JP2004285429A - Method and device for producing extrusion material - Google Patents

Method and device for producing extrusion material Download PDF

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Publication number
JP2004285429A
JP2004285429A JP2003080141A JP2003080141A JP2004285429A JP 2004285429 A JP2004285429 A JP 2004285429A JP 2003080141 A JP2003080141 A JP 2003080141A JP 2003080141 A JP2003080141 A JP 2003080141A JP 2004285429 A JP2004285429 A JP 2004285429A
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Prior art keywords
extrusion
alloy
extruded
producing
alloy material
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Inventor
Kazuhiko Kita
和彦 喜多
Koji Saito
孝治 齋藤
Jiyunichi Nagahora
純一 永洞
Kenji Azuma
健司 東
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YKK Corp
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YKK Corp
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21CMANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C23/00Extruding metal; Impact extrusion
    • B21C23/01Extruding metal; Impact extrusion starting from material of particular form or shape, e.g. mechanically pre-treated
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21CMANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C23/00Extruding metal; Impact extrusion
    • B21C23/001Extruding metal; Impact extrusion to improve the material properties, e.g. lateral extrusion

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alloy and a formed article which have excellent mechanical strength, ductility and impact resistance, and have no anisotropy in mechanical properties. <P>SOLUTION: In the method of producing an extrusion material, the crystal grain size and texture thereof are controlled by dynamic recovery and/or dynamic recrystallization in plastic working. A stage where shear stress is applied to an alloy stock in such a manner that the extruding direction is changed by the internal angle of <180° to the side direction at an extrusion ratio of ≥1 in at least two extrusion transport paths is continuously performed for at least twice or more, and the alloy stock is converged to one extrusion port 6 and is extruded. In the example of illustration, the alloy stock 1 is subjected to shear stress in a shear face I in an extrusion transport path 7 and then in a shear face II, and is extruded from the extrusion port 6. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【0001】
【発明の属する技術分野】
本発明は、塑性加工(特には温間塑性加工)によって合金の結晶微細化を図ると共に、合金の集合組織を制御することによって、変形能及び衝撃特性を改善する方法及び機械的性質、衝撃延性に優れた合金に関する。
【0002】
【従来の技術】
マグネシウム合金は、例えば、室温における延性、加工性、衝撃延性が低いなどの理由により、展伸材、特に押出形材としての研究または実用化が遅れている。従来、合金の展伸材としての加工は圧延や押出等によって行われるが、マグネシウム合金の場合、その結晶構造(稠密六方晶:hcp)に由来して、室温における変形が困難である。高温になると変形が可能になるが、十分な変形が可能な温度では機械的性質が劣化し、従来の加工硬化を利用した十分な機械的性質の強化ができず、また、圧延、押出による加工ではやはり結晶構造に由来して、加工組織に異方性が生じる傾向が強く、2次元、3次元的な応力または変形が発生または要求される部材への応用には限界があった。
【0003】
これらの理由により、マグネシウム合金の利用は鋳造法、固液共存領域における射出成形などによって製造される部材に限られているのが現状であり、強度、延性、特に衝撃的な応力による変形、変形能が要求される部材には利用できない。
本発明者等はこれまで押出方向を内角180°未満で側方に変化させることにより、材料に剪断変形を与えると同時に動的回復、動的再結晶によって結晶粒径を微細に制御してマグネシウム合金の高強度化を図れる方法を発明し、特許出願を行ってきた(特許文献1〜3参照)。この結晶微細化、高強度化の機構は適当な条件を選べば、圧延、押出においても可能な場合がある。
【0004】
また、押出比1以上、好ましくは押出比1で押出方向を側方に変化させる方法の1例はECAE(Equal Channel Angular Extrusion)法として知られており、歪みを無限に付加できる優れた方法である。しかし、ECAE法は基本的にバッチ処理であるとともに、多数回の押出が必要なため、製造コストがかさむ原因となる欠点がある。更にECAE法は押出比1であるため、押出材の直径が50mm以上となると押出回数が少なくなると加工組織が不均一になりやすい。
また本発明者等は上記発明に基づいて、更に、結晶粒径の制御と共に集合組織を制御することによって強度、延性、衝撃性に優れた合金を製造する方法を発明した(特願2001−291260号)。
【0005】
【特許文献1】
特開2000−271631号公報
【特許文献2】
特開2000−271693号公報
【特許文献3】
特開2000−271695号公報
【0006】
【発明が解決しようとする課題】
本発明は、結晶粒径及び集合組織を制御して、強度、延性、衝撃性に優れ、機械的性質に異方性のない合金を製造することができ、長尺な角材、円形、異形の中空材、中実材を作製することができる押出材の製造方法を提供する
【0007】
【課題を解決するための手段】
本発明者らは上記の方法について更に検討を重ねた結果、次の構成を有する発明により上記課題が解決できることを見出した。
本発明は次のとおりである。
【0008】
(1)塑性加工時の動的回復及び/または動的再結晶によって結晶粒径及び集合組織を制御する押出材の製造方法であって、少なくとも2つ以上ある押出搬送路内において押出比1以上で押出し方向を内角180°未満(好ましくは120°未満)で側方に変化させて合金素材に剪断応力を与える工程を少なくとも2回以上連続して行い、合金素材が一つの押出口に収束して押出されることを特徴とする押出材の製造方法。
(2)合金素材がhcp構造を有するものであり、該合金素材の結晶格子(0001)面を、押出し方向または形材の長軸方向(A)に対し、実質的または優先的に傾斜配向させ及び/または断面内(押出し方向に直角面(B))でランダムに制御し、前記(0001)面の底面方位の配向比(B平行/A垂直)を1〜2に制御することを特徴とする上記(1)記載の押出材の製造方法。
(3)前記配向比に制御することで圧縮耐力と引張耐力の差を20%以内にすることを特徴とする上記(1)または(2)記載の押出材の製造方法。
(4)前記押し出し材の断面組織の結晶粒径が実質的に30μm以下となることを特徴とする(1)〜(3)のいずれかに記載の押し出し材の製造方法。
(5)合金素材がマグネシウム合金である上記(1)〜(4)のいずれかに記載の押出材の製造方法。
【0009】
(6)合金素材を押出す押出装置であって、合金素材を投入する素材供給部と、押出装置の一方側に設けられた該合金素材を押し出すステムと、押出装置の他方側に設けた少なくとも2つ以上の押出搬送路と、押出口とを備えており、該押出搬送路が内角180°未満で少なくとも2回以上屈折(屈曲)して、該押出口に収束していることを特徴とする押出材の押出装置。
(7)素材供給部がコンテナに形成され、押出搬送路がインダイスとアウトダイスとに実質的につながって形成され、押出口がアウトダイスに形成されてなる上記(6)記載の押出装置。
(8)合金素材がマグネシウム合金である上記(6)または(7)に記載の押出材の製造装置。
【0010】
【発明の実施の形態】
本発明を説明する前に、まず、図2に基づいて従来法を説明する。
図2に示した従来の一般的な押出法においては、加工が同一方向への連続的断面減少のみであるため、hcp結晶格子の底面が押出し方向(形材の長軸方向)に対し、平行に配向するため、押出し方向と押出し方向に垂直な方向とでは機械的性質に異方性が生じる。そのため、押出しによっても相当伸び10,000%(押出比100)の歪を与えることは可能であるが、引張り試験による伸びはECAE法に代表される側方押出法のそれに劣るのが普通である。
【0011】
また側方押出しは合金素材について同一方向から複数回行う必要性があるためその取り扱いが容易に行うことができず、さらには中空形態の形材を得ることができない。また以上の欠点を改善した押出方法としては図3に示す方法があるが、この方法では、金型構成上、ダイス8を支えるための支持部が必要となるため、短い押出材しか作製することができなかった。
【0012】
これらの欠点を補完し、且つ既存の押出機を用いて目的の形材を工業的に製造することができるようにした方法が本発明の製造方法であり、本発明の方法を実施する装置の例を図1に示す。
【0013】
図1に示す金型構成例では、金型はコンテナー2、インダイス3、アウトダイス4から構成されており、長尺な角形、円形、異形の中空部材、中実材を作製することができる。合金素材1はコンテナー部分に挿入され、ステム5によってインダイス3及びアウトダイス4方向へ押出しされる。合金素材1はインダイス3によって各押出搬送路に分けられ、アウトダイスに突き当たり、剪断面Iで剪断変形を受け側方(内側)へ曲げられる。さらに押出しが継続されると材料は剪断面IIで2回目の剪断変形を受けて押出し方向へ方向を変えて各押出搬送路から押出されてきた合金素材1が一つの押出口に収束して同じ押出材として押出しされる。ここで注目すべきは剪断変形が1回目と2回目で異なる方向に行われること、1回の押出しで求められる形材の最終形状が得られること、さらに、押出搬送路の内側にあるダイスがインダイスとして構成されている点である。
【0014】
この押出し手法は角形、円形、その他異形の中空部材に加え、種々の形状の中実部材に適応でき、さらに図2に示す従来手法ではなし得なかった長尺な押出材も作製できる。本発明で製造された形材は強度、延性、変形能、衝撃延性に優れた性質を持っている。
【0015】
本発明における押出しは、できるだけ低温で行うことが好ましい。しかしながら、合金の変形抵抗は低温になるほど高く、変形能は低温ほど小さくなる傾向がある。押出し工具の強度の観点及び健全な押出材を得るという観点からある程度の温度が必要である。また、結晶微細化という観点からは動的回復、動的再結晶を伴う必要があり、通常は合金によって異なる適切な温度で実施され、一般的なマグネシウム合金においては400℃以下、好ましくは合金の再結晶温度以下、更に好ましくは回復温度以下で行われる。しかし、この回復温度、再結晶温度は材料に加えられる加工度によって変化する。また、押出し温度は押出し角度によっても異なり、角度が大きくなるほど低温での押出が可能となる。これは押出しで剪断変形に要するエネルギーが小さくなることと、材料の変形能による制約が緩和されるからである。通常は90°以上の押出し角度で行われる。
【0016】
材料の変形抵抗は加工温度が低いほど大きくなるため、実際には製造しようとする材料の要求特性、加工コストに合わせて最適な条件が選ばれる。通常100℃〜500℃、AZ系、ZK系では150℃〜400℃の範囲で行われる。500℃を超えても若干の強度低下は伴うが加工組織の制御の効果は利用できる。
【0017】
そして具体的な合金としてはMg―Al―Zn系(AZ系)、Mg―Zn―Zr系(ZK系)などマグネシウム合金一般に有用に適用できる。これらのマグネシウム合金にSc、Zr、Ti、Cr、Mn、Si、Ca、Y、Ce等を少なくとも一種5wt%以下の範囲で含んでいると更に好ましい。
また上記製造方法によって製造した形材に熱処理を加えることによって更なる延性、変形能、特に衝撃延性を改善することができる。
【0018】
本発明の方法で製造された形材の組織は等軸晶で且つ平均結晶粒径は30μm以下、250℃以下の押出しでは5μm以下に調整されている。このままでも、同一合金の最適押出し条件で製造された押出し形材に比べて強度、伸びは大きく上回っているが、更に100〜450℃の温度範囲で0.2〜24時間の熱処理を加えると結晶粒径は押出材と同等の大きさ程度まで成長し、強度は押出材程度まで低下するものの、伸びは大幅に改善される。例えば、AZ31合金のECAE材は0.5〜1μmの粒径であるが、300℃×24時間の熱処理で平均結晶粒径15μmとなり、伸びはECAE材の1.5倍、押出材の2倍程度(〜50%)まで増大する。このような本発明の方法で製造された形材は2次元、3次元的な成形(形鍛造、バルジ成形等)を加える素形材や、自動車等の高速衝撃吸収用部材として適当である。
【0019】
上記製造方法、製造条件で製造される合金はある程度以上の塑性変形(歪み)を加え、マトリックス(母相)の平均粒径を30μm以下にすることによって機械的性質を改善し、同時に塑性変形を加える際に少なくとも1ヶ所で材料の塑性流動方向を変化させることによって剪断変形を加え、加工方向または材料の長軸方向に対し特定の結晶面、特にはマグネシウム合金の場合hcp結晶格子の底面である(0001)面を実質的にまたは優先的に傾斜して配向させ、配向比を1〜2の範囲とすることで、圧縮耐力と引張り耐力の差を20%以下に抑えることができる。
【0020】
以下に、本発明における配向比の定義について説明する
〈配向比の定義について〉
優先すべり系の結晶方位の配向比はX線回折を用いて評価するが、以下にその手順を示す。
(1)押出し方向に対して垂直方向及び平行方向断面のX線回折測定を行う。
(2)X線回折図形から全体の積分強度と底面(優先すべり系)(0001)の積分強度を算出する
(3)全体の積分強度に対する底面の積分強度の割合を算出する。(垂直方向と平行方向断面のX線回折図形からそれぞれA垂直とB平行を求める。)
以下に配向比の計算式を示す。
【0021】
【数1】
【0022】
上記式(3)に示されるように、B平行/A垂直を底面方位の配向比とした。つまりB平行/A垂直の値が1に近いほど底面方位がランダムに配置されていることになる。
上記配向比の計算方法によって定義した配向比によれば、配向比を1に近づければ近づける程、圧縮耐力と引張り耐力の差を小さくすることが可能であることが分かった。すなわち、配向比を小さくすることで、強度、延性、衝撃性に優れ、機械的性質に異方性のない合金が作製できる。逆に配向比が2より大きくなると圧縮耐力と引張り耐力の差が20%を超えるために、異方性も大きく、加工性が悪くなり、押出し製造が困難となる
【0023】
hcp系結晶格子をもつ合金、例えばマグネシウム合金の実用に際して、難加工性、伸び、靭性、衝撃特性の短所が指摘されていることから、伸び、靭性、変形能の著しい改善はマグネシウム合金の展伸材としての用途拡大に大きく寄与すると思われる。
【0024】
従来の側方押し出しにおいてもいえることであるが、側方押出法で合金素材に加えられる剪断変形量は、2つのコンテナーまたはコンテナーとダイとの接合角度によって異なる。一般に、このような剪断変形による押出し1回あたりの歪み量(Δεi)は下記式(1)で与えられる。
Δεi = (2/√3)・cotanφ ・・・・・(1)
ERR = A0/A = exp(Δεi) ・・・・・(2)
EAR = (1―1/ERR)×100 ・・・・・(3)
EE = (ERR−1)×100 ・・・・・(4)
(但し、Δεiは歪み量、φは接合内角の1/2、ERRは加工前後の面積比、A0は加工前の断面積、Aは加工後の断面積、EARは加工前後の相当断面減少率、EEは相当歪み(伸びと同義)を表す。)
【0025】
即ち、2つのコンテナーまたはコンテナーとダイとの接合内角が直角(90°)の場合、1回の押出しで歪み量は1.15(相当伸び:220%)、120°で0.67(95%)が与えられる。
このプロセスを繰り返すことによって、材料の断面積を変えずに材料中に無限に歪みを加えることができる。その繰り返しによって材料に与える積算歪み量εiは下記式(5)で与えられる。
εt = Δεi × N ・・・・・(5)
(但し、εtは積算歪み量、Nは押出し回数)
【0026】
この繰り返し回数Nは理論的には多い程良いが、実際には合金によってある繰り返し数でその効果に飽和が見られる。一般の展伸用合金素材では繰り返し数4回(接合内角90°の場合、積算歪み量4.6、相当伸び10,000%)で十分効果を得ることができる。圧延、押出しによっても無限に歪みを加えることができるが、その場合、断面積は無限に小さくなり、この点が側方押出しとは対照的である。
【0027】
次に、本発明の製造方法を実施例に基づいて詳細に述べると共に、この実施例において作製された合金についての評価結果を示す。なお、本発明はこれらの実施例によって限定されるものではない。
【0028】
【実施例】
マグネシウム合金AZ31合金(Mg−3Al−1Zn−0.2Mnwt%)及びAZ61(Mg−6Al−1Zn−0.15Mn)の鋳造材をφ41×70mm(ビレット)に調製し、概念的に図1に示す装置を用い、内角90°、押出比3.5、押出温度400℃、押出速度(ラム速度)0.5mm/sで押出した。ビレットはインダイスで4つの押出搬送路に分流され、アウトダイス内で90°ずつ2回剪断変形を加えた後、表1、2に示す押出温度及び押出比の条件で押し出して角形の中実の押出材(以下「本発明材」という。)を得た。
【0029】
【比較例】
比較のために、前記AZ31合金及びAZ61合金の鋳造材をφ41×70mm(ビレット)に調製し、図2に示されるような従来の押出方法によって、表1、2に示す押出条件で押出して押出材(以下「従来材」という。)を得た。
【0030】
【評価】
得られた押出材に関して走査電子顕微鏡で組織観察を行ったところ、押出しを行う前の合金素材(被加工材)の結晶粒径は100〜150μmであったのに対し、従来材は20〜50μm、さらに本発明材にいたっては5μm程度まで微細化されていた。
さらに従来材、本発明材をX線回折にかけ、得られたX線回折データから、配向比を調べ、またこれらの押出材について機械的性質を測定した。その結果を表1、表2、図4、図5に示す。
表1及び表2には、AZ31合金及びAZ61合金の押出材の機械的性質を示した。また、図4は、AZ31合金の押出比−耐力の関係を示す図であり、図5は、AZ31合金の配向比−強度比(引張耐力/圧縮耐力)の関係を示す図である。
【0031】
【表1】
【0032】
【表2】
【0033】
従来材についてはいずれの押出比についても伸びが15〜18%であったのに対し、本発明材の伸びは20〜24%であった。さらにここで注目すべきは従来材では圧縮耐力と引張り耐力の差が60〜85MPa差あるのに対し、本発明材は30MPa以下、押出比の小さいものに対しては5MPa以下とさして差がないことがわかる(図4参照)。これは、配向比と強度比(引張り耐力/圧縮耐力)を示した図5に示されるように、配向比に大きく寄与していることがわかる。つまり、加工特性に優れた合金を得たい場合は配向比を1〜2にすることが好ましく、1に近いほど好ましい。(ここで従来の押出法においても配向比が2程度のものが得られてはいるが、押出比が高いものであり、本発明材に比べ小さい押出材しか作製できない。しかし本発明材は押出比が3.5と高い値であっても1.3程度の低い配向比を維持している。)
以上より本発明の製造方法で製造された押出材は異方性の無い加工性に優れた合金であることがわかる。
【0034】
【発明の効果】
本発明によれば、長尺な角形、円形、異形の異方性の無い機械的性質に優れた中空部材、中実材を作製することができる。
【図面の簡単な説明】
【図1】本発明の製造方法を実施するための押出装置の金型構成例を示す図である。
【図2】従来法における金型構成例を示す図である。
【図3】従来法における金型構成例を示す図である。
【図4】AZ31合金の押出比−耐力の関係を示す図である。
【図5】AZ31合金の配向比−強度比(引張耐力/圧縮耐力)の関係を示す図である。
【符号の説明】
1 合金素材
2 コンテナー
3 インダイス
4 アウトダイス
5 ステム
6 押出口
7 押出搬送路
8 ダイス
[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a method for improving the deformability and impact properties by controlling the texture of the alloy while reducing the crystal size of the alloy by plastic working (particularly warm plastic working), and mechanical properties and impact ductility. Related to excellent alloys.
[0002]
[Prior art]
Magnesium alloys have been delayed in research or practical application as wrought materials, especially extruded materials, for example, because of their low ductility, workability, and impact ductility at room temperature. Conventionally, processing as a wrought material of an alloy is performed by rolling, extrusion, or the like. In the case of a magnesium alloy, deformation at room temperature is difficult due to its crystal structure (dense hexagonal: hcp). Deformation is possible at high temperatures, but mechanical properties deteriorate at temperatures where sufficient deformation is possible, and it is not possible to sufficiently strengthen mechanical properties using conventional work hardening, and processing by rolling and extrusion In this case, anisotropy tends to occur in the processed structure due to the crystal structure, and there is a limit in application to a member in which two-dimensional or three-dimensional stress or deformation occurs or is required.
[0003]
For these reasons, the use of magnesium alloys is currently limited to members manufactured by casting, injection molding in the solid-liquid coexistence region, etc., and strength, ductility, especially deformation and deformation due to shocking stress It cannot be used for components that require performance.
By changing the extrusion direction laterally at an inner angle of less than 180 °, the present inventors have imparted shear deformation to the material, and at the same time, dynamically controlled the crystal grain size by dynamic recovery and dynamic recrystallization. We have invented a method for increasing the strength of an alloy and have filed patent applications (see Patent Documents 1 to 3). This mechanism of crystal refinement and high strength may be possible in rolling and extrusion if appropriate conditions are selected.
[0004]
One example of a method of changing the extrusion direction to the side at an extrusion ratio of 1 or more, preferably at an extrusion ratio of 1, is known as an ECAE (Equal Channel Angular Extrusion) method, which is an excellent method capable of infinitely adding distortion. is there. However, the ECAE method is basically a batch process, and requires a large number of extrusions, and thus has a drawback that the production cost is increased. Furthermore, since the extrusion ratio of the ECAE method is 1, when the diameter of the extruded material is 50 mm or more, the processed structure tends to be non-uniform when the number of extrusions is reduced.
Further, based on the above invention, the present inventors have further invented a method for producing an alloy having excellent strength, ductility, and impact resistance by controlling the texture together with controlling the crystal grain size (Japanese Patent Application No. 2001-291260). issue).
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-271631 [Patent Document 2]
Japanese Patent Application Laid-Open No. 2000-271693 [Patent Document 3]
JP 2000-271695 A
[Problems to be solved by the invention]
The present invention controls the crystal grain size and texture, and can produce an alloy having excellent strength, ductility, and impact resistance, and having no anisotropy in mechanical properties. Provided is a method for producing an extruded material capable of producing a hollow material and a solid material.
[Means for Solving the Problems]
The present inventors have further studied the above method and found that the above problem can be solved by the invention having the following configuration.
The present invention is as follows.
[0008]
(1) A method for producing an extruded material for controlling crystal grain size and texture by dynamic recovery and / or dynamic recrystallization during plastic working, wherein an extrusion ratio is 1 or more in at least two or more extrusion conveying paths. The step of changing the extrusion direction to the side at an inner angle of less than 180 ° (preferably less than 120 °) and applying a shear stress to the alloy material is performed at least twice continuously, and the alloy material converges on one extrusion port. A method for producing an extruded material, characterized by being extruded.
(2) The alloy material has an hcp structure, and the crystal lattice (0001) plane of the alloy material is substantially or preferentially tilt-oriented with respect to the extrusion direction or the major axis direction (A) of the profile. And / or controlling randomly in the cross section (plane (B) perpendicular to the extrusion direction) and controlling the orientation ratio (B parallel / A perpendicular ) of the bottom direction of the (0001) plane to 1-2. A method for producing an extruded material according to the above (1).
(3) The method for producing an extruded material according to the above (1) or (2), wherein the difference between the compressive strength and the tensile strength is controlled within 20% by controlling the orientation ratio.
(4) The method for producing an extruded material according to any one of (1) to (3), wherein a crystal grain size of a cross-sectional structure of the extruded material is substantially 30 μm or less.
(5) The method for producing an extruded material according to any one of (1) to (4), wherein the alloy material is a magnesium alloy.
[0009]
(6) An extrusion device for extruding an alloy material, comprising a material supply section for charging the alloy material, a stem provided on one side of the extrusion device for extruding the alloy material, and at least one provided on the other side of the extrusion device. It is provided with two or more extrusion conveyance paths and an extrusion port, and the extrusion conveyance path is bent (bent) at least twice at an inner angle of less than 180 ° and converges on the extrusion port. Extruder extrusion equipment.
(7) The extrusion apparatus according to (6), wherein the material supply section is formed in the container, the extrusion conveyance path is formed substantially in connection with the in-die and the out-die, and the extrusion port is formed in the out-die.
(8) The apparatus for producing an extruded material according to (6) or (7), wherein the alloy material is a magnesium alloy.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Before describing the present invention, a conventional method will be described first with reference to FIG.
In the conventional general extrusion method shown in FIG. 2, since the processing is only continuous section reduction in the same direction, the bottom surface of the hcp crystal lattice is parallel to the extrusion direction (the long axis direction of the section). Therefore, anisotropic mechanical properties occur in the extrusion direction and the direction perpendicular to the extrusion direction. For this reason, it is possible to give a considerable elongation of 10,000% (extrusion ratio 100) by extrusion, but the elongation by a tensile test is generally inferior to that of the side extrusion method represented by the ECAE method. .
[0011]
Further, since the side extrusion needs to be performed a plurality of times from the same direction with respect to the alloy material, it cannot be easily handled, and further, a hollow shaped member cannot be obtained. Although there is a method shown in FIG. 3 as an extrusion method in which the above-mentioned disadvantages have been improved, this method requires a supporting portion for supporting the die 8 due to the configuration of the die, so that only a short extruded material can be manufactured. Could not.
[0012]
A method for compensating for these drawbacks and enabling industrial production of a target shape using an existing extruder is the production method of the present invention. An example is shown in FIG.
[0013]
In the example of the mold configuration shown in FIG. 1, the mold is composed of the container 2, the in-die 3, and the out-die 4, and can produce a long rectangular, circular, irregular hollow member, or a solid material. The alloy material 1 is inserted into the container portion and extruded by the stem 5 in the direction of the in-die 3 and the out-die 4. The alloy material 1 is divided into the respective extrusion conveying paths by the in-die 3, hits the out-die, undergoes a shear deformation at the shear plane I, and is bent to the side (inward). When the extrusion is further continued, the material undergoes the second shear deformation at the shear plane II, changes its direction in the extrusion direction, and the alloy material 1 extruded from each extrusion conveying path converges on one extrusion port to be the same. Extruded as extruded material. It should be noted here that the shear deformation is performed in different directions at the first time and the second time, that the final shape of the shape material required by one extrusion is obtained, and that the dies inside the extrusion conveyance path are formed. The point is that it is configured as an in-die.
[0014]
This extrusion method can be applied to solid members having various shapes in addition to hollow members having a rectangular shape, a circular shape and other irregular shapes, and can also produce a long extruded material which cannot be achieved by the conventional method shown in FIG. The profile produced by the present invention has excellent strength, ductility, deformability and impact ductility.
[0015]
The extrusion in the present invention is preferably performed at a temperature as low as possible. However, the deformation resistance of the alloy tends to increase as the temperature decreases, and the deformability tends to decrease as the temperature decreases. A certain temperature is required from the viewpoint of the strength of the extrusion tool and from the viewpoint of obtaining a sound extruded material. In addition, from the viewpoint of crystal refinement, it is necessary to accompany dynamic recovery and dynamic recrystallization, which is usually performed at an appropriate temperature that differs depending on the alloy. In a general magnesium alloy, 400 ° C. or less, preferably It is carried out at a temperature lower than the recrystallization temperature, more preferably at a temperature lower than the recovery temperature. However, the recovery temperature and the recrystallization temperature vary depending on the degree of processing applied to the material. In addition, the extrusion temperature varies depending on the extrusion angle, and the larger the angle, the lower the extrusion temperature. This is because the energy required for the shearing deformation is reduced by extrusion, and the constraint due to the deformability of the material is relaxed. Usually, the extrusion is performed at an extrusion angle of 90 ° or more.
[0016]
Since the deformation resistance of the material increases as the processing temperature decreases, the optimum conditions are actually selected according to the required characteristics of the material to be manufactured and the processing cost. Usually, it is carried out in the range of 100 ° C to 500 ° C, and in the range of 150 ° C to 400 ° C for AZ type and ZK type. Even if the temperature exceeds 500 ° C., a slight decrease in strength accompanies, but the effect of controlling the processed structure can be used.
[0017]
As a specific alloy, it can be usefully applied to magnesium alloys such as Mg-Al-Zn (AZ) and Mg-Zn-Zr (ZK). More preferably, these magnesium alloys contain at least one kind of Sc, Zr, Ti, Cr, Mn, Si, Ca, Y, Ce, etc. in a range of 5 wt% or less.
The ductility and deformability, particularly impact ductility, can be further improved by applying heat treatment to the profile produced by the above production method.
[0018]
The structure of the shaped material produced by the method of the present invention is equiaxed and has an average crystal grain size of 30 μm or less, and is adjusted to 5 μm or less by extrusion at 250 ° C. or less. Even as it is, the strength and elongation are much higher than those of the extruded profiles manufactured under the optimal extrusion conditions of the same alloy. However, when the heat treatment is further performed in the temperature range of 100 to 450 ° C. for 0.2 to 24 hours, the crystal becomes The particle size grows to the same size as the extruded material, and the strength is reduced to about the extruded material, but the elongation is greatly improved. For example, the ECAE material of the AZ31 alloy has a grain size of 0.5 to 1 μm, but the average crystal grain size becomes 15 μm by heat treatment at 300 ° C. for 24 hours, and the elongation is 1.5 times that of the ECAE material and twice that of the extruded material. To an extent (〜50%). The shaped member manufactured by the method of the present invention is suitable as a shaped member to which two-dimensional or three-dimensional forming (shaping forging, bulge forming, etc.) is applied, or as a high-speed shock absorbing member for automobiles and the like.
[0019]
Alloys manufactured under the above manufacturing method and manufacturing conditions are subjected to plastic deformation (strain) of a certain degree or more, and the mechanical properties are improved by reducing the average particle size of the matrix (matrix) to 30 μm or less, and at the same time, plastic deformation is reduced. The shear flow is applied by changing the plastic flow direction of the material in at least one place during the application, and is a specific crystal plane in the processing direction or the major axis direction of the material, particularly the bottom surface of the hcp crystal lattice in the case of a magnesium alloy. When the (0001) plane is substantially or preferentially inclined and oriented, and the orientation ratio is in the range of 1 to 2, the difference between the compressive strength and the tensile strength can be suppressed to 20% or less.
[0020]
Hereinafter, the definition of the orientation ratio in the present invention will be described <About the definition of the orientation ratio>
The orientation ratio of the crystal orientation of the preferred slip system is evaluated using X-ray diffraction, and the procedure is described below.
(1) X-ray diffraction measurement of cross sections perpendicular and parallel to the extrusion direction is performed.
(2) Calculate the integral intensity of the bottom surface (priority slip system) (0001) from the X-ray diffraction pattern. (3) Calculate the ratio of the integral intensity of the bottom surface to the integral intensity of the whole surface. (A- vertical and B- parallel are determined from X-ray diffraction patterns of cross sections in the vertical direction and the parallel direction, respectively.)
The formula for calculating the orientation ratio is shown below.
[0021]
(Equation 1)
[0022]
As shown in the above formula (3), B parallel / A perpendicular was defined as the orientation ratio of the bottom direction. In other words, the closer the value of B- parallel / A- vertical is to 1, the more randomly the bottom surface orientation is arranged.
According to the orientation ratio defined by the above-described orientation ratio calculation method, it was found that the closer the orientation ratio was to 1, the smaller the difference between the compressive strength and the tensile strength was. That is, by reducing the orientation ratio, an alloy having excellent strength, ductility, and impact properties and having no anisotropy in mechanical properties can be produced. Conversely, if the orientation ratio is greater than 2, the difference between the compressive strength and the tensile strength exceeds 20%, resulting in large anisotropy, poor workability, and difficulty in extrusion manufacturing.
In practical use of an alloy having an hcp crystal lattice, for example, a magnesium alloy, it has been pointed out that there are disadvantages in difficult workability, elongation, toughness, and impact properties. It is thought to greatly contribute to the expansion of use as a material.
[0024]
As can be said with conventional side extrusion, the amount of shear deformation applied to the alloy material by the side extrusion method differs depending on the joining angle between the two containers or the container and the die. Generally, the amount of strain per extrusion (Δεi) due to such shearing deformation is given by the following equation (1).
Δεi = (2 / √3) · cotanφ (1)
ERR = A0 / A = exp (Δεi) (2)
EAR = (1-1 / ERR) × 100 (3)
EE = (ERR-1) × 100 (4)
(However, Δεi is the amount of strain, φ is の of the joining internal angle, ERR is the area ratio before and after processing, A0 is the cross-sectional area before processing, A is the cross-sectional area after processing, and EAR is the equivalent cross-sectional reduction rate before and after processing. , EE represent equivalent strain (synonymous with elongation).)
[0025]
That is, when the inside angle of joining the two containers or the container and the die is a right angle (90 °), the amount of strain is 1.15 (equivalent elongation: 220%) in one extrusion, and 0.67 (95%) at 120 °. ) Is given.
By repeating this process, infinite strain can be applied to the material without changing the cross-sectional area of the material. The cumulative strain εi given to the material by the repetition is given by the following equation (5).
εt = Δεi × N (5)
(However, εt is the accumulated strain, N is the number of extrusions)
[0026]
The number of repetitions N is theoretically better as it is larger, but the effect is actually saturated at a certain number of repetitions depending on the alloy. With a general wrought alloy material, a sufficient effect can be obtained with four repetitions (in the case of a joining inner angle of 90 °, the integrated strain is 4.6, and the equivalent elongation is 10,000%). Infinite strain can also be applied by rolling and extrusion, in which case the cross-sectional area is infinitely small, in contrast to lateral extrusion.
[0027]
Next, the production method of the present invention will be described in detail based on examples, and the evaluation results of the alloys produced in the examples will be shown. The present invention is not limited by these examples.
[0028]
【Example】
A cast material of magnesium alloy AZ31 alloy (Mg-3Al-1Zn-0.2Mnwt%) and AZ61 (Mg-6Al-1Zn-0.15Mn) was prepared to φ41 × 70 mm (billet), and conceptually shown in FIG. Using an apparatus, extrusion was performed at an inner angle of 90 °, an extrusion ratio of 3.5, an extrusion temperature of 400 ° C, and an extrusion speed (ram speed) of 0.5 mm / s. The billet is divided into four extrusion conveying paths by an in-die, subjected to shearing deformation twice at 90 ° in an out-die, and extruded at a condition of an extrusion temperature and an extrusion ratio shown in Tables 1 and 2 to form a square solid. An extruded material (hereinafter, referred to as “material of the present invention”) was obtained.
[0029]
[Comparative example]
For comparison, cast materials of the AZ31 alloy and the AZ61 alloy were prepared into φ41 × 70 mm (billet) and extruded under the extrusion conditions shown in Tables 1 and 2 by a conventional extrusion method as shown in FIG. A material (hereinafter referred to as “conventional material”) was obtained.
[0030]
[Evaluation]
When the structure of the obtained extruded material was observed with a scanning electron microscope, the crystal grain size of the alloy material (worked material) before extrusion was 100 to 150 μm, whereas that of the conventional material was 20 to 50 μm. Further, the material of the present invention was miniaturized to about 5 μm.
Furthermore, the conventional material and the material of the present invention were subjected to X-ray diffraction, the orientation ratio was examined from the obtained X-ray diffraction data, and the mechanical properties of these extruded materials were measured. The results are shown in Tables 1, 2 and 4 and 5.
Tables 1 and 2 show the mechanical properties of the extruded materials of the AZ31 alloy and the AZ61 alloy. FIG. 4 is a diagram showing the relationship between the extrusion ratio and the proof stress of the AZ31 alloy, and FIG. 5 is a diagram showing the relationship between the orientation ratio and the strength ratio (tensile strength / compression strength) of the AZ31 alloy.
[0031]
[Table 1]
[0032]
[Table 2]
[0033]
The elongation of the conventional material was 15 to 18% at any extrusion ratio, whereas the elongation of the material of the present invention was 20 to 24%. Furthermore, it should be noted here that the difference between the compressive strength and the tensile strength is 60 to 85 MPa in the conventional material, whereas the material of the present invention is 30 MPa or less, and the material with a small extrusion ratio is 5 MPa or less. This can be seen (see FIG. 4). It can be seen that this greatly contributes to the orientation ratio as shown in FIG. 5 showing the orientation ratio and the strength ratio (tensile strength / compression strength). That is, when it is desired to obtain an alloy having excellent processing characteristics, it is preferable to set the orientation ratio to 1 to 2, and the closer to 1, the more preferable. (Here, the extrusion ratio of about 2 is obtained by the conventional extrusion method, but the extrusion ratio is high and only an extruded material smaller than the material of the present invention can be produced. Even if the ratio is a high value of 3.5, a low orientation ratio of about 1.3 is maintained.)
From the above, it can be seen that the extruded material manufactured by the manufacturing method of the present invention is an alloy having no anisotropy and excellent workability.
[0034]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, a long rectangular member, a circular member, a hollow member excellent in mechanical properties without anisotropy and a solid material can be produced.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a mold configuration of an extrusion apparatus for performing a production method of the present invention.
FIG. 2 is a diagram showing an example of a mold configuration according to a conventional method.
FIG. 3 is a diagram showing an example of a mold configuration according to a conventional method.
FIG. 4 is a diagram showing the relationship between the extrusion ratio of AZ31 alloy and proof stress.
FIG. 5 is a diagram showing a relationship between an orientation ratio and a strength ratio (tensile strength / compression strength) of an AZ31 alloy.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Alloy material 2 Container 3 In die 4 Out die 5 Stem 6 Extrusion port 7 Extrusion conveyance path 8 Dice

Claims (8)

塑性加工時の動的回復及び/または動的再結晶によって結晶粒径及び集合組織を制御する押出材の製造方法であって、少なくとも2つ以上ある押出搬送路内において押出比1以上で押出し方向を内角180°未満で側方に変化させて合金素材に剪断応力を与える工程を少なくとも2回以上連続して行い、合金素材が一つの押出口に収束して押出されることを特徴とする押出材の製造方法。A method for producing an extruded material in which the crystal grain size and texture are controlled by dynamic recovery and / or dynamic recrystallization during plastic working, wherein the extrusion direction is at an extrusion ratio of 1 or more in at least two or more extrusion conveying paths. Wherein the step of applying a shear stress to the alloy material by changing the angle to the side at an inner angle of less than 180 ° is continuously performed at least twice or more, and the alloy material is converged and extruded into one extrusion port. The method of manufacturing the material. 合金素材がhcp構造を有するものであり、該合金素材の結晶格子(0001)面を、押出し方向または形材の長軸方向(A)に対し、実質的または優先的に傾斜配向させ及び/または断面内(押出し方向に直角面(B))でランダムに制御し、前記(0001)面の底面方位の配向比(B平行/A垂直)を1〜2に制御することを特徴とする請求項1記載の押出材の製造方法。The alloy material has an hcp structure, and a crystal lattice (0001) plane of the alloy material is substantially or preferentially inclinedly oriented with respect to an extrusion direction or a long-axis direction (A) of the profile and / or 3. The method according to claim 1, wherein the orientation ratio (B- parallel / A- perpendicular ) of the bottom direction of the (0001) plane is controlled to be 1-2 in a cross section (a plane perpendicular to the extrusion direction (B)). 2. The method for producing an extruded material according to 1. 前記配向比に制御することで圧縮耐力と引張耐力の差を20%以内にすることを特徴とする請求項1または2記載の押出材の製造方法。The method for producing an extruded material according to claim 1 or 2, wherein the difference between the compression strength and the tensile strength is controlled to be within 20% by controlling the orientation ratio. 前記押し出し材の断面組織の結晶粒径が実質的に30μm以下となることを特徴とする1〜3のいずれかに記載の押し出し材の製造方法。4. The method for producing an extruded material according to any one of claims 1 to 3, wherein a crystal grain size of a cross-sectional structure of the extruded material is substantially 30 μm or less. 合金素材がマグネシウム合金である請求項1〜4のいずれかに記載の押出材の製造方法。The method for producing an extruded material according to any one of claims 1 to 4, wherein the alloy material is a magnesium alloy. 合金素材を押出す押出装置であって、合金素材を投入する素材供給部と、押出装置の一方側に設けられた該合金素材を押し出すステムと、押出装置の他方側に設けた少なくとも2つ以上の押出搬送路と、押出口とを備えており、該押出搬送路が内角180°未満で少なくとも2回以上屈折(屈曲)して、該押出口に収束していることを特徴とする押出材の押出装置。An extrusion device for extruding an alloy material, a material supply unit for charging the alloy material, a stem for extruding the alloy material provided on one side of the extrusion device, and at least two or more provided on the other side of the extrusion device An extruded material comprising: an extrusion conveying path, and an extrusion port, wherein the extrusion conveying path is bent (bent) at least twice or more at an inner angle of less than 180 ° and converges on the extrusion port. Extrusion equipment. 素材供給部がコンテナに形成され、押出搬送路がインダイスとアウトダイスとに実質的につながって形成され、押出口がアウトダイスに形成されてなる請求項6記載の押出装置。7. The extrusion apparatus according to claim 6, wherein the material supply section is formed in the container, the extrusion conveyance path is formed substantially in connection with the in-die and the out-die, and the extrusion port is formed in the out-die. 合金素材がマグネシウム合金である請求項6または7に記載の押出材の製造装置。8. The apparatus for manufacturing an extruded material according to claim 6, wherein the alloy material is a magnesium alloy.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007042002A3 (en) * 2005-10-12 2007-06-07 Univ Clausthal Tech Method for the production of fine-grained, polycrystalline materials or workpieces, and female mold therefor
CN100386466C (en) * 2006-03-22 2008-05-07 西安建筑科技大学 Method and apparatus for preparing fine-grained material
CN102304685A (en) * 2011-10-13 2012-01-04 中国兵器工业第五九研究所 Preparation method of fine grain magnesium alloy

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JP3942873B2 (en) * 2000-12-22 2007-07-11 株式会社小松製作所 Extrusion processing apparatus and extrusion processing method
JP2003096549A (en) * 2001-09-25 2003-04-03 Kenji Azuma Alloy with excellent mechanical property and impact ductility, and its manufacturing method

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Publication number Priority date Publication date Assignee Title
WO2007042002A3 (en) * 2005-10-12 2007-06-07 Univ Clausthal Tech Method for the production of fine-grained, polycrystalline materials or workpieces, and female mold therefor
CN100386466C (en) * 2006-03-22 2008-05-07 西安建筑科技大学 Method and apparatus for preparing fine-grained material
CN102304685A (en) * 2011-10-13 2012-01-04 中国兵器工业第五九研究所 Preparation method of fine grain magnesium alloy

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