Abstract

We investigate the influence of the plasma surfacing and subsequent high-temperature tempering on the surface morphology and the elemental composition of the deposited coatings made of the R18-type high-hardness chromium-tungsten steel additionally alloyed with aluminum and nitrogen (C 0.86%; Cr 4.84%; W 17.0%; Mo 5.40%; V 0.50%; Al 0.65%; N 0.06%). We engaged the 30HGSA steel with high mechanical properties as the base metal. The usage of low-temperature preliminary and accomplished heating, as well as using a thermal surfacing cycle, was a feature of the surfacing. The surfacing cycle consisted of three main stages: the first stage limited the heating duration and provided the high cooling rate within the high temperature domain, prevented the grain growth and the austenite decomposition and thus formation of the equilibrium low-strength structures; the second stage consisted in austenitic state of the deposited metal; in the third stage, we obtained the deposited metal with low tendency to the crack formation. We investigated the surface morphology and the elemental composition of the coatings by means of scanning electron microscopy and X-ray spectral microanalysis in two states: directly after surfacing and after surfacing and high-temperature tempering. In the first case, we discover that the main part of the material surface represents the pearlite grains. The complex composition cementite and the variable composition (Fe₄W₂N, FeWN₂, and Fe₄W₂C) iron-, tungsten-, and molybdenum-based compounds fill the joints and the grain boundaries. There are also aluminum-based solid solutions and, possibly, the AlN phase. The high-temperature tempering results in a hardness increase, a change in the grain shape and size, a quantitative change in the elemental composition, and a uniform distribution of alloying elements over the material volume. We show that the proposed method of the plasma surfacing with the high-temperature tempering meets all basic requirements to the surface of the cold-rolled work rolls – this fact is confirmed by the test results of the surfaced roll batch.

中文翻译：

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氮介质中等离子堆焊及热处理后高速合金的组织。

摘要

我们研究了等离子堆焊及随后的高温回火对由R18型高硬度铬钨钢加铝和氮合金制成的沉积涂层的表面形态和元素组成的影响（C 0.86％； Cr 4.84％; W 17.0％; Mo 5.40％; V 0.50％; Al 0.65％; N 0.06％）。我们使用具有高机械性能的30HGSA钢作为基础金属。使用低温预热和完全加热以及使用热堆焊循环是堆焊的特征。堆焊周期包括三个主要阶段：第一阶段限制了加热时间，并在高温范围内提供了较高的冷却速率，防止晶粒长大和奥氏体分解，从而防止形成平衡的低强度组织；第二阶段为沉积金属的奥氏体状态。在第三阶段中，我们获得了具有低裂纹形成趋势的沉积金属。我们通过扫描电子显微镜和X射线光谱显微分析在两种状态下研究了涂层的表面形态和元素组成：两种状态：直接在堆焊之后，堆焊之后和高温回火之后。在第一种情况下，我们发现材料表面的主要部分代表珠光体晶粒。复杂成分渗碳体和可变成分（铁 我们获得了具有低裂纹形成趋势的沉积金属。我们通过扫描电子显微镜和X射线光谱显微分析在两种状态下研究了涂层的表面形态和元素组成：两种状态：直接在堆焊之后，堆焊之后和高温回火之后。在第一种情况下，我们发现材料表面的主要部分代表珠光体晶粒。复杂成分渗碳体和可变成分（铁 我们获得了具有低裂纹形成趋势的沉积金属。我们通过扫描电子显微镜和X射线光谱显微分析在两种状态下研究了涂层的表面形态和元素组成：两种状态：直接在堆焊之后，堆焊之后和高温回火之后。在第一种情况下，我们发现材料表面的主要部分代表珠光体晶粒。复杂成分渗碳体和可变成分（铁 我们发现材料表面的主要部分代表珠光体晶粒。复杂成分渗碳体和可变成分（铁 我们发现材料表面的主要部分代表珠光体晶粒。复杂成分渗碳体和可变成分（铁₄ W ₂ N，FeWN ₂和Fe ₄ W ₂ C）铁，钨和钼基化合物填充了接头和晶界。也有铝基固溶体，可能还有AlN相。高温回火导致硬度增加，晶粒形状和尺寸变化，元素组成的定量变化以及合金元素在材料体积上的均匀分布。我们表明，提出的高温回火等离子堆焊方法可以满足冷轧工作辊表面的所有基本要求，这一事实已通过表面轧辊批的测试结果得到了证实。