ防止
や使用時の強度確保の見地から強靭性を有する高
級鋳鉄やダクタイル鋳鉄等の黒鉛が晶出した軟質
鋳鉄材で形成されるのが通例である。
また、溶着ロールの場合も、外殻内表面部を軟
質鋳鉄材で形成し、その内面に同鋳鉄材により軸
部を鋳造することが行われている。軸部材溶湯を
外殻内面に鋳込んだとき、外殻内面は一部溶損さ
れて、軸部材溶湯中に溶け込むが、外殻が高合金
硬質鋳鉄材のみで形成されていると、外殻の高合
金成分（炭化物形成元素）が軸部材溶湯中に混入
し、軸部鋳鉄材において炭化物の生成を促進して
硬化させ、軸部材の靭性を劣化させるからであ
る。
前記外殻の外表面部および内表面部は、通常、
外表面部が遠心力鋳造された後、その内面に内表
面部が遠心力鋳造され、両者が溶着一体化され
る。そして、鋳造後、外表面部の耐摩耗性を確保
向上させるため、基地中の残留オーステナイトを
ベーナイトやマルテンサイト組織にするための熱
処理（焼戻し熱処理ともいう。）が施される。
（発明が解決しようとする課題）
しかしなながら、叙上のように、外殻を高合金
硬質鋳鉄材によつて形成された外表面部と軟質鋳
鉄材によつて形成された内表面部とを遠心力鋳造
しようとすると、二種類の溶湯が必要となり、鋳
造作業も煩雑となり、生産性が低下する。また、
従従来の外表面部を形成する高合金硬質鋳鉄材の
炭化物はセメンタイトを主体とするものであるた
め、基地を熱処理により硬化させてもHs70〜80゜
が限度であり、外表面部の硬度向上ひいては耐摩
耗性向上に対する要求も強い。
本発明はかかる問題点に鑑みなされたもので、
外表面部に高硬度の硬質鋳鉄材層が、内表面部に
軟質鋳鉄材層が容易に一体形成される複合ロール
の外殻の鋳造方法を提供することを目的とする。
（課題を解決するための手段）
上記目的を達成するためになされた本発明の鋳
造方法は、化学組成が、
Ｃ：2.5〜4.0％ Ni：3.5〜5.0％
Si：1.0〜2.5％ Cr：1.0〜2.0％
Mn：0.5〜1.5％ Mo：0.2〜1.5％
Ｐ：0.1％以下 Ｗ：10〜25％
Ｓ：0.1％以下
を各重量％含み、残部実質的にFeから成る外殻
溶湯を遠心力鋳造し、鋳放し状態で外殻外表面側
に主としてマルテンサイトと残留オーステナイト
からなるマトリクス中に高硬度のＷ複炭化物を晶
出させると共に外殻内表面側に黒鉛が晶出した軟
質鋳鉄材層を一体的に形成することを発明の構成
とするものである。
（作 用）
本発明に使用する鋳鉄溶湯の化学組成は以下の
理由により限定される。単位は重量％である。
Ｃ：2.5〜4.0％
ＣはSiと共に、外殻の外表面部における炭化
物、内表面部における黒鉛の比率を決定する重要
な元素であり、2.5％未満では、Ｗ、Cr、Mo、
Feの複炭化物の量が少なく、外表面部に高硬度
が得られず耐摩耗性に劣る。一方、4.0％を超え
ると、逆に炭化物の量が過多となり、外表面部が
脆化するので好ましくない。
Si：1.0〜2.5％
Siは黒鉛の晶出・形状に影響を与え、1.0％未
満では炭化物形成傾向の強いＷ、Mo、Crの影響
が大で外殻内表面部において黒鉛の晶出に寄与し
ない。一方、2.5％を超えると内表面部には多量
に黒鉛が晶出されるが、反面黒鉛形状が劣化し、
かえつて強靭性の低下につながる。
Mn：0.5〜1.5％
MnはＳと結合し、Ｓの害を除去しかつ脱酸作
用を有するが、0.5％未満ではその効果がほとん
どなく、一方1.5％を超えると、機械的性質の面
で劣化が著しい。
Ｐ：0.1％以下
Ｓ：0.1％以下
ＰおよびＳはロール材質には少ない程望まし
く、実害のない0.1％を上限とする。
Ni：3.5〜5.0％
Niは外殻外表面部の基地の硬度増及び鋳放し
でマルテンサイト、下部ベイナイトもしくは残留
オーステナイト組織を得るために多く添加され
る。すなわち、3.5％未満では基地部の顕著に硬
度上昇は望めない。しかし、5.0％を超えると、
残留オーステナイトが過剰もしくは安定化し、後
の熱処理におけるマルテンサイトやベイナイトへ
の変態が抑えられ、かえつて硬度低下を来すこと
になる。
Cr：1.0〜2.0％
Crは炭化物中に優先的に入り、他の合金元素
と共に複炭化物を形成し硬度上昇を果すと共に、
一部は基地に固溶し焼入性の向上を果す有効な元
素である。1.0％未満ではこの効果が少なく、一
方2.0％を超えても炭化物形成傾向の強いＷやMo
の影響を受け、またＣ含有量も低いためそれ以上
の添加効果が得られない。
Mo：0.2〜1.5％
Moは焼入・焼戻し軟化抵抗を高めると共に、
析出硬化を促進する効果があり、基地硬度を高め
耐摩耗性の向上に寄与する。Mo2.0％未満ではこ
の効果がほとんどなく、一方1.5％を超えると残
留オーステナイトを増加安定させる。
Ｗ：10〜25％
Ｗは他の合金元素と結合して凝固途中にＷ複炭
化物（例えば、（Fe，Ｗ）6C）を晶出させ、この
複炭化物はセメンタイトと比べると非常に高硬度
であり、従つてＷはHs80〜95゜のような高硬度の
確保更には高耐摩耗性の確保に最も寄与し得る元
素である。10％未満では、Ｗはオーステナイト中
に固溶され易く、すなわちＷ複炭化物を晶出し難
く、また晶出してもその量が少ないため、外殻外
表面部における高硬度を確保できず、一方25％を
超えると逆にその炭化物量が多過ぎて、外殻内表
面部の黒鉛の晶出も抑えるため不適当である。
本発明に係る高Ｗ合金鋳鉄溶湯は、以上の各成
分を各重量％含み、残部は実質的にFeからなる
ものであるが、Ｗと共にFeの一部を置換してＶ、
Ti、Nb等の合金元素を添加することもでき、か
くすれば耐摩耗性の一層の改善が図られる。
尚、高Ｗ合金鋳鉄溶湯の溶製に際しては、Ｗ添
加剤として、例えばJIS Ｇ 2306に規定されたフ
エロタングステンを使用できるので、高価なWC
を使う必要がなく、製造コストを軽減できる。
上記高Ｗ合金鋳鉄溶湯は、遠心力鋳造に供され
て複合ロールの外殻となる。前記溶湯が遠心力鋳
造されると、溶湯中の高比重の多量のＷは遠心力
の作用で外殻の外表面側へ移行し、多量の高硬度
のＷ複炭化物となつて溶湯中より均一に晶出す
る。また、移行の途中に溶湯中より晶出したＷ炭
化物も外表面側に移行し集中する。一方、外殻の
内表面側の溶湯はＷないしＷ複炭化物の外表面側
への移行によりＷ含有量が減少した状態となる。
そして、すべての溶湯が凝固すると、鋳放し状態
で外殻外表面部は主としてマルテンサイトと残留
オーステナイトからなるマトリクス中に高硬度の
Ｗ複炭化物が晶出する組織となり、一方、その内
表面部はＷ含有量の減少によりＷ複炭化物の晶出
がほとんどなく、黒鉛の晶出が見られる強靭な軟
質鋳鉄組織となり、両者は一体的に形成されたも
のとなる。
本発明によつて鋳造された外殻を溶着複合ロー
ルの外殻として用いるときは、外殻内表面部の内
面に高級鋳鉄やダクタイル鋳鉄等の強靭な軟質鋳
鉄材を鋳込んで軸部を鋳造すればよい。この際、
外殻内表面部は、鋳込み時の溶湯においては高濃
度であつたＷ含有量が数％程度まで減少している
ため、軸部材溶湯の鋳込みに際し、外殻内表面部
が一部溶損し、軸部材溶湯中に溶け込んでも、炭
化物の形成を促進するまでには到らず、軸部材の
靭性劣化を招来することはない。尚、上記外殻の
内面に強靭軟質鋳鉄材からなる内層を遠心力鋳造
して、複合スリーブを得る場合も、溶着ロールの
軸部と同様の効果が得られる。
上記外殻をスリーブとして用いるときは遠心力
鋳造後に、一方溶着複合ロールの外殻として用い
るときは軸部の鋳造後に、粗加工後、外殻外表面
部の残留オーステナイトをマルテンサイトやベイ
ナイトに変態させるための熱処理（300〜500℃で
10〜30Hr保持）が施されて、製品スリーブや製
品ロールとされる。上記熱処理により、外殻外表
面部はHs80〜95゜の硬度が得られる。
ところで、特公昭52−15047号公報には、軟質
鋳鉄溶湯とWC粉粒体とを混合し、これを遠心力
鋳造し、WC粒子を比重分離して外周側に偏在さ
せ、外周部にWC粒子を軟質鋳鉄によつて結合し
た硬質層を形成し、一方中心部にはWC粒子をほ
とんど含まない軟質鋳鉄層からなる円筒状鋳物を
鋳造する方法が開示されている。しかし、鋳造に
際してはWC粉粒体と鋳鉄溶湯とが必要であり、
また遠心力鋳造の鋳込期間中、鋳鉄溶湯中にWC
粒子を均一に分散混合しておくことが難しいた
め、外周部全体に亘つて均一な高硬度層を得難
い。特に、大形のものではこの傾向が著しい。更
に外周部のWC粒子は軟質鋳鉄基地中に単に埋入
されているだけであるから欠け落ちが生じ易い。
これに対して、本発明では、鋳造に際しては一種
類の溶湯ですみ、しかも外表面部のＷ複炭化物は
溶湯中に均一に発生した凝固核が成長して晶出し
たもの故、硬度むらが生じることはなく、また欠
け落ちが生じるおそれもほとんどない。
また、特開昭53−25213号公報には、Ｗを0.5〜
3.5％含有したアダマイト材溶湯を遠心力鋳造し
てロール外殻を形成する技術が開示されている
が、Ｗは固体のオーステナイト中に固溶させると
共に冷却に伴つてオーステナイト中より炭化物と
して析出させ、オーステナイトを低Ｃ化するため
のものであつて、溶湯と共存して溶湯中に炭化物
として晶出することはなく、遠心力の作用でＷ複
炭化物を外殻外表面部に晶出させることはできな
い。尚、上記引例によつて形成された外殻はアダ
マイト材（ミクロ組織中に共晶セメンタイトを有
する白鋳的ロール材）であり、黒鉛の晶出は見ら
れないものである。
また、特公昭50−14214号公報には、Ｗを0.5〜
2.0％含有した白鋳鉄又は斑鋳鉄のロール外殻材
が開示されているが、該外殻材におけるＷも前記
アダマイト材と同様、オーステナイト中に固溶
し、あるいはオーステナイト中より炭化物となつ
て析出するものであつて、溶湯中より炭化物とな
つて晶出するものではなく、遠心力の作用で高硬
度のＷ複炭化物を外殻外周部に集中的に晶出させ
ることはできない。
（実施例）
実施例 １
外径240φ×内径140φ×100（単位mm）のスリ
ーブを遠心力鋳造により製造した。この場合、鋳
込厚さ50mm、鋳込重量24Kgで、鋳込溶湯の取鍋成
分は第１表の通りである。尚、成分表における単
位は重量％、残部は実質的にFeである。他の表
においても同様である。
(Industrial Application Field) The present invention relates to a method for casting an outer shell of a composite roll used for intermediate or finish rolling of wire rods, steel bars, flat steel, etc. (Prior Art) Generally, a composite roll is composed of a roll outer shell that contacts the rolled material and a roll shaft that is fixed to the outer shell, and the fixing means is to weld the outer shell and the shaft together There are two methods: one method is to manufacture the outer shell as a cylindrical sleeve, and the other method is to mechanically connect the outer shell to a separately prepared shaft material by shrink fitting or the like. In composite rolls for intermediate and finish rolling of wire rods, steel bars, flat steel, etc., when the outer shell is a sleeve, the outer surface of the outer shell in contact with the rolled material is made of high-alloy chilled material or high-alloy grain material to ensure wear resistance. It is made of high-alloy hard cast iron material with crystallized high-hardness carbides, while the inner surface part that is fixed to the shaft material is a high-grade cast iron material with strong toughness to prevent cracking during casting and ensure strength during use. It is usually made of a soft cast iron material such as cast iron or ductile cast iron in which graphite crystallizes. In the case of welding rolls as well, the inner surface of the outer shell is formed of a soft cast iron material, and the shaft portion is cast from the same cast iron material on the inner surface. When the molten metal of the shaft member is poured into the inner surface of the outer shell, part of the inner surface of the outer shell is eroded and melted into the molten shaft member, but if the outer shell is made only of high-alloy hard cast iron, the outer shell This is because the high alloying components (carbide forming elements) mixed into the molten metal of the shaft member promote the formation of carbides in the shaft cast iron material, causing it to harden and deteriorate the toughness of the shaft member. The outer surface portion and the inner surface portion of the outer shell are usually
After the outer surface part is centrifugally cast, the inner surface part is centrifugally cast on the inner surface thereof, and both are welded and integrated. After casting, heat treatment (also referred to as tempering heat treatment) is performed to transform residual austenite in the base into a bainite or martensitic structure in order to ensure and improve the wear resistance of the outer surface portion. (Problem to be Solved by the Invention) However, as described above, the outer shell has an outer surface portion formed of a high-alloy hard cast iron material and an inner surface portion formed of a soft cast iron material. If centrifugal casting is attempted, two types of molten metals are required, making the casting process complicated and reducing productivity. Also,
Since the carbide of the conventional high-alloy hard cast iron material that forms the outer surface is mainly cementite, even if the base is hardened by heat treatment, the Hs is limited to 70 to 80°, making it difficult to improve the hardness of the outer surface. Furthermore, there is also a strong demand for improved wear resistance. The present invention was made in view of such problems,
It is an object of the present invention to provide a method for casting an outer shell of a composite roll in which a hard cast iron material layer with high hardness is easily integrally formed on the outer surface portion and a soft cast iron material layer is formed on the inner surface portion. (Means for Solving the Problems) The casting method of the present invention made to achieve the above object has the following chemical composition: C: 2.5 to 4.0% Ni: 3.5 to 5.0% Si: 1.0 to 2.5% Cr: 1.0 ~2.0% Mn: 0.5-1.5% Mo: 0.2-1.5% P: 0.1% or less W: 10-25% S: 0.1% or less by weight, with the remainder essentially consisting of Fe, is subjected to centrifugal force A soft cast iron material layer in which high-hardness W double carbide is crystallized in a matrix mainly composed of martensite and retained austenite on the outer surface of the outer shell in an as-cast state, and graphite crystallized on the inner surface of the outer shell. The structure of the invention is to integrally form the. (Function) The chemical composition of the molten cast iron used in the present invention is limited for the following reasons. The unit is weight %. C: 2.5-4.0% C, along with Si, is an important element that determines the ratio of carbides on the outer surface of the shell and graphite on the inner surface.If it is less than 2.5%, W, Cr, Mo,
Due to the small amount of Fe double carbide, high hardness cannot be obtained on the outer surface, resulting in poor wear resistance. On the other hand, if it exceeds 4.0%, the amount of carbides becomes excessive and the outer surface becomes brittle, which is not preferable. Si: 1.0-2.5% Si affects the crystallization and shape of graphite, and if it is less than 1.0%, the influence of W, Mo, and Cr, which have a strong tendency to form carbides, is large and contributes to the crystallization of graphite on the inner surface of the outer shell. do not. On the other hand, if it exceeds 2.5%, a large amount of graphite will crystallize on the inner surface, but on the other hand, the shape of the graphite will deteriorate,
On the contrary, it leads to a decrease in toughness. Mn: 0.5-1.5% Mn combines with S and has a deoxidizing effect and removes the harmful effects of S, but if it is less than 0.5%, it has almost no effect, while if it exceeds 1.5%, it has a negative effect on mechanical properties. Significant deterioration. P: 0.1% or less S: 0.1% or less P and S are preferably as small as possible in roll materials, and the upper limit is 0.1%, which does not cause any actual damage. Ni: 3.5 to 5.0% Ni is added in large amounts to increase the hardness of the matrix on the outer surface of the outer shell and to obtain martensite, lower bainite, or retained austenite structure in as-cast steel. That is, if the content is less than 3.5%, no significant increase in hardness of the base portion can be expected. However, if it exceeds 5.0%,
Retained austenite becomes excessive or stabilized, and transformation into martensite or bainite during subsequent heat treatment is suppressed, resulting in a decrease in hardness. Cr: 1.0~2.0% Cr preferentially enters carbides and forms double carbides with other alloying elements, increasing hardness.
A part of it is an effective element that dissolves in the matrix and improves hardenability. If it is less than 1.0%, this effect will be small; on the other hand, if it exceeds 2.0%, W or Mo will have a strong tendency to form carbides.
Further, since the C content is low, no further effect can be obtained by addition. Mo: 0.2-1.5% Mo increases the resistance to softening during quenching and tempering, and
It has the effect of promoting precipitation hardening, increases base hardness, and contributes to improved wear resistance. If Mo is less than 2.0%, this effect is almost absent, while if it exceeds 1.5%, retained austenite increases and stabilizes. W: 10-25% W combines with other alloying elements to crystallize W double carbide (e.g. (Fe, W) 6 C) during solidification, and this double carbide has extremely high hardness compared to cementite. Therefore, W is an element that can contribute most to ensuring high hardness such as Hs 80 to 95° and also ensuring high wear resistance. If it is less than 10%, W is easily dissolved in austenite, which makes it difficult to crystallize W double carbide, and even if it crystallizes, the amount is small, making it impossible to ensure high hardness on the outer surface of the outer shell. %, on the other hand, the amount of carbide is too large, which is unsuitable because it also suppresses the crystallization of graphite on the inner surface of the outer shell. The high W alloy cast iron molten metal according to the present invention contains each of the above-mentioned components in each weight percent, and the remainder is substantially made of Fe, but some of the Fe is replaced with W, and V, V,
It is also possible to add alloying elements such as Ti and Nb, thereby further improving the wear resistance. When melting high W alloy cast iron, for example, ferrotungsten specified in JIS G 2306 can be used as a W additive, so expensive WC can be used.
There is no need to use , reducing manufacturing costs. The high W alloy cast iron molten metal is subjected to centrifugal force casting to become the outer shell of the composite roll. When the molten metal is centrifugally cast, a large amount of W with high specific gravity in the molten metal moves to the outer surface of the shell due to the action of centrifugal force, and becomes a large amount of highly hard W double carbide, which is more uniform than in the molten metal. crystallizes out. Furthermore, W carbide crystallized from the molten metal during the transition also migrates and concentrates on the outer surface side. On the other hand, the molten metal on the inner surface side of the outer shell has a reduced W content due to the migration of W or W double carbides to the outer surface side.
When all of the molten metal solidifies, the outer surface of the outer shell becomes a structure in which high-hardness W double carbide crystallizes in a matrix mainly composed of martensite and retained austenite, while the inner surface of the shell becomes As the W content decreases, there is almost no crystallization of W double carbides, and a tough soft cast iron structure with crystallization of graphite is formed, and both are formed integrally. When the outer shell cast according to the present invention is used as the outer shell of a welded composite roll, a strong soft cast iron material such as high-grade cast iron or ductile cast iron is cast on the inner surface of the outer shell to form the shaft. do it. On this occasion,
In the inner surface of the outer shell, the W content, which was high in the molten metal at the time of casting, has been reduced to a few percent, so when the molten metal of the shaft member is poured, a portion of the inner surface of the outer shell is eroded and damaged. Even if it melts into the molten metal of the shaft member, it does not promote the formation of carbides and does not cause deterioration of the toughness of the shaft member. Incidentally, when a composite sleeve is obtained by centrifugally casting an inner layer made of tough and soft cast iron on the inner surface of the outer shell, the same effect as that of the shaft of the welding roll can be obtained. When the above shell is used as a sleeve, it is centrifugally cast, and when it is used as the shell of a welded composite roll, after the shaft is cast and rough processed, residual austenite on the outer surface of the shell is transformed into martensite or bainite. Heat treatment (at 300-500℃) to
(retained for 10 to 30 hours) to make product sleeves and product rolls. By the above heat treatment, the outer surface of the outer shell has a hardness of 80 to 95 degrees Hs. By the way, in Japanese Patent Publication No. 52-15047, soft cast iron molten metal and WC powder are mixed, centrifugally cast, WC particles are separated by specific gravity and unevenly distributed on the outer periphery, and WC particles are mixed on the outer periphery. A method is disclosed for casting a cylindrical casting consisting of a hard layer bonded by soft cast iron, and a soft cast iron layer containing almost no WC particles in the center. However, casting requires WC powder and molten cast iron,
In addition, during the pouring period of centrifugal force casting, WC is added to the molten cast iron.
Since it is difficult to uniformly disperse and mix the particles, it is difficult to obtain a uniform high hardness layer over the entire outer periphery. This tendency is particularly remarkable for large-sized ones. Furthermore, since the WC particles at the outer periphery are simply embedded in the soft cast iron base, they are likely to chip.
On the other hand, in the present invention, only one type of molten metal is required for casting, and since the W double carbide on the outer surface is crystallized by the growth of solidification nuclei that are uniformly generated in the molten metal, there is no unevenness in hardness. This does not occur, and there is almost no possibility that chipping will occur. In addition, in Japanese Patent Application Laid-Open No. 53-25213, W is 0.5~
A technique has been disclosed in which a molten adamite material containing 3.5% is centrifugally cast to form a roll shell, but W is dissolved in solid austenite and precipitated as a carbide from the austenite as it cools. This is to lower the carbon content of austenite, and it does not coexist with the molten metal and crystallize as carbides in the molten metal. W double carbides do not crystallize on the outer surface of the shell due to the action of centrifugal force. Can not. Incidentally, the outer shell formed according to the above cited example is an adamite material (a white casting-like rolled material having eutectic cementite in the microstructure), and no crystallization of graphite is observed. In addition, in Japanese Patent Publication No. 50-14214, W is 0.5~
A roll outer shell material of white cast iron or spotted iron containing 2.0% is disclosed, but W in the outer shell material is also dissolved in the austenite as a solid solution or precipitated as a carbide from the austenite, as in the adamite material. However, it does not crystallize as a carbide from the molten metal, and high hardness W double carbide cannot be crystallized intensively on the outer periphery of the outer shell due to the action of centrifugal force. (Examples) Example 1 A sleeve with an outer diameter of 240φ x an inner diameter of 140φ x 100 (unit: mm) was manufactured by centrifugal casting. In this case, the casting thickness was 50 mm, the casting weight was 24 kg, and the ladle components of the molten metal were as shown in Table 1. In addition, the unit in the ingredient list is % by weight, and the remainder is substantially Fe. The same applies to other tables.
【表】
このスリーブに450℃×10Hrの焼戻し熱処理を
施した結果、スリーブ外表面硬度はHs93.8゜が得
られ、またスリーブ肉厚方向の硬度変化を測定し
たところ、第１図に示すような硬度変化が得られ
た。
上記スリーブの外表面から10mmの位置Ａおよび
内表面から10mmの位置Ｂにおける組成を調べた。
その結果を第２表に示す。同表より、内表面部の
Ｗ含有量は溶湯時のものと比べて極めて少ないこ
とがわかる。また、内表面の鋳鉄組織を観察した
ところ、ねずみ鋳鉄系組織であつた。[Table] As a result of subjecting this sleeve to tempering heat treatment at 450°C x 10 hours, the outer surface hardness of the sleeve was Hs93.8°, and when the hardness change in the sleeve thickness direction was measured, the results were as shown in Figure 1. A significant change in hardness was obtained. The composition at position A, which is 10 mm from the outer surface of the sleeve, and position B, which is 10 mm from the inner surface, was investigated.
The results are shown in Table 2. From the same table, it can be seen that the W content in the inner surface portion is extremely small compared to that in the molten metal. Furthermore, when the cast iron structure on the inner surface was observed, it was found to be a gray cast iron structure.
【表】
一方比較のため、同一サイズでかつ下記第３表
のようにＷを含有しない点を除き同等の合金成分
を有する溶湯を鋳造して得られたスリーブについ
て、上記と同一熱処理を施した結果では、その外
表面硬度はHs71.2゜であつた。[Table] On the other hand, for comparison, sleeves obtained by casting molten metal of the same size and having the same alloy composition except that it does not contain W as shown in Table 3 below were subjected to the same heat treatment as above. The results showed that the outer surface hardness was Hs71.2°.
【表】
実施例 ２
400φ×500の溶着複合ロールを製造した。こ
の場合、外殻は外殻厚さ50mm、鋳込重量225Kgで
遠心力鋳造により鋳造し、一方軸部は鋳型を直立
して外殻内に置注き鋳造により鋳込んだ。外殻及
び軸部（高級鋳鉄）の取鍋成分は下記第４表の通
りである。[Table] Example 2 A 400φ×500 welded composite roll was manufactured. In this case, the outer shell was cast by centrifugal force casting with a shell thickness of 50 mm and a casting weight of 225 kg, while the shaft was cast by placing the mold in the outer shell by standing the mold upright and pouring it into the shell. The ladle components of the outer shell and shaft (high-grade cast iron) are as shown in Table 4 below.
【表】
この複合ロールに420℃×15Hrの熱処理を施し
た結果、ロール外殻表面硬度はHs94.2゜が得られ
た。
一方比較のため、同一サイズでかつ下記第５表
のように外殻がＷを含有しない点を除き同等の合
金成分を有する外殻及び軸部溶湯を鋳造して得ら
れた複合ロールについて、上記と同一熱処理を施
した結果では、そのロール外殻表面硬度は
Hs73.0゜であつた。[Table] This composite roll was heat treated at 420°C for 15 hours, resulting in a roll outer shell surface hardness of Hs94.2°. On the other hand, for comparison, the above composite rolls were obtained by casting the outer shell and shaft molten metal of the same size and having the same alloy composition except that the outer shell does not contain W as shown in Table 5 below. According to the result of applying the same heat treatment as , the surface hardness of the roll outer shell is
It was Hs73.0°.
【表】
また、上記両複合ロールの外殻外表面から10mm
深さ位置で摩耗試験片を採出し、アルミナ粉末を
減摩剤とする摩耗試験を実施した結果、本発明に
係るロールのものでは比較ロールのものの0.48倍
の摩耗減量が測定され、本発明に係る複合ロール
がこすり摩耗に対して非常に良好な特性を具備し
ていることが判明した。このことにより、本発明
に係る複合ロールを実際に線材仕上圧延用ロール
として使用した場合、従来の高合金グレンロール
や高合金チルドロールに比べて、非常に高い耐摩
耗性を発揮するものと予測される。
なお、この実施例により得られた本発明に係る
複合ロールを製品分析して調査した結果では、外
殻外表面から25mmの位置ではＷ含有量22.7％であ
り、外表面から100mmの内部ではＷ含有量0.20％
であり、内部へのＷの拡散は非常に少ないことが
確認された。
（発明の効果）
以上説明した通り、本発明の複合ロールの外殻
の鋳造方法によれば、Ｗ：10〜25％を含む所定の
高Ｗ合金鋳鉄溶湯を遠心力鋳造するので、遠心力
の作用で、外表面部に高硬度のＷ複炭化物を多量
に晶出させることができ、一方内表面部に同炭化
物をほとんど含まず、低Ｗ含有量の黒鉛が晶出し
た軟質鋳鉄材層を一体的に形成することができ、
外表面部および内表面部に要求される所期の特性
を備えた外殻を単一の溶湯を用いて極めて容易に
鋳造することができる。
また、外表面部のＷ複炭化物はセメンタイトに
比べて極めて高硬度のもの故、外表面部の基地中
の残留オーステナイトに対しマルテンサイトおよ
びベーナイト化の熱処理を施すことにより、外表
面部をHs80〜95゜の高硬度層とすることができ
る。
また、外表面部のＷ複炭化物は溶湯中より晶出
したものであるから、外表面部全体に亘つて均一
に存在し、硬度むらがなく、欠け落ちが生じにく
く、耐摩耗性のみならず耐肌荒性にも優れる。[Table] Also, 10mm from the outer surface of the outer shell of both of the above composite rolls.
As a result of taking abrasion test pieces at the depth position and conducting an abrasion test using alumina powder as a lubricant, it was determined that the roll according to the present invention had a wear loss of 0.48 times that of the comparative roll. It has been found that such composite rolls have very good properties against rubbing wear. As a result, it is predicted that when the composite roll according to the present invention is actually used as a wire finish rolling roll, it will exhibit extremely high wear resistance compared to conventional high-alloy grain rolls and high-alloy chilled rolls. be done. In addition, according to the results of product analysis and investigation of the composite roll according to the present invention obtained in this example, the W content is 22.7% at a position 25 mm from the outer surface of the outer shell, and W content is 22.7% within 100 mm from the outer surface. Content 0.20%
It was confirmed that the diffusion of W into the interior was extremely small. (Effects of the Invention) As explained above, according to the method for casting the outer shell of a composite roll of the present invention, since a predetermined high W alloy cast iron molten metal containing W: 10 to 25% is centrifugally cast, centrifugal force is reduced. As a result, a large amount of highly hard W double carbide can be crystallized on the outer surface, while a soft cast iron material layer containing almost no double carbide and crystallized graphite with a low W content is created on the inner surface. can be formed integrally,
A shell with the desired properties required for the outer and inner surfaces can be cast very easily using a single molten metal. In addition, since the W double carbide on the outer surface has extremely high hardness compared to cementite, the retained austenite in the matrix on the outer surface is heat treated to martensite and bainite, thereby increasing the outer surface to Hs80~ It can be made into a high hardness layer of 95°. In addition, since the W double carbide on the outer surface is crystallized from the molten metal, it exists uniformly over the entire outer surface, has no uneven hardness, is less prone to chipping, and is not only wear resistant. It also has excellent roughness resistance.
第１図は本発明に係る複合ロールの外殻の一実
施例についての硬度分布を現わす説明図である。
FIG. 1 is an explanatory diagram showing the hardness distribution of an embodiment of the outer shell of the composite roll according to the present invention.
Claims (1)
溶湯を遠心力鋳造し、鋳放し状態で外殻外表面側
に主としてマルテンサイトと残留オーステナイト
からなるマトリクス中に高硬度のＷ複炭化物を晶
出させると共に外殻内表面側に黒鉛が晶出した軟
質鋳鉄材層を一体的に形成することを特徴とする
複合ロールの外殻の鋳造方法。[Claims] 1 Chemical composition: C: 2.5-4.0% Ni: 3.5-5.0% Si: 1.0-2.5% Cr: 1.0-2.0% Mn: 0.5-1.5% Mo: 0.2-1.5% P: 0.1 % or less W: 10 to 25% S: Each weight% contains 0.1% or less, and the remainder is essentially Fe.The outer shell molten metal is centrifugally cast, and in the as-cast state, martensite remains mainly on the outer surface of the outer shell. Casting of the outer shell of a composite roll characterized by crystallizing high-hardness W double carbide in a matrix made of austenite and integrally forming a soft cast iron material layer with crystallized graphite on the inner surface of the outer shell. Method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6437881A JPS57181358A (en) | 1981-04-28 | 1981-04-28 | Wear resistant centrifugally cast single-layer sleeve, composite sleeve and composite roll |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6437881A JPS57181358A (en) | 1981-04-28 | 1981-04-28 | Wear resistant centrifugally cast single-layer sleeve, composite sleeve and composite roll |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57181358A JPS57181358A (en) | 1982-11-08 |
| JPH029882B2 true JPH029882B2 (en) | 1990-03-05 |
Family
ID=13256575
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6437881A Granted JPS57181358A (en) | 1981-04-28 | 1981-04-28 | Wear resistant centrifugally cast single-layer sleeve, composite sleeve and composite roll |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57181358A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2546416B2 (en) * | 1990-07-09 | 1996-10-23 | 住友金属工業株式会社 | Shaped steel rolling roll sleeve and method of manufacturing the same |
| CN113661019B (en) | 2019-04-03 | 2022-09-13 | 日铁轧辊株式会社 | Composite roll for rolling produced by centrifugal casting method and method for producing same |
-
1981
- 1981-04-28 JP JP6437881A patent/JPS57181358A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57181358A (en) | 1982-11-08 |
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