JP2686075B2 - Plastic forming pre-hardened steel for mold - Google Patents
Plastic forming pre-hardened steel for moldInfo
- Publication number
- JP2686075B2 JP2686075B2 JP61262137A JP26213786A JP2686075B2 JP 2686075 B2 JP2686075 B2 JP 2686075B2 JP 61262137 A JP61262137 A JP 61262137A JP 26213786 A JP26213786 A JP 26213786A JP 2686075 B2 JP2686075 B2 JP 2686075B2
- Authority
- JP
- Japan
- Prior art keywords
- steel
- less
- present
- machinability
- mold
- 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 - Fee Related
Links
- 229910000760 Hardened steel Inorganic materials 0.000 title 1
- 229910000831 Steel Inorganic materials 0.000 claims description 53
- 239000010959 steel Substances 0.000 claims description 53
- 239000012535 impurity Substances 0.000 claims description 10
- 238000010137 moulding (plastic) Methods 0.000 claims description 10
- 229910052750 molybdenum Inorganic materials 0.000 claims description 7
- 229910052721 tungsten Inorganic materials 0.000 claims description 7
- 229910052802 copper Inorganic materials 0.000 claims description 6
- 229910052759 nickel Inorganic materials 0.000 claims description 6
- 229910052804 chromium Inorganic materials 0.000 claims description 3
- 229910052748 manganese Inorganic materials 0.000 claims 4
- 229910001563 bainite Inorganic materials 0.000 description 14
- 230000032683 aging Effects 0.000 description 11
- 238000005496 tempering Methods 0.000 description 11
- 230000007797 corrosion Effects 0.000 description 10
- 238000005260 corrosion Methods 0.000 description 10
- 239000011159 matrix material Substances 0.000 description 8
- 238000001556 precipitation Methods 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 238000005520 cutting process Methods 0.000 description 5
- 229910000765 intermetallic Inorganic materials 0.000 description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 4
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 4
- 238000005498 polishing Methods 0.000 description 4
- 229910000859 α-Fe Inorganic materials 0.000 description 4
- 229910003310 Ni-Al Inorganic materials 0.000 description 3
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 150000001247 metal acetylides Chemical class 0.000 description 3
- 238000005121 nitriding Methods 0.000 description 3
- 238000010791 quenching Methods 0.000 description 3
- 230000000171 quenching effect Effects 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 230000003746 surface roughness Effects 0.000 description 2
- 238000009864 tensile test Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910017767 Cu—Al Inorganic materials 0.000 description 1
- 229910017827 Cu—Fe Inorganic materials 0.000 description 1
- 229910003296 Ni-Mo Inorganic materials 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 238000004049 embossing Methods 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009863 impact test Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000007517 polishing process Methods 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000004881 precipitation hardening Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
Landscapes
- Moulds For Moulding Plastics Or The Like (AREA)
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、極めて優れた鏡面仕上性と被切削性を有
し、かつ優れた靭性を兼備した新しいプリハードンタイ
プのプラスチック成形金型用鋼に関するものである。
〔従来の技術〕
高級プラスチック成形金型用鋼としては、
（１）鏡面仕上性が良く、ピンホールやその他微細ピッ
トの発生しないこと、
（２）シボ加工性が良いこと、
（３）耐食、耐発錆性が良いこと、
（４）強度、耐摩耗性が良く、靭性が高いこと、
（５）被切削性が良いこと、
などが要求される。
しかし、近年型の製作期間の短縮や、型の形状複雑化
による薄肉隅角部からの折損への対策が重要な顧客要求
として強く提起され、優れた被切削性と靭性を兼備した
型用鋼の開発が課題となった。
従来、この種用途の型材して特公昭53−23764号、特
公昭59−37744号に開示されたプラスチック成形金型用
鋼が知られている。この金型用鋼は、鏡面仕上性、被切
削性の点では、ほぼ満足できる特性を有するものの、近
年特に強く要求されている被切削性と靭性の兼備という
点では不十分な点があった。
また、本発明者の１人が特開昭60−204869号として鏡
面仕上性、シボ加工性、更に靭性が特に優れた型用鋼を
提供していたが、該型用鋼は被切削性の点で必ずしも十
分な特性を有しないものであった。
〔発明が解決しようとする問題点〕
以上説明のように従来、型用鋼の被切削性を高めるこ
とは逆に靭性の低下を招くことにつながり、両者の特性
を兼備させることは容易ではなかった。
本発明は、上記高級プラスチック成形金型用鋼として
の諸要求性質を同時に満たす型用鋼の提供を目的とする
ものである。
〔問題点を解決するための手段〕
本発明は重量％でC 0.07〜0.16％、Si 0.60％以下、M
n 0.60〜1.50％、Ni 2.50〜3.50％、Al 0.30〜1.40％、
Cu 1.80〜2.50％、残部Feおよび不可避的不純物よりな
り、不可避的不純物であるＳが0.004％以下であること
を特徴とするプラスチック成形プリハードン金型用鋼、
あるいは該金型用鋼にCr 0.60％以下、Mo、Ｗを単独ま
たは複合で1/2W＋Mo 0.10〜0.70％を適宜添加せしめた
プラスチック成形プリハードン金型用鋼である。
以下、本発明をさらに詳細に説明する。
本発明鋼は低Ｃ−中〜低Mn−Ni−Mo（Ｗ）−高Cu−Al
系を基本成分とする合金であり、焼入により均一な上部
ベイナイト組織を生成し、さらに500℃以上の高温焼も
どしにより、低Ｃのベイナイト地にCu−Fe固溶体、Ni−
Al金属間化合物、Mo（Ｗ）炭化物を析出させ、時効（析
出）硬化による強度を付与するとともに、適度に脆化を
生じさせ、良好な被切削性を付与するとともに、使用時
の型薄肉部からの折損に対する適度の靭性を保持させる
ものである。また、Cr、Mo、Ｗ、Cu、Niの含有、またＳ
量の低めへの限定により優れた耐食、耐発錆性が得ら
れ、また低Ｃでもマルテンサイト化しにくく放電加工に
よる硬化が少なく、この点でも仕上加工が容易である。
本発明の最も基本的事項は、逆にCuを高め（1.80〜2.
50％）に限定することにより、従来困難であった優れた
被切削性と低い切削面アラサを兼備させることに成功し
たことにある。また、好ましくはアルミナ系介在物の生
成傾向や靭性の過度の低下を抑制するため、Al量を中程
度ないし低め（0.30〜0.90％）に限定し、鏡面仕上性と
靭性を兼備させるものである。
本発明鋼は、ＨRC37ないしそれ以上の硬さのプリハー
ドン（調質）状態（焼入後400℃以上の焼もどし）で供
給され、そのまま型彫加工→研磨加工、さらに硬度の鏡
面仕上やシボ加工処理を施して使用されるものである。
したがって、ユーザーでの熱処理を要せず、きわめて
良好な被切削性とプラスチック成形型として薄肉部をと
もなう複雑形状の型に加工された場合にも使用中の薄肉
隅角部などからの割れを生ぜず、また、高い硬さと均一
なマトリックス、本質的に優れた鋼質の清浄性とあいま
って極めて優れた鏡面仕上性、シボ加工性をもたらし、
また、へたり、摩耗の懸念を要せず、長寿命を得ること
を可能にする新しいプラスチック成形金型用鋼である。
〔作用〕
次に本願発明鋼の成分限定の理由について述べる。
Ｃは本願発明鋼の焼入組織を被切削性の良好な塊状上
部ベイナイト組織に保ち、かつ焼もどしにおけるCu−F
e、Ni−Al金属間化合物やMo、Ｗ炭化物の析出に基づく
析出硬化をもたらすための基質を与えるための基本的添
加元素である。多すぎると基地をマルテンサイト組織化
して被切削性を減じ、また過度の炭化物を形成して被切
削性を低下させる。また、放電加工面の硬化をまねき研
磨仕上工数の増加をまねくなどの弊害をまねくので0.16
％以下とし、低すぎるとフェライト析出をまねき、かつ
十分な焼もどし（時効）硬さが得られないので0.70％以
上とする。望ましくは0.1％以上である。
Mnは本願発明鋼のベイナイト焼入性を高め、またフェ
ライトの生成を抑制し、適度の焼入焼もどし（時効）硬
さを与えるために添加される。多すぎるとベイナイト変
態温度を低下させ、ベイナイト組織を過度に微細化さ
せ、また基地の粘さを上げて被切削性を低下させるので
1.50％以下とし、低すぎると上記添加の効果が得られな
いので0.60％以上とする。
Siは使用時の雰囲気に対する耐食性を高めるために目
的、用途により添加される。多すぎるとフェライトの生
成をまねき、また被切削性を低下させるので0.60％以下
とする。
Niは本願発明鋼のベイナイト焼入性を高め、またフェ
ライトの生成を抑制し、さらに焼もどし（時効）の際、
Ni−Al金属間化合物を析出させ、所要の硬さを得るとと
もに延性を適度に低下させ、被切削性の向上を得るため
に添加される。多すぎるとベイナイト変態温度を低下さ
せ、ベイナイト組織を過度に微細化させ、また基地の粘
さを上げて被切削性を低下させるので3.50％以下とし、
低すぎると上記添加の効果が得られないので2.50％以上
とする。
Crは本願発明鋼の耐食性を高め、また窒化時の硬さを
高め、さらに研磨加工時あるいは金型保管時の発錆を抑
制するため、目的、用途により添加される。多すぎると
ベイナイト組織を微細化し、とくに高い被切削性を狙い
とする本願発明鋼としての特性を維持するため0.60％以
下とする。
Ｗ、Moは本願発明鋼の500℃を越える高温焼もどし
（時効）処理において、微細炭化物を析出し、析出（時
効）硬化をもたらし、本願発明鋼の強度を形成するた
め、また、使用時の雰囲気に対する耐食性を高めるた
め、目的、用途により添加される。一般的にはMo単独添
加とするが、目的、用途によりMo、Ｗ複合添加あるいは
単独添加が施されるものである。
本用途の場合、多量の添加は必要なく、多すぎると被
切削性の低下をまねくので、1/2W＋Mo 0.70％以下と
し、低すぎると上記添加の効果が得られないので、1/2W
＋Moで0.10％以上とする。
Cuは本願発明鋼の焼もどし（時効）処理において、Fe
−Cu金属間化合物の微細析出による析出（時効）硬化を
もたらし、塊状上部ベイナイト基地とあいまって本願発
明鋼の極めて優れた被切削性を形成させるための、また
所要の硬さを得るための最も重要な添加元素の一つであ
り、また優れた耐食性をもたらすものである。多すぎる
と熱間加工性を低下させ、またベイナイトを微細化さ
せ、かえって被切削性を低下させるので2.50％以下と
し、低すぎると上記添加の効果が得られないので1.80％
以上とする。
Alはベイナイト変態温度を高めて望ましい塊状上部ベ
イナイト組織を得やすくし、焼もどし（時効）処理にお
いてNi−Al金属間化合物の微細析出による析出（時効）
硬化をもたらし、塊状上部ベイナイト基地とあいまって
本願発明鋼の極めて優れた被切削性を形成させるため
の、また所要硬さを得るための重要な添加元素である。
また、窒化時の窒化硬さを上昇させる硬化をもたらす。
多すぎるとアルミナ系介在物の生成量が増加し、鏡面仕
上性を低下させ、また耐孔食性を低下させ、さらに延性
の過度の低下をまねくので1.40％以下、好ましくは0.90
％以下とし、低すぎると上記添加の効果が得られないの
で0.30％以上とする。
Ｓは硫化物系介在物を形成し、孔食やピットの原因と
なり、最高度の鏡面肌を得るためにはS 0.004％以下に
限定される。
〔実施例〕
以下、本発明を実施例に基づき説明する。
第１表に本発明鋼の実施例と従来鋼の化学組成を示
す。従来鋼Ｋは本発明者の１人が既に特開昭60−204869
号として提案している鏡面仕上肌、シボ加工肌が得ら
れ、かつ靭性がとくに優れ、使用時の薄肉隅角部などか
らの折損を生じない型用鋼のＳを制限したものである。
従来鋼ＬはSCM440である。
第２表に本発明鋼のＨRC39前後に熱処理したもののエ
ンドミルによる切削の場合の従来鋼Ｌ（SCM440〈ＨRC3
5〉）を基準とした被切削性（工具寿命）指数および切
削面の最大面アラサ比を示す。 本願発明鋼はSCM440（ＨRC35.1）よりも高硬度である
にもかかわらず、被切削性が明らかに優れており、また
切削面アラサも格段に細かく、以後の研磨加工の工数低
減に効果が大きいことを示している。
第３表は本発明鋼の断面寸法50mmt×150mmw鍛伸材に
つき、ＨRC38前後に焼もどしした後、試験片を鍛伸方向
に対し、平行（Ｌ）および直角（Ｔ）方向に採取して引
張試験およびシャルピー衝撃試験（2mmμノッチ）を行
なった結果を示す。
本願発明鋼は靭性の特に優れた従来鋼Ｋに対比すれ
ば、引張試験における伸び、絞り値およびシャルピー衝
撃値は低く、これが切削時の切粉の剪断による削除を容
易にし、これにより被切削性や切削面のアラサが従来鋼
Ｋのそれよりも優れており、また従来鋼Ｌ（SCM440）に
対して被切削性が大きく高められている。
Al量の少ない本発明高Ａ、Ｃ、Ｅは伸び、絞りおよび
シャルピー衝撃値の極端な低下はなく、複雑形状や薄肉
部を有する型として使用しても折損を生ぜず、良好な被
切削性を兼備している点に特徴がある。
一方、Al量の特に高い本発明鋼Ｊの場合には、被切削
性は良好であるが、引張試験における伸び、絞り値やシ
ャルピー衝撃値、特にＴ方向のそれが低く、複雑形状や
薄肉の隅角部を有する型に適用の場合、欠損や折損を生
じる場合がある。
第４表に本願発明鋼の塩水雰囲気中における耐発錆試
験結果を示す。試料は25mm×25mmで、ペーパーバフ鏡面
仕上の後、塩水雰囲気中に２時間放置した場合の発錆個
数をカウントし、本発明鋼Ｊのそれを100として比で示
したものである。
本願発明鋼はAlを含まない超鏡面仕上用鋼としての従
来鋼Ｋには及ばないが、Alを少なくしていくと腐食孔発
生の原因となるAl2O3系非金属介在物の多量の生成を生
ぜず、従来鋼Ｋに準ずる耐発錆個数特性を示す。本発明
鋼ＪはAl量が多く、アルミナ系介在物の形成傾向が相対
的に大きく、このため発錆特性が相対的に劣っている。
なお、Ｓ量が相対的に高い比較鋼Ｉの場合、硫化物系介
在物がやや増加し、発錆個数比が相対的にやや多い。
第５表は本発明鋼の鏡面仕上性（耐ピット性）を対比
したものである。試料は50mm角で、ＨRC38に焼入焼もど
し処理後、グラインダー→ペーパー→ダイヤモンドコン
パウンド研磨の方式で鏡面仕上を行ない、10倍の拡大鏡
を用いて微細なピット発生個数をカウントしたものであ
る。
本発明鋼ＪはAl量が高く、アルミナ系介在物の発生傾
向が相対的に多くなり、ピットもAlの低い本発明鋼より
発生しやすいことがわかる。なお、Ｓ量が相対的に高い
比較鋼Ｉの場合、硫化物系介在物がやや増加し、ピット
個数が相対的にやや多い。
〔発明の効果〕
以上に詳述したように、本願発明鋼は基地組成、基地
組織および析出（時効）生成物の適切な組合せにより、
ＨRC38以上の硬さでも特に良好な被切削性を保持すると
ともに優れた鏡面仕上性、耐孔食性、耐放電硬化性、シ
ボ加工性を有しており、また適度の延性を備えているた
め、使用時過酷な応力を受ける型用途においても薄肉コ
ーナー部などから折損を生じず、優れた型寿命をもたら
すプラスチック成形プリハードン（たとえばＨRC36〜4
1）金型材料を提供するもので、工業上非常に有益であ
る。TECHNICAL FIELD The present invention relates to a new pre-harden type plastic molding die steel having extremely excellent mirror finish and machinability and excellent toughness. It is a thing. [Prior Art] As a steel for a high-grade plastic molding die, (1) good mirror finish, no pinholes and other fine pits are generated, (2) good grain workability, (3) corrosion resistance, Good rust resistance, (4) good strength and wear resistance, and high toughness, (5) good machinability are required. However, in recent years, it has been strongly raised as an important customer request to reduce the die manufacturing period and to prevent breakage from thin corners due to complicated shape of the die, and die steel with excellent machinability and toughness is strongly proposed. Was the issue. Conventionally, steels for plastic molding dies disclosed in JP-B-53-23764 and JP-B-59-37744 are known as mold materials for this type of application. Although this die steel has almost satisfactory characteristics in terms of mirror finish and machinability, it has been insufficient in terms of combining machinability and toughness, which have been particularly strongly demanded in recent years. . Further, one of the inventors of the present invention has provided a die steel having particularly excellent mirror-finishing properties, grain-workability and toughness as JP-A-60-204869. However, it does not always have sufficient characteristics. [Problems to be Solved by the Invention] As described above, conventionally, increasing the machinability of the die steel leads to a decrease in toughness, and it is not easy to combine the characteristics of both. It was An object of the present invention is to provide a mold steel that simultaneously satisfies various properties required as the high-grade plastic molding mold steel. [Means for Solving Problems] In the present invention, C 0.07 to 0.16% by weight, Si 0.60% or less, M
n 0.60 to 1.50%, Ni 2.50 to 3.50%, Al 0.30 to 1.40%,
1.80 to 2.50% Cu, the balance Fe and unavoidable impurities, and S, which is an unavoidable impurity, is 0.004% or less, a plastic forming pre-hardened die steel,
Alternatively, it is a plastic molding pre-hardened mold steel in which Cr 0.60% or less, Mo and W alone or in a combination of 1 / 2W + Mo 0.10 to 0.70% are appropriately added to the mold steel. Hereinafter, the present invention will be described in more detail. The steel of the present invention is low C-medium to low Mn-Ni-Mo (W) -high Cu-Al.
It is an alloy with the system as a basic component. It produces a uniform upper bainite structure by quenching, and by high temperature tempering at 500 ° C or higher, Cu-Fe solid solution, Ni-
Precipitating Al intermetallic compound and Mo (W) carbide to give strength by aging (precipitation) hardening, and to cause appropriate embrittlement, good machinability, and mold thin part during use It retains an appropriate toughness against breakage from. Also, containing Cr, Mo, W, Cu, Ni, S
By limiting the amount to a lower amount, excellent corrosion resistance and rust resistance can be obtained, and even at low C, martensite hardly occurs and hardening by electric discharge machining is small, and in this respect, finishing work is easy. On the contrary, the most basic matter of the present invention is to increase Cu (1.80 to 2.
By limiting it to 50%), it has succeeded in having both excellent machinability and low surface roughness that were difficult to achieve in the past. Further, preferably, in order to suppress the tendency of alumina inclusions to form and the excessive decrease in toughness, the amount of Al is limited to medium to low (0.30 to 0.90%) to provide both mirror finish and toughness. . The steel according to the present invention is supplied in a pre-hardened state (hardened) with hardness of HRC37 or higher (tempering after tempering at 400 ° C or higher), and as it is, die-cutting → polishing, mirror finishing or graining of hardness. It is used after being processed. Therefore, it does not require heat treatment by the user, and even if it is processed into a mold with a complex shape with a thin portion as a plastic molding die with extremely good machinability, cracks will occur from the thin corners in use. In addition, high hardness and uniform matrix, combined with the inherently excellent cleanliness of steel quality, brings extremely excellent mirror finish and texture workability,
In addition, it is a new plastic molding die steel that enables long life without the need for fatigue and wear. [Operation] Next, the reason for limiting the components of the steel of the present invention will be described. C is the Cu-F in the tempered structure of the steel of the present invention, which maintains the quenched upper bainite structure with good machinability and is tempered.
e, Ni-Al is a basic additional element for providing a substrate for causing precipitation hardening based on the precipitation of intermetallic compounds, Mo and W carbides. If the amount is too large, the matrix is martensite-structured to reduce the machinability, and excessive carbides are formed to reduce the machinability. In addition, since it causes the adverse effects such as hardening of the electric discharge machined surface and increase of the number of polishing finishing steps, 0.16
%, And if it is too low, ferrite precipitation will occur and sufficient tempering (aging) hardness will not be obtained, so it should be 0.70% or more. It is preferably 0.1% or more. Mn is added to enhance the bainite hardenability of the steel of the present invention, to suppress the formation of ferrite, and to give an appropriate quenching and tempering (aging) hardness. If it is too large, the bainite transformation temperature is lowered, the bainite structure is excessively refined, and the machinability is increased by lowering the viscosity of the matrix.
If it is 1.50% or less, the effect of the above addition cannot be obtained if it is too low, so it is made 0.60% or more. Si is added depending on the purpose and application in order to increase the corrosion resistance against the atmosphere during use. If the content is too large, ferrite is formed and the machinability is reduced. Ni enhances the bainite hardenability of the present invention steel, suppresses the formation of ferrite, and further when tempering (aging),
The Ni-Al intermetallic compound is added to obtain the required hardness, appropriately reduce the ductility, and improve the machinability. If it is too much, it lowers the bainite transformation temperature, excessively refines the bainite structure, and increases the viscosity of the matrix to lower the machinability, so it is 3.50% or less,
If it is too low, the effect of the above addition cannot be obtained, so it is set to 2.50% or more. Cr enhances the corrosion resistance of the steel of the present invention, enhances the hardness during nitriding, and suppresses rust during polishing or during die storage, and is added depending on the purpose and application. If it is too much, the bainite structure is refined, and the content is made 0.60% or less in order to maintain the characteristics as the steel of the present invention aiming at particularly high machinability. W and Mo precipitate fine carbides and cause precipitation (aging) hardening during high temperature tempering (aging) treatment of the steel of the present invention at a temperature higher than 500 ° C. to form strength of the steel of the present invention, and also during use. It is added depending on the purpose and application in order to enhance the corrosion resistance to the atmosphere. Generally, Mo alone is added, but depending on the purpose and application, Mo and W composite addition or single addition is performed. In the case of this application, it is not necessary to add a large amount, and if it is too large, the machinability will deteriorate, so 1 / 2W + Mo 0.70% or less, and if it is too low, the effect of the above addition will not be obtained, so 1 / 2W
+ Mo is 0.10% or more. Cu is Fe in the tempering (aging) treatment of the present invention steel.
-Cu brings about precipitation (aging) hardening due to fine precipitation of intermetallic compounds, and together with the massive upper bainite matrix, forms the extremely excellent machinability of the steel of the present invention, and is most suitable for obtaining the required hardness. It is one of the important additive elements and also provides excellent corrosion resistance. If it is too large, the hot workability is reduced, and bainite is made finer, which in turn reduces the machinability, so it is set to 2.50% or less. If it is too low, the effect of the above addition cannot be obtained, so 1.80%
Above. Al raises the bainite transformation temperature to make it easier to obtain the desired massive upper bainite structure, and precipitates by fine precipitation of the Ni-Al intermetallic compound during tempering (aging) (aging)
It is an important additional element for causing hardening and forming an extremely excellent machinability of the steel of the present invention together with the massive upper bainite matrix and for obtaining the required hardness.
Further, it brings about hardening that increases the nitriding hardness during nitriding.
If the amount is too large, the amount of alumina-based inclusions is increased, the mirror finish is lowered, the pitting corrosion resistance is lowered, and the ductility is excessively lowered, so 1.40% or less, preferably 0.90.
% Or less, and if it is too low, the effect of the above addition cannot be obtained, so it is set to 0.30% or more. S forms sulfide inclusions and causes pitting corrosion and pits. S is limited to 0.004% or less in order to obtain the best mirror surface. Examples Hereinafter, the present invention will be described based on examples. Table 1 shows the chemical compositions of the inventive steels and conventional steels. One of the inventors of the conventional steel K has already disclosed in JP-A-60-204869.
The present invention limits the S of the mold steel that can be obtained as mirror-finished skin and textured surface and has excellent toughness, and does not cause breakage from a thin corner portion during use. Conventional steel L is SCM440. Table 2 shows the conventional steel L (SCM440 <HRC3
The machinability (tool life) index based on 5>) and the maximum surface roughness ratio of the cut surface are shown. Although the steel of the present invention has a hardness higher than that of SCM440 (HRC35.1), the machinability is clearly superior, and the roughness of the cutting surface is remarkably fine, which is effective in reducing the number of subsequent polishing processes. It shows that it is big. Table 3 shows the cross-sectional dimensions of 50 mmt x 150 mmw wrought material of the steel of the present invention, after tempering before and after HRC38, the test piece was sampled in parallel (L) and right angle (T) directions with respect to the forging direction and pulled. The results of the test and the Charpy impact test (2 mmμ notch) are shown. Compared with the conventional steel K having particularly excellent toughness, the steel of the present invention has low elongation, drawing value and Charpy impact value in the tensile test, which facilitates the removal of cutting chips by shearing during cutting, thereby improving the machinability. The roughness of the cutting surface is superior to that of the conventional steel K, and the machinability of the conventional steel L (SCM440) is greatly improved. The high A, C, and E of the present invention with a small amount of Al do not cause an extreme decrease in elongation, drawing, and Charpy impact value, and do not cause breakage even when used as a mold having a complicated shape or a thin portion, and have good machinability. It is characterized by having both. On the other hand, in the case of the steel J of the present invention having a particularly high Al content, the machinability is good, but the elongation, the drawing value and the Charpy impact value in the tensile test, especially those in the T direction, are low, and the complex shape and thin wall When applied to a mold having a corner, a chip or breakage may occur. Table 4 shows the results of the rust resistance test of the steel of the present invention in a salt water atmosphere. The sample is 25 mm × 25 mm, and after finishing the paper buff mirror surface, the number of rusting in the case of being left for 2 hours in a salt water atmosphere was counted, and it was shown as a ratio with that of steel J of the present invention as 100. The steel of the present invention does not reach the conventional steel K as a super mirror finishing steel containing no Al, but if the amount of Al is reduced, a large amount of Al 2 O 3 -based non-metallic inclusions that cause corrosion holes are generated. It does not generate, and shows a rusting resistance number characteristic similar to that of conventional steel K. Inventive Steel J has a large amount of Al and has a relatively large tendency to form alumina inclusions, and thus has relatively poor rusting properties.
In the case of Comparative Steel I having a relatively high S content, the sulfide-based inclusions increased slightly and the rusting number ratio was relatively high. Table 5 compares the specular finish (pit resistance) of the steels of the present invention. The sample is 50 mm square, and after quenching and tempering to HRC38, mirror finishing was carried out by the method of grinder → paper → diamond compound polishing, and the number of fine pits generated was counted using a 10 × magnifying glass. It is understood that the present invention steel J has a high Al content, the tendency to generate alumina inclusions is relatively large, and pits are more likely to occur than the present invention steel having a low Al content. In the case of Comparative Steel I having a relatively high S content, the sulfide inclusions increased slightly and the number of pits was relatively high. [Effects of the Invention] As described in detail above, the steel of the present invention has an appropriate combination of matrix composition, matrix structure and precipitation (aging) product,
Even with a hardness of HRC 38 or higher, it retains particularly good machinability, has excellent mirror finish, pitting corrosion resistance, discharge hardening resistance, and embossing workability, and also has appropriate ductility, Plastic molding pre-hardened (for example, HRC36-4) that does not cause breakage from thin-walled corners and has excellent mold life even in mold applications that are subjected to severe stress during use.
1) It provides the mold material, which is very useful in industry.
Claims (1)
〜1.50％、Ni 2.50〜3.50％、Al 0.30〜1.40％、Cu 1.8
0〜2.50％、残部Feおよび不可避的不純物よりなり、不
可避的不純物であるＳが0.004％以下であることを特徴
とするプラスチック成形プリハードン金型用鋼。 ２．重量％でC 0.07〜0.16％、Si 0.60％以下、Mn 0.60
〜1.50％、Ni 2.50〜3.50％、Cr 0.60％以下、Al 0.30
〜1.40％、Cu 1.80〜2.50％、残部Feおよび不可避的不
純物よりなり、不可避的不純物であるＳが0.004％以下
であることを特徴とするプラスチック成形プリハードン
金型用鋼。 ３．重量％でC 0.07〜0.16％、Si 0.60％以下、Mn 0.60
〜1.50％、Ni 2.50〜3.50％、Mo、Ｗを単独または複合
で1/2W＋Mo 0.10〜0.70％、Al 0.30〜1.40％、Cu 1.80
〜2.50％、残部Feおよび不可避的不純物よりなり、不可
避的不純物であるＳが0.004％以下であることを特徴と
するプラスチック成形プリハードン金型用鋼。 ４．重量％でC 0.07〜0.16％、Si 0.60％以下、Mn 0.60
〜1.50％、Ni 2.50〜3.50％、Cr 0.60％以下、Mo、Ｗを
単独または複合で1/2W＋Mo 0.10〜0.70％、Al 0.30〜1.
40％、Cu 1.80〜2.50％、残部Feおよび不可避的不純物
よりなり、不可避的不純物であるＳが0.004％以下であ
ることを特徴とするプラスチック成形プリハードン金型
用鋼。(57) [Claims] C 0.07 to 0.16% by weight, Si 0.60% or less, Mn 0.60
~ 1.50%, Ni 2.50 ~ 3.50%, Al 0.30 ~ 1.40%, Cu 1.8
A plastic molding pre-hardened die steel, which comprises 0 to 2.50%, the balance Fe and unavoidable impurities, and S, which is an unavoidable impurity, of 0.004% or less. 2. C 0.07 to 0.16% by weight, Si 0.60% or less, Mn 0.60
~ 1.50%, Ni 2.50 ~ 3.50%, Cr 0.60% or less, Al 0.30
-1.40%, Cu 1.80-2.50%, balance Fe and unavoidable impurities, and S, which is an unavoidable impurity, is 0.004% or less, a plastic forming pre-hardened mold steel. 3. C 0.07 to 0.16% by weight, Si 0.60% or less, Mn 0.60
~ 1.50%, Ni 2.50 ~ 3.50%, Mo, W alone or in combination 1 / 2W + Mo 0.10 ~ 0.70%, Al 0.30 ~ 1.40%, Cu 1.80
~ 2.50%, the balance Fe and unavoidable impurities, S is 0.004% or less inevitable impurities, plastic molding pre-hardened mold steel. 4. C 0.07 to 0.16% by weight, Si 0.60% or less, Mn 0.60
~ 1.50%, Ni 2.50 ~ 3.50%, Cr 0.60% or less, Mo, W alone or in combination 1/2 W + Mo 0.10 to 0.70%, Al 0.30 to 1.
40%, Cu 1.80 to 2.50%, balance Fe and unavoidable impurities, and S, which is an unavoidable impurity, is 0.004% or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61262137A JP2686075B2 (en) | 1986-11-04 | 1986-11-04 | Plastic forming pre-hardened steel for mold |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61262137A JP2686075B2 (en) | 1986-11-04 | 1986-11-04 | Plastic forming pre-hardened steel for mold |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63114942A JPS63114942A (en) | 1988-05-19 |
| JP2686075B2 true JP2686075B2 (en) | 1997-12-08 |
Family
ID=17371568
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61262137A Expired - Fee Related JP2686075B2 (en) | 1986-11-04 | 1986-11-04 | Plastic forming pre-hardened steel for mold |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2686075B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2745587B1 (en) * | 1996-03-01 | 1998-04-30 | Creusot Loire | STEEL FOR USE IN PARTICULAR FOR THE MANUFACTURE OF MOLDS FOR INJECTION OF PLASTIC MATERIAL |
| GB201604910D0 (en) | 2016-03-23 | 2016-05-04 | Rolls Royce Plc | Nanocrystalline bainitic steels, shafts, gas turbine engines, and methods of manufacturing nanocrystalline bainitic steels |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60174854A (en) * | 1984-02-20 | 1985-09-09 | Hitachi Metals Ltd | Free-cutting steel for prehardened metallic mold for molding plastic |
-
1986
- 1986-11-04 JP JP61262137A patent/JP2686075B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63114942A (en) | 1988-05-19 |
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